Available via license: CC BY 4.0
Content may be subject to copyright.
water
Article
The Negative Impact of Blockage on Storm Water
Drainage Network
Ismail Fathy 1, Gamal M. Abdel-Aal 1, Maha Rashad Fahmy 1, Amira Fathy 2and
Martina Zele ˇnáková3, *
1Department of Water and Water Structures Engineering, Faculty of Engineering, Zagazig University,
Zagazig 44519, Egypt; ismailfathy1982@gmail.com (I.F.); drgamal_abdelaal@yahoo.com (G.M.A.-A.);
maharashad@yahoo.com (M.R.F.)
2Engineer, Ministry of Water Resources and Irrigation, Sharkia 44519, Egypt; amiraamff@yahoo.com
3Department of Environmental Engineering, Faculty of Civil Engineering, Technical University of Kosice,
042 00 Kosice, Slovakia
*Correspondence: martina.zelenakova@tuke.sk
Received: 30 May 2020; Accepted: 8 July 2020; Published: 12 July 2020
Abstract:
Storm water drainage system in urban areas became a deterministic system, especially in
light of the current climate changes. This system eliminates the excess water resulting from heavy
rainfall, which leads to disruption of daily life. Irregular maintenance of the network system, problems
appear, especially the blockage of the covers or network pipes, which affects the efficiency of the
network. This study deals with the experimental investigation of blockage on storm network system
and the relationship between efficiency of the system and blockage parameters. Many scenarios of
blockage within grate and pipe were studied and its impact on storm system efficiency calculated.
For the pipe system, two scenarios were studied; the first one is the blockage of end main pipe with
relative blockage height (15%, 30%, 50%, 70%, and 90%). The second one is the blockage through
the main pipe with relative blockage height (25%, 50%) and relative blockage length (33%, 67%,
and 100%). For grate, the blockage is investigated with the blockage area ratio (12.5%, 25%, 37.5%,
and 50%). In addition, the combined blockage of grate and pipe was studied. Finally, an equation has
been created to estimate the system efficiency as a function of blockage ratios and system discharges.
The results indicated that for surface blockage (12.5%, 25%, 37.5%, and 50%), the discharge efficiency
decreased as the amount of blockage increased with different grate blockage by (17.8%, 19.3%, 21%,
and 24.6%), respectively.
Keywords: storm grate; pipe blockage; drainage system; discharge efficiency; surface flow
1. Introduction
Blocked storm network is the main element that affects system overall efficiency and has a negative
impact on the surrounding area. Storm network systems carry water from ranking water in grassy
areas and other places in which leaves, twigs, pebbles, and soil can get washed through the grate
inlets of a storm system and potentially block the outlet pipe or actually fill up the catch basin itself.
Material items can appear on top of the grating and stop water flowing through the slats of grate inlet;
a different blockage view can be seen in Figure 1. Thus, the efficiency of drainage system will decrease,
so that storm drain checks and sometimes routine maintenance is needed on a semi-regular or annual
basis. In fact, just checking and removing a foreign object from the grate is needed to keep a storm
network working at 100% efficiency.
Water 2020,12, 1974; doi:10.3390/w12071974 www.mdpi.com/journal/water
Water 2020,12, 1974 2 of 20
Water 2020, 12, x FOR PEER REVIEW 3 of 20
coefficient is solely dependent on the dimensionless drop parameter for free surface outflow without
a downstream backwater effect. Based on experimental results, empirical equations for different
outflow conditions are proposed for practical applications.
Several studies used the dimensional analysis technique to get the empirical equations that relate
their studied parameters together; see Čarnogurská et al. (2016) [15], Zeleňáková et al. (2012) [16] and
Zeleňáková et al. (2013) [17].
Tu and Traver (2018) [18] used ANCOVA (Analysis of Covariance) to inspect the clogging
influence with flow rate plotted next to the actual pipe length times the square root of the mean
pressure head and found that it was important during little or no rainfall. During larger storms,
clogging had a slight effect on pipe performance because larger storms might also move the debris,
thus exposing the orifices. The study concluded that the recent maintenance schedule was adequate
to keep the distribution pipe at an acceptable performance even though partial clogging can exist.
Vani et al. (2019) [19] presented a plan for using flow sensor and ultrasonic sensor in pipe
network system to detect leakage and overflow, respectively, with the help of Wireless Sensor
Network (WSN) which is based on ZigBee technology and Internet of Things (IOT). The system
problem, which can be detected by an alert, is sent through the mobile app to the authorities in the
Municipal Corporation prior overflow or any blockage to avoid leakage.
Hesarkazzazi et al. (2020) [20] elaborated on the significance of owning severance (e.g., different
flow paths as in loops) under simultaneous hydraulic design in storm networks. An innovative
approach based on complex network properties is introduced to analytically and sequentially
minimize the number of loops and, therefore, the level of redundancy, from a given grid-like (street)
network. A procedure based on hydrodynamic modelling is utilized to find the ideal design costs for
all shaped structures while satisfying a number of hydraulic design limitations. The results indicated
that having loop and introducing extra capacity without determining suitable added pipes positions
in the system (flow direction) can even worsen the efficiency of water discharge.
This paper aims to study the effect of blockage ratio on the efficiency of storm drainage systems.
Three scenarios were considered through this study. The first scenario studied the effect of pipe
blockage for two ratios (the first at the end of pipe and the second along the pipe). The second scenario
studied the effect of surface blockage at grate inlets. The third scenario investigated the effect of
combined blockage (pipe and grate blockage). Finally, an empirical equation was created to calculate
system efficiency as s function of blockage ratio and system discharge.
(A)
(B)
Figure 1.
Different ratios of blockage. (
A
) blockage through grate cover (
B
) blockage through storm
pipes https://www.alamy.com/stock-photo/blocked-drain.html (2019).
Woo and Jones (1974) [
1
] carried out experiments to make suggestions on both the hydraulic
capacity and safety of the inlets for bicycle riders by trying inlets with different tilting angles.
Forbes (1976) [
2
] presented a numerical procedure to calculate the flow into both depressed and
under-pressed curb inlets. Assuming steady flow, he divided the flow field into several intermediate
cross-sections and studied the flow over a succession of short intervals for which the flow conditions
could be assumed to remain constant. At the end of each time step, the quantity, direction, and velocity
of the flow at each cross-section were recomputed. In this way, he was able to calculate the amount of
water that flowed over the inlet lip between cross-sections.
Hotchkiss (1994) [
3
] and Soares (1991) [
4
] studied the effects of altering a curb inlet’s entrance and
exit transitions with the hope of improving inlet efficiency. Their experiments tested several sharp
and smooth entrance and exit transitions, yet none had any significant effects on inlet efficiency or
reducing the oblique standing wave. Pezzaniti et al. (1999) [
5
] presented an investigation on street
hydraulic capacity. It was found that the street storm water capacity at a sump is in fact dictated by the
storage capacity rather than the conveyance capacity.
Russo and G
ó
mez (2009) [
6
] studied experimentally four types of grates found typically in Spain
and differing in the alignment and distribution of the slots, under different longitudinal slopes and
five approaching flows. They formulated four linear relations, one for each grating type, which link
the hydraulic efficiency to some particular flow conditions (Froude number and water depth) and
the grating length. The efficiency of Portuguese gullies was numerically studied by Patil and Patil
(2011) [
7
]. Talking about effects of bad drainage on roads, they explained that the effect of poor drainage
condition on roads is very adverse. It causes the failure of the road in different ways. A proper drainage
system provided to the road increases its life, but an improper drainage system causes the failure of
the road at its early age.
Water 2020,12, 1974 3 of 20
Comport and Thornton (2012) [
8
] examined a curb inlet and two combination inlets in accordance
with the different road conditions by means of designing a one-third Froude-scale model of a two-lane
road section, and they developed equations for practical applications.
Beniamino et al. (2013) [
9
] studied the hydraulic efficiency of continuous transverse grates, despite
the importance and the general use of this type of surface drainage structure. They used flume with
dimension 1.5 m wide and 5.5 m long with a platform able to simulate road lanes with transverse
slopes up to 4% and a longitudinal slope up to 10%. With the available system capacity, it is possible to
test inlet grates and study their hydraulic capacity for a large set of flows (0–200 L
\
s). Linear equations
relating to hydraulic efficiency, E, and Froude number, F, were presented.
Sezenöz et al. (2014) [
10
] conducted a numerical study to analyze a recently planned grated inlet
system for small roads. For this reason, Flow 3D software was used to model the physical conditions of
the setup including a rectangular channel of 0.9 meters’ width and continuous transverse grate system,
which was located based on the setup. The results obtained in this study were compared with the
previous ones that had been based on the experimental data collection.
Cumhur et al. (2015) [
11
] observed that there is a close interdependence between the total flow
rate and the grate efficiency. The results indicate that hydraulic efficiency increases when the total
flow increases as well. Nevertheless, after a certain point, degradation of efficiency occurs despite
the progressing increase in the total flow rate. Grate opening areas ratio is taken into consideration;
the inlet having 1 cm bars and 2 cm spacing is hydraulically the most efficient grate, and it corresponds
to an opening area ratio of 49.5%. Hydraulic performance of the grate systems and the corresponding
grate efficiency is influenced by various configurations of the grates such as location, number of grates,
and the distance between the two successive grate inlets.
