Conference PaperPDF Available

Scaling of low flows in Czechia

Authors:

Abstract

This is the extended abstract related to the poster presentation exhibited during the 6th EGU Leonardo Conference held in Prague in November 2014. Unlike the original version presented in the book of abstracts (available e.g. at http://www.eguleonardo2014.com/abstracts/), this text was improved. Also, the numbers of long memory processes or unit root processes detected were corrected. Moreover, selected references were added since the submission system did not allow them to be shown.
EGU Leonardo Conference Series on the Hydrological Cycle
6th Leonardo Conference 2014
Book of Abstracts
13–14 November 2014
Prague, Czech Republic
Organized by:
European Geophysical Union
UNESCO FRIEND-Water Program
T. G. Masaryk Water Research Institute, p.r.i., Prague
Czech University of Life Sciences, Prague
University of Natural Resources and Life Sciences, Vienna (BOKU)
Vienna University of Technology
Central Institute of Meteorology and Geodynamics, Vienna
Cite as:
Vizina, A. & Laaha, G. (Eds.) (2014): HYPER Droughts: Hydrological Pre-
cipitation Evaporation Runoff Droughts - Book of Abstracts of the 6th EGU
Leonardo Conference, 13-14 Nov 2014, Prague, Czech Republic, 139 p.
Foreword
The Leonardo Conferences on Earth’s Hydrological Cycle is a well-established
conference series of the European Geosciences Union (EGU) that focuses on top-
ical questions related to water and its interactions with environment and society,
with particular attention for water resources management, flood risk mitigation
and environmental protection. After five conferences around the hydrological
dimensions of remote sensing (Frascati, 2009), catchments (Luxembourg, 2010),
floods (Bratislava, 2011), society and policy (Torino, 2012), and uncertainty
(Kos, 2013), the sixth conference held from 13-14 November 2014 in Prague
(Czech Republic) was dedicated again to a hydrological extreme: hydrological
drought within the various, connected components of the water cycle.
Under the title HYPER Droughts (Hydrological Precipitation – Evaporation
Runoff Droughts), experts from a broad number of disciplines, including
surface- and groundwater hydrology, climatology and meteorology, (hydro-)ecology
and water quality, geography and history, wood science, water monitoring and
management, and environmental statistics, were brought together to compare
the current status of drought research in these disciplines, and to assess the im-
plications of drought for water resources management.
The conference was organised around the following topics:
1. Drought governing processes including climate and catchment drivers
2. Indices and tools for monitoring and prediction
3. Regional modelling of low flows and droughts
4. Reconstruction of historic and prehistoric droughts (from modelling, doc-
umentary sources and other proxies, such as tree rings)
5. Hydrological change (climate change and human impacts)
6. Drought forecasting (meteorological, hydrological and agricultural perspec-
tives)
7. Drought impacts (ecological and economic)
8. Implications for water management
This volume bundles the abstracts of 2 Leonardo lectures, 4 keynote lectures,
30 oral presentations and 39 poster presentations from over 31 countries which
reflect the international dimension of the low flow and drought topic. Our thanks
go to the organizing committee of the Czech University of Life Sciences, Prague,
1
T. G. Masaryk Water Research Institute, p.r.i., Prague and the European Low
Flow and Drought group of the UNESCO FRIEND-Water program for making
this event possible.
We hope that the conference will stimulate international cooperation and
initiatives, crossing national boundaries and disciplines and, thereby, will con-
tribute to a better assessment of our water resources under current, past and
future environmental conditions.
