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Nat. Hazards Earth Syst. Sci., 20, 197–220, 2020
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Sandbag replacement systems – a nonsensical and costly alternative
to sandbagging?
Lena Lankenau, Christopher Massolle, Bärbel Koppe, and Veronique Krull
Institute for Hydraulic and Coastal Engineering, City University of Applied Sciences,
28199 Bremen, Germany
Correspondence: Lena Lankenau (lena.lankenau@hs-bremen.de)
Received: 20 May 2019 – Discussion started: 27 May 2019
Revised: 21 November 2019 – Accepted: 27 November 2019 – Published: 17 January 2020
Abstract. In addition to flood defence with sandbags, differ-
ent sandbag replacement systems (SBRSs) have been avail-
able for a number of years. The use of sandbags is time-
consuming as well as highly intensive in terms of materi-
als and personnel. In contrast, SBRSs are reusable and re-
quire lower costs in terms of helpers and logistics, offsetting
the comparatively higher initial investment costs through re-
peated use. So far, SBRSs have rarely been used in Germany
in operational flood protection. The reasons lie in different fi-
nancing modalities of investment, operational costs and low
confidence in the technical performance of SBRSs. These
problems are addressed by a research programme at the Insti-
tute of Hydraulic Engineering (IWA), City University of Ap-
plied Sciences, Bremen. A series of systematic large-scale
tests of sandbag systems and SBRSs with a focus on func-
tionality, stability and handling was carried out. The results
showed that the majority of the SBRSs tested are able to pro-
vide protection comparable to that of sandbag systems but
with a significantly reduced use of materials, simplified lo-
gistics and fewer helpers. Nevertheless, it is advisable to de-
velop and perform well-defined certification tests for SBRSs,
in order to define clear instructions for and to identify limits
to the use of certain SBRSs. For example, not all systems
work equally well on different surfaces.
Supplementary to the practical tests, costs of the procure-
ment and use of various sandbag systems and SBRSs were
determined on the basis of realistic scenarios. This provides
a methodology as well as concrete figures to cost the provi-
sion and use of different protection systems from a holistic
perspective. It turns out that the higher investment costs of
the SBRSs investigated compared to sandbag systems are al-
ready offset on the second use of the reusable systems.
1 Introduction
The classic aid in operative flood defence is the sandbag. So-
called sandbag replacement systems (SBRSs) have also been
available for some time now although their use is still very
limited. Figure 1 shows such mobile, location-independent
flood defence systems, which can be subdivided into tube,
basin, flap, trestle, dam or panel systems, and bulk elements.
The systems counteract flooding either by their bulk weight,
which is induced by water, sand or concrete (in container and
bulk systems), or by their geometry in connection with the
vertical hydrostatic water pressure (in flap, trestle, dam and
air-filled tube systems – not shown in Fig. 1), with both ap-
proaches resulting in frictional forces on the ground. Panel
systems consist of panels which are held in place by sticks
driven in the ground on alternate sides. But, commonly,
location-independent mobile flood protection systems do not
need additional anchoring to the ground. However, some pro-
ducers offer such a possibility, which introduces a safety sur-
plus or can be necessary when high-flow velocities or wind
stress on the non-jet-impounded system are expected. Sand-
bags as well as SBRSs are used in flood disaster manage-
ment, especially in cases when permanent flood protection
systems like dikes fail or when no permanent flood protec-
tion schemes are available because the endangered area was
thought not to be at risk. Thus, sandbags as well as SBRSs are
used in extreme flood events. There has been no regulatory
obligation to demonstrate the functionality of an SBRS so far.
In general, however, SBRSs are suitable for flood protection
and can be equated with sandbagging in terms of function-
ality (cf. Pinkard et al., 2007; Niedersaechsischer Landtag,
2014; Massolle et al., 2018). The effectiveness of the indi-
vidual system might differ depending on construction, geom-
Published by Copernicus Publications on behalf of the European Geosciences Union.
198 L. Lankenau et al.: Sandbag replacement systems
etry and filling. Nevertheless, decision makers need to have
reliable information about the general functionality of an in-
dividual SBRS. This information is not always available, es-
pecially not from an independent source.
Sandbagging is time-consuming as well as highly inten-
sive with respect to materials and personnel. SBRSs have the
potential to be much more efficient flood defences as their
use entails significantly lower material, personnel and time
requirements than conventional sandbagging. For example,
16 500 sandbags and 250 t of sand are required to build up
a 100 m long and 1.0 m high sandbag dam (cf. THW, 2017).
Without considering additional efforts, such as the logistics
of supplying materials and personnel, 60 helpers would take
about 10 h to fill the sandbags and set up the dam (cf. THW,
2017). However, the advantage of using sandbags lies in the
possibilities for flexible deployment and many years of prac-
tical experience. Figure 2 shows firefighters raising a dike by
setting up a temporary sandbag dam.
SBRSs either do not need a filling at all or the filling is
put in place with technical assistance such as pumps (water
filling), wheel loaders (sand filling) or cranes (bulk elements
made of concrete). Thus, the systems can be set up and dis-
mantled with considerably less time and fewer people (cf.
Massolle et al., 2018). Logistical efforts are minimised if no
filling is needed or if water, which can usually be obtained
locally, is used. In contrast to sandbags, SBRSs are reusable
and do not have to be disposed of at high cost after a flood
event. From these points of view, SBRSs can also be suit-
able for scheduled flood protection measures in areas where
no permanent flood protection schemes can be applied. The
main disadvantage of SBRSs is the higher cost of acquisi-
tion. However, the lower expenditure on helpers, logistics
and disposal of material means that these higher investment
costs can be offset through reuse. Furthermore, there is lim-
ited confidence in and a lack of knowledge of the function-
ality of SBRSs. Besides the low confidence in the general
functionality of an SBRS, possible vandalism or mechani-
cal influences, e.g. the impact of flotsam or vehicles as well
as the collective failure (causing a domino effect) of SBRSs,
are of great concern. In general, the functionality of sandbag
dams can also be endangered by vandalism or mechanical
influences but rather less by a collective failure, unless the
sandbag dam heavily overflows with the flow travelling over
long distances.
Temporary flood dams made out of sandbags or linear
SBRSs are set up in order to protect the hinterland from in-
undation. Beyond that, sandbags are also used on inner em-
bankments, securing saturated dikes either on selected points
where there is considerable seepage (using a temporary ring
dam) or over a larger area (using a load drain). Flutschutz
offers corresponding SBRSs (Fig. 3). See Simm at al. (2013)
for an explanation of the hydraulic situation at saturated dikes
during a flood event. Sandbag dams and linear SBRSs are di-
rectly exposed to flooding. In contrast, temporary ring dams
and load drains are generally exposed to lower loads as they
are not subject to the direct influence of high hydrostatic
pressures or the dynamic impact caused by waves and flot-
sam. They are therefore less endangered in terms of their
functionality.
In Germany, operational flood defence is regulated as part
of hazard prevention or disaster control at the federal state
level. Direct responsibility lies at the municipal level and thus
with the local districts and cities. This includes the responsi-
bility of providing the necessary material for the protection
of the general public, and sandbags – which are the signifi-
cantly cheaper option – are as a rule preferred over SBRSs.
In the case of a disaster event, assistance can be requested
from the federal state or the federal government although
the financing of such assistance will still remain initially
with the affected administrative districts or cities. Ultimately,
the costs of major damage events, such as those caused by
the Elbe floods of 2002, 2006 and 2013, will be borne pre-
dominantly by the federal state and the federal government.
Once such an event occurs, however, no time can be lost in
procuring SBRSs if they are not already standing by. Thus,
the cost of procuring and stocking SBRSs, in addition to a
lack of confidence in or knowledge about their functionality,
presents a major hurdle to their use.
Therefore, in Germany during the Elbe flood in 2013,
SBRSs were only used in isolated cases (AQUARIWA, 2019;
Mobildeich, 2019) despite the fact that the use of sandbag-
ging for operational flood defence is very time-, material-
and labour-intensive. Figure 4 shows two SBRSs after the
Elbe flood in 2013. The two systems were successfully used
to prevent the hinterland from flooding (Niedersaechsischer
Landtag, 2014).
In order to increase the confidence of decision makers
in SBRSs and to promote the availability of only well-
functioning SBRSs, it is desirable to carry out systematic
tests on functionality, stability and handling and to develop
relevant certification procedures. In addition to the function-
ality of SBRSs, their costs and efficiency in terms of person-
nel, time and logistics compared to sandbagging should be
investigated to likewise support decision makers.
At the international level, corresponding certification al-
ready exists. It can be awarded by the globally active test-
ing and certification service, FM Approvals (FM Approvals,
2019), based on the American National Standard for Flood
Abatement Equipment (ANSI and FM Approvals, 2014), and
by the British Standards Institution (BSI, 2019a) based on
the Publicly Available Specification (PAS) for flood pro-
tection products (specification type 2, temporary and de-
mountable flood protection products; BSI, 2014). Specific
SBRSs certified by FM Approvals can be found via the Na-
tional Flood Barrier Testing & Certification Program (NF-
BTCP, 2019), and SBRSs certified by the BSI Kitemark can
be found via the BSI (BSI, 2019b). In Germany, no corre-
sponding certification or testing system for SBRSs is cur-
rently available. However, some information can be found
on the design and both the scheduled and unscheduled use of
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L. Lankenau et al.: Sandbag replacement systems 199
Figure 1. Classification of mobile, location-independent flood protection systems (Massolle et al., 2018).
Figure 2. Firefighters during the Elbe flood in 2013, setting up a
sandbag dam to raise a dike.
SBRSs in German-speaking countries, especially in the rec-
ommendations of the leaflet Mobile Flood Defence Systems,
issued by the German Association of Engineers for Water
Management, Waste Management and Cultural Construction
(BWK, 2005), in the handbook Mobile Flood Protection, is-
sued by the Austrian Water and Waste Management Associ-
ation (ÖWAV, 2013), and in the decision-making aid Mobile
Flood Protection, issued by the Swiss Association of Can-
tonal Fire Insurers and the Swiss Federal Office for Water
and Geology (VKF and BWG; see Egli, 2004).
There are relatively few publications on comparative stud-
ies of sandbagging and SBRSs. Within the scope of test set-
ups in the test basin of the US Army Corps of Engineers
(USACE), one sandbag dam, two sand-filled container sys-
tems and one trestle system were investigated (Pinkard et al.,
2007). In addition to the time spent on system installation and
dismantling, the operational costs of a system set-up with a
length of around 305 m and a height of around 0.91 m were
also estimated. However, logistical aspects were not taken
into account, and it was assumed that labour on the construc-
tion of the sandbag dam would be free on a voluntary basis.
In addition, the sandbag requirement estimated in the study
differs from the usual approaches in Germany as sandbag
dams in the US are constructed on a broader basis.
