Risk in Water Resources Managementhydrologie.org/redbooks/a347/P347 Description, Preface, … · Web viewEdited by . GÜNTER BLÖSCHL. Vienna University of Technology, Austria

Risk in Water Resources Management

Risk in Water Resources Management

Edited by

GÜNTER BLÖSCHL

Vienna University of Technology, Austria

KUNI TAKEUCHI

ICHARM, Public Works Research Institute, Japan

SHARAD JAIN

Indian Institute of Technology, India

ANDREAS FARNLEITNER


ANDREAS SCHUMANN

Ruhr-Universität Bochum, Germany

Water resources management has to deal with incomplete knowledge of the current dynamics and the future evolution of water resource systems. Risk is a concept that helps in making management decisions under incomplete and/or incorrect knowledge by relating water-related hazards and their consequences. Risks related to floods and droughts, to the environment and to health, as well as economic and financial risk, are encompassed by water resources management. Obviously, it is not possible to completely eliminate uncertainty, but better understanding of the sources and magnitude of the uncertainties involved in a particular project will clearly lead to improved decisions: this volume aims towards that end.

IAHS Publ. 347 (2011) 276 + x pp. ISBN 978-1-907161-22-3 £62.00

Preface

Water resources management has to deal with incomplete knowledge of the current dynamics and the future evolution of water resource systems. Risk is a concept that helps in making management decisions under incomplete and/or incorrect knowledge by relating water-related hazards and their consequences. A variety of risks exist in water resources management – risks related to floods and droughts, risks related to environment and health, as well as economic and financial risks. Changes in the boundary conditions (e.g. water uses, hydrological conditions, legal framework) can significantly affect the risk and hence the performance of projects.

While many disciplines face the issues of risk, they face them in different ways. In hydrogeology, the difficulty lies in accurately estimating flow and transport paths. Health- related risks have to deal with a broad range of chemical and microbial agents in water bodies. It is a very challenging task to estimate health risk with high confidence taking exposure to a mixture of chemical and microbial hazards into account. In surface hydrology, the stochasticity of rainfall is one of the main sources of uncertainty. Finally, when operating a water infrastructure project, uncertainty of the inflows, demands and the system state (e.g. conditions in the downstream areas during flooding) are of critical importance. In many cases, the specification of consequences, e.g. by damage assessments, provides a major challenge. In water resource systems dominated by water supply issues, optimisation and the development of robust management systems is a major goal. In all instances, it is wise to integrate the various levels of uncertainty in the management decisions and strategies.

During the XXV General Assembly of the International Union of Geodesy and Geophysics, 28 June–7 July 2011, in Melbourne, a symposium was held entitled Risk in Water Resources Management. The symposium was organised by the International Commission on Water Resources Systems (ICWRS) together with the International Commissions on Surface Water (ICSW) and on Water Quality (ICWQ) of the International Association of Hydrological Sciences (IAHS). The importance of risk in water resources management is reflected in the large number of contributions to the symposium drawn from a range of disciplines. Out of these contributions, 41 papers were selected for this volume.

The purpose of this symposium was to bring together the various concepts of risk, tools and methodologies to specify them, and new approaches to address risk in water resource systems. The contributors were asked to address aspects of water-related risks in a broad way in order to integrate across the disciplines and/or sectors and thus contribute in a pro-active way to water resources management. The papers were grouped pragmatically into three themes: (1) Flood and Drought Hazards, (2) Uncertainty and Climate, and (3) Water Use and Risk, notwithstanding the many interactions between these aspects of water resources management.

The volume starts with the keynote presentation of the symposium, which deals with the conjunctive use of surface water and groundwater, and the management of multi-objective storage systems. The following set of five papers is concerned with increasing the accuracy of flood hazard estimates in terms of flood discharge. The papers propose new methods based on flood data, rainfall and hydrogeological information. Six papers present examples from case studies around the world, including effects of floods on groundwater supply, and inundation mapping. Drought hazards are discussed in two papers. The section on uncertainty and climate related to risk starts with four papers on the uncertainty of runoff measurements and runoff modelling. Five papers deal with uncertainty in water resources assessment and allocation, and

four papers analyse the effects of climate variability and change on future water resources and the associated risks. The final section is introduced by five papers on water resources optimisation to minimise supply risks, followed by two papers on groundwater assessment and use. Case studies of integrated water resources management with a focus on risk are presented in six papers, including one paper that maps the feedbacks between the components of a water resources system relating demand and supply. The final paper provides a global perspective on water availability and the potential sources of conflict in water resources management.

It is sometimes argued that risk assessment and uncertainty are central to decision making. Without uncertainty, decision making would be rather simple and straightforward. Obviously, it is not possible to completely eliminate uncertainty, but better understanding of the sources and magnitude of the uncertainties involved in a particular project will clearly lead to improved decisions. It is hoped that the present volume will be a step towards that end.

The editors gratefully acknowledge the assistance of the reviewers in bringing together this volume. Many thanks to Penny Perrins and Cate Gardner of IAHS Press for their professional approach and all their help with the processing of the manuscripts.

Editor-in-chief

Günter Blöschl


Co-editors

Kuni Takeuchi

ICHARM, Public Works Research Institute, Japan

Sharad Jain

Indian Institute of Technology, India

Andreas Farnleitner


Andreas Schumann

Ruhr-Universität Bochum, Germany

Contents

ADVANCE \U 8.45

Preface by Günter Blöschl, Kuni Takeuchi, Sharad Jain, Andreas Farnleitner & Andreas Schumann

v

1

Flood and Drought Hazards

Keynote: Multi-objective storages for flood mitigation and water resources development in small catchments Pedro Simone & Trevor M. Daniell

3

Reducing uncertainty in derived flood frequency analysis related to rainfall forcing and model calibration Uwe Haberlandt & Imke Radtke

10

Towards understanding the differences between deterministic and probabilistic flood hazard estimation methods Magdalena Rogger, Alberto Viglione, Ralf Merz, Robert Kirnbauer, Herbert Pirkl & Günter Blöschl

16

Imprecise probabilities to specify hydrological loads for flood risk management Andreas H. Schumann, Markus Pahlow, David Nijssen & Bastian Klein

22

Assessment of extreme flood characteristics based on a dynamic-stochastic model of runoff generation and the probable maximum discharge L. S. Kuchment & A. N. Gelfan

29

Prévention du risque pluvial par l’élaboration des courbes intensité–durée–fréquence (IDF): application à la ville de Tipasa dans le Nord Ouest Algérien / Storm water risk prevention through the establishment of intensity–duration–frequency curves (IDF): application to the city of Tipasa in northwestern Algeria Mustapha Boukhelifa, Benina Touaibia & Pierre Hubert

36

Drinking water extraction facilities at risk of flooding from rivers and groundwater – flood impact assessment for water extraction facilities in Ljubljana area L. Globevnik & B. Bračič Železnik

43

Mountain risks in downstream water resource management in Upper Bhagirathi basin, Indian Himalayas R. B. Singh & Subodh Kumar

49

A new assessment methodology for flood risk: a case study in the Indus River basin Youngjoo Kwak, Akira Hasegawa, Hironori Inomata, Jun Magome, Kazuhiko Fukami & Kuniyoshi Takeuchi

55

Determination of inundation area based on flood hazard for a global water risk assessment Jonggeol Park & Youngjoo Kwak

61

Elaboration of products derived from geospatial data for flood risk analysis in Romania Gheorghe Stancalie, Vasile Craciunescu, Argentina Nertan, Denis Mihailescu & Ion Nedelcu

65

Zoning groundwater flooding risks in the cities and urban agglomeration areas of Ukraine Oleksandr Chebanov & Anastasia Zadniprovska

71

Low-flow risk assessment for water management Mikhail Bolgov & Elena Korobkina

77

Assessing drought hazard under non-stationary conditions on southeast of Spain Sandra G. García Galiano, Juan D. Giraldo Osorio, Mario A. Urrea Mallebrera, Adolfo Mérida Abril & Claudia N. Tetay Botía

85

2

Uncertainty and Climate

Risks in hydrological modelling due to uncertainties in discharge determination Martijn J. Booij, Sander P. M. van den Tillaart & Maarten S. Krol

95

Propagation of input errors: implications for model simulations and risk analysis Kerrie M. Tomkins & Andrew J. Davidson