Gregor Laaha
Institute of Applied Statistics and Computing
University of Natural Resources and Life Sciences, Vienna (BOKU)
2
Contents
Anne Van Loon : How to characterise hydrological drought? ........ 27
James Howard Stagge, Daniel G. Kingston, Lena Merete Tallaksen, David
M. Hannah : Climate drivers of regional drought in Europe . . . . 29
Ted Veldkamp, Stephanie Eisner, Yoshihide Wada, Jeroen Aerts Philip Ward
: Sensitivity of stream flow droughts and water scarcity events to
ENSO driven inter-annual climate variability at the global scale . . 31
Michael Stoelzle, Kerstin Stahl, Andreas Morhard, Markus Weiler : Recharge
scenarios to identify controls of catchments’ sensitivity to drought . 33
Miroslav Trnka, : Integrated drought monitoring systems – a tool for drought
research and practical applications ................ 34
John P. Bloomfield, Ben P. Marchant : Characterisation of groundwater drought 35
Simon Parry, Christel Prudhomme, Robert Wilby, Paul Wood : An alterna-
tive definition and characterisation of drought termination ..... 37
Sophie Bachmair, Kerstin Stahl, Jamie Hannaford, Lucy J. Barker, Irene
Kohn, Cecilia Svensson, Maliko Tanguy : Linking drought indicators
with impacts: Insights from a case study in Germany and the UK . 39
Michal Jenicek, Jan Seibert, Massimiliano Zappa, Maria Staudinger, Tobias
Jonas : Influence of seasonal snowpack on summer low flows . . . . 41
Urszula Somorowska : Relationship between groundwater level and NDVI:
summer drought development analysed by in-situ and MODIS-derived
data .............................. 43
Boud Verbeiren, Marijke Huysmans, Sven Vanderhaegen, Frank Canters,
Klaartje Verbeeck, Guy Engelen, Ingrid Jacquemin, Bernard Ty-
chon, George Tsakiris, Harris Vangelis, Okke Batelaan : Differen-
tiating between influencing factors land use and climate to assess
drought effects on groundwater recharge in a temperate context . . 45
Laurie Caillouet, Jean-Philippe Vidal, Eric Sauquet, Muriel Haond : Recon-
struction of meteorological droughts in France since 1871 through
the probabilistic downscaling of a global atmospheric reanalysis . . 47
Sandra Karanitsch-Ackerl, Michael Grabner, Franz Holawe, Gregor Laaha :
Tree rings as a tool for reconstructing historic droughts in northeast-
ern Austria ........................... 49
20
Jamie Hannaford John Bloomfield Ian Holman Bettina Lange Ralph Ledbet-
ter Mark McCarthy Tony McEnery Rebecca Pearce Steven Wade :
Developing a multi-disciplinary inventory of UK droughts from the
late 19th century ........................ 51
Petr Maca, Adam Vizina, Stanislav Horacek, Martin Hanel, Ladislav Kas-
parek, Pavel Pech : The analysis of storage discharge relationship for
the identification of low flows on selected watersheds in the Czech
republic ............................. 53
David Haro, Abel Solera, Javier Paredes-Arquiola, Joaquín Andreu : Current
and future drought vulnerability assessment in the Jucar River basin
(Spain) ............................. 55
Christel Prudhomme, : Droughts in the 21st century: a global perspective . 57
Henny A.J. van Lanen, Niko Wanders, Marjolein H.J. van Huijgevoort, Yoshi-
hide Wada, Marcel A. A. Alderlieste : Future hydrological drought
on a global and continental scale: overview and outlook ...... 58
Jean-Philippe Vidal, Eric Sauquet, Claire Magand, Agnès Ducharne, Benoît
Hingray : Hierarchy of climate and hydrological uncertainties in low
flow projections ......................... 60
Venkatachalam Ramaswamy : Impacts of Anthropogenic Emissions on Hy-
drologic Cycle .......................... 62
Lukas Gudmundsson : Are runoff changes in Europe attributable to anthro-
pogenic climate change? ..................... 63
Marzena Osuch, Joanna Doroszkiewicz, Hadush Kidane Meresa, Renata Ro-
manowicz : Spatio-Temporal Drought Analysis Under Varying Cli-
matic Conditions ........................ 64
Anne Fangmann, Uwe Haberlandt : Statistical Modeling of Low Flow Con-
ditions based on Climatic Indicators ............... 65
Ben Marchant, John Bloomfield, Jon MacKay : Spatial and temporal mod-
elling of UK groundwater droughts using empirical models . . . . . 66
Gaetano Di Franca, Peter Molnar, Paolo Burlando, Antonio Cancelliere :
Spatial and temporal variability of droughts in Switzerland . . . . 68
21
Pierre Nicolle, Raji Pushpalatha, Charles Perrin, Didier François, Dominique
Thiéry, Thibault Mathevet, Matthieu Le Lay, François Besson, Jean-
Michel Soubeyroux, Christian Viel, Fabienne Regimbeau, Vazken
Andréassian, Pascal Maugis, Bénédicte Augeard, Emmanuel Morice :
The PREMHYCE project: a comparative evaluation of hydrological