Investigations into the functionality of SBRSs were also
carried out by the UK Environment Agency (EA; Ogunyoye
et al., 2011) on the basis of three sources of information: the
literature, user workshops, and interviews with manufactur-
ers and distributors of products. It was found that most of
the systems provided adequate protection but that in some
cases operational processes or inaccurate hydraulic assess-
ments led to system failure. The assessments covered the
physical, operational and structural characteristics of tem-
porary flood products available on the UK market in 2009.
The systems were subdivided into tubular systems, contain-
ers, freestanding barriers and frame barriers. The report fur-
thermore highlights the relevance of life cycle costs when us-
ing SBRSs. In addition to the acquisition costs, these include
costs of maintenance and repair of the systems, employment
costs (in the investigation the helpers were permanently em-
ployed), training costs, costs of the performance of field ex-
ercises, and costs of the storage and transport of the systems.
A benefit of an SBRS, on the other hand, is the prevention
of damage costs during its service life when a properly func-
tioning system is assumed. An example calculation of the life
cycle costs of an SBRS is not carried out in the report. Only
the acquisition costs of SBRSs, partly including the train-
ing of helpers (employees) by the manufacturers, for a 100 m
long system with a protection height of about 1.0 m across
the four categories examined – tubes, containers, freestand-
ing barriers and frame barriers – are mentioned.
In a Canadian study that assessed the suitability of inno-
vative systems as an alternative to sandbags primarily on the
basis of the literature, commercial brochures, theoretical con-
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200 L. Lankenau et al.: Sandbag replacement systems
Figure 3. Dike defence measures for a saturated dike over an extensive area (load drain) and for heavy punctual seepage discharge (temporary
ring dam). Sandbagging systems (a, b) and corresponding SBRSs (c, d) are shown.
Figure 4. SBRSs near Gartow (Lower Saxony, Germany) after the
Elbe flood in 2013 using (a) AQUARIWA and (b) Quick Damm
Type E.
siderations and stability calculations, four different system
types were examined. The types studied were water- or air-
filled tube systems, gabion-like systems filled with sand or
soil, dam beams, and motorway crash barriers. Besides as-
sessing the functionality of the systems, the factors to be
considered for a cost calculation of SBRSs are named, but
no comparative calculations are carried out. The stated costs
refer to manufacturers’ prices for a system with a protection
length of 30 m and a protection height of about 1.0 m. The
additional financial resources to be considered include costs
of the storage, assembly and dismantling of the systems as
well as of training the helpers. Moreover, the durability of
the systems must also be taken into account as a long service
life has a positive effect on the number of times a system can
be reused (Biggar and Masala, 1998)
In a study conducted by the University of Kentucky (Mc-
Cormack et al., 2012), the possible uses of sand-filled tem-
porary flood defence barriers to protect roads from flooding
were analysed on the basis of existing operational experi-
ence. However, the systems considered are not comparable
with those covered in the present study.
In Germany SBRSs have been tested according to ANSI
and FM Approvals guidelines at the Centre for Climate Im-
pact Research (KLIFF) at the Hamburg University of Tech-
nology (TUHH) on concrete ground (Gabalda et al., 2013).
The tests were mainly performed on behalf of the manufac-
turers, who have published the information only sporadically
(cf. Massolle et al., 2018). Recently Popp et al. (2019) the-
oretically investigated the functionality and related costs of
SBRSs in comparison to sandbagging when used to tem-
porarily increase the height of a dike. Their investigations
do not relate to individual SBRSs but rather to different sys-
tem types (tube, basin and trestle). However, it is not clear
what was included in the cost calculation. They conclude that
SBRSs will be used more frequently in the future to tem-
porarily raise the height of a dike because of the reduced re-
quirements of SBRSs in terms of time, materials and person-
nel.
None of the examples mentioned in the literature exam-
ined the functionality or costs of temporary ring dams or load
drains.
SBRSs can make an essential contribution to operational
flood defence owing to their functionality, time-saving char-
acteristics, and lower requirements for materials and person-
Nat. Hazards Earth Syst. Sci., 20, 197–220, 2020 www.nat-hazards-earth-syst-sci.net/20/197/2020/
L. Lankenau et al.: Sandbag replacement systems 201
nel. This contribution becomes even more pertinent in view
of the expected consequences of climate change. However,
only a small amount of information is available on indepen-
dent, practical tests of SBRSs. For some SBRSs, no practi-
cal or independent tests are available at all, and a compara-
tive study of the overall costs of sandbagging and SBRSs is
entirely missing. Both factors – functionality and economic
viability – are especially relevant to decision makers for as-
sessing the suitability of using SBRSs, which introduce great
potential to make operational flood defence measures, espe-
cially for disaster management, much more efficient in terms
of time, personnel and materials. It was therefore decided
that systematic testing of SBRSs would be carried out in the
test facility of the Institute for Hydraulic and Coastal Engi-
neering (IWA) at the City University of Applied Sciences,
Bremen, Germany, to increase the amount of available in-
formation on the functionality of SBRSs. The focus of the
test set-ups was on the functionality and stability as well as
the handling of the systems tested. The first results of the
test set-ups with regard to installation times, water heads
and seepage rates were published in Massolle et al. (2018).
The present article summarises the experience gained from
the test set-ups with regard to the functionality, stability and
handling of the individual systems in accordance with the
guidelines for loss prevention issued by the German Insurers
for Mobile Flood Defence Systems (VdS Schadenverhütung
GmbH, 2014), which are in turn based on the recommen-
dations of the BWK (BWK, 2005), the VKF and the BWG
(Egli, 2004). The system assessments obtained in this way
serve to provide a practical assessment of the operational
capability of SBRSs. Furthermore, the present article com-
pares sandbagging with SBRSs in fictitious realistic scenar-
ios in order to enable a comparison of the costs surround-
ing system deployment, the time involved and the number of
helpers. The comparison serves to further clarify the practi-
cal suitability of SBRSs and, in addition to the acquisition
costs, takes into account the costs, efforts and logistics of in-
stalling and dismantling the systems. In addition to a tempo-
rary flood protection dam, appropriate dike defence measures
for operational flood defence (load drains and ring dams) are
also considered. The calculated operational costs always de-
pend on the underlying system model or the dimensions of
the sandbag system as well as other factors. This necessarily
calls for a certain degree of simplification, resulting in devi-
ations between the findings of the above-mentioned studies
by Pinkard et al. (2007) and Ogunyoye et al. (2011) and the
present study.
2 Sandbag replacement systems and equivalent
sandbagging methods
The investigations described here focus on the following
three operational flood protection measures: (1) temporary
flood dams, (2) load drains applied to a saturated dike over
an extensive area and (3) ring dams used for reinforcement
against heavy punctual seepage discharge on the inner em-
bankment of a dike. The classic aid for constructing these
measures are sandbags. Sandbagging has proven itself dur-
ing many years of application. Sandbags are made out of jute
or plastic, are not standardised in size, and cannot be reused
once they have been used in a flood event. Especially for long
and/or high protection structures, a multitude of bags and a
large amount of sand is required. If stored properly, filled
sandbags have a maximum shelf life of 5 years. If unfilled,
they can be stored for up to 10 years. However, it should be
noted that the shelf life of filled sandbags may be severely
limited if they are stored under poor conditions. When stored
outdoors, sandbags can become so decomposed that they are
no longer fit for use after only a few months. Sandbags are
usually stored unfilled, thereby giving them a longer shelf
life. In principle, this also minimises logistical efforts be-
cause it is easier to transport large numbers of sandbags and
large amounts of sand separately.
In case of a flood event, sandbags and/or sand need to be
transported to the scene of the flooding and, if necessary, the
sandbags are filled either manually with, for example, shov-
els or with the aid of sandbag-filling machines. The filled
sandbags are transported to the flood defence line with ve-
hicles or, if accessibility is limited owing to, for example, a
poor subsoil situation, with the help of human chains, heli-
copters or boats. If applicable, the sandbags have to be un-
loaded after transportation and are put in place individually.
Altogether, these steps result in significant logistical efforts,
personnel requirements and time demands.
The construction of the three operational flood protection
measures with sandbags is not standardised; slightly different
techniques and quantities of sandbags might be used. How-
ever, in principal the following structures are used: (1) the
temporary flood dam is a trapezium-shaped sandbag dam that
sets up a temporary flood protection line, (2) the load drain is
layers of sandbags that place additional weight on the toe of
a dike and (3) a U-shaped or circular dam is used to dam up
punctual seepage through the inner embankment of a dike.
SBRSs on the other hand require much less logistical effort
and time and many fewer personnel mainly because the sys-
tems consist of larger units which are either not filled at all or
filled by technical means. Furthermore, the filling material of
water can often be obtained directly at the flood defence line.
Unlike sandbags, SBRSs hold potential for subsequent reuse
during their service life. In the case of SBRSs, the guarantee
period specified by the manufacturer must be compared to
the actual shelf life. Inquiries to manufacturers have shown
that not all producers give a guarantee or that the guaran-
tee often only amounts to a few years. When interviewed,
however, some manufacturers stated that the service life of
demonstration models reached 10 years or more. Consider-
ing the materials used in the production of the SBRSs, such
as tarpaulin fabric, galvanised steel or fibreglass-reinforced
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202 L. Lankenau et al.: Sandbag replacement systems
plastic, it can certainly be assumed that an SBRS can have a
service life of 10 years or more.
Table 1 gives a short description of the systems investi-
gated, and Fig. 5, as well as Fig. 3, shows the SBRSs tested
in the testing facility. At least one of the container types and
wall systems shown in Fig. 1 was selected for each of the test
set-ups. Flap systems could not be tested because no manu-
facturer was found who was prepared to provide their system
for the tests. Bulk elements and panel systems were not con-
sidered because in operational practice the use of bulk ele-
ments requires technical aids being available to install the el-
ements at short notice. This is often impractical for logistical
reasons or because the load-bearing capacity of the founda-
tion soil is impaired during flooding. The use of panel sys-
tems is limited to suitable soils and low water levels. Bulk
elements and panel systems, with their framework conditions
such as accessibility for heavy equipment and the avoidance
of damage to test set-ups from the deep ramming of retaining
stakes, were therefore not taken into account.
For a comparison of the functionality, stability and han-
dling of the different systems, a 0.8 m high and 2.1 m wide
sandbag dam was set up in the test facility (Fig. 6); see Mas-
solle et al. (2018) for further details. In addition to the lin-
ear SBRSs, a Flutschutz load drain and Flutschutz ring dam
were set up on the embankment of the dike in the test fa-
cility (see Fig. 3). The systems were set up on the dry and
therefore stable dike, which does not fully correspond to the
reality. The systems’ dimensions and further properties of the
SBRSs tested are shown in Table A1. For assembly instruc-
tions, please refer to the manufacturers’ home pages.