101

Assimilation of streamflow discharge into a continuous flood forecasting model Yuan Li, Dongryeol Ryu, Q. J. Wang, Thomas Pagano, Andrew Western, Prasantha Hapuarachchi & Peter Toscas

107

Application of a particle swarm optimization to the tank model Celso Augusto Guimarães Santos, Paula Karenina De Macedo Machado Freire, S. K. Mishra& Amílcar Soares Júnior

114

Reducing the uncertainty associated with water resources planning in a developing country basin with limited runoff data through AI rainfall–runoff modelling Adebayo J. Adeloye

121

Hydrological and stochastic uncertainty: linking hydrological and water resources yield models in an uncertainty framework Denis A. Hughes, Stephen J. L. Mallory, Bennie Haasbroek & Geoffrey G. S. Pegram

127

Evaluation of combined contribution of uncertainty sources to total output uncertainty in water resource estimation in South Africa Tendai Sawunyama, Denis A. Hughes & Stephen J. L. Mallory

133

Water resource allocation for the Songhua River Region, China under the uncertainty of water supply Suxia Liu & Yaowei Zhang

139

How to quantify uncertainty in water allocation models? An exploratory analysis based on hypothetical case studies J. Lerat, K. Tomkins, Q. Shao, L. Peeters, A. Yang & D. Rassam

146

Risks in water management associated with changing climate systems: reflections and case analysis Juan Carlos Bertoni

153

Risk-based assessment of water availability in a changing climate Atef Kassem, Tamas Hamory, Ivana Vouk & David Harvey

159

Assessing the impacts of global changes on the water resources of the Mediterranean basin M. Milano, D. Ruelland, S. Fernandez, A. Dezetter, S. Ardoin-Bardin, J. Fabre, G. Thivet & E. Servat

165

Drought analysis based on precipitation generation from GCMs for the Qingjiang River Basin Kunxia Yu, Lihua Xiong, Leihua Dong & Min Wan

173

3

Water Use and Risk

Optimal multi-year operation of a water supply system under uncertainty: robust methods Mashor Housh, Avi Ostfeld & Uri Shamir

183

Daily reservoir operating rules by implicit stochastic optimization and artificial neural networks in a semi-arid land of Brazil Camilo Allyson Simões de Farias, Celso Augusto Guimarães Santos & Alcigeimes Batista Celeste

191

Development and application of water allocation model based on ET-control J. J. You, Z. Gan, H. Gan & L. Jia

198

Accounting for uncertainty in pumping rate optimisation for sustainable aquifer management Luk Peeters, David Rassam & Julien Lerat

206

Evaluating potentials and corresponding risks of optimal deficit irrigation strategies under climate change and other sources of uncertainty Niels Schütze, Jens Grundmann, Sebastian Kloss & Gerd H. Schmitz

212

Risks, hazards and vulnerability associated with overexploitation of groundwater in northwest India Mukand Brar & Preeti Roychand

218

Physically-based groundwater vulnerability assessment using sensitivity analysis methods Jean Beaujean, Jean-Michel Lemieux, Pascal Goderniaux & Serge Brouyère

224

Water supply and the impact on human development in Nigeria Shakirudeen Odunuga, Ifeyinwa Okeke, Fidelis Okorie & Olatunde Olaniyi

230

The application of rural threshold water consumption model in water supply studies Ifeyinwa Okeke, Lekan Oyebande & Shakirudeen Odunuga

235

Small farm dams research project in the semi-arid northeastern region of Brazil Ana Cristina Souza da Silva, Alain Marie Passerat de Silans, Gerald Souza da Silva, Flavia Augusta dos Santos, Renato de Queiroz Porto & Cristiano Almeida Neves

241

Incorporating hydrological reliability in rural rainwater harvesting and run-of-river supply John Ndiritu, John Odiyo, Rachel Makungo, Celiwe Ntuli & Beason Mwaka

247

Managing socio-economic and hydrological risks in northeast India U. C. Sharma & Vikas Sharma

253

Water demand forecasting under changing environment: a System Dynamics approach Wang Xiao-Jun, Zhang Jian-Yun, Amgad Elmahdi, He Rui-Min, Zhang Li-Ru & Chen Feng

259

Water conflict vulnerability of regions Nilupul Gunasekara & So Kazama

267

Key word index

275

____________________________________________________________________________________________Risk in Water Resources Management (Proceedings of Symposium H03 held during IUGG2011 in Melbourne, Australia, July 2011) (IAHS Publ. 347, 2011). 3-9

Keynote: Multi-objective storages for flood mitigation and water resources development in small catchments

PEDRO SIMONE1 & TREVOR M. DANIELL2

1Shared Watercourses Support Project, Administração Regional de Águas do Centro, 67 Sancho de Toar St. Beira, Mozambique

[email protected]

2School of Civil, Environmental and Mining Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia

Abstract In order to alleviate the continual increase in water demand over the available water resources, non-traditional water sources should be brought into the water supply cycle. Detention basins primarily designed for flood control have the potential to become part of this solution by delineating particular operational aspects. This paper proposes a framework for conjunctive use of detention basins for water supply purposes. An operational rule to ensure water supply without affecting the ability to control floods is developed. A study carried out found that this objective can be achieved through adopting a system of two levels of spills, where the first spill is aimed at ensuring continual release of inflows before the reservoir achieves full storage. The proposed approach was simulated using Monte Carlo analysis for Brown Hill Creek detention basins in Adelaide, South Australia, and satisfactory results were achieved.

Key words water; detention basins; flood control; sustainable yield; first spill level; risk management of water resources


Reducing uncertainty in derived flood frequency analysis related to rainfall forcing and model calibration

Uwe Haberlandt & Imke radtke

Institute of Water Resources Management, Leibniz University Hannover, Appelstr. 9a, 30176 Hannover, Germany

[email protected]

Abstract Hourly precipitation data sets are generated with a stochastic rainfall model and using a statistic disaggregation approach. The synthetic rainfall data are used as input for a continuous hydrological model applied to a mesoscale catchment in the Bode River basin in Germany. The simulated flows are analysed regarding the derived probability distributions of annual peak flows. The results show significant differences in flood probabilities for using spatially random rainfall, homogeneous rainfall or spatially structured rainfall. The direct calibration of the hydrological model using stochastic rainfall on flood probability distributions generally reduces both the bias and the variability in the simulated flows compared to the standard procedure using observed rainfall and runoff time series for calibration.

Key words derived flood frequency analysis; continuous hydrologic modelling; stochastic rainfall; rainfall disaggregation; model calibration; uncertainty


Towards understanding the differences between deterministic and probabilistic flood hazard estimation methods

MAGDALENA ROGGER1, ALBERTO VIGLIONE1, RALF MERZ1, ROBERT KIRNBAUER1, HERBERT PIRKL2 & GÜNTER BLÖSCHL1

1Vienna University of Technology, Institute of Hydraulic Engineering and Water Resources Management, Austria

[email protected]

2 Technical Office for Geology, Vienna, Austria

Abstract This paper presents the first results of a study on understanding discrepancies between flood estimates from local-scale, process-based deterministic methods and regional-scale probabilistic methods. Runoff processes in 10 pilot catchments in Tyrol were modelled with a continuous distributed rainfall–runoff model using detailed catchment information to assist in selecting the model parameters. Hydrogeologic information from field trips was found to be extremely useful for setting the spatial patterns of the storage capacities in the model. Parameters not identifiable from the field trips were obtained from a multi-step calibration to runoff. It is expected that the model is able to extrapolate more accurately to extreme events than a model based on calibration alone.

Key words flood hazard; design floods; hydrogeology; runoff modelling


Imprecise probabilities to specify hydrological loads for flood risk management

ANDREAS H. SCHUMANN1, MARKUS PAHLOW1, David Nijssen1 & Bastian Klein2

1 Institute of Hydrology, Water Resources Management and Environmental Engineering, Ruhr-University Bochum. D-44780 Bochum, Germany

[email protected]

2 German Federal Institute of Hydrology, Referat M2, Am Mainzer Tor 1, D-56068 Koblenz, Germany

Abstract Assessments of the performance and the risk of failures of complex technical flood retention systems demand the specification of hydrological loads under a wide range of possible circumstances. The outcome of risk assessments depends on these pre-assumptions. The existing lack of information demands new approaches to characterise uncertainties. As it is more widely recognised that the concept of uncertainty is too broad to be captured by probability theory alone, the application of imprecise probabilities can be useful in this context. In a case study, a wide range of possible flood events was specified by hydrological models, which combine stochastic and deterministic components. The simulation results were analysed by multivariate statistics. With respect to the uncertainties of simulations the plausibility of the flood scenarios was specified by fuzzy sets. This measure of plausibility was incorporated subsequently in a decision support system as basic characteristic of impact assessments of planning decisions.