Manuel et al. (2016) [
12
] studied grate efficiency numerically and experimentally. The results
indicate that the comparison is acceptable in most cases. Therefore, inlet grates that cannot be tested
in a laboratory can be studied with the 3D model, to approach its efficiency. Veerappan R. and Le
(2016) [
13
] studied the effect of different type of grates on the hydraulic efficiencies in terms of flow
interception by using a network of overhanging pipes. The results indicated that the existing grate
inlet designs can intercept up to 96% of the surface run-off. Feidong et al. (2017) [
14
] found that drop
manholes are effective energy dissipaters widely employed in urban drainage networks. The hydraulic
performance of circular manholes was investigated experimentally concerning their energy dissipation
in three models of different drop heights. It was concluded that the local head loss coefficient is
solely dependent on the dimensionless drop parameter for free surface outflow without a downstream
backwater effect. Based on experimental results, empirical equations for different outflow conditions
are proposed for practical applications.
Several studies used the dimensional analysis technique to get the empirical equations that relate
their studied parameters together; see ˇ
Carnogursk
á
et al. (2016) [
15
], Zeleˇn
á
kov
á
et al. (2012) [
16
] and
Zeleˇnákováet al. (2013) [17].
Tu and Traver (2018) [
18
] used ANCOVA (Analysis of Covariance) to inspect the clogging influence
with flow rate plotted next to the actual pipe length times the square root of the mean pressure head
and found that it was important during little or no rainfall. During larger storms, clogging had a
slight effect on pipe performance because larger storms might also move the debris, thus exposing
the orifices. The study concluded that the recent maintenance schedule was adequate to keep the
distribution pipe at an acceptable performance even though partial clogging can exist.
Vani et al. (2019) [
19
] presented a plan for using flow sensor and ultrasonic sensor in pipe network
system to detect leakage and overflow, respectively, with the help of Wireless Sensor Network (WSN)
which is based on ZigBee technology and Internet of Things (IOT). The system problem, which can be
detected by an alert, is sent through the mobile app to the authorities in the Municipal Corporation
prior overflow or any blockage to avoid leakage.
Hesarkazzazi et al. (2020) [
20
] elaborated on the significance of owning severance (e.g., different
flow paths as in loops) under simultaneous hydraulic design in storm networks. An innovative
Water 2020,12, 1974 4 of 20
approach based on complex network properties is introduced to analytically and sequentially minimize
the number of loops and, therefore, the level of redundancy, from a given grid-like (street) network.
A procedure based on hydrodynamic modelling is utilized to find the ideal design costs for all shaped
structures while satisfying a number of hydraulic design limitations. The results indicated that having
loop and introducing extra capacity without determining suitable added pipes positions in the system
(flow direction) can even worsen the efficiency of water discharge.
This paper aims to study the effect of blockage ratio on the efficiency of storm drainage systems.
Three scenarios were considered through this study. The first scenario studied the effect of pipe
blockage for two ratios (the first at the end of pipe and the second along the pipe). The second scenario
studied the effect of surface blockage at grate inlets. The third scenario investigated the effect of
combined blockage (pipe and grate blockage). Finally, an empirical equation was created to calculate
system efficiency as s function of blockage ratio and system discharge.
2. Materials and Methods
2.1. Dimensional Analysis
Dimensional analysis based on Buckingham (1914) [
21
] theory is used to develop a functional
relationship between the system efficiency (£), which is the “ratio of intercepted discharge and total
discharge through the flume”, and the other physics quantities involved in the phenomenon as shown
in Figures 2–4. Figure 2shows the horizontal plan of the flume, arrangement of grates and spread
width of water along flume length. Longitudinal section of flume and main pipe system can be seen in
Figure 3. Blockages through grate and pipe (end pipe blockage and through pipe length) can be seen
in Figure 4. By applying the Buckingham theory, Equation (1) can be written in dimensionless form as:
£=ƒ (Q, Lo, Wo, Hg, HB, LB, AB) (1)
in which
hg: water depth at upstream grate; Q: the total inlet discharge;
g1, g3, g5: refers to the grate’s number; £: efficiency of discharge =(q/Q);
nag: net area of grate; L: the length of the flume;
ab: blockage area of grate; Lg: the length from the beginning of flume to the grate;
AB: relative blockage area (ab/nag); Lo: relative grate length =(Lg/L);
hU: water depth at flume upstream; hb: height of blockage;
Hg: relative water height =hg/hU; rp: radius of main pipe;
Wg: the water spread beside every grate; HB: relative blockage height within pipe (hb/2rp);
W: the flume width; Lb: length of blockage;
Wo: relative water spread width =(Wg/W); Lp: length of main pipe;
q: intercepted discharge; LB: relative blockage length within pipe (Lb/Lp).
Water 2020, 12, x FOR PEER REVIEW 4 of 20
2. Materials and Methods
2.1. Dimensional Analysis
Dimensional analysis based on Buckingham (1914) [21] theory is used to develop a functional
relationship between the system efficiency (£), which is the “ratio of intercepted discharge and total
discharge through the flume”, and the other physics quantities involved in the phenomenon as
shown in Figures 2, 3, and 4. Figure 2 shows the horizontal plan of the flume, arrangement of grates
and spread width of water along flume length. Longitudinal section of flume and main pipe system
can be seen in Figure 3. Blockages through grate and pipe (end pipe blockage and through pipe
length) can be seen in Figure 4. By applying the Buckingham theory, Equation (1) can be written in
dimensionless form as:
£ = ƒ (Q, Lo, Wo, Hg, HB, LB, AB) (1)
in which
hg : water depth at upstream grate; Q: the total inlet discharge;
g1, ,g3, ,g5: refers to the grate’s number; £: efficiency of discharge = (q/Q);
nag: net area of grate; L: the length of the flume;
ab: blockage area of grate; Lg: the length from the beginning of flume to the grate;
AB: relative blockage area (ab /nag); Lo: relative grate length = (Lg/L);
hU : water depth at flume upstream; hb: height of blockage;
Hg: relative water height = hg/hU; rp: radius of main pipe;
Wg: the water spread beside every grate; HB: relative blockage height within pipe (hb /2rp);
W: the flume width; Lb: length of blockage;
Wo: relative water spread width = (Wg/W); Lp: length of main pipe;
q: intercepted discharge; LB: relative blockage length within pipe (Lb /Lp).
Figure 2. Plan of flume and arrangement of grates.
Figure 3. Longitudinal cross section of flume and main pipe system.
Figure 2. Plan of flume and arrangement of grates.
Water 2020,12, 1974 5 of 20
Water 2020, 12, x FOR PEER REVIEW 4 of 20
2. Materials and Methods
2.1. Dimensional Analysis
Dimensional analysis based on Buckingham (1914) [21] theory is used to develop a functional
relationship between the system efficiency (£), which is the “ratio of intercepted discharge and total
discharge through the flume”, and the other physics quantities involved in the phenomenon as
shown in Figures 2, 3, and 4. Figure 2 shows the horizontal plan of the flume, arrangement of grates
and spread width of water along flume length. Longitudinal section of flume and main pipe system
can be seen in Figure 3. Blockages through grate and pipe (end pipe blockage and through pipe
length) can be seen in Figure 4. By applying the Buckingham theory, Equation (1) can be written in
dimensionless form as:
£ = ƒ (Q, Lo, Wo, Hg, HB, LB, AB) (1)
in which
hg : water depth at upstream grate; Q: the total inlet discharge;
g1, ,g3, ,g5: refers to the grate’s number; £: efficiency of discharge = (q/Q);
nag: net area of grate; L: the length of the flume;
ab: blockage area of grate; Lg: the length from the beginning of flume to the grate;
AB: relative blockage area (ab /nag); Lo: relative grate length = (Lg/L);
hU : water depth at flume upstream; hb: height of blockage;
Hg: relative water height = hg/hU; rp: radius of main pipe;
Wg: the water spread beside every grate; HB: relative blockage height within pipe (hb /2rp);
W: the flume width; Lb: length of blockage;
Wo: relative water spread width = (Wg/W); Lp: length of main pipe;
q: intercepted discharge; LB: relative blockage length within pipe (Lb /Lp).
Figure 2. Plan of flume and arrangement of grates.
Figure 3. Longitudinal cross section of flume and main pipe system.
Figure 3. Longitudinal cross section of flume and main pipe system.
Water 2020, 12, x FOR PEER REVIEW 5 of 20
Figure 4. Definition sketch for blockage through pipe and grate.
2.2. Experimental Work
The experimental work was carried out in the hydraulics and water engineering laboratory,
Faculty of Engineering, Zagazig University. The Flume was made from glass reinforced plastic. The
dimension of this flume is 0.63 m width, 0.10m depth, and 6.00m length as shown in Figure 5. The
longitudinal slope and cross-section slope were 0.3% and 2%, respectively. The total discharge is
measured using a pre-calibrated orifice meter. The point gauge with mobile bed was used for
measuring the water depths. There were three grates at the bottom of the flume through a distance
of 1.08 m, which was far away from the edge of flume (2 cm). The grates are connected by a pipe with
a diameter of 5 cm through which it has disposal to a large tank with dimensions 1.20, 0.60, and 0.60
m, as shown in Figure 6. In addition, the radius of grate was 5cm with net area 51%. Blockage of
grates with various dimensions will be investigated. Moreover, the end of pipe blockage with height
0.75, 1.5, 2.5, 3.5, and 4.5 cm was studied as shown in Figure 7, as well as blockage along the main
pipe at three lengths (108, 216, and 324 cm) with blockage height (1.25 and 2.5cm). On the other hand,
surface blockage was examined for a different blockage area of grates (12.5%, 25%, 37.5%, and 50%),
as shown in Figure 8. A total of of 156 runs were done; each run took 30 minutes time. Water surface
level along the flume in two directions and the amount of water that drained from grates are
measured.