models for low-flow simulation and forecasting on French catchments 70
Stephan Thober, Luis Samaniego, Rohini Kumar : Trade-Offs between dy-
namical and statistical forecasting of the European 2003 Drought . 72
Brunella Bonaccorso, Antonino Cancelliere, Giuseppe Rossi : Investigating
The Potential Contribution Of Teleconnection Indices To Forecast
Short Term Drought Class Transitions In Sicily (italy) ...... 74
Kerstin Stahl, Irene Kohn, Lucia De Stefano, Lena M. Tallaksen, Francisco
M.C. Castro Rego, Dionysis Assimacopoulos, Antonio Massarutto,
Sonia I. Seneviratne, Henny H.A.J. van Lanen : An impact perspec-
tive on pan-European drought sensitivity ............. 75
Petr Paril, Světlana Zahrádková, Marek Polášek, Vít Syrovátka, Michal Straka,
Lenka Šikulová, Denisa Němejcová, Pavla Řezníčková : BIODROUGHT
project – developing effective tools for retrospective bioindication
of dry episodes in stream history and selection of watersheds with
drought risk using aquatic macroinvertebrates .......... 76
Noémie Neverre, Patrice Dumas : Assessing future droughts economic losses
with generic hydroeconomic modelling .............. 78
Lena M. Tallaksen : Low flow and drought in Europe - lessons from the past 80
Klaus Haslinger : Droughts and low flows in present and future climate –
pacing the path between climatology and hydrology ........ 82
Mark D. Svoboda : National Drought Mitigation Center Drought Services:
Collaborations Towards a Global Drought Early Warning and Infor-
mation System ......................... 83
David Haro, Abel Solera, Javier Paredes-Arquiola, Joaquín Andreu : Multi-
sectorial Partnerships for drought management and mitigation. The
experience of the Jucar River Basin (Spain) ............ 84
22
Jürgen Vogt A. de Jager, D. Magni, L. Valentini, F. Micale, C. Cammalleri,
G. Sepulcre, C. Lavaysse, S. Russo, P. Barbosa, J. Spinoni : Towards
a comprehensive drought information system for Europe ...... 86
Erik Tijdeman, Kerstin Stahl, Sophie Bachmair, Jamie Hannaford : Drought
Duration Curves: A method to quantify continental differences in
hydrological droughts ...................... 88
Miriam Fendekova, Marian Fendek : The influence of catchment parameters
on drought occurrence in the Tatra Mts., Slovakia ......... 90
Blaz Kurnik : An assessment of actual evapotranspiration and soil water
deficit in agricultural regions in Europe .............. 91
Ye Su, Jakub Langhammer, Jana Kaiglova, Jerker Jarsjö : Response of simple
stream hydro-chemical indicators to rainfall-runoff events in forest
disturbed basins in upper Vydra, Central Sumava Mountains . . . 92
Franziska Gaupp : Identifying a global drought structure using the copula
methodology .......................... 94
Ji Yae Shin, Jiyoung Yoo, Minsung Kwon, Tae-Woong Kim : Investigation of
Drought Occurrence and Propagation between Meteorological, Agri-
cultural, and Hydrological Drought ................ 96
Maria Staudinger, Jan Seibert, Kerstin Stahl : A drought index accounting
for snow ............................ 97
Livia Labudova, Lukas Schefczyk, Milan Trizna : Identification of Consec-
utive Dry Days (CDD) using observational and model data from
COSMO CLM .......................... 98
Dilyara Utkuzova : Spatio-temporal characteristics of wet and drought ex-
tremes over territory of Russia .................. 99
Zhiyong Liu, Lucas Menzel : Assessing the drought risk based on the joint
probability of precipitation and soil moisture in Rhineland-Palatinate,
southwest Germany ....................... 100
Arash Malekian : Stochastic modeling of spatio-temporal characteristics of
drought in southern Iran ..................... 101
Yoshinobu Sato : Influence of the Water Channel Network Facility in the
Kiso River System ........................ 103
23
Juraj Parajka, Alberto Viglione, Günter Blöschl : Rainfall-runoff projections
of low flows in Austria ...................... 105
Vladimir Matskovsky, Olga Solomina, Sergey Matveev, Alexander Chernokul-
sky : Drought Signatures in the tree-ring records of European Russia 107
Concepcion Rodriguez-Puebla : A comparative study of dryness indices over
Europe ............................. 109
Martin Hanel, Adam Vizina, Adri Buishand : Analysis of uncertainty in
climate change projections of drought indices for the Czech Republic 110
Ondrej Ledvinka : Scaling of low flows in Czechia ............. 111
Xiao Jing Yang, Z. X. Xu, D. P. Zuo, L. Liu : A Statistical Analysis of the
temporal-spatial changing characteristics of extreme precipitation in
Yunnan Province from 1958-2013 ................. 113
Tae-Woong Kim Ji Yaes Shin Joo-Heon Lee Hyun-Han Kwon : Conceptual
