6th Scientific Assembly of the International Association of Hydrological Sciences: A New Hydrology F

Venue: Maastricht

Location: Maastricht, Netherlands

Event Date/Time: Jul 18, 2001 End Date/Time: Jul 27, 2001
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Description

6th Scientific Assembly of the International Association of Hydrological Sciences

A New Hydrology For A Thirsty Planet

18 – 27 July, 2001, Maastricht, The Netherlands

Scientific Program

Introduction

Water is an integral part of the environment, and its availability is indispensable to human beings, the functioning of the biosphere and to economic development. Because of lack in scientific knowledge, misuse of water resources and poor water management practices depleted supplies, falling groundwater tables, and diminished stream flows have often resulted. Water pollution, originating mostly from human activities, occurs more frequently than ever before and is more widespread, causing decreases in availability of water suitable for many uses. In contrast, there are also examples of ‘good’ water management practice and excellent opportunities to learn from these examples and to evaluate the potential transfer of these techniques to other regions.

Because of the rapidly increasing global demand on fresh water and the high vulnerability of freshwater resources including the quality, the main theme of the IAHS Scientific Assembly Maastricht 2001 will be ‘A New Hydrology for a Thirsty Planet’.

The main idea of the Scientific Program is firstly to review the problem of the water related threats (S1), then to probe why it went wrong and what we have learnt to date and how to cope with a fast-changing global environment (S2-S5, W1-W8) and finally to conclude with what needs to be done in the future (Concluding session).

Maastricht 2001 will pay particular attention in its symposia and workshops to the unique challenges of water scarcity and availability in developing countries. These countries are often faced with economic and bureaucratic constraints. These constraints are juxtaposed with problems of infrastructure, socio-economic development and maintenance in areas frequently associated with high climatic susceptibility (e.g. water availability and storage). A primary focus of the Scientific Assembly is to encourage participation and foster communication for developing viable solutions of effective water resources management. Hydrologists as well as water resources planners and managers from developing countries are therefore especially encouraged to attend and make presentations.

Commission presidents on the Maastricht 2001 Scientific Committee:

Alan Gustard (ICSW), Ed Sudicky (ICGW), Bent Hasholt (ICCE), Elizabeth Morris (ICSI), Norman E. Peters (ICWQ), Slobodan Simonovic (ICWRS), Al Rango (ICRS), Karsten Jensen (ICASVR), Alain Dassargues (ICT)

The Dutch Delegation of the Scientific Committee:

Reinder Feddes (chairman), Jacob de Vries, Hans Gehrels (secretary)

The Scientific Programme

Symposia Call for papers: Participants who wish to present a paper or a poster at one of the symposia should send an extended abstract (300 - 400 words) in either English or French directly to the symposium convenor by 15 May 2000. After a decision by the convenors of acceptance or rejection, authors of accepted papers will receive instructions for the preparation of their complete papers and will be asked to submit them before 1 October 2000.

S1 Association Lectures on Water-related threats on social and economic developments (Details S1)

S2 Regional management of water resources (Details S2)

S3 Impact of human activity on groundwater dynamics (Details S3)

S4 Hydrogeochemical and transport processes with emphasis on aquifer characteristics and reactivity (Details S4)

S5 Soil-Vegetation-Atmosphere Transfer schemes and large scale hydrological models (Details S5)

Workshops Call for papers: Participants who wish to present a paper or a poster at one of the workshops should send an extended abstract (300 - 400 words) in either English or French directly to the workshop convenor before 1 October 2000.