Figure 5. The flume of experimental tests.
Figure 4. Definition sketch for blockage through pipe and grate.
2.2. Experimental Work
The experimental work was carried out in the hydraulics and water engineering laboratory, Faculty
of Engineering, Zagazig University. The Flume was made from glass reinforced plastic. The dimension
of this flume is 0.63 m width, 0.10m depth, and 6.00m length as shown in Figure 5. The longitudinal
slope and cross-section slope were 0.3% and 2%, respectively. The total discharge is measured using
a pre-calibrated orifice meter. The point gauge with mobile bed was used for measuring the water
depths. There were three grates at the bottom of the flume through a distance of 1.08 m, which was
far away from the edge of flume (2 cm). The grates are connected by a pipe with a diameter of 5 cm
through which it has disposal to a large tank with dimensions 1.20, 0.60, and 0.60 m, as shown in
Figure 6. In addition, the radius of grate was 5cm with net area 51%. Blockage of grates with various
dimensions will be investigated. Moreover, the end of pipe blockage with height 0.75, 1.5, 2.5, 3.5,
and 4.5 cm was studied as shown in Figure 7, as well as blockage along the main pipe at three lengths
(108, 216, and 324 cm) with blockage height (1.25 and 2.5cm). On the other hand, surface blockage was
examined for a different blockage area of grates (12.5%, 25%, 37.5%, and 50%), as shown in Figure 8.
A total of of 156 runs were done; each run took 30 min time. Water surface level along the flume in
two directions and the amount of water that drained from grates are measured.
Water 2020, 12, x FOR PEER REVIEW 5 of 20
Figure 4. Definition sketch for blockage through pipe and grate.
2.2. Experimental Work
The experimental work was carried out in the hydraulics and water engineering laboratory,
Faculty of Engineering, Zagazig University. The Flume was made from glass reinforced plastic. The
dimension of this flume is 0.63 m width, 0.10m depth, and 6.00m length as shown in Figure 5. The
longitudinal slope and cross-section slope were 0.3% and 2%, respectively. The total discharge is
measured using a pre-calibrated orifice meter. The point gauge with mobile bed was used for
measuring the water depths. There were three grates at the bottom of the flume through a distance
of 1.08 m, which was far away from the edge of flume (2 cm). The grates are connected by a pipe with
a diameter of 5 cm through which it has disposal to a large tank with dimensions 1.20, 0.60, and 0.60
m, as shown in Figure 6. In addition, the radius of grate was 5cm with net area 51%. Blockage of
grates with various dimensions will be investigated. Moreover, the end of pipe blockage with height
0.75, 1.5, 2.5, 3.5, and 4.5 cm was studied as shown in Figure 7, as well as blockage along the main
pipe at three lengths (108, 216, and 324 cm) with blockage height (1.25 and 2.5cm). On the other hand,
surface blockage was examined for a different blockage area of grates (12.5%, 25%, 37.5%, and 50%),
as shown in Figure 8. A total of of 156 runs were done; each run took 30 minutes time. Water surface
level along the flume in two directions and the amount of water that drained from grates are
measured.
Figure 5. The flume of experimental tests.
Figure 5. The flume of experimental tests.
Water 2020,12, 1974 6 of 20
Water 2020, 12, x FOR PEER REVIEW 6 of 20
Figure 6. The outfall of the experimental flume.
Figure 7. Different blockage heights at the end of pipe.
Figure 8. Different sizes of grate blockage. (A) surface blockage 12.50%, (B) surface blockage 25%,
(C) surface blockage 37.50%, (D) surface blockage 50%,
3. Results and Discussion
The experimental work studied the effect of blockage on storm water drainage system efficiency
with passing discharge from (1.00 L/sec to 6.00 L/sec). The scenario of this study was divided into
three groups. Each group has been studied to see its effect on storm system efficiency, relative grate
water height, and relative water spread width. The first scenario studied the effect of main pipe
blockage for two ratios (the first at the pipe end and the second along the pipe length with end pipe
blockage). The second scenario studied the effect of surface blockage at grate. The third scenario
investigated the effect of combined blockage (pipe and grate) on the efficiency of storm discharge.
Finally, a comparison was made between previous blockage ratios to study their effect in reducing
discharge efficiency.
(A) (B) (C) (D)
Figure 6. The outfall of the experimental flume.
Water 2020, 12, x FOR PEER REVIEW 6 of 20
Figure 6. The outfall of the experimental flume.
Figure 7. Different blockage heights at the end of pipe.
Figure 8. Different sizes of grate blockage. (A) surface blockage 12.50%, (B) surface blockage 25%,
(C) surface blockage 37.50%, (D) surface blockage 50%,
3. Results and Discussion
The experimental work studied the effect of blockage on storm water drainage system efficiency
with passing discharge from (1.00 L/sec to 6.00 L/sec). The scenario of this study was divided into
three groups. Each group has been studied to see its effect on storm system efficiency, relative grate
water height, and relative water spread width. The first scenario studied the effect of main pipe
blockage for two ratios (the first at the pipe end and the second along the pipe length with end pipe
blockage). The second scenario studied the effect of surface blockage at grate. The third scenario
investigated the effect of combined blockage (pipe and grate) on the efficiency of storm discharge.
Finally, a comparison was made between previous blockage ratios to study their effect in reducing
discharge efficiency.
(A) (B) (C) (D)
Figure 7. Different blockage heights at the end of pipe.
Water 2020, 12, x FOR PEER REVIEW 6 of 20
Figure 6. The outfall of the experimental flume.
Figure 7. Different blockage heights at the end of pipe.
Figure 8. Different sizes of grate blockage. (A) surface blockage 12.50%, (B) surface blockage 25%,
(C) surface blockage 37.50%, (D) surface blockage 50%,
3. Results and Discussion
The experimental work studied the effect of blockage on storm water drainage system efficiency
with passing discharge from (1.00 L/sec to 6.00 L/sec). The scenario of this study was divided into
three groups. Each group has been studied to see its effect on storm system efficiency, relative grate
water height, and relative water spread width. The first scenario studied the effect of main pipe
blockage for two ratios (the first at the pipe end and the second along the pipe length with end pipe
blockage). The second scenario studied the effect of surface blockage at grate. The third scenario
investigated the effect of combined blockage (pipe and grate) on the efficiency of storm discharge.
Finally, a comparison was made between previous blockage ratios to study their effect in reducing
discharge efficiency.
(A) (B) (C) (D)
Figure 8.
Different sizes of grate blockage. (
A
) surface blockage 12.50%, (
B
) surface blockage 25%,
(C) surface blockage 37.50%, (D) surface blockage 50%.
3. Results and Discussion
The experimental work studied the effect of blockage on storm water drainage system efficiency
with passing discharge from (1.00 L/sec to 6.00 L/sec). The scenario of this study was divided into three
groups. Each group has been studied to see its effect on storm system efficiency, relative grate water
height, and relative water spread width. The first scenario studied the effect of main pipe blockage
for two ratios (the first at the pipe end and the second along the pipe length with end pipe blockage).
The second scenario studied the effect of surface blockage at grate. The third scenario investigated the
effect of combined blockage (pipe and grate) on the efficiency of storm discharge. Finally, a comparison
was made between previous blockage ratios to study their effect in reducing discharge efficiency.
Water 2020,12, 1974 7 of 20
3.1. First Group: Blockage in Storm Main Pipe
The effect of blockage was investigated within two ratios. The first ratio at the end of main pipe
had five relative blockage heights (15%, 30%, 50%, 70%, and 90%). The second ratio was along the
main pipe and had relative blockage length (33%, 67%, and 100%) with two relative blockage heights
(25%, and 50%).
3.1.1. End Pipe Blockage
The blockage was investigated at the end of the main pipe with five different relative heights
(15%, 30%, 50%, 70%, and 90%). In general, the negative effect on the efficiency of discharge increased
by increasing the relative height of the blockage. This can be explained by the pre-obstruction zone
becoming a dead zone once it is filled with water. Reducing the size of the pipe needed to discharge the
water has an effect on drainage efficiency. Figure 9shows the end pipe blockage in experimental work,
which indicates the minimized disposal area. Figure 10 shows the relationship between efficiency of
system and passing discharge, using 5 relative blockage heights. From this figure, it was concluded
that as the relative blockage height increased by 90%, the efficiency of the system decreased by (46.5%).
Moreover, the effect of blockage-relative heights (15%, 30%) on efficiency was not very impressive.
Water 2020, 12, x FOR PEER REVIEW 7 of 20
3.1. First Group: Blockage in Storm Main Pipe
The effect of blockage was investigated within two ratios. The first ratio at the end of main pipe
had five relative blockage heights (15%, 30%, 50%, 70%, and 90%). The second ratio was along the
main pipe and had relative blockage length (33%, 67%, and 100%) with two relative blockage heights
(25%, and 50%).
3.1.1. End Pipe Blockage
The blockage was investigated at the end of the main pipe with five different relative heights
(15%, 30%, 50%, 70%, and 90%). In general, the negative effect on the efficiency of discharge increased
by increasing the relative height of the blockage. This can be explained by the pre-obstruction zone
becoming a dead zone once it is filled with water. Reducing the size of the pipe needed to discharge
the water has an effect on drainage efficiency. Figure 9 shows the end pipe blockage in experimental
work, which indicates the minimized disposal area. Figure 10 shows the relationship between
efficiency of system and passing discharge, using 5 relative blockage heights. From this figure, it was
concluded that as the relative blockage height increased by 90%, the efficiency of the system
decreased by (46.5%). Moreover, the effect of blockage-relative heights (15%, 30%) on efficiency was
not very impressive.