In cases where the suppliers offered more than one system
size, a variant suitable for a water head of 0.6m was selected
for the test set-ups. This height corresponds to the recom-
mendations contained in the technical bulletin Mobile Flood
Protection Systems (BWK, 2005) for the unscheduled use of
SBRSs in operational flood fighting. The height recommen-
dation results from the increasing danger of foundation sur-
face failure with increasing water levels. Not exceeding the
specified maximum water level minimises the risk of base
failure. If larger system heights are required, the risk must be
weighed on a case-by-case basis. The problem is that, even
if a foundation expert is available on site during the flood
event, time pressures and limited information on soil param-
eters do not allow for an accurate analysis. Since some sys-
tems are not specifically designed for water heads of 0.6 m,
systems with surplus dimensions, such as AQUARIWA, aqua
defence, Hydrobaffle and Tiger Dam, were used.
The SBRSs tested are only a selection of the systems avail-
able on the market. In addition, one of the systems investi-
gated, the Quick Damm Type M, is no longer produced but
still in use. Market analysis showed that some system types,
such as basin systems and tube systems, are more frequently
present on the market than others. However, the number of
products available of a particular system type does not allow
for conclusions to be drawn about its functionality.
Tube systems and basin systems are usually filled with wa-
ter to ensure their stability; not many tube or basin systems
can be filled with sand. Sand fillings were not considered
during the test set-ups as the filling and dismantling require-
ments could not be met in the test facility. Therefore, tube
and basin systems filled only with water were tested. The
Öko-Tec tubewall is an exception. With this system, the tube
is inflated with air. The system is stabilised by a plastic sheet
called a skirt, which is spread out on the water side of the
system and friction locked to the tube. The tube is stabilised
solely by the vertical hydrostatic pressure acting on the hor-
izontally laid skirt. None of the other tested systems using a
plastic tarpaulin as an upstream skirt used such friction lock-
ing. A non-friction-locked skirt is mostly used to improve
the leak tightness of an SBRS, which also reduces buoyancy
forces under the SBRS. An upstream skirt must always be
weighted down at the water-side edge, often with sandbags.
The trestle and dam systems do not require filling.
3 The functionality, stability and handling of the
SBRSs tested
3.1 Description of the test
The tests were carried out in the IWA test facility, which
was set up on the premises of the THW Training Centre
Hoya as part of the research and development project, De-
ichSCHUTZ (2014–2017), for the development of systems
to reduce buoyancy in dikes at risk of failure, funded by the
German Federal Ministry of Education and Research. The
facility consists of a U-shaped basin in which a 15 m wide
opening is closed by a dam (see Massolle et al., 2018). For
the SBRS tests, the systems were set up across the entire
width of the basin, parallel to the dam line and the space
between the dam, and the system was then filled with water
(Fig. 7). This allows for a realistic simulation of the hydro-
static load on the systems. Other possible load parameters
such as current, waves, wind, flotsam and vessel impact can-
not be investigated in the IWA test facility.
During the test set-ups, the systems impounded water. Wa-
ter heights were increased successively until system failure
occurred. Typical failure mechanisms of SBRSs are shown
in Fig. 8. The systems failed owing to sliding and rolling
or tipping; stability failure did not occur in any of the sys-
tems tested. If no system failure occurred, the systems were
made to not only impound as much water as possible but
also overflow. Seepage rates, the sum of seepage through
the subsoil and leakage through the system, were measured,
and the results were published in Massolle et al. (2018). An
SBRS should be not only functional but also practical in
many respects; considerations include handling during set-
up, dismantling, the space required during both operation and
storage, reusability, and protection against vandalism. Alto-
gether, statements about the reliability as well as the prac-
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L. Lankenau et al.: Sandbag replacement systems 203
Table 1. Short description of the SBRSs tested.
Product name Description
Basin
AQUARIWA Plates bend to cylindrical basins. If filled with water (other filling materials are possi-
ble), water sacks within the basins are necessary. The bottom of the basin is covered
with a plastic grid which is welded to the plates in order to increase the stability of the
basins. Spaces between the basins are sealed with a plastic tarpaulin which is weighed
down with sandbags.
INDUTAINER A basin with plastic sacks filled with water. The upper end is tied up. The basins are
connected to each other with wooden scantlings. The space between the basins is sealed
with a plastic tarpaulin which is weighed down with sandbags.
Quick Damm Type M Open, collapsible steel frame with a plastic basin filled with water. Spaces between the
basins are sealed by the system itself.
Trestle
Aqua defence Hard foam panels covered with plastic tarpaulin on collapsible support elements. The
tarpaulin is weighed down with sandbags.
Aqua Barrier EUR-pallets covered with plastic tarpaulin on collapsible support elements. The
tarpaulin is weighed down with sandbags.
Dam
NOAQ boxwall Plastic brackets inserted into each other and connected on the top side with a clamp.
The underneath is sealed with a thin strip of foam on the water side and shaped in a way
that any water under the system can run off to the air side.
Tube
Tiger Dam Closed, water-filled system, strapped into a pyramid shape and secured with wedges.
The joints are sealed with a sleeve. Use of a plastic tarpaulin and anchoring to the
ground are possible.
Hydrobaffle Closed, water-filled system with an intermediate baffle to prevent rolling. The system is
laid to overlap at the joints.
Mobildeich Closed, water-filled system held together in two- to three-tube packages with net sheath-
ing and sealing tarpaulin. The tarpaulin is weighed down with iron chains. A geotextile
is placed below the tubes.
Flutschutz double-
chamber tube
Closed, water-filled system with two tubes of different diameters. The tubes are welded
together in order to prevent rolling. A sealing mat is placed below the upstream tube.
Spaces between the tubes are sealed by the system itself whereas the joints are secured
with a rope.
Öko-Tec tubewall Closed air-filled system with a welded upstream skirt and plastic grid. A drainage mat
is placed at the bottom between the skirt and grid. The skirt is weighed down with lead
belts.
Load drain
Flutschutz load drain Closed, water-filled basin. A drainage mat is placed below the system.
Temporary ring dam
Flutschutz ring dam Closed, water-filled tube with a triangular stabilising canvas welded to the tube.
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204 L. Lankenau et al.: Sandbag replacement systems
Figure 5. The various SBRSs tested. (T) is tube system, (B) is basin system, (D) is dam system and (TR) is trestle system.
Figure 6. Sandbag dam in the IWA test facility.
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L. Lankenau et al.: Sandbag replacement systems 205
Figure 7. Illustration of the test set-up in the test facility. An SBRS with an upstream skirt is shown.
ticality and handling of the systems tested could be derived
from the test set-ups and related investigations.
The systems were initially dammed up to a water height of
0.6 m, in accordance with the recommendations of the BWK
leaflet Mobile Flood Protection Systems (BWK, 2005). Af-
ter setting a constant seepage rate at a dam height of 0.6 m
(see Massolle et al., 2018), the water head was further in-
creased in stages until a system failure occurred owing to the
water height exceeding the load limits of the system or un-
til a partial overflow of the system occurred. See Massolle
et al. (2018) for an overview of the system heights and the
impounded water levels achieved. The Quick Damm Type M
and Aqua Barrier systems were not available in a sufficient
length and were therefore installed in combination with the
AQUARIWA system. The test basin was only briefly filled
with water up to a height of 0.6 m. The NOAQ boxwall sys-
tem only has a feasible protection height of 0.5 m but was
nevertheless tested because of its simplicity and speed of
installation. In principle, the manufacturer recommends the
use of the NOAQ boxwall system on paved surfaces as this
results in a better sealing effect on the underlying surface.
According to the manufacturer’s training material, the Tiger
Dam system can be used with or without anchoring to the
ground and additional plastic skirts on the water side, but
it only qualifies for FM Approvals certification if the skirts
and the anchoring system are in place (NFBTCP, 2019).
Both variants were investigated. The tightening belts pulled
around the tubes were fastened on every second wedge with
a rope affixed to stakes on the land side and water side. Fi-
nally, a plastic skirt was spread in front of the system on the
water side, which reached up to the apex of the upper tube.
Full impoundment of water in the systems tested and wa-
ter overflow cannot be realised over the entire length of the
SBRSs owing to unevenness of the basin floor and limited
pumping capacity in the IWA test facility. This restriction is
particularly relevant in cases when an overflow load occurred
as the unevenness meant that only a slight overflow height
could be achieved in the right-hand area of the test facility
(Fig. 9).
If overflow occurs when using SBRSs, it must be pre-
vented from washing away the soil on the land side, other-
wise system failure can occur. The overflowing water must
be discharged or distributed over a sufficiently large area.
Theoretically, an SBRS can overflow if the system is sealed
via vertical water pressure since with increasing water lev-
els the system is increasingly stable via the vertical pressure.
A protruding skirt on the water side will afford more pro-
tection as the buoyancy forces under the system are thereby
minimised. Whether the system will overflow depends on its
geometry and/or bulk. With increasing water levels, the prob-
ability of failure due to tilting, slipping or rolling increases.
Systems that do not benefit from the stabilising effect of ver-
tical water pressure are not stabilised further with an increas-
ing water level. In terms of stability, a large bulk and/or a low
centre of gravity are fundamentally advantageous here. The
tests do not take into account the possibility of the foundation
soil giving way with increasing water levels since damming
within the test set-ups only took place on a defined and stable
floor. However, especially at high water levels, underground
failure can be an important source of failure.
3.2 Test results
The systems were tested on a grass surface and were set up
by two people. In some cases, there were major differences
between the manufacturer’s time specifications and the times
measured during the test set-ups (Massolle et al., 2018). To
be set up, the systems had to be transported manually from
the edge of the basin to the point of installation and thus
over a maximum distance of 15–20 m. It is quite conceiv-
able that faster installation times can be achieved on surfaces
suitable for vehicles and which offer better logistical condi-
tions. On the other hand, significantly longer manual trans-
port distances – and thus longer assembly times compared to
the test conditions – may occur in practice. The installation
times for the water-filled SBRSs also depend strongly on the
available pump capacity and the water supply. In principle,
however, it can be said that the installation and dismantling
of the systems is generally possible with just two people and
is many times faster than the construction of a sandbag dam.
In addition, it is also possible to optimise installation times
by using more helpers. Systems that have no filling require-
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206 L. Lankenau et al.: Sandbag replacement systems
Figure 8. Typical failure mechanisms of SBRSs (BWK, 2005, modified).
Figure 9. An overflowing SBRS (aqua defence).
ment also show a clear time advantage during assembly and
dismantling.
Setting up the systems is often self-explanatory, and in-
structions are easy to follow. It is still recommended, how-
ever, to involve an expert in order to avoid possible assembly
errors which could have far-reaching consequences. With the
Öko-Tec tubewall system, for example, there is a risk that the
drainage mat located under the upstream skirt will become
inverted, thus endangering the functionality of the system.
Taking precautions against buoyancy can be generally rec-
ommended. Systems such as the NOAQ boxwall, Tiger Dam
or Öko-Tec are dependent on this safety precaution. Protec-
tion can be ensured by an upstream skirt, a drainage system,
a seal on the water-side edge or anchoring of the system.