Framework for Satellite Data Based Drought Outlook in Korea . . 115
Lucas Menzel Tobias Törnros : Current and future agricultural droughts in
the southeastern Mediterranean region .............. 116
Veit Blauhut Julia Urquijo Itziar Gonzalez Tanago Kerstin Stahl Lucia De
Stefano Mario Ballesteros : Towards pan–European drought risk
maps: comparing an impact-based approach with a factor-based vul-
nerability assessment ...................... 118
Marek Polášek Petr Pařil Světlana Zahrádková Vít Syrovátka Lenka Šikulová
Michal Straka Denisa Němejcová : Different approaches to drought
capture – how do aquatic invertebrates indicate dry episode in Cen-
tral European streams? ..................... 119
Orhan Dengiz, Markéta Miháliková : Atmospheric drought in Belgium - Sta-
tistical analysis of precipitation deficit .............. 121
Roman Kožín : Testing of Linear Trend Appearance in Precipitation and
Temperature .......................... 122
Radek Vlnas, Adam Beran : A project of the hydrological drought monitoring
in the Czech Republic ...................... 124
Adam Vizina, Martin Hanel, Ladislav Kašpárek, Petr Máca, Pavel Pech :
Drought propagation by using weather generators ......... 125
24
Benedikt Heudorfer, Kerstin Stahl : Drought propagation analysis using dif-
ferent threshold level methods .................. 126
Sepideh Zamani : Atmospheric drought in Belgium - Statistical analysis of
precipitation deficit ....................... 127
Irene Kohn, J.H. Stagge, V. Blauhut, L. M. Tallaksen, S. Bachmair, K. Stahl
: The European Drought Impact report Inventory (EDII): major
drought events ......................... 128
Stefan Willem Ploum, Anne Frederike van Loon : Investigating seasonal vari-
ables for droughts in cold climates: a comparative study in Austria
and Norway ........................... 129
Wojciech Jakubowski : Application of trivariate Gumbel–Hougaard copula
for short term prognosis of extreme low-flow events ........ 130
Willem Maetens, Brecht Ingels, Willem Defloor, Kris Cauwenberghs : Op-
timization of the Standardized Precipitation Index (SPI) for opera-
tional drought monitoring .................... 131
Willem Maetens, Pieter Cabus, Inge De Jongh, Willem Defloor, Kris Cauwen-
berghs : A comprehensive and effective representation of the drought
situation: implementation through the web portal www.waterinfo.be 133
Willem Maetens, Brecht Ingels, Willem Defloor, Kris Cauwenberghs : SWAT-
modelling of drought impact on two catchments in Flanders . . . . 135
Damian Ferney Cordoba Melgarejo, Concepción Rodríguez Puebla, Jazna
Rodríguez Segovia : Analysis of two climatological data sources to
apply to description of the precipitation behavior in an arid area:
Case of Region of Tarapacá, Northern Chile ........... 137
Dario Musolino, : Evaluation of the socio-economic impacts of drought events:
evidence from some areas in Europe ............... 139
Francesco Vuolo : An application of remote sensing to support to water
resources management ...................... 140
Ewa Bogdanowicz Witold Gustaw Strupczewski Sisay Debele Krzysztof Kochanek
: Flow-duration-frequency and duration-flow-frequency approaches
in low-flow analysis, advantages and constraints .......... 141
25
Kamila Hlavcova Silvia Kohnová Miroslav Sabo Andrea Stevková Jan Szolgay
: Comparison of SOM and non-hierarchic clustering techniques by
pooling of low flows in Slovakia ................. 142
Jude Lubega Musuuza Rohini Kumar Anne F. Van Loon Roland Barthel
Jurriaan ten Broek Luis E. Samaniego Adriaan J. Teuling Sabine
Attinger : The inadequacy of the standardized precipitation index
as a groundwater drought indicator ................ 143
26
111
Scaling of low flows in Czechia
Ondrej Ledvinka1
ledvinka@chmi.cz
1 Czech Hydrometeorological Institute, Prague, Czech Republic
Although some nationwide studies on trends in the series of hydrological drought
characteristics were conducted in Czechia, each of them utilized either the trend
tests that do not account for persistence at all, or the modifications considering
short-term persistence only. In fact, similarly as in the case of short-term
persistence, also long-term persistence, often manifested through scaling, may
adversely influence the results of trend tests. The presence of both short-term
persistence and long-term persistence means that the independence among data,
which is required prior to the application of a trend test, is violated. In particular,
the variance of test statistic is altered, which causes the null hypothesis of no trend
to be rejected too often on the one hand, or rarely on the other.