Key words water; rivers; groundwater


Assessment of extreme flood characteristics based on a dynamic-stochastic model of runoff generation and the probable maximum discharge

L. S. Kuchment & A. N. Gelfan

Water Problems Institute of the Russian Academy of Sciences, 119991 Gubkin 3, Moscow, Russia

[email protected]

Abstract A dynamic-stochastic model of flood generation consisting of a distributed physically-based model of snowmelt runoff genesis and a stochastic weather generator has been used for the assessment of extreme flood risk. Coupling this model with the Monte Carlo simulations of meteorological series allows the calculation of long series of runoff hydrographs and the exceedance probabilities of flood characteristics, as well as avoiding the application of the hypothesis of stationarity of hydrological series. However, for very rare events, the uncertainty in estimating flood risk because of the model inadequacy and insufficient lengths of the used data series may significantly increase. To decrease this uncertainty, it has been suggested that the peak discharge series obtained by dynamic-stochastic simulations be combined with the probable maximum discharge (PMD) calculated through the physically-based model of snowmelt runoff generation. This combining is achieved by fitting the estimated exceedance probabilities of simulated peak discharges by the Johnson distribution with the PMD as the parameter. Sensitivity of the fitted Johnson distribution to the errors of the PMD estimations is analysed. A case study was carried out for the Vyatka River basin in Russia (catchment area of 124 000 km2) and the Seim River basin (catchment area of 7460 km2).

Key words distributed hydrological model; flood risk; stochastic weather generator; probable maximum discharge


Prévention du risque pluvial par l’élaboration des courbes intensité–durée–fréquence (IDF): application à la ville de Tipasa dans le Nord Ouest Algérien

MUSTAPHA BOUKHELIFA1, BENINA TOUAIBIA2 & PIERRE HUBERT3

1Résidence Concorde, C4, no. 6, Blida 09000, Algérie

[email protected]

2Ecole Nationale Supérieure de l’Hydraulique, Laboratoire d’Hydrologie, BP31, Blida 09000, Algérie

3 Université Pierre & Marie Curie Paris VI, UMR Sisyphe, Paris, France

Résumé Au cours de la dernière décennie et sous l’effet d’une urbanisation toujours croissante, les villes Algériennes ont connu des inondations dévastatrices dues à des averses de courte durée et de forte intensité. Les courbes IDF des précipitations représentent un outil de première importance dans la planification, la gestion et la prévention du risque pluvial. Traditionnellement les courbes IDF sont dérivées des séries des maxima annuels (SMA). Dans un contexte d’absence de SMA sur de longues périodes d’observation, une approche basée sur les séries de durées partielles (SDP) est préférable. Cette dernière permet d’inclure un grand nombre d’évènements extrêmes occultés par une approche SMA. Toutefois, le choix du seuil de dépassement pour la constitution d’une SDP sur différentes durées d’agrégation requiert une préparation particulière. En effet, le test de Spearman a permis de garantir l’indépendance des valeurs des intensités et le test de Kruskal-Wallis a permis de s’assurer que ces dernières étaient identiquement distribuées. La SDP, pour un nombre de dépassements annuels lambda = 1, présente la meilleure adéquation à la distribution généralisée de Pareto, le test d’Anderson-Darling ayant permis de s’en assurer. La méthodologie retenue pour l’établissement des courbes IDF est celle avancée par Koutsoyiannis en 1998, où la relation des courbes IDF découle explicitement de la fonction de distribution de probabilité sous-jacente, et ses paramètres sont estimés globalement, sur huit durées d’agrégation (de 1 à 360 min), par la méthode d’estimation robuste. Les courbes IDF établies permettent d’extrapoler les intensités jusqu’à des durées de 24 heures.

Mots clefs courbes IDF; series durée partielle; seuil; series maxima annuel; distribution généralisée de Pareto; test de Spearman; test d’Anderson-Darling; test de Kruskal-Wallis; L-moment; Algérie.

Storm water risk prevention through the establishment of intensity–duration–frequency curves (IDF): application to the city of Tipasa in northwestern Algeria

Abstract During the last decade, as a result of increasing urbanization, Algerian cities experienced devastating floods caused by short duration high intensity rainfall. IDF curves for precipitation represent a major tool in planning, management and prevention of storm water risk. Traditionally IDF curves are derived from annual maxima series (AMS). In the context of unavailability of AMS over long periods of observation, an approach based on partial duration series (PDS) is more suitable. The latter allows the inclusion of a large number of extreme events neglected by the AMS approach. However, the exceedence threshold selection for the sampling of a PDS over different aggregation durations requires specific preparation. Indeed, the Spearman test has ensured the independence of the values of intensities and the Kruskal-Wallis test has ensured that they were identically distributed. The PDS for a number of annual exceedence lambda = 1 gives the best fit to the generalized Pareto distribution; the Anderson-Darling test has ensured this. The method to establish IDF curves is one proposed by Koutsoyiannis in 1998, where the relationship of the IDF curves derives explicitly from the underlying probability distribution function, and its parameters are estimated globally over eight aggregation durations (1–360 min) using the robust estimation method. The IDF curves established allow extrapolation of the intensities up to a duration of 24 h.

Key words IDF curves; partial duration series; threshold; annual maxima series; generalized Pareto distribution; Spearman test; Anderson-Darling test; Kruskal-Wallis test; L-moment; Algeria


Drinking water extraction facilities at risk of flooding from rivers and groundwater – flood impact assessment for water extraction facilities in Ljubljana area

L. Globevnik1 & B. Bračič Železnik2

1Institut for Water of the Republic of Slovenia, Hajdrihova 28c, 1000 Ljubljana, Slovenia

[email protected]

2Public Water Utility JP Vodovod-Kanalizacija d.o.o., Ljubljana, Vodovodna cesta 90, 1000 Ljubljana, Slovenia

Abstract In this paper, risk to the Brest drinking water facility due to an extreme hydrological event in September 2010 is analysed. Groundwater is pumped from the Iška River fan gravel aquifer, which drains mountains in the south. When reaching its fan gravel aquifer, the Iška River starts to infiltrate the aquifer. Its flow decreases to a minimum and increases at geomorphological break between torrential fan and flat Ljubljana Moor surface. The water works at Brest are therefore at risk of flooding from surface water. In September 2010 Ljubljana Moor was flooded for five days. The specific phenomena happened due to Iška River. It overflowed its banks upstream of the Brest water field. It was the first time that the Brest field was also flooded. On the fifth day Iška River disappeared for two days into the groundwater. The operation of drinking water extraction facilities was stopped in the succeeding days.

Key words flood risk; groundwater; drinking water; gravel fan


Mountain risks in downstream water resource management in Upper Bhagirathi basin, Indian Himalayas

R. B. SINGH & SUBODH KUMAR

Department of Geography, Delhi School of Economics, University of Delhi, Delhi 110007, India

[email protected]

Abstract Mountainous areas tend to be prone to a wide range of potentially hazardous geomorphic and hydrological processes, such as rock falls, landslides, debris flow, soil erosion, snow avalanches, flash floods and cloudbursts on higher ridges. Risk assessment is carried out by evaluating the vulnerability and types of hazards existing in the region. The Upper Bhagirathi basin, particularly between Uttarkashi town and Gaumukh, has been selected. A separate hazard map was drawn and superimposed using the GIS technique. The main basin and areas close to the road in Upper Bhagirathi basin lie in the category of very high risk zone. The regions along tributaries of the Bhagirathi River, and away from the national highway, lie in the moderate risk zone. The increasing intensity of anthropogenic activities may contribute to the fragility and the vulnerability to flooding and challenges to downstream water resource management. The afforestation programme should be promoted on the vulnerable slopes to mitigate the risks.