Figure 9. End pipe blockage with HB = 90%.
Figure 10. Relationship between £ and Q for different relative blockage heights.
The water depth along the flume was measured at upstream each grate to investigate the effect
of end pipe blockage on water surface profile and redistribution of water along the flume. Figures 11
and 12 show the relationship between relative grate water depth and relative grate length with
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
00.511.522.533.544.555.566.57
£
Q (L/S)
without pipe end b lockage
pipe end blockage 15%
pipe end blockage 30%
pipe end blockage 50%
pipe end blockage 70%
pipe end blockage 90%
Figure 9. End pipe blockage with HB =90%.
Water 2020, 12, x FOR PEER REVIEW 7 of 20
3.1. First Group: Blockage in Storm Main Pipe
The effect of blockage was investigated within two ratios. The first ratio at the end of main pipe
had five relative blockage heights (15%, 30%, 50%, 70%, and 90%). The second ratio was along the
main pipe and had relative blockage length (33%, 67%, and 100%) with two relative blockage heights
(25%, and 50%).
3.1.1. End Pipe Blockage
The blockage was investigated at the end of the main pipe with five different relative heights
(15%, 30%, 50%, 70%, and 90%). In general, the negative effect on the efficiency of discharge increased
by increasing the relative height of the blockage. This can be explained by the pre-obstruction zone
becoming a dead zone once it is filled with water. Reducing the size of the pipe needed to discharge
the water has an effect on drainage efficiency. Figure 9 shows the end pipe blockage in experimental
work, which indicates the minimized disposal area. Figure 10 shows the relationship between
efficiency of system and passing discharge, using 5 relative blockage heights. From this figure, it was
concluded that as the relative blockage height increased by 90%, the efficiency of the system
decreased by (46.5%). Moreover, the effect of blockage-relative heights (15%, 30%) on efficiency was
not very impressive.
Figure 9. End pipe blockage with HB = 90%.
Figure 10. Relationship between £ and Q for different relative blockage heights.
The water depth along the flume was measured at upstream each grate to investigate the effect
of end pipe blockage on water surface profile and redistribution of water along the flume. Figures 11
and 12 show the relationship between relative grate water depth and relative grate length with
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
00.511.522.533.544.555.566.57
£
Q (L/S)
without pipe end b lockage
pipe end blockage 15%
pipe end blockage 30%
pipe end blockage 50%
pipe end blockage 70%
pipe end blockage 90%
Figure 10. Relationship between £ and Q for different relative blockage heights.
Water 2020,12, 1974 8 of 20
The water depth along the flume was measured at upstream each grate to investigate the effect of
end pipe blockage on water surface profile and redistribution of water along the flume. Figures 11
and 12 show the relationship between relative grate water depth and relative grate length with different
relative blockage heights using three grates at passing discharge (1.20 and 6.00 L/sec), respectively.
These figures show that as relative blockage height increased, the water surface profile was increased
along the flume due to the negative effect on the drainage efficiency. In addition, relative blockage
height, 90%, was the worst one, which increased the relative grate water depth by (16% and 19%) for
discharges (1.20 and 3.30 L/sec), respectively.
Water 2020, 12, x FOR PEER REVIEW 8 of 20
different relative blockage heights using three grates at passing discharge (1.20 and 6.00 L/sec),
respectively. These figures show that as relative blockage height increased, the water surface profile
was increased along the flume due to the negative effect on the drainage efficiency. In addition,
relative blockage height, 90%, was the worst one, which increased the relative grate water depth by
(16% and 19%) for discharges (1.20 and 3.30L/ sec), respectively.
Figure 11. Relationship between Hg and LO for different relative blockage heights at Q = 1.20L/sec.
Figure 12. Relationship between Hg and LO for different relative blockage heights at Q = 3.30L/sec.
Moreover, the water spread width was observed along the flume according to end pipe blockage
Figures 13 and 14 show the relationship between relative water spread width and relative grates
distance for various relative blockage heights at passing discharge 1.00 L/sec and 1.20 L/sec,
respectively. The relative water spread width tends to increase at higher blockage height by about
16% and 21% at Q = 1.00 L/sec and Q = 1.20 L/sec, respectively. Based on the figures below, it can be
concluded that the small relative blockage height has minimal impact on the relative water spread
width.
30%
40%
50%
60%
70%
80%
90%
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1. 00
H
g
Lo (grate position)
Witho ut pipe en d blockage
Pipe end blockage =15%
Pipe end blockage=30%
Pipe end blockage =50%
Pipe end blockage= 70%
Pipe end blockage=90%
Lo = 23% Lo=48% % Lo=74% Lo
g1 Ig2 I4 g3
I6
20%
30%
40%
50%
60%
70%
80%
90%
0.00 0.10 0. 20 0.30 0. 40 0.50 0.60 0. 70 0.80 0.90 1. 00
H
g
Lo (grate position)
Without pipe end blockage
Pipe end blockage =15%
Pipe end blockage=30%
Pipe end blockage =50%
Pipe end blockage= 70%
Pipe end blockage=90%
Lo = 23% Lo=48% % Lo=74% Lo
g1 Ig2 I4 g3
I6
Figure 11. Relationship between Hg and LO for different relative blockage heights at Q =1.20 L/sec.
Water 2020, 12, x FOR PEER REVIEW 8 of 20
different relative blockage heights using three grates at passing discharge (1.20 and 6.00 L/sec),
respectively. These figures show that as relative blockage height increased, the water surface profile
was increased along the flume due to the negative effect on the drainage efficiency. In addition,
relative blockage height, 90%, was the worst one, which increased the relative grate water depth by
(16% and 19%) for discharges (1.20 and 3.30L/ sec), respectively.
Figure 11. Relationship between Hg and LO for different relative blockage heights at Q = 1.20L/sec.
Figure 12. Relationship between Hg and LO for different relative blockage heights at Q = 3.30L/sec.
Moreover, the water spread width was observed along the flume according to end pipe blockage
Figures 13 and 14 show the relationship between relative water spread width and relative grates
distance for various relative blockage heights at passing discharge 1.00 L/sec and 1.20 L/sec,
respectively. The relative water spread width tends to increase at higher blockage height by about
16% and 21% at Q = 1.00 L/sec and Q = 1.20 L/sec, respectively. Based on the figures below, it can be
concluded that the small relative blockage height has minimal impact on the relative water spread
width.
30%
40%
50%
60%
70%
80%
90%
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1. 00
H
g
Lo (grate position)
Witho ut pipe en d blockage
Pipe end blockage =15%
Pipe end blockage=30%
Pipe end blockage =50%
Pipe end blockage= 70%
Pipe end blockage=90%
Lo = 23% Lo=48% % Lo=74% Lo
g1 Ig2 I4 g3
I6
20%
30%
40%
50%
60%
70%
80%
90%
0.00 0.10 0. 20 0.30 0. 40 0.50 0.60 0. 70 0.80 0.90 1. 00
H
g
Lo (grate position)
Without pipe end blockage
Pipe end blockage =15%
Pipe end blockage=30%
Pipe end blockage =50%
Pipe end blockage= 70%
Pipe end blockage=90%
Lo = 23% Lo=48% % Lo=74% Lo
g1 Ig2 I4 g3
I6
Figure 12. Relationship between Hg and LO for different relative blockage heights at Q =3.30 L/sec.
Moreover, the water spread width was observed along the flume according to end pipe blockage
Figures 13 and 14 show the relationship between relative water spread width and relative grates
distance for various relative blockage heights at passing discharge 1.00 L/sec and 1.20 L/sec, respectively.
The relative water spread width tends to increase at higher blockage height by about 16% and 21% at
Q=1.00 L/sec and Q =1.20 L/sec, respectively. Based on the figures below, it can be concluded that the
small relative blockage height has minimal impact on the relative water spread width.
Water 2020,12, 1974 9 of 20
Water 2020, 12, x FOR PEER REVIEW 9 of 20
Figure 13. Relationship between WO and LO for different relative blockage heights at Q = 1.00L/sec.
Figure 14. Relationship between WO and LO for different relative blockage heights at Q = 1.20 L/sec.
3.1.2. Effect of Blockage along the Pipe Length
The effects of different blockages along the main pipe with three relative lengths (33%, 67%, and
100%) combined with two relative blockage heights (25% and 50%) was investigated. Figure 15
indicates the blockage along pipe length and end pipe blockage.
Figure 15. (A) The blockage along main pipe length and (B) end pipe blockage.
40%
50%
60%
70%
80%
90%
0.00 0.50 1.00
W
o
L
o (grate position)
Without pipe end blockage
pipe end blockage15%
Pipe end blockage=30%
Pipe end blockage=50%
Pipe end blockage=70%
Pipe end blockage 90%
Lo = 23% Lo=4 8% Lo= 74% Lo
g1 Ig2 g3 I6
50%
60%
70%
80%
90%
100%
0.00 0.25 0. 50 0.75 1.00
W
o
L
o (grate position)
Without pipe end blockage
pipe end blockage15%
Pipe end blockage=30%
Pipe end blockage=50%
Pipe end blockage=70%
Pipe end blockage 90%
Lo = 23% Lo=48% % Lo=74% Lo
g1 Ig2 I4 g3 I6
(A) (B)
Figure 13. Relationship between WO and LO for different relative blockage heights at Q =1.00 L/sec.