Systems such as the Flutschutz double-chamber tube (DCT)
have good protection against failure owing to the buoyancy
afforded by their high bulk weight, and no further measures
are called for. However, completely weighting down an up-
stream skirt with sandbags or other weights is still generally
recommended as this can also considerably minimise the oc-
currence of seepage (see Massolle et al., 2018).
Systems with a restricted contact surface (aqua defence,
Aqua Barrier and Tiger Dam) are especially prone to the dan-
ger of sinking into saturated ground. This risk also applies to
the AQUARIWA system, the filled base of which is flat but
whose plastic skin lies somewhat unevenly. Precise data on
how long it would take for the system to fail due to sink-
ing at the contact surfaces cannot be derived from the test
carried out, owing to the test’s relatively short duration of
just a few hours (Massolle et al., 2018). In principle, there
is a correlation between the depth of subsidence, the magni-
tude of the load exerted, the type and the antecedent wetness
of the ground underneath, and the duration of a flood event,
which can last up to several days or even weeks. Some sub-
sidence of the systems with a restricted contact surface could
be observed during water impoundment, but this did not lead
to failure during the test set-ups presumably because of the
short damming time of just a few hours. Figure 10 shows the
aqua defence system during dismantling. The system sank
the most deeply into the foundation soil in the area of the
greatest water depths during damming, seen at the top of
Fig. 10. In this area, however, the system also overflowed
while the test basin was being filled with water, so some of
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L. Lankenau et al.: Sandbag replacement systems 207
Figure 10. Supporting columns sunk into the saturated foundation
soil after damming (aqua defence).
the increased subsidence was probably due to erosion of the
foundation soil.
Particularly in the case of fine sandy soils, there is a risk
of foundation soil failure owing to hydraulic heave or ero-
sion caused by water flowing under the system. Especially
when additional pumping is used, care must be taken that
the soil under the systems is not removed with the flow of
water being pumped out. There is also a risk that the fric-
tion between the soil and system on paved ground will be
reduced by the presence of loose grains of sand or gravel. In
these cases, sweeping the areas around the contact surfaces
prior to installation is recommended. Minor unevenness can
be levelled out with sandbags or with lime that swells on con-
tact with water. When installing the systems, attention must
be paid to whether there are gradients in the terrain across
or along the planned system line as this would increase the
risk of tipping, sliding or rolling. Some systems (Flutschutz
DCT, Hydrobaffle, Tiger Dam and Aqua Barrier) shifted or
were deformed when the test basin was being filled with wa-
ter, owing to flexibility in their construction or expansion of
the material they are made of, but then stabilised again. The
pending failure of all the systems when overloaded was al-
ways indicated by visible shifting, but this indication usually
happened so quickly that there was no possibility of taking
countermeasures over longer periods.
In terms of seepage rates, the tested systems are either
comparable to a sandbag dam or to a sandbag dam with a
protruding plastic skirt (Massolle et al., 2018).
In summary, it can be stated that all the systems tested re-
mained stable at the water levels specified by their manufac-
turers (Fig. 11). The systems aqua defence, NOAQ boxwall,
Mobildeich, Öko-Tec tubewall (Öko-Tec TW), and Tiger
Dam with anchoring and skirt (Tiger Dam with A) held a full
water head with low incidences of overflow. The systems we
could not dam up to maximum capacity (AQUARIWA, IN-
DUTAINER, Flutschutz DCT and Hydrobaffle) were capable
of reaching higher water levels than those specified by the
manufacturers. The Tiger Dam tube system was only able to
achieve the protection height of 0.6m specified by the man-
ufacturer by the additional use of an upstream skirt and an-
choring to the ground; a test set-up without the skirt and an-
choring threatened an early system failure. The Quick Damm
Type M and Aqua Barrier systems were not available in suffi-
cient quantities and could only be tested in combination with
the AQUARIWA system. Therefore, water was only dammed
up to a height of 0.6 m. Since the tests were carried out with-
out any further loads caused by currents, waves, flotsam, etc.,
the possibility of increasing the protection heights given by
the manufacturers cannot be deduced. Table 2 summarises
the advantages and disadvantages of the various system types
as determined within the framework of our test set-ups.
The dismantling of the SBRSs tested was generally un-
complicated. In the case of water-filled systems, the number,
position and size of the openings for emptying the systems
significantly influence the emptying time as well as the pos-
sibility of simple complete emptying. Even if only a small
amount of residual water remains in the system, the result-
ing weight can exceed a manageable level. All systems must
always be cleaned and dried before being stored for reuse.
The INDUTAINER system may be considered a disposable
system as cleaning and drying is difficult owing to its intri-
cate design. However, it has a comparatively low purchase
price, so the use of the system can be economical even if
only used once. Some other SBRSs have limited disposal
costs after use. This applies in particular to systems in which
the upstream skirt is (preferably) weighted down with sand-
bags. However, the sandbag requirement, at approximately
four sandbags per metre, is low.
Admittedly, these tests were carried out under idealised
conditions using a bundle of wooden slats as flotsam. Since
the failure of an SBRS threatens the flooding of the hin-
terland with a correspondingly high damage potential and
SBRSs are to be regarded as more susceptible to mechanical
impacts and vandalism due to their design, these risks should
be evaluated particularly critically. Mechanical impacts and
vandalism, however, are also possible when using sandbag
systems. In the opinion of the authors, these aspects, despite
their particular relevance to SBRSs, should therefore not be
an exclusion criterion. Instead, it is advisable to place higher
demands on the monitoring of SBRSs during use.
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208 L. Lankenau et al.: Sandbag replacement systems
Figure 11. Water levels achieved during the test set-ups (Massolle et al., 2018). The red line marks the maximum water height of 0.6 m,
which is recommended for the unscheduled use of SBRSs (BWK, 2005).
The guidelines for loss prevention issued by the German
Insurers for Mobile Flood Defence Systems (VdS Schaden-
verhütung GmbH, 2014) contain a specimen evaluation form
for SBRSs, which is intended to serve as a decision-making
aid when evaluating systems for use in flood defence. The
SBRSs tested were evaluated in accordance with these guide-
lines; for comparison, the sandbag dam was also evaluated
according to these guidelines (Table 3). For sandbagging, the
evaluation is, where applicable, comparable with the evalua-
tion of the sandbag dam, load drain and temporary ring dam.
The evaluation criteria relate to application, stability, pro-
curement, durability, installation, dismantling, maintenance
and logistics. If a specification could not be determined or
derived from the results of the test set-ups, manufacturers’
specifications were used or the evaluation was carried out on
the basis of theoretical assessments. The failure mechanisms
that are related to the surface an SBRS is installed on, such
as those caused by hydraulic heave or erosion, were not con-
sidered owing to their dependence on the variable site condi-
tions encountered in operational practice. The systems’ con-
nections to walls or the like, the possibility of laying the sys-
tems in curves or with angles, and the systems’ behaviour on
different substrates (such as soft, solid, rough, smooth, even,
uneven, permeable and impermeable) were also not consid-
ered. The criteria on which the system evaluations are based
are described in Table 4.
4 Deployment costs, time involved, helpers and logistics
4.1 Description of scenarios
The costs as well as the time, helper and logistical require-
ments for the installation and dismantling of sandbag sys-
tems and SBRSs were determined for the following three dif-
ferent cases:
1. temporary flood dam,
2. load drain in the case of a saturated dike over an exten-
sive area and
3. ring dam for reinforcement against heavy punctual exit
of seepage on the inner embankment of a dike.
In case 1, in addition to the sandbag dam, three different
SBRS types (basin, tube and trestle) were considered. Re-
garding the temporary flood dam, based on the experiences
of the test performances described in Sect. 2, one manufac-
turer of each system type was selected. Although there was
more than one suitable system for each system type avail-
able, the scope of the investigations had to be limited owing
to financial and temporal reasons. Regarding their function,
i.e. protection against flooding, the chosen systems can be
seen as equivalent to sandbagging based on the experience of
the test set-ups. Although the systems show different safety
margins, the degree of safety can only be defined in detail
knowing relevant parameters such as the coefficient of fric-
tion, which were outside the scope of the analysis carried out.
In cases 2 and 3, the only suitable SBRSs on the market are
provided by Flutschutz. The systems’ performances on the
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L. Lankenau et al.: Sandbag replacement systems 209
Table 2. Summary of the most important advantages and disadvan-
tages of different system types.
Basin system
Advantages – High stability even with a low volume of or
no retained water (with the influence of wind or
similar)
– Seals well even with a low volume of retained
water
– Sand filling offers a high level of safety
Disadvantages – Installation time
– Filling material
Tube system
Advantages – High stability even with a low volume of or
no retained water (with the influence of wind or
similar)
– Seals well even with a low volume of retained
water
Disadvantages – Installation time
– Filling material
Flap, trestle and dam systems
Advantages – Installation time
– No filling material
– Usually allows for overflow
Disadvantages – Good stability only with an increasing height
of retained water (problematic with wind influ-
ence or similar)
– Good seal only with higher levels of retained
water
dry dike were in accordance with the manufacturer’s state-
ments. Furthermore, the mode of action of the corresponding
SBRSs is the same as for sandbagging. The authors there-
fore assume the SBRS Flutschutz load drain and Flutschutz
ring dam equivalent to sandbagging, not taking into account
possible differences in safety margins. When determining the
costs of the installation and dismantling of the systems the
costs of logistics (hiring the truck and driver and paying for
fuel and repair) and helpers were taken into account as well
as the costs of materials (sand, sandbags and acquisition cost
of SBRSs, including component parts) and the disposal of
sand and sandbags.
In the case of the temporary flood dam, a protection length
of 100 m and a protection height of 1.0 m were assumed.
The height of the sandbag dam was assumed to be 1.0 m as
the dam can theoretically protect against water levels up to
its full height. The SBRS AQUARIWA (basin system) with
a protection height of 1.0 m and a freeboard of 0.5 m, the
Flutschutz DCT system with a protection height of 0.6 m and
a freeboard of 0.3 m, and the aqua defence product (trestle
system) with a maximum protection height of 1.3 m (identi-
cal to system height) were compared. The differences in the
protection heights are system specific and cannot therefore
be avoided. The practical tests (cf. Massolle et al., 2018) have
shown that the Flutschutz DCT can dam a water head up to
a height of 1.0 m; due to the lateral pressure exerted when
filling the test basin, performance can be increased above
the system height of 0.9 m as specified by the manufacturer.
In case 2, one Flutschutz load drain was compared with the
equivalent length of a sandbag load drain, and, in case 3, one
Flutschutz ring dam was compared with one sandbag ring
dam (see Fig. 3).