W1 Flood forecasting with reference to global change (Details W1)

W2 Hydrological impacts of long-term exploitation and climatic evolution: contributions of studies based on tracers and modelling (Details W2)

W3 The role of Information Technology in sustainable water resources management: case studies from developed and developing regions (Details W3)

W4 High-mountain regions: hydrological processes and cryospheric processes, models and the variability of available water resources; in anticipation of the ‘Year of the Mountains 2002’ (Details W4)

W5 Application of Geographic Information Systems and Remote Sensing for quantifying patterns of erosion and water quality (Details W5)

W6 Hydrogeological evolution in coastal lowlands: role of density- and compaction-driven groundwater flow (Details W6)

W7 Optimisation of monitoring strategies for groundwater quantity and quality (Details W7)

CONCLUDING GENERAL SESSION (Details)

Threats and challenges to water quantity and quality on a thirsty planet


Symposia

S1 Association Lectures on Water-related threats on social and economic developments

Leading Commission: all commissions involved

Convenor: Pierre Hubert hubert@cig.ensmp.fr

The theme of this symposium is problems of water related threats in relation to society, policy and hydrology. The objective is to provide a general audience with current and anticipated water-scarcity impacts for a range of socio-economic and cultural areas. The topic will be approached in an integrated way with primarily invited presentations, incorporating information from other organisations such as WMO, FAO, UNESCO, WHO, UNEP, IUCN and IAHS.

S1.1 Water, the economy and politics

Human impact on water resources is generally governed by economic motives, especially in countries having difficulties with infrastructure. Economic benefits seem to support further interference on the water resources, while pricing, taxing and other financial penalties reduce this tendency. Market approaches to water management are gaining support in many countries. However, equity and efficiency both demand that governments continue to intervene in water distribution through pricing controls, taxation and other financial penalties.

The first session focuses on the effects of a market- and people-oriented water management. The effects will be discussed using real data. By looking at field observations of the price elasticity of demand, the participants are able to verify the effectiveness of financial control mechanisms in water management. Moreover, the effects of various forms of water market organisation -with various degrees of liberalisation on water management will be discussed. The session is completed with a discussion of the role of hydrological experts in these, often political, debates.

A second session addresses the economic analysis of water management activities. Various ecosystem-oriented methods of cost-benefit analysis, and techniques such as contingent valuation, choice modelling, have been developed over the past years. These approaches and the experiences gained from them will be discussed. Their contribution to more sustainable water resources management and the role of hydrological expertise in these analyses will be priority topics for discussion.

S1.2 Water and health

Shortage and poor quality of fresh water are severe threats to human health, both short and a long term, and particularly in developing countries. In both the scientific and political domain, water scarcity and quality problems and solutions are high on the agenda for the 21st century. Sustainable solutions can be developed through enormous investments in infrastructure and technology; improvements also can be developed through better land and water management techniques. Low cost solutions are needed in developing countries. Meanwhile, building capacity and improving and/or extending of the institutional and legal framework are of eminent importance. Hydrological sciences play a crucial role in data/system analysis for problem identification, for developing monitoring strategies and for providing alternative solutions. However, how can hydrological scientists contribute to understanding and solving the interdisciplinary problems of water and health? In this latter context, it is important to assess the data requirements and data availability for improving the interdisciplinary assessment of water and health.

The objective of this session is: (1) to discuss results of associated hydrological research (including case studies) and the linkage of the research with the decision making process on water and health issues, (2) to evaluate experiences, and (3) to identify research gaps. The scope will be broad to stimulate cross-sectoral discussions across different dimensions of health related water issues: health risks (water shortage for drinking, sanitation and food production, polluting chemicals and pathogenic micro-organisms), geographic scale (from local to global) climatic and socio-economic conditions, and institutional support.

S1.3 Water and ecosystems

Since the general recognition that water is an "economic good" and the simultaneous recognition that environmental quality of aquatic ecosystems should be conserved, water managers have struggled with how these two principles can be matched. Consensus is growing that in developed countries the demands of ecosystems on the water resources system should be given a higher priority than other economic uses of water, so that the costs and benefits of reserving water for the health of ecosystems does not enter into the economic trade-off analysis. In many developing countries, the sufficient water supplies of acceptable water quality is high and although little or no emphasis is placed on the conserving the environmental quality of aquatic ecosystems, the preservation or restoration of aquatic ecosystems results in overall quality of water resources.