Water 2020, 12, x FOR PEER REVIEW 9 of 20
Figure 13. Relationship between WO and LO for different relative blockage heights at Q = 1.00L/sec.
Figure 14. Relationship between WO and LO for different relative blockage heights at Q = 1.20 L/sec.
3.1.2. Effect of Blockage along the Pipe Length
The effects of different blockages along the main pipe with three relative lengths (33%, 67%, and
100%) combined with two relative blockage heights (25% and 50%) was investigated. Figure 15
indicates the blockage along pipe length and end pipe blockage.
Figure 15. (A) The blockage along main pipe length and (B) end pipe blockage.
40%
50%
60%
70%
80%
90%
0.00 0.50 1.00
W
o
L
o (grate position)
Without pipe end blockage
pipe end blockage15%
Pipe end blockage=30%
Pipe end blockage=50%
Pipe end blockage=70%
Pipe end blockage 90%
Lo = 23% Lo=4 8% Lo= 74% Lo
g1 Ig2 g3 I6
50%
60%
70%
80%
90%
100%
0.00 0.25 0. 50 0.75 1.00
W
o
L
o (grate position)
Without pipe end blockage
pipe end blockage15%
Pipe end blockage=30%
Pipe end blockage=50%
Pipe end blockage=70%
Pipe end blockage 90%
Lo = 23% Lo=48% % Lo=74% Lo
g1 Ig2 I4 g3 I6
(A) (B)
Figure 14. Relationship between WO and LO for different relative blockage heights at Q =1.20 L/sec.
3.1.2. Effect of Blockage along the Pipe Length
The effects of different blockages along the main pipe with three relative lengths (33%, 67%,
and 100%) combined with two relative blockage heights (25% and 50%) was investigated. Figure 15
indicates the blockage along pipe length and end pipe blockage.
Figures 16 and 17 show the relationship between the discharge efficiency and passing discharge,
using relative blockage heights (25% and 50%) with different relative blockage lengths (33%, 67%,
and 100%). From these figures, it can be noted that with the increased relative blockage height,
the efficiency of discharge decreases for different relative blockage lengths. From these figures, it is
clear that the efficiency of discharge dropped about 4.8% to 8.1% with relative blockage heights of
25% and 50% respectively, due to the volume’s reduction of the main pipe. It is a matter of fact that
increasing the blockage length will automatically decrease the efficiency of discharge; the reduction in
efficiency is equal to about 1.6%, 3.1%, and 5.1%, for three relative lengths, respectively.
Water 2020,12, 1974 10 of 20
Water 2020, 12, x FOR PEER REVIEW 9 of 20
Figure 13. Relationship between WO and LO for different relative blockage heights at Q = 1.00L/sec.
Figure 14. Relationship between WO and LO for different relative blockage heights at Q = 1.20 L/sec.
3.1.2. Effect of Blockage along the Pipe Length
The effects of different blockages along the main pipe with three relative lengths (33%, 67%, and
100%) combined with two relative blockage heights (25% and 50%) was investigated. Figure 15
indicates the blockage along pipe length and end pipe blockage.
Figure 15. (A) The blockage along main pipe length and (B) end pipe blockage.
40%
50%
60%
70%
80%
90%
0.00 0.50 1.00
W
o
L
o (grate position)
Without pipe end blo cka ge
pipe end blocka ge15%
Pipe end blockage=30%
Pipe end blockage=50%
Pipe end blockage=70%
Pipe end blockage 90%
Lo = 23% Lo=4 8% Lo= 74% Lo
g1 Ig2 g3 I6
50%
60%
70%
80%
90%
100%
0.00 0.25 0. 50 0.75 1.00
W
o
L
o (grate position)
Without pipe end blockage
pipe end blockage15%
Pipe end blockage=30%
Pipe end blockage=50%
Pipe end blockage=70%
Pipe end blockage 90%
Lo = 23% Lo=48% % Lo=74% Lo
g1 Ig2 I4 g3 I6
(A) (B)
Figure 15. (A) The blockage along main pipe length and (B) end pipe blockage.
Water 2020, 12, x FOR PEER REVIEW 10 of 20
Figures 16 and 17 show the relationship between the discharge efficiency and passing discharge,
using relative blockage heights (25% and 50%) with different relative blockage lengths (33%, 67%,
and 100%). From these figures, it can be noted that with the increased relative blockage height, the
efficiency of discharge decreases for different relative blockage lengths. From these figures, it is clear
that the efficiency of discharge dropped about 4.8% to 8.1% with relative blockage heights of 25% and
50% respectively, due to the volume's reduction of the main pipe. It is a matter of fact that increasing
the blockage length will automatically decrease the efficiency of discharge; the reduction in efficiency
is equal to about 1.6%, 3.1%, and 5.1%, for three relative lengths, respectively.
Figure 16. Relationship between £ and Q for different LB with HB 25%.
Figure 17. Relationship between £ and Q for different LB with HB 50%.
The effect of pipe blockage on water surface profile was studied, as shown in Figures 18 and 19.
In general, as relative blockage ratio increased, the water surface profile increased within 5.50 % and
6.20% at Q = 6.00 L/sec, for relative blockage heights 25% and 50%, respectively.
20%
30%
40%
50%
60%
70%
80%
90%
00.511.522.533.544.555.566.57
£
Q (L/S)
without blockage
pipe blockage= 25% , L(b)= 33%
pipe blockage = 25% , L(b)= 67%
pipe blockage = 25% , L(b)= 100%
10%
20%
30%
40%
50%
60%
70%
80%
90%
00.511.522.533.544.555.566.57
£
Q (L/S)
without blockag e
pipe blockage= 50% , L(b)= 33%
pipe blockage = 50% , L(b)= 67%
pipe blockage = 50% , L(b)= 100%
Figure 16. Relationship between £ and Q for different LB with HB 25%.
Water 2020, 12, x FOR PEER REVIEW 10 of 20
Figures 16 and 17 show the relationship between the discharge efficiency and passing discharge,
using relative blockage heights (25% and 50%) with different relative blockage lengths (33%, 67%,
and 100%). From these figures, it can be noted that with the increased relative blockage height, the
efficiency of discharge decreases for different relative blockage lengths. From these figures, it is clear
that the efficiency of discharge dropped about 4.8% to 8.1% with relative blockage heights of 25% and
50% respectively, due to the volume's reduction of the main pipe. It is a matter of fact that increasing
the blockage length will automatically decrease the efficiency of discharge; the reduction in efficiency
is equal to about 1.6%, 3.1%, and 5.1%, for three relative lengths, respectively.
Figure 16. Relationship between £ and Q for different LB with HB 25%.
Figure 17. Relationship between £ and Q for different LB with HB 50%.
The effect of pipe blockage on water surface profile was studied, as shown in Figures 18 and 19.
In general, as relative blockage ratio increased, the water surface profile increased within 5.50 % and
6.20% at Q = 6.00 L/sec, for relative blockage heights 25% and 50%, respectively.
20%
30%
40%
50%
60%
70%
80%
90%
00.511.522.533.544.555.566.57
£
Q (L/S)
without blockage
pipe blockage= 25% , L(b)= 33%
pipe blockage = 25% , L(b)= 67%
pipe blockage = 25% , L(b)= 100%
10%
20%
30%
40%
50%
60%
70%
80%
90%
00.511.522.533.544.555.566.57
£
Q (L/S)
without blockag e
pipe blockage= 50% , L(b)= 33%
pipe blockage = 50% , L(b)= 67%
pipe blockage = 50% , L(b)= 100%
Figure 17. Relationship between £ and Q for different LB with HB 50%.
Water 2020,12, 1974 11 of 20
The effect of pipe blockage on water surface profile was studied, as shown in Figures 18 and 19.
In general, as relative blockage ratio increased, the water surface profile increased within 5.50 % and
6.20% at Q =6.00 L/sec, for relative blockage heights 25% and 50%, respectively.
1
18
Figure 18. Relationship between Hg and LO for different LB at HB 25% at Q =6.00 L/sec.
2
19
Figure 19. Relationship between Hg and LO for different LB at HB 50% at Q =6.00 L/sec.
On the other hand, Figures 20 and 21 show the relationship between relative water spread width
and relative grate distance, using different relative blockage heights (33%, 67%, and 100%) for relative
blockage heights (25% and 50%), respectively. The results indicated that as relative blockage height
increased, the relative width increased within 7.3% to 9.8% at Q =1.00 L/sec.
Water 2020,12, 1974 12 of 20
Water 2020, 12, x FOR PEER REVIEW 12 of 20
Figure 20. Relationship between WO and LO for different LB at HB 25% at Q = 1.00 L/sec.
Figure 21. Relationship between WO and LO for different LB at HB 50% at Q = 1.00 L/sec.
3.2. Second Group: Surface Blockage on Grate
Hydraulic efficiency was obtained for different ratios of surface blockage, as shown in Figure 22.
The effect of surface blockage on drainage efficiency was examined for different blockage areas of
grates (12.5%, 25%, 37.5%, and 50%).
Figure 22. Surface blockage.