All cost calculations assumed technical assistance would
be provided by the disaster services of the German Federal
Agency for Technical Relief (THW). Such federal assistance
takes place within the framework of inter-agency coopera-
tion and is generally requested by the responsible state au-
thorities during extreme flood events in Germany. For the
resources made available – primarily vehicles, pumps and
hoses as well as THW helpers – the costs were calculated on
the basis of the Ordinance on the Implementation and Invoic-
ing of Assistance provided by the THW (Verordnung über
die Durchführung und Abrechnung von Hilfeleistungen des
Technischen Hilfswerks), in accordance with the Annex to
Sect. 4 (3) of the THW Invoicing Ordinance (Bundesminis-
terium der Justiz und für Verbraucherschutz, 2019). During
a flood, the Bundeswehr and other relief organisations such
as fire brigades and the police can be deployed in addition
to the THW. Depending on the organisation, the individual
costs may vary; however, this has not been taken into consid-
eration for the present cost estimate.
The distance between the filling station for sandbagging
or the storage site of the SBRSs and the site of operation
is 5 km, i.e. 10 km for one round trip. Optimum access to the
site of operation allows for the use of trucks. Due to the heav-
ily soaked subsoil in cases 2 and 3, the access from the dike
defence road to the dike toe is limited; therefore, additional
helpers are needed to form a sandbag chain and pass on the
sandbags to the dike. The comparable SBRSs in cases 2 and
3 can be carried to the dike by two people. The operation is
carried out with THW personnel and means. The THW pro-
vide trucks, as well as pumps and hoses, for the water-filled
SBRSs. Furthermore, it is assumed that the travel distances
for the installation and dismantling of the systems are the
same length. That is why the logistics of installation and dis-
mantling show no differences.
The requirement for sandbags and sand, as well as the
labour needed for filling and laying the sandbags, is based
on empirical values supplied by the THW (THW, 2017). The
labour time needed for the installation of the SBRSs was esti-
mated on the basis of the authors’ empirical values (cf. Mas-
solle et al., 2018). In the case of water-filled systems in par-
ticular, the time required to dismantle an SBRS is less than
that required for the installation as the system components
can be allowed to drain at the same time without the need for
pumps. For the water-filled systems, therefore, the time re-
quired for dismantling was estimated to be 20 % of the time
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210 L. Lankenau et al.: Sandbag replacement systems
Table 3. System evaluation. Abbreviations are as follows: double-chamber tube (DCT), tubewall (TW), Tiger Dam (TD), skirt and anchoring (A), ring dam (RD), and load drain (LD).
Sandbagging1AQUARIWA INDUTAINER Quick Aqua Aqua NOAQ Flutschutz Hydrobaffle Mobildeich Öko-Tec TD without TD with Flutschutz Flutschutz Explanation and
Damm Barrier defence boxwall DCT TW A A RD LD remarks
Application area
Uneven ground +– – o o o o o + + o+ + + + Test and own estimate
Unsurfaced ground +– – +– – o + + + + o o + + Test and own estimate
Height of retainable
water
+o2o o o o – o +2+2o2–+2/ / Test
Height adjustable +– – – – – – – – o – o o / o Manufacturer’s data
Can overflow n/s o3– n/s o o +– – + + –+ + / Test
Installation in water +o – – o o o – +4+4– – – / / Own estimate
Space requirement
in use
o – – o – – +– o – – +– / / Manufacturer’s data
Stability
Tipping stability +– – o o o o + + + + o+/ / Test and own estimate
Roll and/or slide
stability
+ + o o + + o o – +o – +o o Test and own estimate
Buoyancy stability + + + o+ + o o – +o – +/ / Test and own estimate
Anchoring – – – – o o – – – – +/+/ / Manufacturer’s data
Resistance against
mechanical effects
+o o o o o – o – +– – o +5+5Own estimate
Resistance against
vandalism
– – +– – – – – – – – – o – – Own estimate
Domino effect + + –+o o – – o – – – +/ / Own estimate
Procurement and durability
Costs +o+n/s o – o o o o – + + – – Manufacturer’s data
Service life o o/+8–6n/s n/s n/s o7+ + o7o7+ + + + Own estimate
Reusability – o o + + + + + + + + + + + + Manufacturer’s data
Installation
Installation time – o9o9n/s + + + o9o9o9+–9–9+9+9Test
Equipment require-
ment
– – – o o o +o o o o o – o o Manufacturer’s data
Persons – + + + + + + o+ + + + + + + Manufacturer’s data or own estimate
Requirement of fill-
ing material
– o10 o o10 + + + o o o +o o o o Manufacturer’s data
Number of individ-
ual elements
– – o + + o+ + + o o – – + + Manufacturer’s data
Simplicity of instal-
lation
+ + + + + o+ + + + o – – + + Tests
Weight of individ-
ual elements
+ + + o+ + + o-11 o-11 o12 o o o +o Manufacturer’s data
Dismantling and maintenance
Simplicity of dis-
mantling
+o13 +o13 + + + o+ + + + o o +Test
Disposal effort – o10 o o10 – o + + + + + + o+ + Manufacture’s data
Cleaning effort / o – o o o o o o o o o o o o Own estimate
Repairs and spares / +–+ + + –+ + + + + + + + Own estimate
Logistics
Space for storage
and transport
–+ + o+ + + o o o o + + o o Manufacturer’s data
The symbols can be understood as follows: good is +, medium is o, poor is –, not relevant is / and not specified is n/s. 1Forsandbagging the manufacturer’s data are based on our own estimates. 2Manufacturer’s data (because not all system heights were tested). 3Perchance with sand filling –. 4Manufacturer’s data. 5Only from land side. 6During
continuous operation. 7Legal warranty,manufacturer’s data. 8o: Water sack, manufacturer’s data; +: Glass-fibre reinforced plastic panel, manufacturer’sdata. 9According to pumping capacity. 10 With sand filling –. 11 According to system length. 12 With reel. 13 Sand filling, own estimate.
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L. Lankenau et al.: Sandbag replacement systems 211
Table 4. Evaluation criteria.
Area of application Evaluation criteria
Uneven ground Applicable on unevenness, curbstones, etc.
Unsurfaced ground Special requirements for the condition of the foundation surface
Height of retainable water Height of retainable water up to 0.6 m is –, up to 1.5m is o and up to 3.0 m is +
Recommendations for unscheduled use of SBRSs according to BWK are observed (2005)
Height adjustable Subsequent increase possible
Can overflow Overflow capability according to manufacturer (M) or determined in authors’ tests (AT)
No is –, yes (AT or M) is o, and yes (AT and M) is +
Installation in water Manufacturer’s specification or own estimate based on system characteristics
Space requirement in use Depth including any upstream skirt
≤1.0 m is +,≤2.0 m is o, and >2.0 m is – (refers to the system variants tested)
Stability
Tipping stability Tube systems are less prone to tipping than dam or trestle systems. The heavier the installed systems,
the less prone they are to tipping. Sinking, including selective sinking, into the ground increases the risk
of tipping. Anchoring or securing against buoyancy counteracts tipping.
Roll and/or slide stability Tube systems are generally more susceptible to rolling away. The lower the weight and the smoother the
foundation surface of the system, the easier it is for the system to slip. Anchoring or securing against
buoyancy counteracts sliding or rolling. The Flutschutz load drain and ring dike always have to be
positioned partly on the horizontal plane in front of the land-side dike embankment.
Buoyancy stability The risk of system failure due to buoyancy is greater for filled systems with a lower weight. Depending
on the shape, buoyancy forces can also act on the water side (e.g. in tube systems). Systems with a large
foundation surface which achieve their load-bearing effect through the vertical water pressure from
the outside also have a greater risk of failure due to buoyancy. An upstream skirt, drainage, a seal or
anchoring counteracts failure caused by buoyancy.
Anchoring System can be anchored against wind, current, slipping or rolling
Resistance to mechanical effects Susceptibility to damage, e.g. by flotsam impact
Resistance against vandalism. Susceptibility to deliberate damage
Domino effect Threat to the entire dam due to failure of individual elements
Procurement and durability
Costs EUR ≤100 per metre is +, EUR ≤300 per metre is o, EUR > 300 per metre is –
Refers to the system variants tested
Service life Service life according to the manufacturer
≤1 year is –, ≤5 years is o, > 5 years is +
Reusability Manufacturer’s data
Installation
Installation time Installation time according to manufacturer or from own test. For all water-filled systems, the installa-
tion time depends on the pump used.
Equipment requirement Tarpaulins, sandbags, hoses, pumps, adapters or blowers
tarpaulin and others is –, tarpaulin or others is o, no equipment requirement is +
People ≤2 people is +
Requirement of filling material Sand filling is –, water filling is o, no filling is +
Number of individual elements Number of individual parts
Simplicity of installation System installation easy to understand and to perform
Weight of individual elements ≤35 kg is +,≤100 kg is o, >100 kg is –
Refers to the system variants tested
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212 L. Lankenau et al.: Sandbag replacement systems
Table 4. Continued.
Area of application Evaluation criteria
Dismantling and maintenance
Simplicity of dismantling System dismantling easy to understand and easy to perform
Disposal costs Disposal of foils, tarpaulins and sandbags or general disposal after use
Cleaning costs Effort involved in system cleaning
Repairs and spares Minor damage can be repaired by the user. Material and spare parts are available.
Logistics
Space for storage and transport Compactness of the dismantled system
required for installation. In practice, it should be noted that
these estimates depend on the conditions and accessibility on
site and, moreover, at least in Germany, dismantling is gener-
ally not financed by the federal authorities and therefore not
by the THW. With the end of the flood hazard, and thus the
disaster event, assistance on the part of the federal authorities
is terminated; the municipalities and administrative districts
become responsible for the measures taken. Due to a lack of
helpers, this can often lead to considerable problems follow-
ing major flood events.
The following times were assumed for cleaning the sys-
tems:
–Flutschutz DCT, length 10m – 1.5 h,
–aqua defence, length 1.22 m – 5 min,
–AQUARIWA, length 1.5 m – 5 min,
–Flutschutz load drain – 1 h, and
–Flutschutz ring dam – 1 h.
The sandbag requirement for SBRSs with upstream skirt
(AQUARIWA and aqua defence) is four sandbags per lin-
ear metre. The basic helper requirement is 10 people for
sandbagging and 2.5 people per SBRS, taking supervisors
(lower command such as group leaders) into account. In the
case of SBRSs, group leaders can take care of two differ-
ent areas of application simultaneously; therefore, only half
a helper is counted for the lower command of the installa-
tion of an SBRS per 100 m. The other two helpers install
the SBRS, resulting in 2.5 people per SBRS in total. In
practice, the systems should be set up by a larger team of
helpers, but fictitious helper teams with a minimum number
of helpers were assumed for the calculation. The estimated
remuneration to be reimbursed is estimated to be EUR 22.00
per helper hour (Bundesministerium der Justiz und für Ver-
braucherschutz, 2019). The average weight of a sandbag is
12 kg (THW, 2017). A requirement of 15 kg sand per sand-
bag was assumed in order to take overfilling and sand losses
into account. On the other hand, no reserve margin for de-
fective sandbags is taken into account but is considered to be
included in the excess demand for sand. A sandbag purchase
price of EUR 0.20 takes into account the slight price increase
to be expected during a flood event; sand is calculated at a
price of EUR 10.5 per tonne. Travel costs were assumed to
be EUR 1.52 per litre diesel and 25 L per 100 km. No volun-
tary or private-sector assistance is taken into account. How-
ever, the participation of other volunteers, for example local
people, can significantly reduce the costs of the construction
of a sandbag dam as the helper costs make up the largest
cost factor. It should be taken into account, though, that in
the case of volunteers from the local population, the result-
ing costs are usually borne by the volunteers themselves; the
costs are therefore only transferred. The calculation also does
not include costs of (1) travel, food, accommodation or the
sanitary needs of the helpers; (2) upper command; (3) long
transport routes and alternative means of transport in cases of
poor access; (4) other material requirements (such as shovels
for filling the sandbags); (5) the transport of sand and supple-
mentary materials; (6) the storage of SBRSs, sandbags and
shovels, etc.; and (7) necessary repairs to SBRSs.