Key words mountain risk; downstream water management; Bhagirathi basin, Himalayas, India


A new assessment methodology for flood risk: a case study in the Indus River basin

YOUNGJOO KWAK1, AKIRA HASEGAWA1, Hironori Inomata1, Jun Magome2, Kazuhiko Fukami1& Kuniyoshi Takeuchi1

1International Centre for Water Hazard and Risk Management (ICHARM) under the auspices of UNESCO, Public Works Research Institute (PWRI), 1-6 Minamihara, Tsukuba, Ibaraki 305-8516, Japan

[email protected]

2International Research Centre for River Basin Environment (ICRE), Interdisciplinary Graduate School of Medicine and Engineering, Yamanashi University,4-4-22 Takeda, Kofu, Yamanashi 400-8511, Japan

Abstract In this paper, the authors suggest a new flood risk assessment based on extreme discharge of the end-of-the-21st century scenario, and developed a model based on the concept of flood hazard that was composed of extreme discharge in climate change scenarios, saturation deficit during the extreme discharge, and flood periphery related to the flood disaster. The purpose of this study was to estimate, on a national scale, the number of the population possibly affected by flooding with each additional metre of inundation. The Indus River basin in Pakistan was selected as the prime research focus area. As a result, our integrated analysis was capable of predicting disaster damage caused by a hazard in a given area, considering the occurrence probability of the hazard and the vulnerability of the area. This approach is expected to play an important role in emergency response on a national level.

Key words flood hazard; extreme discharge; saturation deficit; inundation depth


Determination of inundation area based on flood hazard for a global water risk assessment

JONGGEOL PARK1 & YOUNGJOO KWAK2

1Tokyo University of Information, 4-1 Onaridai, Wakaba, Chiba 265-8501, Japan

[email protected]

2International Centre for Water Hazard and Risk Management (ICHARM) under the auspices of UNESCO, Public Works Research Institute (PWRI), 1-6 Minamihara, Tsukuba, Ibaraki 305-8516, Japan

Abstract The authors determined flood areas accurately in emergency response efforts as soon as possible. Estimation of a flood periphery is important to determine a fundamental hazard for risk management. The purpose of this study was to accurately extract the spatial distribution of nationwide flood risk using MODIS time series images and to estimate a simple algorithm for computing the flood inundation depth using DEM, flow direction and river network. The authors improved the accuracy of the water extent boundary using flood inundation depth (FID) data from a one-year time series of MODIS data.

Key words flood risk; flood inundation depth (FID); MODIS; time series


Elaboration of products derived from geospatial data for flooding risk analysis in Romania

Gheorghe Stancalie1, Vasile Craciunescu1, Argentina Nertan1, Denis Mihailescu1 & Ion Nedelcu2

1National Meteorological Administration, 97, Soseaua Bucuresti-Ploiesti, sector 1, 013686 Bucharest, Romania

[email protected]

2Romanian Space Agency, 21-25 Mendeleev str., 010362 sector1, Bucharest, Romania

Abstract In the last years, important floods occurred in Romania, engulfing wide areas and triggering loss of life and heavy damage. The modern management of geospatial data related to river flood risk relies on the functional facilities supplied by the GIS, combined with Earth Observation information and hydrological modelling, in view of establishing a methodology, which should further allow the elaboration of products useful for flooding risk analysis, such as: updated maps of land cover/land use, thematic maps with the extent of the flooded areas and the affected zones, maps of the hazard prone areas, risk maps for several probabilities of the maximum discharge occurrence, etc. These kinds of products started to contribute to preventive consideration of flooding in land development and special planning in the flood-prone areas, and for optimizing the distribution of flood-related geo-information to end-users.

Key words flood; flooding risk; geospatial data; satellite; Romania


Zoning groundwater flooding risks in the cities and urban agglomeration areas of Ukraine

Oleksandr CHEBANOV & ANASTASIA ZADNIPROVSKA

State Center for Integrated Surface- & Groundwater Management (SCIM UkrWodGeo), 6 Shevchenko Vul., 61200 Kharkiv, Ukraine

[email protected]

Abstract The rising of groundwater levels up to the soil surface is a phenomenon called groundwater flooding. It appears as soil moistening, swamping, and flooding in the area. In some cities of Ukraine it takes a hazardous scale under conditions of urban development. The application of the groundwater flooding risk assessment and zoning method has been shown. It considers spatial distribution of local factors of “groundwater flooding hazard” and “susceptibility”. The hazard factor is dependent on groundwater level and quality, and on soil properties. The susceptibility factor takes into account urban development characteristics: building density, number of floors, development functionality, and basement types. Analysing these factors on the thematic map layers allows zoning of groundwater flooding risk using the following scale of risk: low, moderate, medium, high, and critical. Such kind of zoning has been performed for the six large cities of Ukraine (Dnipropetrovsk, Kharkiv, Kherson, Odessa, Poltava, Zaporizhya) and resulted in the thematic maps album.

Key words groundwater flooding; hazard; susceptibility; risk factor


Low-flow risk assessment for water management

MIKHAIL BOLGOV1 & ELENA KOROBKINA2

1 Water Problems Institute, RAS, Gubkin St., Moscow 119333, Russia

[email protected]

2 Institute for Water and Environmental Problems, SB RAS, Morskoy Prosp., 2, Novosibirsk 630090, Russia

Abstract Risk assessments related to increasing aridity of climate are important, particularly for stable operation of water systems and optimization of water resources management. For this purpose several approaches for regionalization and evaluation of parameters of long-term river flow fluctuations are considered and the method of simulation of synthetic time series of inflow to reservoirs is proposed. To validate the applicability of the Markov stochastic model to describe the of probability of cycling of dry and wet years, the characteristics of distribution of excursions below thresholds (duration and frequency of events) and the minima in the time series of fluvial discharge smoothed regarding N-years were calculated. This approach has been used for assessment of reliability of the complex water system in the Volga River basin under drought conditions and can be applied to evaluation of probability of long periods of low flows on the rivers in Siberia and in the Far East (Russian Federation).

Key words river–runoff; low flow; stochastic modelling; parameters of distribution

____________________________________________________________________________________________Risk in Water Resources Management (Proceedings of Symposium H03 held during IUGG2011 in Melbourne, Australia, July 2011) (IAHS Publ. 347, 2011) 85-92

Assessing drought hazard under non-stationary conditions on southeast of Spain

sandra g. garcía galiano1, juan d. giraldo osorio1, mario a. urrea mallebrera2, adolfo mérida abril2 & claudia n. tetay botía1

1Technical University of Cartagena, Department of Civil Engineering, R&D Group of Water Resources Management, Paseo Alfonso XIII, 52, 30203 Cartagena, Spain

[email protected]

2Confederación Hidrográfica del Segura, Plaza Fontes 1, 30001 Murcia, Spain

Abstract The vulnerability of semi-arid basins such as the Segura River basin (southeast Spain), to rainfall variability, implies uncertainties in agricultural activities. Increasing the knowledge about plausible trends of drought events will improve the adaptation and mitigation measures. The non-stationary character of hydrometeorological series, based on climate and anthropogenic changes, is the main criticism of traditional frequency analysis. An innovative methodology for non-stationary analysis of droughts events, applying GAMLSS (Generalized Additive Models for Location, Scale and Shape) is presented. The analyses were based on observed data and selected regional climate models (RCMs). The series of maximum length of dry spells (MDSL) from observed data show an intensification of drought events in headwater catchments from the 1980s onwards. From various RCMs, plausible trends of MDSL are identified. By adjusting pdf to series of observed MDSL, applying GAMLSS and bootstrapping techniques, the assessment of regional trends associated to return period, from hazard maps is possible.