30%
40%
50%
60%
70%
80%
0.00 0.50 1. 00
Wo
L
o (grate position)
NO BL OCKAGE
RBH=25%, RBL=33%
RBH=25%, RBL=67%
RBH=25%, RBL=100 %
Lo = 2 3% Lo=48% Lo=74% Lo
g1 g2 g3
I6
30%
40%
50%
60%
70%
80%
0.00 0.50 1. 00
W
o
L
o (grate position)
NO BLOCKAGE
RBH=50%, RBL=33%
RBH=50%, RBL=67%
RBH=50%, RBL=100%
Lo = 23% Lo=48% Lo=74% Lo
g1 g2 g3
I6
Figure 20. Relationship between WO and LO for different LB at HB 25% at Q =1.00 L/sec.
Water 2020, 12, x FOR PEER REVIEW 12 of 20
Figure 20. Relationship between WO and LO for different LB at HB 25% at Q = 1.00 L/sec.
Figure 21. Relationship between WO and LO for different LB at HB 50% at Q = 1.00 L/sec.
3.2. Second Group: Surface Blockage on Grate
Hydraulic efficiency was obtained for different ratios of surface blockage, as shown in Figure 22.
The effect of surface blockage on drainage efficiency was examined for different blockage areas of
grates (12.5%, 25%, 37.5%, and 50%).
Figure 22. Surface blockage.
30%
40%
50%
60%
70%
80%
0.00 0.50 1. 00
Wo
L
o (grate position)
NO BL OCKAGE
RBH=25%, RBL=33%
RBH=25%, RBL=67%
RBH=25%, RBL=100 %
Lo = 2 3% Lo=48% Lo=74% Lo
g1 g2 g3
I6
30%
40%
50%
60%
70%
80%
0.00 0.50 1. 00
W
o
L
o (grate position)
NO BLOCKAGE
RBH=50%, RBL=33%
RBH=50%, RBL=67%
RBH=50%, RBL=100%
Lo = 23% Lo=48% Lo=74% Lo
g1 g2 g3
I6
Figure 21. Relationship between WO and LO for different LB at HB 50% at Q =1.00 L/sec.
3.2. Second Group: Surface Blockage on Grate
Hydraulic efficiency was obtained for different ratios of surface blockage, as shown in Figure 22.
The effect of surface blockage on drainage efficiency was examined for different blockage areas of
grates (12.5%, 25%, 37.5%, and 50%).
Water 2020, 12, x FOR PEER REVIEW 12 of 20
Figure 20. Relationship between WO and LO for different LB at HB 25% at Q = 1.00 L/sec.
Figure 21. Relationship between WO and LO for different LB at HB 50% at Q = 1.00 L/sec.
3.2. Second Group: Surface Blockage on Grate
Hydraulic efficiency was obtained for different ratios of surface blockage, as shown in Figure 22.
The effect of surface blockage on drainage efficiency was examined for different blockage areas of
grates (12.5%, 25%, 37.5%, and 50%).
Figure 22. Surface blockage.
30%
40%
50%
60%
70%
80%
0.00 0.50 1. 00
Wo
L
o (grate position)
NO BL OCKAGE
RBH=25%, RBL=33%
RBH=25%, RBL=67%
RBH=25%, RBL=100 %
Lo = 2 3% Lo=48% Lo=74% Lo
g1 g2 g3
I6
30%
40%
50%
60%
70%
80%
0.00 0.50 1. 00
W
o
L
o (grate position)
NO BLOCKAGE
RBH=50%, RBL=33%
RBH=50%, RBL=67%
RBH=50%, RBL=100%
Lo = 23% Lo=48% Lo=74% Lo
g1 g2 g3
I6
Figure 22. Surface blockage.
Water 2020,12, 1974 13 of 20
Figure 23 shows the relationship between discharge efficiency and passing discharge for various
relative blockage areas of grates. It is obvious that by increasing surface blockage to 50% the efficiency
decreases by (17.9%).
Water 2020, 12, x FOR PEER REVIEW 13 of 20
Figures 23 shows the relationship between discharge efficiency and passing discharge for
various relative blockage areas of grates. It is obvious that by increasing surface blockage to 50% the
efficiency decreases by (17.9%)
Figure 23. Relationship between £ and Q for different surface blockages without pipe blockage.
3.3. Third Group: Combined Blockage (Pipe and Grate Blockage)
A combined grate and main pipe blockage was investigated. A comparison between no
blockage, grate blockage, and pipe blockage with relative height blockages of 25% and 50%,
combining various surface blockages (12.5%, 25%, 37.5%, and 50%) was shown in Figures 24 to 27.
From these figures, it is clear that the discharge efficiency decreased as the amount of blockage
increased with different grate blockages of 17.8%, 19.3%, 21%, and 24.6%, respectively. From the
previous discussion, the blockage on the grate’s screen reduces the capture of surface water as well
as the blockage within the main pipe reduces the size of the pipe needed for the transfer of excess
water, which negatively affects the efficiency of the drainage system.
Figure 24. Relationship between £ and Q for different ratios of blockage height at surface blockage
12.5%.
20%
30%
40%
50%
60%
70%
80%
90%
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7
£
Q (L/S)
scre en blockage 0 %
scre en blockage 1 2.5 %
scre en blockage 2 5%
scre en block age37.5%
scre en blockage 5 0%
20%
30%
40%
50%
60%
70%
80%
90%
11.522.533.544.555.566.57
£
Q(L/S)
pipe blockage 0% scr een blockage 0%
pipe blockage 0% scr een blockage 12.5%
pipe blockage 25% sc reen blockag e12.5%
pipe blockage 50% sc reen blockag e12.5%
Figure 23. Relationship between £ and Q for different surface blockages without pipe blockage.
3.3. Third Group: Combined Blockage (Pipe and Grate Blockage)
A combined grate and main pipe blockage was investigated. A comparison between no blockage,
grate blockage, and pipe blockage with relative height blockages of 25% and 50%, combining various
surface blockages (12.5%, 25%, 37.5%, and 50%) was shown in Figures 24–27. From these figures, it is
clear that the discharge efficiency decreased as the amount of blockage increased with different grate
blockages of 17.8%, 19.3%, 21%, and 24.6%, respectively. From the previous discussion, the blockage
on the grate’s screen reduces the capture of surface water as well as the blockage within the main
pipe reduces the size of the pipe needed for the transfer of excess water, which negatively affects the
efficiency of the drainage system.
Water 2020, 12, x FOR PEER REVIEW 13 of 20
Figures 23 shows the relationship between discharge efficiency and passing discharge for
various relative blockage areas of grates. It is obvious that by increasing surface blockage to 50% the
efficiency decreases by (17.9%)
Figure 23. Relationship between £ and Q for different surface blockages without pipe blockage.
3.3. Third Group: Combined Blockage (Pipe and Grate Blockage)
A combined grate and main pipe blockage was investigated. A comparison between no
blockage, grate blockage, and pipe blockage with relative height blockages of 25% and 50%,
combining various surface blockages (12.5%, 25%, 37.5%, and 50%) was shown in Figures 24 to 27.
From these figures, it is clear that the discharge efficiency decreased as the amount of blockage
increased with different grate blockages of 17.8%, 19.3%, 21%, and 24.6%, respectively. From the
previous discussion, the blockage on the grate’s screen reduces the capture of surface water as well
as the blockage within the main pipe reduces the size of the pipe needed for the transfer of excess
water, which negatively affects the efficiency of the drainage system.
Figure 24. Relationship between £ and Q for different ratios of blockage height at surface blockage
12.5%.
20%
30%
40%
50%
60%
70%
80%
90%
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7
£
Q (L/S)
scre en blockage 0 %
scre en blockage 1 2.5 %
scre en blockage 2 5%
scre en block age37.5%
scre en blockage 5 0%
20%
30%
40%
50%
60%
70%
80%
90%
11.522.533.544.555.566.57
£
Q(L/S)
pipe blockage 0% scr een blockage 0%
pipe blockage 0% scr een blockage 12.5%
pipe blockage 25% sc reen blockag e12.5%
pipe blockage 50% sc reen blockag e12.5%
Figure 24. Relationship between £ and Q for different ratios of blockage height at surface blockage 12.5%.
Water 2020,12, 1974 14 of 20
Water 2020, 12, x FOR PEER REVIEW 14 of 20
Figure 25. Relationship between £ and Q for different ratios of blockage height at surface blockage
25%.
Figure 26. Relationship between £ and Q for different ratios of blockage height at surface blockage
37.5%.
10%
20%
30%
40%
50%
60%
70%
80%
90%
11.522.533.544.555.566.57
£
Q (L/S)
pipe blockage 0% scr een blockage 0%
pipe blockage 0% scr een blockage 25%
pipe blockage 25% scree n blockag e25%
pipe blockage 50% scree n blockag e25%
10%
20%
30%
40%
50%
60%
70%
80%
90%
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7
£
Q(L/S)
pipe blo ckage 0% scr een blockage 0%
pipe blockage 0% scr een blockage 37. 5%
pipe blockage 25% sc reen blockag e37.5%
pipe blockage 50% sc reen blockag e37.5%
10%
20%
30%
40%
50%
60%
70%
80%
90%
11.522.533.544.555.566.57
£
Q(L/S)
pipe blockage 0% screen blockage 0%
pipe blockage 0% screen blockage 50%
pipe blo ckage 25% sc ree n blockage50%
pipe blo ckage 50% sc ree n blockage50%
Figure 25.
Relationship between £ and Q for different ratios of blockage height at surface blockage 25%.
Water 2020, 12, x FOR PEER REVIEW 14 of 20
Figure 25. Relationship between £ and Q for different ratios of blockage height at surface blockage
25%.