There is a growing awareness that an aquatic ecosystem should be considered as a chain of temporarily inter-linking water bodies (stepping stones), that have different functions in conserving the enviromental health and biodiversity. Probably the conservation of the quality of these stepping stones is more important than the simple maintenance of (often polluted) base flows. The following questions remain. How much water is needed for the maintenance of "essential life-support" ecosystems? What is the spatial and temporal distribution required of the water? Contributions are invited that address these questions or the relation between water resources and the health of ecosystems.

S1.4 Water scarcity and food

This session addresses the links between hydrology and food production. Prospectively, the largest global problem is population increase. Population increase requires an increase in food supply. Food production requires vast amounts of water — where will the water come from to provide the increase in food supply? What parts of the world will be most affected by water scarcity? How can the use of existing water resources be made more efficient?

S1.5 Floods and land-use

The lands located along the rivers have always been very attractive for human societies. They often are fertile lands of high agricultural value and offer convenient locations for all human settlements, the value of which is enhanced by easy communication links on, along and across the rivers. But these lands are also flood plains episodically innundated by large floods, while playing a significative geomorphological and ecological role. Some civilization have choosen to live with the floods, some others have been trying for centuries to protect themselves from these threathening effects. Management of floods and planning of floodplain land use is a fundamental issue where structural and non-structural actions have to be combined in order to achieve in a satisfactory way the social and ecological goals.

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S2 Regional management of water resources

Leading Commission: ICWRS

Co-operating commissions: ICWQ; ICASVR, ICRS, ICCE, ICSW

Convenor: Andreas Schumann, Ruhr- University- Bochum, Institute for Hydrology and Water Management, D- 44780 Bochum, Germany. fax +49 234 3214153. andreas.schumann@ruhr-uni-bochum.de

Co-convenor: Dr. Xia Jun, Wuhan University, China (on leave at the University of Regina, Canada). xiajun@uregina.ca

More effective and better integrated water resources management at a regional scale is needed now more than in the past to complement the increasing demand on water resources associated with socio-economic development and population growth. This need is not only important for regions composed of developing countries where water scarcity prevails but also in other regions where extreme hydrologic events have major impacts on the society. In all cases it is necessary to differentiate between natural variability, anthropogenic impacts and the effects of water management in assessing the water resources of a region. The objectives of this symposium are (1) to evaluate the effects of past management practices on water resources, (2) to address issues of equitable supply and management for competing interests, (3) to evaluate new techniques for integrated regional water resource management and (4) to address specific issues of floodplain and wetland resource management.

S2.1 Lessons learned from past management practices

Within a few decades, the global population is expected to increase to 8 billion. The majority of this population will live in large urbanised areas. The scarcity of water, as affected by quantity and quality, will cause serious problems for the supply of potable water and other essential uses, such as hygiene and food preparation. In addition, water demand for food production will strongly increase, especially in arid and semi-arid areas. Surface water and fossil groundwater resources are being mined at an increasing rate. In some regions the traditional methods of food production using irrigation water already has caused water shortages resulting in national and international conflicts. Large-scale schemes of transport of water over long distances, over-drainage and over-irrigation of agricultural lands, and landscape alteration are only a few examples of resource mis-management affecting water resources.

Impact studies and the implementation of efficient techniques in agricultural water supply are a prerequisite for future sustainable water resource development. Examples of techniques of good water management and the possibilities to transfer these techniques to other regions also will be discussed.