Key words drought; non-stationary probabilistic models; GAMLSS; Segura River Basin; Spain


Risks in hydrological modelling due to uncertainties in discharge determination

Martijn J. Booij1, Sander P. M. van den Tillaart1,2 & Maarten S. Krol1

1Department of Water Engineering and Management, University of Twente, Enschede, The Netherlands

[email protected]

2Water Board Rijn and IJssel, Doetinchem, The Netherlands

Abstract Uncertainties in discharge determination may have serious consequences for hydrological modelling and resulting discharge predictions affecting flood and drought risk assessment and decision making. The aim of this study is to quantify the effect of discharge errors on parameters and performance of a conceptual hydrological model for discharge prediction applied to two catchments. Four error sources in discharge determination are considered: a combination of systematic and random measurement errors without autocorrelation; random measurement errors with autocorrelation; hysteresis in the discharge-water level relation; and effects of an outdated discharge–water level relation. Results show that systematic errors and an outdated discharge–water level relation have a considerable influence on model performance, while other error sources have a small to negligible effect. The effects of errors on parameters are large if the effects on model performance are large, and vice versa. Parameters controlling the water balance are influenced by systematic errors, and parameters related to the shape of the hydrograph are influenced by random errors. Large effects of discharge errors on model performance and parameters should be taken into account when using discharge predictions for risk assessment and decision making.

Key words uncertainty; discharge determination; hydrological modelling; model calibration; SCEM-UA; Meuse River


Propagation of input errors: implications for model simulations and risk analysis

kerrie M. tomkins1 & andrew J. davidson2

1CSIRO Land and Water, Black Mountain Laboratories, PO Box 1666, Canberra, Australia Capital Territory, ACT 2601, Australia

[email protected]

2New South Wales Office of Water, Government Service Centre, PO Box 189, Queanbeyan, New South Wales 2620, Australia

Abstract Hydrological models are widely used in water resources management in Australia. Unpinning these models is streamflow data, which is commonly used as inputs, for calibration of parameters and, for verification of model performance. One of the lesser investigated issues in modelling and uncertainty analysis is how the choice of error models impacts on simulations, and how this propagates into decision-making where simulations are used to determine the volume, frequency and reliability of flows. We used an analysis of the deviations in gaugings from flow gauges in the Namoi River catchment, to derive empirically-based error models for the data. The error models were used to generate uncertainty in tributary and residual inflows in the Namoi River Integrated Quality and Quantity Model (IQQM). Several scenarios were run, including empirically-derived best-fit, empirically-derived Gaussian and standard Gaussian error models, with reference to a baseline simulation where the data are assumed to be error free. Analysis of end-of-system flows showed that there was no conclusive difference in the effect of the error models; however, this was likely to be due to the addition of random rather than auto-correlated errors, which arise from fitting of rating curves to gaugings. This study highlights the need for further investigation into rating curve uncertainty, error autocorrelation and sampling of error models.

Key words uncertainty; river model; rating curve; Namoi River


Assimilation of streamflow discharge into a continuous flood forecasting model

Yuan Li1,2, Dongryeol Ryu1, Q. J. Wang2, Thomas Pagano2, andrew Western1, Prasantha Hapuarachchi2 & Peter toscas3

1Department of Civil and Environmental Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia

[email protected]

2CSIRO Land and Water, Highett, Victoria 3190, Australia

3CSIRO Mathematics Informatics and Statistics, Clayton, Victoria 3168, Australia

Abstract Four state updating schemes are explored to integrate the observed discharge data into a flood forecasting model. Hourly streamflow discharge measured in the Ovens River catchment, Australia, is assimilated into the Probability Distributed Model (PDM) using the ensemble Kalman filter. The results show that the overall forecast accuracy improves when the discharge observations are integrated, mainly due to better initialisation of the model. Setting error covariance proportional to each state variable gives better results than setting error covariance as a constant value. Updating routing states of PDM affects discharge prediction instantly, while the effect of soil moisture updating results in a lagged response in discharge leading to a poorer update performance. However, during the forecast lead time, updating soil moisture results in slower degradation of the forecast accuracy, which is mainly because the soil moisture store is the only state influencing discharge volume, while the routing storages only describe the flow delay.

Key words discharge assimilation; flood forecasting; ensemble Kalman filter; state updating


Application of a particle swarm optimization to the tank model

Celso Augusto guimarães Santos1, PAULA KARENINA DE MACEDO MACHADO FREIRE1, s. k. mISHRA2 & AMÍLCAR SOARES JÚNIOR3

1Federal University of Paraíba, Department of Civil and Environmental Engng, 58051-900 João Pessoa, PB, Brazil

[email protected]

2North-Eastern Hill University, Shillong, India

3Federal University of Paraíba, Department of Computer Science, 58051-900 João Pessoa, PB, Brazil

Abstract A major risk concerning the modelling of hydrological processes with conceptual models is the optimization of the parameters because they cannot be directly measured in the field, mainly in nonlinear models. Several optimization methods have been tested in the past during the calibration of such models, but it is difficult to ensure that the final values are not trapped in a local minimum. Thus, the difficulties involved in calibration of hydrological models have been partly attributable to the lack of robust optimization tools. This paper presents the essential concepts and application to optimize the main parameters in a conceptual hydrological model, with a global optimization method known as Repulsive Particle Swarm (RPS), which is a variant of the Particle Swarm Optimization (PSO) method. The hydrological model that was chosen is the tank model, whose basic principle consists of representing the river basin as a set of tanks in which the outflows of each tank are proportional to the water height from the respective outlets. The tank model is nonlinear and mathematics is nearly useless for nonlinear problems. Therefore, mathematics could not be used for the tank model calibration, and consequently, the RPS technique seems to be suitable for such a task. The optimization technique was tested with the field data from Ishite River Dam, which is the reservoir that supplies water to the city of Matsuyama, Japan. On the basis of these results, the parameter values are given, which could serve as an initial estimate for other similar Japanese watersheds.

Key words hydrological modelling; optimization; RPS; tank model


Reducing the uncertainty associated with water resources planning in a developing country basin with limited runoff data through AI rainfall–runoff modelling

ADEBAYO J. ADELOYE

School of the Built-Environment, Heriot-Watt University, Riccaton, Edinburgh EH14 4AS, UK

[email protected]

Abstract A major bane of water resources assessment in developing countries is the insufficiency or total lack of hydrometeorological data, resulting in huge uncertainties and ineffectual performance of water schemes. This study reports on the application of the Kohonen Self-organizing Map (KSOM) unsupervised artificial neural networks in harnessing the multivariate correlations between the rainfall and runoff for an inadequately gauged basin in southwest Nigeria, for the sole purpose of extending the runoff records, and through them, reducing water resources planning uncertainty associated with the use of short data records. The extended runoff records were then analysed to determine possible abstractions from the main river source at different exceedence probabilities. The study demonstrates the successful use of emerging tools in reducing the uncertainty associated with lack or insufficiency of data for water resources planning assessment.

Key words water resources assessment; hydrological data; Kohonen Self Organising Map (KSOM); reliability; water abstractions; Nigeria


Hydrological and stochastic uncertainty: linking hydrological and water resources yield models in an uncertainty framework

DENIS A. HUGHES1, STEPHEN J. L. MALLORY1, BENNIE HAASBROEK2 & GEOFFREY G. S. PEGRAM3

1 Institute for Water Research, Rhodes University, Grahamstown 6140, South Africa

[email protected]

2 Hydrosol, Pretoria, South Africa

3 Department of Civil Engineering, University of KwaZulu-Natal, Durban, South Africa

Abstract Standard approaches to water resources assessments in South Africa involve generating time series of natural hydrology using a hydrological model coupled with simulating reservoir storage, abstractions, return flows, etc. using a system yield model. To account for some of the uncertainties in the representivity of the natural flow simulations, the yield models currently include a stochastic streamflow generator and output a curve quantifying likely yields with different probabilities of exceedence. Recent hydrology model developments emphasise the importance of including parameter uncertainty, especially in ungauged basins. However, this has been considered difficult to achieve with existing yield models without major structural changes or large increases in computer run time. The alternative is to add a stochastic rainfall generator within a hydrological model that also includes parameter uncertainty, and to use the output ensembles with a yield assessment model without using the stochastic streamflow generation component. This paper reports on a comparison of the two approaches in terms of modelling efficiency, similarity of yield probability assessments, and the relative contributions of parameter and stochastic uncertainty. This initial study is limited to a single basin in KwaZulu-Natal Province, South Africa.