In principle, the selected SBRSs are reusable. Only the
AQUARIWA system needs to have the inner bags replaced
after using the system; the price per bag is low and was
therefore neglected in the calculation. However, to replace
worn-off elements, 5 % of the investment costs are estimated.
It is assumed that with smaller quantities of SBRSs, stor-
age on site, e.g. by local dike management units (Deichver-
baende), is possible without difficulty. Only in the case of
larger stocks are higher demands placed on storage capaci-
ties. Just like SBRSs, sandbags must be stored, but they have
a significantly shorter shelf life than SBRSs (see Sect. 2). In
view of this, the calculation equates the repair requirements
of SBRSs with the inspection and renewal requirements of
stored sandbags.
The need to regularly test the construction of SBRSs is
likewise equated with the requirement to carry out flood pro-
tection exercises when relying on the use of sandbag sys-
tems. It was also assumed that the sandbag systems, like the
SBRSs, should be continuously monitored during a flood
event in order to monitor their functionality and to check
the systems for damage caused by mechanical influences or
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L. Lankenau et al.: Sandbag replacement systems 213
vandalism. If deemed appropriate, the SBRSs should be in-
spected at shorter intervals than sandbag systems. However,
the additional requirement for labour to carry out inspections
is comparatively low and was therefore neglected.
4.2 Costs of deployment
The overview of the total cost of installing and disman-
tling the flood protection systems shows that, under the as-
sumed conditions, the costs resulting from the one-off use of
the SBRSs are around 30 %–50 % higher than for sandbag-
ging. However, since the SBRSs, in contrast to sandbags, are
largely reusable, the higher investment costs of the SBRSs
are already offset during their second application. Table 5
shows the cost estimates for the temporary flood dams (case
1), and Table 6 shows the cost estimates for the load drain
(case 2) and the ring dam (case 3). In each case, the costs
incurred for installing the systems exceed the costs of their
dismantling. Whereas the costs of dismantling the sandbag
dam amount to approximately 70 % of the costs of installa-
tion, the dismantling costs of SBRSs are in the low single-
digit percentage range when compared with their respective
installation costs.
In the case of sandbagging, both sand and sandbags must
first be procured. These are usually only stocked in limited
quantities, and in the event of procurement during a flood
event it must be expected that prices will rise sharply, even
exceeding the cost of sandbags assumed here. The sandbags
must then be filled and laid with a great deal of time and ef-
fort. These aspects must be weighed against the high initial
investment costs of the SBRSs, which, however, can be used
several times. In order to replace damaged systems after use,
an average new procurement requirement of 5% of the ini-
tial investment cost is assumed within the system service life.
The number of sandbags required to weigh down and seal
the upstream skirt of an SBRS are comparatively insignifi-
cant. The logistical costs of installation and dismantling are
quite similar for sandbags and SBRSs due to the equal travel
distances assumed; for sandbagging they are slightly higher
compared to SBRSs, owing to the greater bulk of sandbag-
ging systems. Basically, the logistical costs of all the systems
are comparatively low, which is also due to the comparatively
low costs of the use of THW vehicles assumed here. When
dismantling, the costs of sandbagging are higher than of the
SBRSs, owing to the extra need for helpers and the disposal
of sandbags. However, if it is possible to deploy heavy equip-
ment for the dismantling of a sandbag dam, these costs can be
lower than those estimated in the present calculation because
of the lower requirement for helpers and the shorter time in-
volved. Overall, the largest cost items for sandbagging are
the costs of the deployment of helpers, the procurement of
materials (sand and sandbags), and, for the SBRSs, the pro-
curement of the systems. If, in addition to the costs of instal-
lation, the costs of dismantling are also taken into account,
the purchase of SBRSs makes sense from a financial point of
view as the additional costs compared with sandbagging are
already offset during the second deployment. The investment
costs did not include a quantity discount for the purchase of
longer system lengths.
From a financial point of view, the use of SBRSs as a tem-
porary flood dam is particularly worthwhile for protection
against higher flood levels. If the protective height is reduced,
the installation costs of the temporary sandbag dam decrease
owing to the lower sandbag requirement. SBRSs, on the other
hand, can rarely be flexibly adjusted in height, so, with lower
system heights, the offsetting of costs in comparison to sand-
bag dams of low height only takes place after a number of
deployments. For example, the costs of constructing a sand-
bag dam with a height of 0.50 m and a length of 100 m are
only approximately EUR 8090 for installation and approxi-
mately EUR 5352 for dismantling, giving a total of approx-
imately EUR 13 442 for installation and dismantling. If an
SBRS is offered in different system heights, savings can also
be expected if lower system heights are used, but these are
less significant. It should also be noted that the procurement
costs of SBRSs supplied by other manufacturers may differ
from those of the manufacturers considered here.
If there is insufficient water available from natural sources
(e.g. river water) in the immediate vicinity of where water-
filled systems are to be installed, the costs of the water fill-
ing of hydrants are comparatively low (approx. EUR400
Flutschutz DCT and EUR 150 AQUARIWA). If tank trucks
have to be used, however, the logistical effort increases.
Notwithstanding, the time, material and helper advantages of
SBRSs remain in all of the cases considered here.
The calculations did not take into account the costs of up-
per command or of travel, meals, overnight accommodation
and sanitary requirements of the helpers. For upper com-
mand, i.e. the disaster control management, technical inci-
dent command and platoon, EUR 5 per helper in the lower
command and day can be assumed. The costs of upper com-
mand are realistic overhead costs related to the number of
helpers in action. With an estimate of EUR25 per day to
cover the overnight accommodation, food and sanitary needs
of the helpers and with a helper day of 12 h, in cases 1, 2 and
3, approximately 6 % and 1 % more costs are incurred per
sandbag system and SBRS respectively.
4.3 Time, helper and logistics requirements
For cases 1, 2 and 3, the estimated time, helper and logistics
requirements are shown in Tables 7 and 8. Time materials
refers to the time needed to fill the sandbags; aqua defence
and AQUARIWA SBRSs need sandbags in order to weight
down the upstream skirt. Time logistics covers the time for
loading and unloading the trucks as well as the time for the
outward and return journey between the filling station or stor-
age site and the site of operation, which is calculated as 1 h
per truck. It is assumed that there is an unrestricted number of
trucks available, which is of course only theoretical, result-
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214 L. Lankenau et al.: Sandbag replacement systems
Table 5. Comparison of the costs of the installation and dismantling of sandbag systems and SBRSs – temporary flood dam, protection length
100 m (case 1).
Sandbag dam Flutschutz DCT Aqua defence AQUARIWA
Helpers, incl. lower command 10 2.5 2.5 2.5
Sandbag requirement (40 ×60cm, empty) 16 500 – 400 400
Installation
Time per dam (h) 61.88 7.50 8.48 10.71
Costs of helpers (EUR) 13 612.50 412.50 466.40 589.05
Costs of materials, incl. replacements (EUR) 5 898.75 42 930.33 47 400.15 51 758.87
Costs of trucks, incl. fuel (EUR) 641.47 35.06 37.56 28.02
Total installation costs without materials (EUR) 14 253.97 447.56 503.96 617.07
3 % sundry costs (EUR), based on total 150.00 15.00 15.12 18.51
operating costs of EUR 15–150
Total costs of installation (EUR) 20 302.72 43 392.89 47 919.23 52 416.95
Dismantling
Time per dam (h) 20.63 16.55 12.96 9.10
Costs of helpers (EUR) 4537.50 907.50 712.80 390.61
Costs of materials (EUR) 8250.00 – 200.00 200.00
Costs of trucks, incl. fuel (EUR) 641.47 35.06 37.56 28.02
Total dismantling costs without materials (EUR) 5178.97 942.56 750.36 418.63
3 % sundry costs (EUR) based on 150.00 28.28 22.51 15.00
total operating costs of EUR 15–150
Total costs of dismantling (EUR) 13 578.97 970.83 972.87 633.63
Installation and dismantling totals
Total costs (EUR) 33 881.69 44 363.72 48 892.10 53 050.58
ing in an overall time for logistics of 1 h. In reality, the overall
time would increase depending on the actual available num-
ber of trucks. Time installation refers to the installation of the
specific system, including if necessary additional time for a
sandbag chain. Time dismantling refers to the dismantling of
the individual systems as well as to time spent cleaning the
SBRSs if necessary, and also including additional time for
a sandbag chain. Time taken for the disposal or storage of
SBRSs was not taken into account.
The advantages of the SBRSs in terms of time, materials
and helpers are clearly visible. In case 1, the use of SBRSs re-
quires approximately 25 %–30 % of the time, approximately
5 %–7 % of the helper hours and approximately 5 % of the
trucks compared to the sandbag dam. If more helpers or
trucks are used, the respective proportions shift, but the total
effort remains the same. In case 2 and case 3, approximately
40 % of the time and approximately 6 % of the helper hours
are required when using SBRSs as opposed to sandbagging
systems. The logistics data in case 2 and case 3 were cal-
culated assuming fully loaded trucks. Eight Flutschutz load
drains or Flutschutz ring dams can be transported per truck,
so when using these SBRSs there is a need for only approxi-
mately 8 %–9 % of the trucks required for sandbagging.
When sandbagging is used, poor access, and thus the need
for sandbags to be passed over longer distances by means of
a sandbag chain (see Fig. 2), may result in a significantly in-
creased need for helpers or in the use of alternative means
of transport, such as helicopters or boats, which can only
transport sandbags in small numbers. This can also consid-
erably increase the time required for transport as well as the
costs incurred. The possible scenarios are manifold and could
therefore not be considered in detail. SBRSs do not need ad-
ditional helpers in cases of poor accessibility, because, due
to their relatively low weight, the required number can be
put in place much more easily, e.g. by the use of special ve-
hicles which can access wet ground but cannot carry a lot of
weight.
5 Conclusion
Tests of various SBRSs with a focus on stability, function-
ality and handling were carried out. The experiences from
the test set-ups show that SBRSs, owing to their function-
ality, their labour- and time-saving characteristics, and their
lower requirement for materials, have the potential to make
operational flood defence more efficient than with the use of
sandbags alone. Since SBRSs are technical systems whose
functional capability must be proven before they can be used,
the introduction of a test and certification system is urgently
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L. Lankenau et al.: Sandbag replacement systems 215
Table 6. Comparison of the costs of the installation and dismantling of sandbag systems and SBRSs – load drain (case 2) and ring dam (case
3).