S2.2 Sustainable regional water management for conflicting interests

On a regional scale, agriculture, the natural environment, recreational land use, and urbanisation have different interests regarding groundwater, surface water and related water quality. In addition, impacts caused by climate change, sea level rise and land use make water management adaptations necessary to safeguard sustainability. Planning of water management on a regional scale, therefore, needs to be integrated for both water quantity and quality of groundwater and surface water, and needs to account for the costs and benefits of different interests and for the entire society. Management decisions with far reaching effects should only be evaluated using adequate monitoring data and generally accepted modelling procedures. Items related to sustainable regional water management are:

the general concern that data collection in hydrological and meteorological networks generally is in decline globally;
hydrological changes (quantity and quality) induced by measures that influence stream flow characteristics (canalisation, water level control, aquatic weed control, external water inputs, etc.) and their associated costs and benefits;
changes in agricultural land use and their associated effects on water resources (water quantity and quality), particularly irrigated agriculture;
change in urbanisation and its effect on groundwater resources (quantity and quality), its demands on surface water resources and on stream flow through storm water discharges (high peaks);
groundwater - surface water interaction in the flood plains.
effects of climate change and climate variability on wetland and floodplain health
eco-hydrology of flood plains.
problems of salt-water intrusion, sea induced flooding, and sea-level rise.
methods for environmental impact assessment of river (re)construction; hydrological and eco-hydrological.
hydrological basis for ecological development and management of wetlands under various morphological conditions.
erosion and sedimentation on flood plains
the effect of climate change and climate variability on water resources and water management approaches to reduce risks for the relevant water dependent functions.
S2.3 Tools for water resources management

This session will focus on development and application of dedicated tools for sustainable management of water resources, particularly under extreme hydrologic conditions such as droughts and floods. While in recent years a consensus has emerged that the principle of sustainability should prevail in the management of water resources, there is less agreement about the selection of the appropriate tools. Several important issues should be analysed and discussed during the symposium, including stakeholder participation, demand management, decision-making procedures and techniques for assessment and modelling of environmental, economic and social impacts. Emphasis will be on water resources management viewed in cross-sectoral and integrated perspectives. For reliable water resources assessments, remote sensing is an important tool to provide data for inventory and monitoring and as input for hydrological models. Flood and drought forecasting is an important aspect in the context of operational water management. In addition, this session also will address the data requirements for effective management and the availability of these data, including measures of data quality, are a prerequisite for resource assessment and effective management.

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S3 Impact of human activity on groundwater dynamics

Leading Commission: ICWQ

Co-operation of: ICGW, ICWRS, ICT, ICASVR, IAEA

Convenor: Norman (Jake) E. Peters nepeters@usgs.gov

Editor/co-convenor: Hans Gehrels j.gehrels@nitg.tno.nl

Groundwater abstraction has increased to complement the increasing water demand by a continuously increasing population. The objectives of this symposium are to evaluate groundwater with respect to methods for quantifying recharge, impacts of human activities and land-use change on groundwater quantity and quality, and linkages between groundwater and surface water. Human activities are intricately linked to the evolution and dynamics of the groundwater quantity and the quality. For example, water-quality of abstracted water is affected by evaporation and additions of agrichemicals to recharge water, especially in regions where groundwater is the major source of potable and agricultural water supply. Moreover, the recharge rate is often the most important variable in groundwater models, as recharge also affects natural groundwater dynamics. In a similar context for many areas, groundwater is the major source of surface water, and in other areas, surface water infiltration is a major source of recharge. Consequently, understanding the interaction of groundwater and surface water is important to the understanding of groundwater dynamics. Finally given the alarming rate of land-use change globally, it is important to understand the linkages between land-use change and groundwater dynamics, particularly as land-use change affects the quantity and chemical quality of recharge.

S3.1 Quantification of groundwater recharge

Calibration of groundwater model parameters is only meaningful if the recharge rate and its uncertainty are known. Recharge rates are relatively well known for several agricultural crops in some regions, but much less so for many types of natural vegetation. Recharge may be estimated from unsaturated zone tracer studies, and hydrometric measures of soil water content, groundwater levels, and micrometeorological measurements. Papers are welcomed that address methods for groundwater recharge measurement (for both arid and temperate conditions) and provide estimates for different (natural) vegetation. Of special interest are papers that address the formulation of upper boundary conditions in groundwater flow models and/or the issues related to vegetation cover.