Key words uncertainty; hydrology models; stochastic modelling; yield estimation


Evaluation of combined contribution of uncertainty sources to total output uncertainty in water resource estimation in South Africa

TENDAI Sawunyama, DENIS A. Hughes & STEPHEN J. L. Mallory

Institute for Water Research, Rhodes University, PO Box 94 Grahamstown, 6140, South Africa

[email protected]

Abstract While the importance of quantifying different sources of uncertainty is well recognized, there have only been a few attempts within southern Africa to incorporate uncertainty estimates in water resources assessments, and their overall impacts are not well understood. Uncertainties are model, basin, region and climate zone specific, and while the basic principles referred to in the hydrological literature are relevant, they do not provide the specific answers for the region. The focus of this study was on the use of datasets and modelling tools that are frequently used for practical water resources estimation in South Africa. The analyses are based on scenarios of different sources of uncertainty which are then combined and propagated through the model to generate simulation ensembles that include the expected ranges of model output uncertainty. The results indicate that the major source of uncertainty is either rainfall or parameter value estimation depending on the sub-basin. The study suggests that, while input climate data always contributes substantially to total output uncertainty, there may be many situations where parameter uncertainty dominates and there is very little impact from evaporation and water-use uncertainties.

Key words model uncertainty; rainfall–runoff model; South Africa


Water resource allocation for the Songhua River Region, China, under the uncertainty of water supply

Suxia Liu & YAOWEI ZHANG

Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

[email protected]

Abstract Water resources allocation (WRA) is a useful and yet complicated topic in water resources management. The solution of WRA may be uncertain due to the uncertainty of the input, the structure itself, and the parameters of the models. So far, very few studies deal with the topic about how much these uncertainties influence the solution and how to adapt the situation. By using Dependent-Chance Goal Programming (DCGP), this paper built a WRA under the uncertainty of water supply for the Songhua River Region (SHRR) located in the northeast of China, one of China’s most important commercial grain bases. Two sets of WRA results were obtained under the two ranges of uncertainty relative to bad (S1) and good (S2) water supply situations. Situation S1 takes a higher water shortage rate and S2 takes a lower water shortage rate than the routine WRA results by the SHRR Commission’s comprehensive plan, but all keeping the rate of water resources exploitation approaching or lower than the international standards. The result helps SHRR to make a more resilient decision to the change of water supply condition in meeting the national needs of Newly Increasing Yield of 10 ( 1011 Jin.

Key words water resources allocation; uncertainty; dependent-chance global programming


How to quantify uncertainty in water allocation models? An exploratory analysis based on hypothetical case studies

J. LERAT1, K. TOMKINS1, Q. SHAO2, L. PEETERS1, A. YANG1 & D. RASSAM1

1CSIRO Land and Water, GPO Box 1666, Canberra, Australian Capital Territory 2601, Australia

[email protected]

2CSIRO Mathematical and Information Sciences, Private Bag no. 5, Wembley, Western Australia 6913, Australia

Abstract Water allocation models are the principal tools used to build water sharing plans in regulated river systems across Australia. These models associate components describing the physical system (e.g. rainfall–runoff transformation and flow routing) and the management rules (e.g. operation of dams and irrigation extractions). In a context of growing pressure on water resources, the uncertainty associated with these highly parameterised models needs to be quantified in a defensible and transparent way. This paper is an exploratory analysis based on the application of two uncertainty methods to hypothetical river system case studies. First, a simplified model structure is developed by using existing characteristics from six regions of the Murray-Darling basin. Each model contains a schematic representation of the region with: (1) one upstream storage, (2) ungauged and gauged tributaries inflows, and (3) one downstream irrigation extraction point. Second, the model outputs (streamflow) are corrupted and an alternative model is calibrated based on the corrupted data using the standard least-squares method. Finally, the uncertainty in the output is generated using two uncertainty post-processors and compared with the uncorrupted (“true”) outputs using deterministic and probabilistic scores. The uncertainty post-processor based on the empirical distribution of the residuals proved simple yet effective, especially when compared to the more advanced bootstrapping method. It performed systematically better when applied to the stored volumes in the reservoir. However, the predictive uncertainty was greatly improved by the bootstrapping method to assess the uncertainty on streamflow. This highlights the important differences that can occur in the uncertainty analysis for a multivariate model.

Key words water allocation models; synthetic experiments; uncertainty assessment; calibration; bootstrap


Risks in water management associated with changing climate systems: reflections and case analysis

Juan Carlos Bertoni

Hydrology and Hydraulics Processes Chair. Faculty of Exacts, Physics and Natural Sciences, Cordoba National University, Argentina

[email protected]

Abstract Climate variability, climate change and hydrological variability are distinct phenomena whose effects on water resources can mean, among other consequences, changes in the conditions originally assumed in the design of hydraulic facilities. Hydrological variability takes place when there are changes in the main inputs and/or outputs of a hydrological system (precipitation, evapotranspiration, flows). This paper presents some considerations concerning the hydrological behaviour of river basins in situations associated with climate change, climate variability and hydrological variability. Several case studies in the central region of Argentina illustrate the issues discussed. The considerations presented are intended to contribute to the awareness of new risks that arise in operational water management.

Key words hydrological variability; climate change; climate variability; Argentina


Risk-based assessment of water availability in a changing climate

ATEF KASSEM, TAMAS HAMORY, IVANA VOUK & DAVID HARVEY

Environment Canada, Sustainable Water Management Division, Environmental Stewardship Branch, Ottawa K1A 0H3, Canada

[email protected]

Abstract Water availability assessment is a complex undertaking and is becoming more challenging given the uncertainty associated with climate change. It requires the evaluation of not only water supplies, but also of the competing water demands for socio-economic development and maintaining a healthy ecosystem. Both water supplies and water demands are subject to significant seasonal and annual variation, which is expected to be exacerbated by climate change. By analysing the time varying water supplies and water demands, water availability can be presented in terms of probability or in a risk-management context. The large uncertainty surrounding climate change, as well as future socio-economic and other developments can be dealt with by using scenario analysis that incorporates a wide range of future socio-economic and climate scenarios or possibilities. Such analysis allows the establishment of the relative change in risk to the water resources system (e.g. frequency of occurrence of shortages) as a result of climate change (scenarios) and the analysis of the impacts of adaptation measures on reducing such risk.

Key words MACROBUTTON

MACROBUTTON water availability; climate variability; climate change; risk; climate adaptation


Assessing the impacts of global changes on the water resources of the Mediterranean basin

M. MILANO1,4, D. RUELLAND2, S. FERNANDEZ4, A. DEZETTER3, S. ARDOIN-BARDIN3, J. FABRE1,4, G. THIVET4 & E. SERVAT3

1UM2– UMR HydroSciences Montpellier, Place E. Bataillon, 34395 Montpellier Cedex 5, France

[email protected]

2 CNRS – UMR HydroSciences Montpellier, Place E. Bataillon, 34395 Montpellier Cedex 5, France

3 IRD – UMR HydroSciences Montpellier, Place E. Bataillon, 34395 Montpellier Cedex 5, France

4Plan Bleu, 15 rue Beethoven, 06560 Valbonne Sophia-Antipolis, France

Abstract The Mediterranean basin is characterized by limited and unequally distributed water resources, as well as by important development of its anthropogenic activities. The latter has led to continuously increasing water withdrawals. Moreover, the region should be particularly affected by climate change, with rising temperatures and more frequent and intense drought periods affecting water resources availability. This paper assesses the impacts of those changes by investigating the current and future situation of both water availability and water withdrawals. Over the reference period (1971–1990), a conceptual rainfall–runoff gridded model was applied to evaluate freshwater availability, and an overview of agricultural and domestic water use was completed according to national reports. To evaluate the future trends in water availability at short (2025) and mid (2050) terms, climatic scenarios were generated by applying unbias and delta methods to projections from four global climate models. These climatic scenarios were used as inputs to the hydrological model but also to an irrigation management model to evaluate future agricultural water withdrawals. Domestic water use was estimated using demographic scenarios. For both sectors, progress in water-use efficiency was also considered. A water stress index accounting for those various indicators was then computed. The results show that both climate and socio-economic changes will have a significant impact on water resources. The Mediterranean basin might be subjected to a more arid climate and increasing local disparities. Some areas might experience increasing water stress. This study is a first step towards providing indicators combining water resources availability and water use in line with planning decisions at a regional level.