Load drain Ring dam
Sandbag Flutschutz Sandbag Flutschutz
Helpers, incl. lower command 10 2.5 10 2.5
Sandbag requirement (40 ×60cm, empty) 980 – 900 –
Installation
Time per element (h) 4.90 0.50 4.50 0.50
Costs of helpers (EUR) 1078.00 27.50 990.00 27.50
Costs of materials, incl. replacements (EUR) 350.53 3068.78 321.75 3748.51
Costs of trucks, incl. fuel (EUR) 41.31 6.93 38.18 6.93
Total costs without materials (EUR) 1119.31 34.43 1028.18 34.34
3 % sundry costs (EUR) based on 33.58 15.00 30.85 15.00
total operating costs of EUR 15–150
Total costs of installation (EUR) 1503.24 3118.21 1380.78 3797.93
Dismantling
Time per dam (h) 2.45 1.10 2.25 1.10
Costs of helpers (EUR) 539.00 60.50 495.00 60.50
Costs of materials (EUR) 490.00 – 450.00 –
Costs of trucks, incl. fuel (EUR) 41.31 6.93 38.18 6.93
Total operating costs without materials (EUR) 580.31 67.43 533.18 67.43
3 % sundry costs (EUR) based on 17.41 15.00 16.00 15.00
total operating costs of EUR 15–150
Total costs of dismantling (EUR) 1087.72 82.43 999.18 82.43
Installation and dismantling totals
Total costs (EUR) 2590.96 3200.63 2379.96 3880.36
Table 7. Comparison of time, helpers and logistics requirements for the installation and dismantling of sandbag systems and SBRSs –
temporary flood dam (case 1).
Sandbag dam FlutschutzDCT Aqua defence AQUARIWA
Helpers, incl. lower command 10 2.5 2.5 2.5
Trucks 26 2 2 1
Installation
Time materials (h) 41.25 – 2.00 2.00
Time logistics (h) 1.00 1.00 1.00 1.00
Time installation (h) 20.63 7.50 6.48 8.71
Total time, incl. logistics (h) 62.88 8.50 9.48 11.71
Total helper hours (h) 618.75 18.75 21.20 26.78
Dismantling
Time materials (h) – – – –
Time logistics (h) 1.00 1.00 1.00 1.00
Time dismantling, incl. cleaning the SBRS (h) 20.63 16.50 12.96 7.10
Total time, incl. logistics (h) 21.63 17.50 13.96 8.10
Total helper hours (h) 206.25 41.25 32.40 17.76
Installation and dismantling totals
Total time, incl. logistics (h) 84.50 26.00 23.44 19.81
Total helper hours (h) 825.00 60.00 53.60 44.53
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216 L. Lankenau et al.: Sandbag replacement systems
Table 8. Comparison of time, helpers and logistics requirements for the installation and dismantling of sandbag systems and SBRSs – load
drain (case 2) and ring dam (case 3).
Load drain Ring dam
Sandbag Flutschutz Sandbag Flutschutz
Helpers, incl. lower command 10 2.5 10 2.5
Trucks 2 1 2 1
Installation
Time materials (h) 2.45 – 2.25 –
Time logistics (h) 1.00 1.00 1.00 1.00
Time installation (h) 2.45 0.50 2.25 0.50
Total time, incl. logistics (h) 5.90 1.50 5.50 1.50
Total helper hours (h) 49.00 1.25 45.00 1.25
Dismantling
Time materials (h) – – – –
Time logistics (h) 1.00 1.00 1.00 1.00
Time dismantling, incl. cleaning the SBRS (h) 2.45 1.10 2.25 1.10
Total time incl. logistics (h) 3.45 2.10 3.25 2.10
Total helper hours (h) 24.50 2.75 22.50 2.75
Installation and dismantling totals
Total time, incl. logistics (h) 9.35 3.60 8.75 3.60
Total helper hours (h) 73.50 4.00 67.50 4.00
recommended. A basis for the development of a certification
system according to German standards is already available
in the BWK leaflet Mobile Flood Protection Systems (BWK,
2005) and the international certification systems of FM Ap-
provals (FM Approvals, 2019) and BSI Kitemark (2019a), as
well as in the test results described here and in Massolle et
al. (2018).
Further aspects have to be considered when using SBRSs
instead of sandbagging. These include the lower flexibility
of SBRSs to be adaptively applied in emergency situations,
higher demands on trained personnel, the creation of hazards
by assembly errors, defects in their construction, mechanical
influences due to flotsam, vehicles and people, vandalism, the
possibility of collective failure (domino effect), and the influ-
ences of currents, winds and waves. The hazards introduced
through the use of SBRSs cannot entirely be ruled out; but
the hazards can be minimised by taking appropriate precau-
tions, e.g. installing safety zones adjacent to the systems, an-
choring systems to the ground, and tightly monitoring SBRSs
and water-side environments. SBRSs also easily allow for
the impounding of higher floodwater levels, which is on the
one hand an advantage but on the other hand results in the
greater probability of subsoil failure if high water levels are
impounded. In general, the use of SBRSs can lead to higher
demands on subsoils. Many of the aspects mentioned can
be laid down in guidelines to support decision makers with
regard to the possible use of SBRSs. However, taking into
account possible catastrophic consequences in the event of
failure, the installation of SBRSs should be planned and ex-
ecuted under the supervision of specialists and under special
observation during the flood event. From the authors’ point
of view, SBRSs are a suitable supplement to rather than a
full replacement of sandbagging. Especially because of their
easy, flexible handling and their reliable usability within a
wide range of scenarios, sandbags are an essential means in
operational flood defence. No matter whether SBRSs find in-
creasing applications in the future, sandbags will continue to
play an important role in flood defence owing to their simple
application and high flexibility even if, for example, they are
only used to close gaps for which prefabricated systems of a
certain length are not suitable.
The authors’ determination of the operational costs was
carried out for specific scenarios and with several simplifi-
cations but nevertheless allows for an approximate estimate
of the operational costs of sandbagging and SBRSs under re-
alistic conditions. When used once, all SBRSs show higher
overall costs, including costs of investment, logistics, instal-
lation and dismantling. The higher total costs result from the
higher acquisition costs of the SBRSs investigated. SBRSs
are reusable; therefore, with regard to offsetting the higher
acquisition costs of SBRSs, the number of times a system
can be used within its service life plays a decisive role since
the acquisition costs of the systems are offset during their
subsequent reuse. Because SBRSs can be transported with
comparatively low logistical effort, a more centralised stor-
age system is conceivable, whereby, in the event of flood-
Nat. Hazards Earth Syst. Sci., 20, 197–220, 2020 www.nat-hazards-earth-syst-sci.net/20/197/2020/
L. Lankenau et al.: Sandbag replacement systems 217
ing, the systems can be transported from more distant regions
that are not immediately affected by the flood to where there
is a current need. This would be in the interest of a cross-
municipal and therefore cost-effective acquisition.
All SBRSs investigated show clear time-, material- and
personnel-saving advantages. All of these aspects, in par-
ticular the time-saving advantage, which could be crucial
in quickly providing protection, should be taken into ac-
count. The time-, material- and personnel-saving characteris-
tics of SBRSs might offer the possibility to use SBRSs during
heavy-precipitation events and flood events with only short-
notice early warning times. Such events can entail high flow
velocities, resulting in high potential dynamic loads. Further
investigations and a special testing routine would be neces-
sary in order to make reliable statements about the function-
ality of an SBRS during such events.
From a technical point of view, decision makers are con-
fronted with questions about the reliability of SBRSs, which
in general show good functionality comparable to sandbag-
ging and, in terms of time, personnel and material need, bet-
ter results than sandbagging alone. The question of the func-
tionality of SBRSs can be addressed by introducing indepen-
dent test routines and certifications. From an economic point
of view, decision makers are confronted with the challenge of
higher investment costs if SBRSs are purchased. The inves-
tigations carried out here indicate that this is not connected
to economic losses only if SBRSs are subsequently reused.
In addition to the economic aspects, however, it should also
be noted that SBRSs can be set up in a significantly shorter
period of time, which can often be the basis for effective pro-
tection.
Data availability. Relevant underlying data can be requested by
mail from the authors.
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218 L. Lankenau et al.: Sandbag replacement systems
Appendix A
Table A1. The system dimensions and further properties of SBRSs tested.
Manufacturer/distributor Product name Water height
(m)
System height
(m)
Length
(m)
Width
(m)
Unfilled
weight (kg)
Diameter (m) System Main material Fill material Water perme-
able
Anchoring Material requirements Home page
Basin system
Aquariwa GmbH AQUARIWA 0.5–1.0 (sand
filled)
0.9–1.5 – – 15.0–39.0 1–1.5 Plates bend to cylindri-
cal containers filled with
water, sand or gravel
Glass-fibre reinforced board
with grid, foil water sack
Water, sand,
gravel
No None Tarpaulins, sandbags, hoses,
pumps or wheel loaders,
dumpers
http://www.aquariwa.de/home/∗
1.0–1.5
(water filled)
Indutainer INDUTAINER n.s. 1.05 0.93 0.93 7.0 – Water-filled basin sys-
tem
Polypropylene fabric,
polyurethane foam
Water No None Tarpaulin, pumps, hoses,
filling aid if necessary
http://www.indutainer.com/∗
Quick Damm GmbH Quick Damm 1.0 1.0 2.0 1.0 50.0 – Open, collapsible steel
frame with a geotextile
container filled with sand
or gravel or a plastic con-
tainer filled with water
Steel frame, geotextile
or plastic-coated fabric
tarpaulin
Water, sand,
gravel
Differs None Wheel loaders, dumper or
pumps, hoses
http://www.quick-damm.de/start.
html∗
Trestle system
ALTRAD plettac assco
GmbH
aqua defence 1.3 1.3 1.3 1.71 approx. 41.5
per metre
– Hard foam panels cov-
ered with tarpaulin on
collapsible support ele-
ments
Hard foam panels, gal-
vanised support elements,
tarpaulin
– No n.s. Sandbags https://plettac-assco.de/de/
produkte/aqua-defence∗
Geodesign Barriers
(formerly RS Stepanek
KG)
Aqua Barrier 0.65–1.8 0.65–1.8 1.23 n.s. n.s. – EUR-pallets covered
with tarpaulin on
foldable collapsible
elements
Wooden pallets, galvanised
support elements
– No n.s. Wooden pallets, tarpaulins,
sandbags
https://www.hs-silberbauer.