The series of 7-day low flows together with the series of their occurrence
dates at 144 water-gauging stations from all over Czechia during the hydrological
period 1961–2005 were tested for trends by Fiala et al. (2010). The investigation
was done separately for the whole year, defined specifically for these purposes, and
for summer and winter seasons to distinguish between droughts triggered by
evapotranspiration and droughts triggered by freezing. In addition, the authors
assessed the series comprising the deficit volumes and the numbers of days under
the thresholds delineated by M-day discharges Q330d and Q355d. The Mann–Kendall
test was employed and the abovementioned problem was handled via the Bayley–
Hammersley–Matalas–Langbein–Lettenmaier equivalent sample size approach
which solely accounts for short-term persistence. However, as stated in Khaliq et
al. (2008), long-term persistence may be present in the series of hydrological
112
drought characteristics. The aim of the current study was therefore to discover
whether long-term persistence could have an influence on findings in Fiala et al.
(2010).
Scaling behaviour can be summarized by means of the dimensionless
Hurst exponent ranging form 0 to 1. The values of this exponent falling into the
interval between 0.5 and 1 indicate persistence. Here, due to the short length series
examined, the Hurst exponent was estimated as the fractional differencing
parameter of the FARIMA(0, d, 0) model, to which the value of 0.5 was added. To
better understand what kind of stochastic process generates a series, so-called unit
root tests such as the Phillips–Perron test and the Kwiatkowski–Phillips–Schmidt–
Shin test were jointly applied. Persistence is distinct at more than a half of the
stations, no matter whether annual or seasonal series are studied. However, the
share of stations with persistence rapidly decreases in the winter period. An
exception applies to the series of dates of occurrence in which almost no
persistence can be recognized. The numbers of series likely generated by long
memory or unit root processes are as follows: 38 (annual and summer 7-day low
flows), 17 (winter 7-day low flows), 38 (deficit volumes defined by Q
330d
), 28
(deficit volumes defined by Q
355d
), 37 (numbers of days with discharge under
Q
330d
), 36 (numbers of days with discharge under Q
355d
), 9 (dates of annual 7-day
low flow occurrence) and 17 (dates of summer 7-day low flow occurrence). These
series seem to be clustering in southwest and northeast Czechia.
References
Fiala, T., Ouarda, T. B. M. J. and Hladný, J.: Evolution of low flows in the Czech Republic, J. Hydrol.,
393(3-4), 206–218, doi:10.1016/j.jhydrol.2010.08.018, 2010.
Khaliq, M. N., Ouarda, T. B. M. J., Gachon, P. and Sushama, L.: Temporal evolution of low-flow
regimes in Canadian rivers, Water Resour. Res., 44(8), W08436, doi:10.1029/2007WR006132,
2008.
Article
Full-text available
Although a nationwide study focusing on the evolution of low flows in Czechia was conducted in the past, a need for the revision of the results has arisen. By means of the trend analysis, which specifically considers the presence of significant serial correlation at the first lag, the former study highlighted areas where 7-day low flows increase or decrease. However, taking into account only the lag-one autoregressive process might still have led to the detection of so-called pseudo-trends because, besides short-term persistence, also long-term persistence may adversely influence the variance of the test statistic when the independence among data is required. Therefore, one should carefully investigate the presence of persistence in time series. Before the trend analysis itself, the authors' previous studies aimed at the discrimination between short memory processes and long memory processes employing jointly the Phillips–Perron test and the Kwiatkowski–Phillips–Schmidt–Shin test. This analysis was accompanied by the Hurst exponent estimation. Here, the subsequent identification of trends is carried out using three modifications of the Mann–Kendall test that allow different kinds of persistence. These include the Bayley–Hammersley–Matalas–Langbein–Lettenmaier equivalent sample size approach, the trend-free pre-whitening approach and a block bootstrap with automatic selection of the block length, which was applied for the first time in hydrology. The general results are similar to those presented in the former study on trends. Nevertheless, the divergent minimum discharges evolution in the western part of Czechia is now much clear. Moreover, no significant increasing trend in series incorporating Julian days was found.