Figure 26. Relationship between £ and Q for different ratios of blockage height at surface blockage
37.5%.
10%
20%
30%
40%
50%
60%
70%
80%
90%
11.522.533.544.555.566.57
£
Q (L/S)
pipe blockage 0% scr een blockage 0%
pipe blockage 0% scr een blockage 25%
pipe blockage 25% scree n blockag e25%
pipe blockage 50% scree n blockag e25%
10%
20%
30%
40%
50%
60%
70%
80%
90%
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7
£
Q(L/S)
pipe blo ckage 0% scr een blockage 0%
pipe blockage 0% scr een blockage 37. 5%
pipe blockage 25% sc reen blockag e37.5%
pipe blockage 50% sc reen blockag e37.5%
10%
20%
30%
40%
50%
60%
70%
80%
90%
11.522.533.544.555.566.57
£
Q(L/S)
pipe blockage 0% screen blockage 0%
pipe blockage 0% screen blockage 50%
pipe blo ckage 25% sc ree n blockage50%
pipe blo ckage 50% sc ree n blockage50%
Figure 26. Relationship between £ and Q for different ratios of blockage height at surface blockage 37.5%.
Water 2020, 12, x FOR PEER REVIEW 14 of 20
Figure 25. Relationship between £ and Q for different ratios of blockage height at surface blockage
25%.
Figure 26. Relationship between £ and Q for different ratios of blockage height at surface blockage
37.5%.
10%
20%
30%
40%
50%
60%
70%
80%
90%
11.522.533.544.555.566.57
£
Q (L/S)
pipe blockage 0% scr een blockage 0%
pipe blockage 0% scr een blockage 25%
pipe blockage 25% scree n blockag e25%
pipe blockage 50% scree n blockag e25%
10%
20%
30%
40%
50%
60%
70%
80%
90%
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7
£
Q(L/S)
pipe blo ckage 0% scr een blockage 0%
pipe blockage 0% scr een blockage 37. 5%
pipe blockage 25% sc reen blockag e37.5%
pipe blockage 50% sc reen blockag e37.5%
10%
20%
30%
40%
50%
60%
70%
80%
90%
11.522.533.544.555.566.57
£
Q(L/S)
pipe blockage 0% screen blockage 0%
pipe blockage 0% screen blockage 50%
pipe blo ckage 25% sc ree n blockage50%
pipe blo ckage 50% sc ree n blockage50%
Figure 27.
Relationship between £ and Q for different ratios of blockage height at surface blockage 50%.
Water 2020,12, 1974 15 of 20
Figures 28 and 29 show the relationship between relative grate water heights and relative grate
length according to pipe blockage of 25% and 50%, with different grate blockage at Q =6.00 L/sec.
From these figures, it can be noted that as surface blockage increased, the relative grate heights
increased within 6.15%, 8.6%, 10%, and 12%) due to shortage in discharge efficiency, which lead to
increased water surface profile.
3
28
Figure 28.
Relationship between Hg and LO for different ratios of grate blockage with pipe blockage
25% at Q =6.00 L/sec.
4
29
Figure 29.
Relationship between Hg and LO for different ratios of grate blockage with pipe blockage
50% at Q =6.00 L/sec.
Water 2020,12, 1974 16 of 20
3.4. Summary of Results
Results of all blockage ratios through storm water drainage system can be summarized according
to the following tables and figures:
Table 1shows the reduction of overall discharge efficiency of system according to pipe height
blockage. The table also demonstrates the efficiency of system for discharge of 6.00 L/s and 1.00 L/s.
Moreover, the table shows the average efficiency of discharge (AEOD) of discharges Q =1.00 L/s to
6.00 L/s.
Table 1. The results of efficiency reduction for different blockage heights.
HB(%) £
For Q =6.00 L/s and 1.00 L/s, Respectively
(£)
AEOD Efficiency Reduction %
15% 34.9%–76.6% 59% 0.93%
30% 34.2%–76.5% 58% 0.93%
50% 27.9%–72.8% 53% 6.53%
70% 15.44%–71.7% 37% 16.77%
90% 4.7%–29.8% 12% 46.49%
Table 2shows the reduction of overall discharge efficiency for combined pipe blockage (end and
length blockage).
Table 2. The results of efficiency reduction for different relative blockage lengths and heights.
HB(%) LB(%) £
For Q =6.00 L/s and 1.00 L/s, Respectively
(£)
AEOD Efficiency Reduction %
25% 33% 35.38%–77.56% 71% 0.89%
25% 67% 34.96%–76% 56% 3.52%
25% 100% 25.16%–75.56 49% 10.02%
50% 33% 34.96%–75.11% 58% 2.49%
50% 67% 33.78%–71.78% 53% 6.60%
50% 100% 20.96%–71.56% 44% 15.11%
Finally, Table 3illustrates the overall reduction efficiency by combined pipe and grate blockage.
Table 3. Experimental results for various ratios of blockage.
HB(%) LB(%) Relative Blockage Area (AB)£
For Q =6.00 L/s and 1.00 L/s, Respectively
(£)
AEOD Efficiency Reduction %
0 0 12.5% 25% to 66.22% 57.67% 2.27%
0 0 25% 34.09% to 63.7% 55.16% 4.78%
0 0 37.5% 31.56% to 60.36% 50.24% 9.70%
0 0 50% 24% to 54.75% 42.06% 17.88%
25% 100% 12.5% 24.47% to 63.86% 48.14% 11.80%
25% 100% 25% 22.87% to 59.87% 45.96% 13.98%
25% 100% 37.5% 20.13% to 56.78% 42.15% 17.79%
25% 100% 50% 20.1% to 51.25% 38.29% 21.65%
50% 100% 12.5% 20.49% 64.56% 42.19% 17.75%
50% 100% 25% 19.96% to 61.67% 40.66% 19.28%
50% 100% 37.5% 19.11% to 59.22% 38.99% 20.95%
50% 100% 50% 18.36% to 50% 35.34% 24.60%
Moreover, Figure 30 shows discharge efficiency for different remaining ratios of blockages.
Water 2020,12, 1974 17 of 20
Water 2020, 12, x FOR PEER REVIEW 17 of 20
Figure 30. Reduction in efficiency tor different ratios.
where
Relative blockage height (RBH) = 50%
RBH = 50%, relative blockage length (RBL) = 33%
RBH = 50%, RBL = 66%
RBH = 50%, RBL = 100%
RBH = 50%, RBL = 100%, relative blockage of grate area (RBGA) = 12.5%
RBH = 50%, RBL = 100%, RBGA = 25%
RBH = 50%, RBL = 100%, RBGA = 37.5%
RBH = 50%, RBL = 100%, RBGA = 50%
3.5. Prediction of Efficiency
By analyzing measured data, Equation (2) was developed to correlate the water discharge
efficiency (£) with relative blockage height, relative blockage length, relative area blockage, and flume
discharge.
£ = 0.916 + 0.0268 𝐿− 0.085𝑄 − 0.381𝐻− 0.352
𝐴
(2)
where
LB = relative blockage length (decimal)
HB = relative blockage height (decimal)
AB = relative blockage area (decimal)
Q = flume discharge (L/s)
£ = system discharge efficiency (decimal)
The correlation coefficient and the standard error of estimate for Equation (2) are 90% and 0.07
respectively. Figure 31 shows the relationship between the predicted values of £ using Equation (2)
versus the measured ones, while Figure 32 shows the distribution of the residuals around the line of
zero error. Both figures indicate that Equation (2) represented the measured data very well and hence
could be used safely to predict the discharge efficiency of storm system for system discharge ranging
from 1.00 to 6.00L/sec.
2.5%
6.6%
8.0%
15.1%
17.1%
19.0%
20.8%
25.7%
0%
10%
20%
30%
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
Reduction in efficiency
Different cases of blockage
Figure 30. Reduction in efficiency tor different ratios.
where
Relative blockage height (RBH) =50%
RBH =50%, relative blockage length (RBL) =33%
RBH =50%, RBL =66%
RBH =50%, RBL =100%
RBH =50%, RBL =100%, relative blockage of grate area (RBGA) =12.5%
RBH =50%, RBL =100%, RBGA =25%
RBH =50%, RBL =100%, RBGA =37.5%
RBH =50%, RBL =100%, RBGA =50%
3.5. Prediction of Efficiency
By analyzing measured data, Equation (2) was developed to correlate the water discharge efficiency
(£) with relative blockage height, relative blockage length, relative area blockage, and flume discharge.
£=0.916 +0.0268 LB−0.085Q −0.381HB−0.352AB(2)
where
LB=relative blockage length (decimal)
HB=relative blockage height (decimal)
AB=relative blockage area (decimal)
Q=flume discharge (L/s)
£=system discharge efficiency (decimal)
The correlation coefficient and the standard error of estimate for Equation (2) are 90% and 0.07
respectively. Figure 31 shows the relationship between the predicted values of £ using Equation (2)
versus the measured ones, while Figure 32 shows the distribution of the residuals around the line of
zero error. Both figures indicate that Equation (2) represented the measured data very well and hence
could be used safely to predict the discharge efficiency of storm system for system discharge ranging
from 1.00 to 6.00 L/sec.
Water 2020,12, 1974 18 of 20
Water 2020, 12, x FOR PEER REVIEW 18 of 20
Figure 31. Measured £ versus Predicted ones from Equation (2).
Figure 32. Residuals versus Predicted £ from Equation (2).
4. Conclusions
The conclusions, which are valid within the experimental study, could be summarized as
follows.