at/hochwasserschutz/
aqua-barrier-mobiles-plattensystem/
index.html∗
https://geodesignbarriers.com/∗
Dam system
NOAQ Flood Protec-
tion AB
NOAQ boxwall 0.5 0.528 0.705 0.68 3.4 – Boxes connected to each
other
ABS (acrylonitrile butadi-
ene styrene)
– No None None http://noaq.com/de/home-2/∗
Tube system
European Flood Con-
trol GmbH
Tiger Dam 0.4; 0.75; 1.0 0.5 per tube 15.0 – 30per tube 0.5 per tube Closed, water-filled
tube system, strapped in
pyramid-shaped
PVC Water No Possible for
additional
protection
against slip-
ping
Tarpaulins, sandbags,
pumps, hoses
http://www.eu-floodcontrol.eu/∗
Hochwasserschutz
Agentur
Hydrobaffle 0.23–1.83 0.31–2.44 3.0–32.0 0.7–5.49 2.61–20.32 0.7–5.49 Closed, water-filled tube
system
Plastic-coated fabric
tarpaulin
Water No None Pumps, hoses, square
wrenches for the seals
https://www.
hochwasserschutz-agentur.de/∗
Mobildeich GmbH Mobildeich 0.45–2.6 0.45–2.6 10.0–50.0 0.4–2.6 5–56 per me-
tre
0.45–1.5 Closed, water-filled tube
system held together as
two- to three-tube pack-
ages with net sheathing
and sealing tarpaulin
PVC-coated polyester fabric Water No None Pumps, hoses, Y-piece http://www.mobildeich.de/de/
index.php∗
Optimal Umwelttech-
nik GmbH
Flutschutz
double-
chamber
tube
0.6 0.9 10.0; 15.0;
20.0
– 110.0–220.0 1.5/0.9 Closed, water-filled tube
system
Polyester fabric coated on
both sides
Water No None Leaf blower,pumps, hoses https://optimal-umwelttechnik.
de/hochwasserschutz/
doppelkammerschlauch-flutschutz∗
Öko-Tec
Umweltschutzsys-
teme GmbH
Öko-Tec tube-
wall
0.5–1.5 0.5–1.5 5.0–20.0 1.5–2.3 4.0–9.5 per
metre
0.5–1.5 Closed air-filled tube
system
PVC Air No If necessary
with wind on
the side of
the protection
zone or with
current on the
water side
Blower https://oeko-tec.de/
oeko-tec-schlauchwall/∗
Load drain
Optimal Umwelttech-
nik GmbH
Flutschutz load
drain
– 0.6 7.0 3.5 70.0 – Closed, water-filled tube
system
Polyester fabric coated on
both sides
Water No None Pumps, hoses https://optimal- umwelttechnik.
de/hochwasserschutz/
auflastfilter-flutschutz∗
Temporary ring dam
Optimal Umwelttech-
nik GmbH
Flutschutz ring
dam
1.0 1.0 2.9 2.9 35.0 – Closed, water-filled tube
system
Polyester fabric coated on
both sides
Water No None Leaf blower,pumps, hoses https://optimal-umwelttechnik.
de/hochwasserschutz/
quellkade-flutschutz∗
∗Last access: 27 December 2019.
Nat. Hazards Earth Syst. Sci., 20, 197–220, 2020 www.nat-hazards-earth-syst-sci.net/20/197/2020/
L. Lankenau et al.: Sandbag replacement systems 219
Author contributions. BK conceptualised the study; LL and CM
developed the methodology; CM and LL procured the resources;
and LL, CM and VK conducted formal analysis. LL prepared the
original draft of this manuscript; BK, CM and LL reviewed and
edited it; and LL and VK created the visualisations. BK and LL su-
pervised the project and BK administered the project and acquired
funding.
Competing interests. The authors declare that they have no conflict
of interest.
Acknowledgements. The test set-ups were carried out within the
framework of the project, Adaptation of flood protection training
and dike defence of the THW Training Centre Hoya to the chal-
lenges of climate change’ (HWS-Bildung, duration 2016–2018),
funded within the framework of the German Strategy for Adapta-
tion to Climate Change by the Federal Ministry for the Environ-
ment, Nature Conservation and Nuclear Safety and by the THW
Foundation. We would like to thank the manufacturers and their
distributors for making their systems available for the tests and our
student assistants for their active support during the test set-ups. We
would furthermore like to thank the anonymous referees for their
helpful comments and suggestions.
Financial support. This research has been supported by the Bun-
desministerium für Umwelt, Naturschutz und nukleare Sicherheit
(grant no. 03DAS080) and the THW Foundation.
Review statement. This paper was edited by Heidi Kreibich and re-
viewed by two anonymous referees.
References
American National Standards Institute (ANSI) and FM Approvals:
American National Standard for Flood Abatement Equipment,
ANSI/FM Approvals 2510, FM Approvals, Norwood, 2014.
AQUARIWA: Mobiler Hochwasserschutz in Gartow
im Juni 2013, available at: http://www.aquariwa.de/
die-einsaetze/aquariwa-in-gartow-juni- 2013/#die-einsaetze/
aquariwa-in-gartow-juni-2013/, last access: 25 September 2019.
Biggar, K. and Masala, S.: Alternatives to sandbags for temporary
flood protection, Alberta Transportation and Utilities Disaster
Services Branch and Emergency Preparedness Canada, Edmon-
ton, AB and Ottawa, ON, Canada, 1998.
British Standards Institution (BSI): PAS 1188-2:2014 Flood protec-
tion products – Specification, Part 2: Temporary products, Third
Edition, The British Standards Institution Group Headquarters,
London, 2014.
British Standards Institution (BSI): British Standards Institution
Homepage, available at: https://www.bsigroup.com/en-GB/, last
access: 25 September 2019a.
British Standards Institution (BSI): Product directory search, avail-
able at: https://www.bsigroup.com/en-GB/Product-Directory/,
last access: 25 September 2019b.
Bund der Ingenieure für Wasserwirtschaft, Abfallwirtschaft
und Kulturbau (BWK) e.V.: Merkblatt: Mobile Hochwasser-
schutzsysteme – Grundlagen für Planung und Einsatz, BWK-
Bundesgeschäftsstelle, Sindelfingen, Deutschland, 2005.
Egli, T.: Entscheidungshilfe Mobiler Hochwasserschutz, Vereini-
gung Kantonaler Feuerversicherungen, Bern und Bundesamt für
Wasser und Geologie, Biel, 2004.
FM Approvals: FM Approvals Homepage, available at: https://
www.fmapprovals.com/, last access: 25 September 2019.
Gabalda, V., Garvin, S., Hunter, K., Florence, C., Salagnac,
J.-L., Golz, S., ten Veldhuis, M.-C., Diez, J., and Monnot, J.
V.: Flood Resilience Technologies, SMARTeST, available at:
https://www.ioer.de/fileadmin/internet/IOER_Projekte/PDF/
FB_R/Flood-Resilience-Technologies_SMARTeST-Project_
D23-final-July13.pdf (last access: 25 September 2019), 2013.
Massolle, C., Lankenau, L., and Koppe, B.: Emergency
Flood Control: Practice-Oriented Test Series for the Use
of Sandbag Replacement Systems, Geosciences, 8, 482,
https://doi.org/10.3390/geosciences8120482, 2018.
McCormack, S. M., Van Dyke, C., Suazo A., and Kreis, D.: Tem-
porary Flood Barriers, Research Report KYSPR-12-448, Ken-
tucky Transportation Center, College of Engineering, University
of Kentucky, Kentucky Transportation Cabinet Commonwealth
of Kentucky and Federal Highway Administration U.S. Depart-
ment of Transportation, Kentucky, 2012.
Mobildeich: Referenzen, available at: https://www.mobildeich.de/
de/referenz.php#filme, last access: 25 September 2019.
National Flood Barrier Testing & Certification Program (NFBTCP):
Products, available at: https://nationalfloodbarrier.org/products/
#!/prodsub-peri-barriers, last access: 25 September 2019.
Niedersaechsischer Landtag: Antwort auf eine Grosse Anfrage.
Niedersaechsischer Landtag – 17. Wahlperiode, Drucksache
17/1730, available at: https://www.landtag-niedersachsen.de/
drucksachen/drucksachen_17_2500/1501-2000/17-1730.pdf
(last access: 25 September 2019), 2014.
Ogunyoye, F., Stevens, R., and Underwood, S.: Delivering benefits
through evidence. Temporary and Demountable Flood Protection
Guide, Environment Agency, Bristol, 2011.
Österreichischer Wasser- und Abfallwirtschaftsverband (ÖWAV):
Arbeitsbehelf 42: Mobiler Hochwasserschutz, Wien, 2013.
Pinkard, F., Pratt, T., Ward, D., Holmes, T., Kelley, J., Lee, L. T.,
Sills, G., Smith, E., Taylor, P. A., Torres, N., Wakeley, L., and
Wibowo, J.: Flood-Fighting Structures Demonstration and Eval-
uation Program: Laboratory and Field Testing in Vicksburg, Mis-
sissippi, U.S. Army Corps of Engineers, Washington, 2007.
Popp, F., Lehmann, S., and Lehmann, B.: Flexibilität und Ef-
fizienz in der Deichverteidigung durch mobile Aufkadungssys-
teme, Wasserwirtschaft, 01, 29–33, 2019.
Simm, J., Sharp, M., Hemert, H. V., Igigabel, M., Pohl, R.,
Tourment, R., Wallis, M., Drake, C., Banks, J., Bram-
ley, M., Chassé, P., Conforti, T., Jenkins, O., Mallet, T.,
Matheu, E., Royet, P., and Verigin, S. (Editorial Steer-
ing Board): The international levee handbook, C731,
Construction Industry Research and Information Associa-
tion (CIRIA), London, available at: https://www.ciria.org/
ItemDetail?iProductCode=C731F&Category=FREEPUBS&
www.nat-hazards-earth-syst-sci.net/20/197/2020/ Nat. Hazards Earth Syst. Sci., 20, 197–220, 2020
220 L. Lankenau et al.: Sandbag replacement systems
WebsiteKey=3f18c87a-d62b-4eca-8ef4-9b09309c1c91 (last
access: 25 September 2019), 2013.
Technisches Hilfswerk (THW): THW-pocket card “Hochwasser-
schutz und Deichverteidigung” (“flood protection and dyke de-
fence”), status 02.08.2017, unpublished, THW Training Centre
Hoya, Hoya, Germany, 2017.
Bundesministerium der Justiz und für Verbraucherschutz: Verord-
nung über die Durchführung und Abrechnung von Hilfeleistun-
gen des Technischen Hilfswerks (THW-V), available at: http:
//www.gesetze-im-internet.de/thw-abrv/anlage.html, last access:
16 March 2019.
VdS Schadenverhütung GmbH: Mobile Hochwasserschutzsysteme:
Hinweise für die Beschaffung, den Einsatz und die Bereitstel-
lung, VdS 6001: 2014 – 02 (01), Köln, 2014.
Nat. Hazards Earth Syst. Sci., 20, 197–220, 2020 www.nat-hazards-earth-syst-sci.net/20/197/2020/