Poster
Full-text available
EGU Leonardo Conference HYPER Drought 2014
Conference Paper
Full-text available
Drought is one of the most disastrous natural hazards in Europe. It cannot be prevented; but its impacts can be reduced by mitigation to increase resilience. In Europe, numerous studies have proposed various investigation-specific (case-specific) drought indicators. Only few studies have tested how commonly used drought hazard indices actually relate to drought impacts and susceptibility, and they have been limited to the local scale. Even fewer studies have attempted to link drought impacts with large-scale meteorological and hydrological drought indicators commonly used to describe events across Europe’s different geo-climatic regions. Thus, there is a need for a comprehensive pan-European investigation of historical events and their impacts building upon a common data source, against which existing (observational as well as model-based) studies can be compared. The European Drought Impact report Inventory (EDII) developed as part of the EU FP7 project Drought R&SPI (Fostering European Drought Research and Science-Policy Interfacing) aims to collect and build a database of past drought impacts in Europe reported by various sources. Impact information is (a) classified into pre-defined impact categories (b) referenced temporally and spatially and (c) complemented with additional reported impact information including drought response measures where applicable. The current, initial version of the database is still project-internal, but the aim is to make it publicly accessible as a web-GIS supported online database in a future version. This contribution presents the concept and gives examples of the analysis potential.
Book
Full-text available
Parameters relevant for hydro(geo)logy are spatially distributed and may show significant temporal variability. Earth Observation (EO) data, when used jointly with in situ data, can provide an essential contribution for the creation of inventories of surface water resources, the extraction of thematic maps relevant for hydrogeological studies and models (landcover, surface geology, lineaments, geomorphology…) or for the retrieval of (bio)geophysical parameters (water quality and temperature, soil moisture…) for a more detailed list, refer to Schultz and Engman (2000). The large area coverage of each observation, on the one hand, helps moving beyond the point-based readings provided by gauge networks to –for instance- basin-wide measurements of discharge and storage, and on the other hand derives common databases of inter-country comparable information. Repeatability of observations allows the generation of a time-series of observed parameters and may result in an improved capability to analyse, monitor and forecast the evolution of phenomena, facilitating water resources management. In Africa, where a 90% decline in available infrastructure at water stations was reported (Brown, 2002) and where there are issues related to occurrence, distribution, protection and management of available water resources as well as to the management of competing demands for such resources (ECA et al., 2000), exploitation of EO data has been marginal in the past. Only in 2002 the European Space Agency (ESA) in the context of the Committee of Earth Observation Satellites (CEOS) started the TIGER initiative as a concrete action following the resolutions of the World Submit on Sustainable Development held in Johannesburg. The initiative aims at assisting African countries to overcome problems faced in the collection, analysis and dissemination of water related geo-information by exploiting the advantages of EO technology. In the last few years, under the leadership of the African Ministerial Council on Water (AMCOW), TIGER has evolved with main contributions by ESA, UNESCO and the Canadian Space Agency (CSA) and with collaboration of other partners such as the Economic Commission for Africa (UN-ECA), the African Development Bank (AfDB) and other African and International organizations. During the first implementation period, the initiative followed a three-step approach — from research to pre-operational and operational stages — aimed at preparing the ground for further activities (Fernandez- Prieto and Palazzo, 2007). This resulted in:  Successful implementation of fifty research projects focusing on the status of water resources in Africa and Integrated Water Resources Management (IWRM) exploiting Earth Observation data provided by ESA. These projects involved partnerships between numerous universities, technical centres and water authorities. Research teams were supported with dedicated training, capacity building actions and tools.  Support of sixteen pre-operational projects (development and demonstration projects) funded by ESA and CSA at 6 Million Euro and involving more than 30 African water authorities working with technical consortia involving African, European and Canadian companies. The projects developed EO-based water information services adapted to specific user needs and demonstrated their real applicability in Africa. The result of this II activity was a solid portfolio of potential operational services ready to be transferable to a full operational level.  