Key words Mediterranean basin; water availability; water withdrawals; water stress index; water balance model; CROPWAT; scenarios

____________________________________________________________________________________________Risk in Water Resources Management (Proceedings of Symposium H03 held during IUGG2011 in Melbourne, Australia, July 2011) (IAHS Publ. 347, 2011) 173-180

Drought analysis based on precipitation generation from GCMs for the Qingjiang River Basin

Kunxia YU, Lihua XIONG, Leihua DONG & Min WAN

State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China

[email protected]

Abstract This paper aims to assess model reliability of 21 global climate models (GCMs) to reproduce observed historical monthly rainfall and drought, especially extreme events over Qingjiang River Basin. Monthly areal precipitation series were downscaled from 21 GCMs using the Statistical DownScaling Model (SDSM). All the downscaling rainfalls were evaluated against the 1960–1999 observed rainfall data over Qingjiang River Basin. The main conclusions include: (a) most downscaled rainfalls can reasonably reproduce the observed monthly areal rainfall series in both calibration period and validation period, although downscaled rainfall time series are more stationary; (b) downscaled rainfalls perform poorly when they come to drought, and observed drought characteristics cannot be well reproduced, but category simulation accuracy is generally satisfactory to some degree; (c) there is no clear difference in the ability to produce historical rainfall characteristics between GCMs, but the difference in the capability to simulate droughts and extreme events is significant.

Key words precipitation; drought; extreme; downscaling; global climate models; Qingjiang River Basin


Optimal multi-year operation of a water supply system under uncertainty: robust methods

Mashor HOUSH, avi ostfeld & uri shamir

Faculty of Civil and Environmental Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel

[email protected]

Abstract The Robust Optimization (RO) methodology (Ben-Tal et al., 2009) is applied to optimize the operation of a water supply system (WSS) which supplies water from aquifers with uncertain recharge and desalination plants through a network to consumers. The objective is to minimize the total cost of multiyear operation, while satisfying operational and physical constraints. The RO methodology optimizes the uncertain problem by requesting that the uncertain parameters reside within a user-defined uncertainty set. The static (“here and now”) version of RO is called Robust Counterpart (RC), in which the original problem is converted into a deterministic equivalent problem. A generic RC model for optimal operation of a WSS is developed and demonstrated. The policies obtained by the RO methodology, each requiring a different reliability, are compared with other decision making approaches.

Key words water supply systems; optimal operation; uncertain recharge; robust counterpart; robust optimization


Daily reservoir operating rules by implicit stochastic optimization and artificial neural networks in a semi-arid land of Brazil

CAMILO ALLYSON SIMÕES DE FARIAS1, CELSO AUGUSTO GUIMARÃES SANTOS2 & ALCIGEIMES BATISTA CELESTE3

1 Academic Unit of Environmental Science and Technology, Federal University of Campina Grande, Rua Jairo Vieira Feitosa, S/N, Pereiros, 58840-000 Pombal – PB, Brazil

[email protected]

2 Dept of Civil and Environmental Engineering, Federal University of Paraíba, 58051-900 João Pessoa – PB, Brazil

3 Dept of Civil Engineering, Federal University of Sergipe, Av. Mal. Rondon, S/N, Jardim Rosa Elze, 49100-000 São Cristóvão – SE, Brazil

Abstract This paper presents a model based on Implicit Stochastic Optimization (ISO) and Artificial Neural Networks (ANN) for deriving daily operating rules for a reservoir system located in a semi-arid region of Brazil. The ISO procedure consists of optimizing the reservoir system for possible inflow scenarios and then analysing the optimal outcomes in order to generate operating rules. Unlike the common use of regression equations, this study makes use of ANN to develop reservoir hedging rules relating end-of-period reservoir storage to initial storage and other system variables. After the establishment of the ISO-ANN rules, they were tested over a new series of inflows and the outcomes were assessed by means of sustainability criteria. The ISO-ANN rules were shown to be superior to the so-called Standard Linear Operating Policy (SLOP) and equivalent to the results derived by deterministic optimization taking the same inflows as perfect forecasts for one year ahead.

Key words reservoir operation; artificial neural networks; implicit stochastic optimization; hedging rules; sustainability; semi-arid


Development and application of water allocation model based on ET-control

J. J. YOU, Z. GAN, H. GAN & L. JIA

China Institute of Water Resources and Hydropower Research, Beijing, China

[email protected]

Abstract Traditionally, water allocation is to distribute water to different regions and sectors, without enough consideration on the amount of water consumed after water distribution. Water allocation based on ET (evaporation and transpiration) control changes this idea and emphasizes the absolute amount of evaporation and transpiration in a specific area. With this ideology, the amount of ET involved in the water allocation includes not only water consumed from the sectors, but also the natural ET. Therefore, the water allocation consists of two steps, the first step is to estimate reasonable ET quantum in regions, then allocate water to more detailed regions and various sectors with the ET quantum according to the operational rules. To make qualified ET distribution and water allocation in various regions, a framework is put forward in this paper, in which two models are applied to analyse the different scenarios with predefined economic growth and ecological objective. The first model figures out rational ET objective with multi-objective analysis for compromised solution in economic growth and ecological maintenance. Food security and environmental protection are also taken as constraints in the optimization in the first model. The second one provides hydraulic simulation and water balance to allocate the ET objective to corresponding regions under operational rules. These two models are combined into an integrated ET-control water allocation. Scenario analysis through the ET-control model could discover the relation between economy and ecology, and to give suggestions on measures to control water use with conditions of changing socio-economic growth and ecological objectives. To confirm the methodology, Haihe River is taken as a study case. Rational water allocation is an important branch of decision making in water planning and management in Haihe River Basin, since water scarcity and deteriorating environment fights for water in this basin, and reasonable water allocation between economy and ecology is a focus. Considering water scarcity conditions in Haihe River Basin, the ET quota is taken as an objective for water allocation in provinces to realise the requirement of water inflow into the Bohai Sea. Scenario analysis provides the results of water evaporation from the natural water cycle and artificial use. A trade-off curve based on fulfilment of ecological and economic objectives in different scenarios discovers the competitive relation between human activities and nature.

Key words water allocation; ET management; Haihe River Basin; multi-objective analysis


Accounting for uncertainty in pumping rate optimisation for sustainable aquifer management

Luk Peeters1, David Rassam2 & Julien Lerat3

1 CSIRO Land and Water, Adelaide, Private Bag No 2, Glen Osmond, South Australia 5064, Australia

[email protected]

2 CSIRO Land and Water, 41 Boggo Rd, Dutton Park, Queensland 4102, Australia

3 CSIRO Land and Water, GPO Box 1666, Canberra, Australia Capital Territory 2601, Australia

Abstract Optimisation of pumping rates for sustainable aquifer management is commonly based on groundwater models. The optimal pumping rate estimate will therefore be affected by uncertainty in input, parameters and model conceptualization. Pumping rates in a hypothetical groundwater model of an alluvial aquifer in a semi-arid climate are maximized subject to constraints on piezometric level, drawdown and fluxes to surface water. A new model is calibrated, using the hypothetical model as reference, to obtain a new estimate of optimal pumping rates. While keeping the mismatch between observed and calculated values below an acceptable level, uncertainty arising from input data and model parameters is propagated through the model to obtain an informal prediction interval for the optimal pumping rate prediction. Instead of a single optimal pumping rate, the informal prediction interval informs management of the range of pumping rates justified by the groundwater model within an acceptable level of calibration.

Key words aquifer management; pumping; optimisation; calibration; uncertainty


Evaluating potentials and corresponding risks of optimal deficit irrigation strategies under climate change and other sources of uncertainty

Niels Schütze, Jens Grundmann, Sebastian Kloss & Gerd H. Schmitz

Institute of Hydrology and Meteorology, Dresden University of Technology, Dresden, Germany

[email protected]

Abstract In this contribution we introduce a stochastic framework for decision support for optimal planning and operation of water supply in irrigation. This consists of: (i) a weather generator for simulating regional impacts of climate change on the basis of IPCC scenarios; (ii) a tailor-made evolutionary optimization algorithm for optimal irrigation scheduling with limited water supply; (iii) a mechanistic model for simulating water transport and crop growth in a sound manner; and (iv) a kernel density estimator for estimating stochastic productivity, profit and demand functions by a nonparametric method. As a result of several simulation/optimization runs within the framework, we present stochastic crop–water production functions (SCWPF) for different crops, which can be used as a basic tool for assessing the impact of climate variability on the risk for the potential yield or, furthermore, for generating maps of uncertainty of yield for specific crops and specific agricultural areas. In addition, micro-economic impacts of climate change and the vulnerability of the agro-ecological systems are discussed. Finally, we show how additional sources of uncertainty (e.g. soil conditions and management) can be included in the new stochastic framework.