Maintenance of storm network is an important process that should be taken into account every
time period, which may be a year, or after the end of rainstorms. The maintenance process depends
on two main factors: the first is raising the network’s efficiency, and the second is reducing
maintenance costs. It is known that the design of storm networks will be done for the worst rainstorm
conditions, but in normal case conditions, there is no need to increase its efficiency; thus, the network
will be operating in low efficiency mode to save costs and reduce the number of maintenance
intervals. The research provides engineers interested in designing and maintaining a storm network
with important information for this purpose by identifying the efficiency of a storm system for most
blockage ratios. Finally, an empirical equation was developed to estimate the discharge efficiency of
the storm drainage system as a function of relative blockage height (H
B
), relative blockage pipe length
(L
B
), relative blockage area (A
B
), and system discharge.
Author Contributions: Conceptualization, I.F.; Data curation, G.M.A.-A. and A.F.; Formal analysis, M.Z.;
Investigation, G.M.A.-A.; Methodology, A.F.; Project administration, I.F. and M.Z.; Resources, G.M.A.-A.;
Software, M.R.F.; Supervision, M.Z.; Validation, M.R.F.; Visualization, M.R.F.; Writing – original draft, I.F.;
Writing – review & editing, A.F.
Figure 31. Measured £ versus Predicted ones from Equation (2).
Water 2020, 12, x FOR PEER REVIEW 18 of 20
Figure 31. Measured £ versus Predicted ones from Equation (2).
Figure 32. Residuals versus Predicted £ from Equation (2).
4. Conclusions
The conclusions, which are valid within the experimental study, could be summarized as
follows.
Maintenance of storm network is an important process that should be taken into account every
time period, which may be a year, or after the end of rainstorms. The maintenance process depends
on two main factors: the first is raising the network’s efficiency, and the second is reducing
maintenance costs. It is known that the design of storm networks will be done for the worst rainstorm
conditions, but in normal case conditions, there is no need to increase its efficiency; thus, the network
will be operating in low efficiency mode to save costs and reduce the number of maintenance
intervals. The research provides engineers interested in designing and maintaining a storm network
with important information for this purpose by identifying the efficiency of a storm system for most
blockage ratios. Finally, an empirical equation was developed to estimate the discharge efficiency of
the storm drainage system as a function of relative blockage height (H
B
), relative blockage pipe length
(L
B
), relative blockage area (A
B
), and system discharge.
Author Contributions: Conceptualization, I.F.; Data curation, G.M.A.-A. and A.F.; Formal analysis, M.Z.;
Investigation, G.M.A.-A.; Methodology, A.F.; Project administration, I.F. and M.Z.; Resources, G.M.A.-A.;
Software, M.R.F.; Supervision, M.Z.; Validation, M.R.F.; Visualization, M.R.F.; Writing – original draft, I.F.;
Writing – review & editing, A.F.
Figure 32. Residuals versus Predicted £ from Equation (2).
4. Conclusions
The conclusions, which are valid within the experimental study, could be summarized as follows.
Maintenance of storm network is an important process that should be taken into account every
time period, which may be a year, or after the end of rainstorms. The maintenance process depends on
two main factors: the first is raising the network’s efficiency, and the second is reducing maintenance
costs. It is known that the design of storm networks will be done for the worst rainstorm conditions,
but in normal case conditions, there is no need to increase its efficiency; thus, the network will be
operating in low efficiency mode to save costs and reduce the number of maintenance intervals.
The research provides engineers interested in designing and maintaining a storm network with
important information for this purpose by identifying the efficiency of a storm system for most
blockage ratios. Finally, an empirical equation was developed to estimate the discharge efficiency of
the storm drainage system as a function of relative blockage height (H
B
), relative blockage pipe length
(LB), relative blockage area (AB), and system discharge.
Author Contributions:
Conceptualization, I.F.; Data curation, G.M.A.-A. and A.F.; Formal analysis, M.Z.;
Investigation, G.M.A.-A.; Methodology, A.F.; Project administration, I.F. and M.Z.; Resources, G.M.A.-A.; Software,
Water 2020,12, 1974 19 of 20
M.R.F.; Supervision, M.Z.; Validation, M.R.F.; Visualization, M.R.F.; Writing—original draft, I.F.; Writing—review
& editing, A.F. All authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Acknowledgments:
This work was supported by projects of the Ministry of Education of the Slovak Republic
VEGA 1/0308/20, Mitigation of hydrological hazards—floods and droughts—by exploring extreme hydroclimatic
phenomena in river basins.
Conflicts of Interest: The authors declare no conflicts of interest.
References
1.
Woo, D.C.; Jones, S.J. Hydraulic Characteristics of Two Bicycle Safe Grate Inlet Designs; Final Technical Report,
FHWA-RD-74-77; Federal Highway Administration: Washington, DC, USA, 1974.
2. Forbes, C. Capacity of Lateral Storm Water Inlets. Civ. Eng. J. 1976,18, 195–205.
3.
Hotchkiss, H. Improvements in curb opening and grate inlet efficiency. Recent Res. Hydraul. Hydrol.
1994
,
1471, 24–30.
4.
Soares, E. Analysis of the Efficiency of an Alternative South Carolina Storm Water Drainage Structure.
Master’s Thesis, Clemson University, Clemson, SC, USA, 1991.
5.
Pezzaniti, D.; Johnson, L.; Argue, J. Road Surface Storm Water Drainage Hydraulics, New Design Information.
In Proceedings of the 8th International Conference on Urban Storm Drainage, Sydney, Australia, 30 August–3
September 1999.
6.
Russo, B.; G
ó
mez, M. Hydraulic Efficiency of Continuous Transverse Grates for Paved Areas. J. Irrig. Drain.
Eng. 2009,135, 225–230. [CrossRef]
7. Patil, A.; Patil, J. Effects of Bad Drainage on Roads. Civ. Environ. Res. 2011,1, 1–7.
8.
Comport, C.; Thornton, I. Hydraulic efficiency of grate and curb inlets for urban storm drainage. J. Hydraul.
Eng. 2012,138, 878–884. [CrossRef]
9.
Beniamino, R.; Manuel, V.; Jackson, A. Estimate the Hydraulic Efficiency of Non tested Continuous Transverse
Grates. J. Irrig. Drain. Eng. 2013,139, 864–871.
10.
Sezenöz, B.; Canan, Ö.; Ahmet, Y.; ¸Sahnaz, T. Numerical Modelling of Continuous Transverse Grates for
Hydraulic Efficiency. Master’s Thesis, Engineering Department, Middle East Technical University, Ankara,
Turkey, 2014.
11.
Cumhur, Ö.; Gülbin, Ü.; Ahmet, Y.;
˙
Gahnaz, T. Laboratory Investigation of Hydraulic Efficiency of Transverse
Grates in Roads. Master’s Thesis, Engineering Department, Middle East Technical University, Ankara,
Turkey, 2015.
12.
Manuel, G.; Joan, R.; Beniamino, R.; Eduardo, M. Assessment of inlet efficiency through a 3D simulation:
Numerical and experimental comparison. Water Sci. Technol. 2016,74, 1926–1935.
13.
Veerappan, R.; Le, J. Hydraulic efficiency of road drainage inlets for storm drainage system under clogging
effect. In Proceedings of the 5th International Conference on Flood Risk Management and Response,
San Servolo, Venice, Italy, 29 June–1 July 2016; Volume 165. [CrossRef]
14.
Zheng, F.; Li, Y.; Zhao, J.; An, J. Energy Dissipation in Circular Drop Manholes under Different Outflow
Conditions. Water J. 2017,9, 752. [CrossRef]
15.
ˇ
Carnogursk
á
, M.; Pˇr
í
hoda, M.; Zele ˇn
á
kov
á
, M.; L
á
z
á
r, M.; Brestoviˇc, T. Modelling the Profit from Hydropower
Plant Energy Generation Using Dimensional Analysis. Pol. J. Environ. Stud. 2016,25, 73–81. [CrossRef]
16.
Zeleˇn
á
kov
á
, M.; ˇ
Carnogursk
á
, M. A dimensional analysis-based model for the prediction of nitrogen
concentrations in Laborec River, Slovakia. Water Environ. J. 2012,9, 1–8. [CrossRef]
17.
Zeleˇn
á
kov
á
, M.; ˇ
Carnogursk
á
, M.; Slezingr, M.; Słys, D.; Purcz, P. Model based on dimensional analysis for
prediction of nitrogen and phosphorus concentrations at the river station Ižkovce, Slovakia. Hydrol. Earth
Syst. Sci. 2013,17, 201–209. [CrossRef]
18.
Tu, M.; Traver, R. Clogging Impacts on Distribution Pipe Delivery of Street Runoffto an Infiltration Bed.
Water 2018,10, 1045. [CrossRef]
19.
Vani, V.; Mohana, M.; Vanishree, D.; Subiksha, K.; Sushanthika, M. Smart Drainage System using Zig Bee
and IoT. Int. J. Recent Technol. Eng (IJRTE) 2019,8.
Water 2020,12, 1974 20 of 20
20.
Hesarkazzazi, S.; Hajibabaei, M.; Reyes-Silva, J.; Krebs, P.; Sitzenfrei, R. Assessing Redundancy in Stormwater
Structures Under Hydraulic Design. Water 2020,12, 1003. [CrossRef]
21.
Buckingham, E. On physically similar systems; illustrations of the use of dimensional equations. Phys. Rev.
1914,4, 345–376. [CrossRef]
©
2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