On the basis of the results from successful demonstration projects, trans-boundary or national projects led by African water authorities are being implemented, aimed at supporting the transition from a pre-operational stage to a sustainable operational phase in partnership with development partners. The first TIGER operational project, the GEOAQUIFER which is a successor of the AQUIFER pre-operational project, is ongoing and is co-funded by the African Water Facility (AWF) and the Sahara and Sahel Observatory (OSS). Other projects are under evaluation. This approach was complemented by:  A strong capacity building component involving dedicated training support for African partners (water authorities, technical centres, universities, remote sensing centres) to develop skills in the utilization of EO technology to support IWRM. More than 20 training sessions have been organized under the TIGER umbrella, focusing on the needs of both the different TIGER research and pre-operational projects.  The TIGER Capacity Building Facility was activated in 2006, led by the International Institute for Geo-Information Science and Earth Observation, ITC (www.itc.nl), and has provided further support to a number of African teams involved in the Research stage (Vekerdy et al., 2008). Capacity building efforts of the facility have benefited more than 90 African scientists with tailor-made courses in four basic activities: basic training, applied short courses, project-oriented supervision of researchers and advanced courses. UNESCO through its International Hydrological Programme, IHP, agreed to publish the results provided by several different groups involved in the TIGER research and pre-operational projects in the series IHP Technical Documents in Hydrology. It is our hope that this publication will stimulate researchers worldwide to perform additional in-depth work and analysis on the exploitation of space borne remote sensing technology for water resources in Africa. The papers in this special issue fall under four interrelated themes: (1) use of multi-source EO data to facilitate analysis and management (through ingestion in Decision-Support Systems or models) of large aquifers (transboundary such as SASS and SAI and national such as Sous-Massa); (2) exploitation of EO data to derive information about catchment characteristics (lineaments and geology, landcover and land use etc.); (3) extraction of water bodies from multi-temporal datasets for the creation of inventories and assessment of flooding patterns; and (4) the derivation of soil moisture information on a dynamic basis from satellite data.
Presentation
Hydroclimate projections for the 21st century agree on an increase in low flow severity that could undermine current water management practice and require drastic measures for adapting water uses and for sharing resources among different economic sectors (irrigation, hydropower production, etc.). Understanding droughts and low flows is all the more crucial in this current context of adaptation to climate change. A deep knowledge of the major historical droughts in France constitutes a perfect framework to assess the recent observed events but also future events projected by climate change impact studies. Indeed, a fundamental way of adapting to climate change tomorrow is to adapt to climate variability today. This work proposes a reconstruction of precipitation fields in France over the last century built on the NOAA 20th century global atmospheric reanalysis (20CR). This reanalysis provides for the first time an evolution of atmospheric circulation at high temporal resolution since 1871, assimilating surface pressure observations only. The coarse spatial resolution of 20CR however prevents using directly surface variables like precipitation at the scale of a French catchment. The Sandhy (Stepwise ANalogue Downscaling method for Hydrology) statistical downscaling method is used here to bridge the scale gap between 20CR and precipitation relevant for catchmentscale hydrology. This method is based on the idea that similar large scale circulation patterns (predictors) lead to similar local precipitation (predictand). For a given target large scale situation, the dates with the most similar large scale situations in an archive are identified, and the corresponding local scale observations are selected as the targeted local scale predictions. For each target date, Sandhy gives an ensemble of 125 analogue dates and corresponding precipitation values, taking into account equifinality in the optimization of predictor geographical domains. Such an optimization is moreover done independently for 608 climatically homogeneous zones covering France. Sandhy draws here analogue dates from an archive covering the 1958-2008 period for which local precipitation is also available through the Safran near-surface reanalysis. It is then applied to target situations given by 20CR over the whole 1871-2012 period to derive an ensemble of 125 equally plausible gridded precipitation time series. Precipitation data are then monthly aggregated for each time series to compute the Standardized Precipitation Index (SPI) at different time scales and therefore characterize meteorological drought events in a probabilistic way. The SPI critically allows for comparing historical events and their spatio-temporal development. Results allow us to identify severe events for periods with few available precipitation observations, such as the record-breaking 1921 drought. Such an event – much more severe than the recently experienced ones like 1976 or 2003 – may thus serve as a benchmark reference event for adaptation purposes.