Key words deficit irrigation; crop–water production function; optimal scheduling; risk assessment; climate uncertainty; climate change


Risks, hazards and vulnerability associated with overexploitation of groundwater in northwest India

MUKAND BRAR1 & PREETI ROYCHAND2

1 Soil Science, Punjab Agricultural University, Ludhiana, India

[email protected]

2 Department of Agricultural Sciences, Latrobe University, Bundoora, Victoria 3086, Australia

Abstract Overexploitation of groundwater in the most productive area in Indo-Gangetic plains of northwest India is a matter of concern. If the current rate of overexploitation is not stopped and the sharp fall in level of groundwater is not arrested, there is a great risk of conversion of the most productive area of northwest India into desert. Overexploitation of groundwater is mainly caused by a change in cropping pattern, increase in area under irrigation and number of tube wells, decline in rainfall and canal irrigated area, and lack of proper planning for systematic groundwater extraction. Management strategies for the arrest of declining water have been discussed. With limitation of water resources there needs to be a paradigm shift from agronomic yield maximization to maximization of water-productivity, and diversification from cultivation of high-water consuming crops to low-water consuming crops.

Key words groundwater; overexploitation; risks; management strategies


Physically-based groundwater vulnerability assessment using sensitivity analysis methods

Jean Beaujean1,2, jean-michel lemieux3, Pascal goderniaux1 & serge brouyère1

1Hydrogeology & Environmental Geology, Geo3 Group, ArGEnCo Dept., Aquapôle, University of Liège, Liège, Belgium

[email protected]

2Now at: Applied Geophysics, Geo3 Group, ArGEnCo Dept., University of Liège, Liège, Belgium

3Département de Géologie et de Génie Géologique, Université Laval, Québec, Canada

Abstract Management of water resource systems requires adequate decision making to protect the water-related functions of fundamental importance to human life, ecosystem preservation and economic development. Groundwater vulnerability assessment studies are useful tools for land-use planning and groundwater protection. A generalized physically-based method using numerical models of groundwater flow is proposed for quantifying the impact on groundwater resources to external pressures, in terms of both quantity and quality. The proposed method is based on the definition of groundwater state sensitivity and groundwater vulnerability coefficients. The vulnerability coefficient is defined as a ratio that reflects the “distance” between the current state of degradation of the water resource system and the “damaged state”. Different numerical methods are proposed to compute the sensitivity coefficients. The uses of these concepts in risk assessment for groundwater resources are discussed and the computation algorithms are illustrated using a simple, yet insightful case study.

Key words vulnerability; sensitivity; physically-based; artificial recharge; risk assessment

____________________________________________________________________________________________Risk in Water Resources Management (Proceedings of Symposium H03 held during IUGG2011 in Melbourne, Australia, July 2011) (IAHS Publ. 347, 2011) 230-234 .

Water supply and the impact on human development in Nigeria

SHAKIRUDEEN ODUNUGA1, IFEYINWA OKEKE1, FIDELIS OKORIE2 & OLATUNDE OLANIYI3

1 Department of Geography, University of Lagos, Akoka 101017 Lagos, Nigeria

[email protected]

2 Department of Geography and Environmental Management, Evan Enwerem University Owerri, Imo State, Nigeria

3 Department of Geography, Joseph Ayo Babalola University Ikeji, Osun State, Nigeria

Abstract The development of a society is incomplete without adequate water supply. Uncertainties and risks of pollution (industrial, human and bacterial contamination), land-use change, unhygienic human practices, climatic and seasonal variations are often prevalent in most communities, and consequently have adverse short- and long-term effects on the quality of water, and the living and health conditions of the inhabitants. This paper adopts an intensive field work survey and personal observations to examine some risks of water shortages, inadequate storages, rainfall variations, affordability and opportunity cost, as well as their effects in the development of water supply in three local government areas of Anambra State: Nnewi South, Idemili North and Idemili South. Solutions to minimizing these risks, as well as adequate measures to boosting water development in the state, are presented.

Key words uncertainties; rural; water supply; impact and development


The application of rural threshold water consumption model in water supply studies

IFEYINWA OKEKE, LEKAN OYEBANDE & SHAKIRUDEEN ODUNUGA

Department of Geography, University of Lagos, Akoka, 101017 Lagos, Nigeria

[email protected]

Abstract The development of the Rural Threshold Water Consumption (RTWC) model for solving rural water problems has contributed valuable data in hydrological sciences modelling. The model objective is to quantify domestic water consumption, generate a threshold value and delineate areas of deficits, balances or surpluses at regular and supplemental periods using local techniques. The end result is the prediction of risks, as well as solutions to rural water problems. The paper thus establishes the use of the RTWC model as an analytical tool, and a planning kit for water sector planners and decision makers for sustainable year-round domestic usage water allocation.

Key words RTWC model; rural water supply; Nigeria

____________________________________________________________________________________________Risk in Water Resources Management (Proceedings of Symposium H03 held during IUGG2011 in Melbourne, Australia, July 2011) (IAHS Publ. 347, 2011) 241-246 .

Small farm dams research project in the semi-arid northeastern region of Brazil

Ana Cristina Souza da Silva1, Alain Marie Passerat de Silans2, Gerald Souza da Silva3, Flavia Augusta dos Santos3, Renato de Queiroz Porto3 & CRISTIANO ALMEIDA NEVES3

1UFCG – University of Campina Grande, Campina Grande, Brazil

[email protected]

2AESA - Water management agency of the state of Paraiba, João Pessoa, Brazil

3UFPB – University of Paraiba, João Pessoa, Brazil;

Abstract The semi-arid northeastern region of Brazil has a unique natural character, which historically, demanded several scientific and political efforts in order to improve the living conditions for the population in this region. The most suitable use of water resources has been the subject of much research for several reasons. Small farm dams represent one of the main sources of water during the dry season in the semi-arid region of Brazil. To know these water sources the aim of the study and the project named DISPAB was more appropriate. Conservation conditions, maintenance and estimated volumes were the object of the survey, as well as social benefits brought by this source of water for the semi-arid population. The results showed that these small dams are an important source of water for the region. However, for the state water agency, the real magnitude of importance and risks provoked by them is still unknown. Through the results of the research, methodological parameters have been obtained to support licensing actions related to the available water resources in small watersheds in semi-arid regions.

Key words semi-arid; small dams; water management; Brazil


Incorporating hydrological reliability in rural rainwater harvesting and run-of-river supply

JOHN NDIRITU1, JOHN ODIYO2, RACHEL MAKUNGO2, CELIWE NTULI3 & BEASON MWAKA3

1 University of the Witwatersrand, School of Civil and Environmental Engineering, P/Bag X3, Wits 2050, South Africa

[email protected]

2 University of Venda, Department of Hydrology and Water Resources, P/Bag X5050, Thohoyandou 0950, South Africa

3 Department of Water Affairs, P/Bag X313, Pretoria 0001, South Africa

Abstract Many households in rural areas obtain water from rainwater harvesting (RWH) and/or run-of-river (ROR) flow, but many of the methods used to assess the yield of RWH and/or ROR supply unrealistically aggregate data into monthly or annual time steps, and do not incorporate measures of reliability. Most approaches do not assess the improvement in supply that would be obtained from integrated utilization of the two sources. This paper demonstrates: (i) the incorporation of reliability for the widely applied mass curve method, and (ii) realistic incorporation of reliability and integration in RWH and ROR hydrologic analysis via behaviour analysis of household supply and frequency analysis of the annual levels (number of days) of supply. The behaviour analysis approach has the ability to simulate complex operating rules and configurations while including measures of performance comprehensively. It is therefore considered the method of choice for RWH and ROR supplies.

Key words yield-reliability analysis; rainwater harvesting; run-of-river; rural water supply; mass curve; behaviour analysis


Managing socio-economic and hydrological risks in northeast India

U. C. SHARMA1 & VIKAS SHARMA2

1Centre for Natural Resources Management, VPO Tarore, District Jammu 181133, Jammu and Kashmir, India

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