Article
Following is a continuation of the list of titles and authors of the papers presented: Use of Thermal Infrared Scanning in Evaluating Predictive Models for Power Plant Thermal Plume Mixing in Italian Coastal Waters. By G. Dinelli, David T. Hodder, and F. Parrini. Applications of Thermal Remote Sensing to Detailed Ground Water Studies. By Joel Souto-Maior. Digital Processing Techniques in Thermal Plume Analysis. By Ronald W. Stingelin and Glen B. Avis. Utilization of Aerial Photographs for Measuring Land Use Changes in Watersheds. By Donald B. Stafford, James T. Ligon, and M. Eugene Nettles. Water Pollution Surveillance Using Local Remote Sensing Equipment. By W. B. McCoy and T. H. Lackie. Use of Remote Sensing for Mapping of Aquatic Vegetation in the Kawartha Lakes. By Ivanka Wile. Spectral Reflectance of Water Containing Suspended Sediment. By Bruce J. Blanchard and Ross W. Leamer.
Article
This study investigates temporal evolution of 1-, 7-, 15-, and 30-day annual and seasonal low-flow regimes of pristine river basins, included in the Canadian reference hydrometric basin network (RHBN), for three time frames: 1974–2003, 1964–2003, and 1954–2003. For the analysis, the RHBN stations are classified into three categories, which correspond to stations where annual low flows occur in winter only, summer only, and both summer and winter seasons, respectively. Unlike in previous studies for the RHBN, such classification is essential to better understand and interpret the identified trends in low-flow regimes in the RHBN. Nonparametric trend detection and bootstrap resampling approaches are used for the assessment of at-site temporal trends under the assumption of no persistence or short-term persistence (STP). The results of the study demonstrate that previously suggested prewhitening and trend-free prewhitening approaches, for incorporating the effect of STP on trend significance, are not adequate for reliably identifying trends in low-flow regimes compared to a simple bootstrap-based approach. The analyses of 10 relatively longer records reveal that trends in low-flow regimes exhibit fluctuating behavior, and hence, their temporal and spatial interpretations appear to be sensitive to the time frame chosen for the analysis. Furthermore, under the assumption of long-term persistence (LTP), which is a possible explanation for the fluctuating behavior of trends, many of the significant trends in low-flow regimes, noted under the assumption of STP, become nonsignificant and their field significance also disappears. Therefore correct identification of STP or LTP in time series of low-flow regimes is very important as it has serious implications for the detection and interpretation of trends.
Article
This study investigates the temporal evolution of annual and seasonal low-flow regimes of 144 Czech river basins for the 1961–2005 period. Summer and winter low-flow seasons are identified and delimited. The gauging stations are classified into two categories, mountain and lowland, according to their low-flow regime. The standard and modified versions of the Mann–Kendall trend test were used in the study to detect trends in several low-flow variables. These include 7-day annual, summer and winter low flows, number of days with discharge under two low-flow thresholds and deficit volumes delimited with the same two low-flow thresholds. At majority of stations, trends in low-flow variables are not significant. Among significant trends, decreasing summer low flows, increasing winter low flows and increasing drought durations as well as deficit volumes are observed. Such combination of trends is typical for the north-eastern part of the Czech Republic and if it continues in the future this area might become drought-prone. It was found that proportions of positive and negative trends between mountain and lowland stations are similar. Thus the low-flow evolution is irrespective of the basins altitudes and climates. Dates of low flows were evaluated to study the evolution of the timing of summer and winter low flows. Non-significant trends prevail for the timing of seasonal low flows, but at a number of stations the dates of summer minima shift towards earlier dates. This can be explained by an earlier onset of the spring flood caused by warmer winters.
Analysis of two climatological data sources to apply to description of the precipitation behavior in an arid area: Case of Region of Tarapacá
  • Damian Ferney Cordoba Melgarejo
  • Concepción Rodríguez Puebla
  • Jazna Rodríguez Segovia
Damian Ferney Cordoba Melgarejo, Concepción Rodríguez Puebla, Jazna Rodríguez Segovia : Analysis of two climatological data sources to apply to description of the precipitation behavior in an arid area: Case of Region of Tarapacá, Northern Chile........... 137
Kris Cauwenberghs : SWATmodelling of drought impact on two catchments in Flanders
  • Willem Maetens
  • Brecht Ingels
  • Willem Defloor
Willem Maetens, Brecht Ingels, Willem Defloor, Kris Cauwenberghs : SWATmodelling of drought impact on two catchments in Flanders.... 135