S3.2 Impact of human activity on groundwater quantity

Groundwater level fluctuations result from the combined effect of climatic fluctuations, processes of soil water transport in the unsaturated zone, hydrogeological properties of the aquifer, and numerous human influences. Human activities have an increasing effect on groundwater levels. Statistical and physical analysis of groundwater level fluctuations provides insight in the hydrogeological system and the effects of natural and non-natural influences. Papers are welcomed dealing with developments in the simulation of groundwater level fluctuations, time series analysis and identification of separate components.

S3.3 Impact of land use change on water quality

Groundwater quality is determined by the quality of the infiltrating water, which is susceptible to pollution derived for example from atmospheric deposition, solid and liquid waste disposal, agricultural practice, urbanisation, and deforestation. In some cases, changes in land use may result in improved water quality. For example, land conversion from agriculture to natural vegetation may decrease nutrient load. However, these practices also might cause trace metals to be mobilised because of changing chemical characteristics of natural areas. Contributions also are welcomed regarding spatial and temporal changes in the downward transport of chemical constituents (including tracers) through the unsaturated and saturated zones related to changes in land use.

S3.4 Water quality and quantity at the interface between groundwater and surface water

Modelling of both surface water and groundwater with respect to quantity and quality has become highly complex. During the last few decades, the model developments in each field generally has occurred in parallel, but without a distinctive interaction. In many hydrological systems, however, the surface and ground water components are very much integrated, especially in lowlands and shallow aquifers. Managers of some urban water supplies must manage ground and surface waters jointly, and environmental managers (e.g., wetlands) must consider both water sources. Model codes that combine both components have been developed only during the last few years. In this session, papers are welcomed that deal with new modelling concepts and calibration and validation techniques using tracers. Also of interest are case studies and experiments in which surface water and groundwater processes have been combined.

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S4 Hydrogeochemical and transport processes with emphasis on aquifer characteristics and reactivity

Leading Commission: ICGW

Co-operation of: ICWQ, ICT, ICCE

Convenor: Jasper Griffioen j.griffioen@nitg.tno.nl

Co-convenor: Bruce Webb

The subsurface of densely populated countries is increasingly being used for many new activities (infrastructural) in addition to more traditional applications, such as groundwater abstraction. For drinking water supply, infiltration systems are implemented that introduce surface water of varying quality into deeper aquifers. In situ remediation is becoming more popular in which the natural attenuation of soil and groundwater pollution depends on the (bacterial and chemical) characteristics of the aquifer material. In all of these developments, changes in groundwater quality have to be predicted in a more intensely utilised subsurface hydrological system. This session also will assess the data requirements and availability to not only assess the impact of human activities but to predict future impacts at a range of spatial scales.

S4.1 Aquifer characteristics and hydrogeochemical reactivity

Information is needed not only about the pre-existing and new water quality for the prediction of changes in groundwater quality, but also about the biogeochemical reactivity of the porous medium. Increasingly, porous media are being sampled for the determination of biogeochemical characteristics. However, the physical heterogeneity of the subsurface complicates the estimation of these characteristics. Specific sampling and analytical strategies are needed to obtain a representative estimate of the aquifer ‘reactivity’. Also, the characteristics at the measurement scale (point scale) have to be scaled up for local and regional studies, whether or not using simulation models. Papers are welcomed that address sampling strategy of aquifer materials, determination of reactivity, and upscaling especially of biogeochemical aquifer-material characteristics. Papers addressing the issues of data requirements and data availability also are welcomed.

S4.2 Characterisation and prediction of groundwater contamination

Human activities have resulted in contamination of regional groundwater and surface water resources. The magnitude of source contamination are associated with exploration and refinement of natural resources, agricultural activities, waste dumps or industrial and military complexes. Groundwater contamination is the resultant of physical mass transfer and flow processes together with biogeochemical reactions. Processes such as dissolution from NAPL’s and biogeochemical degradation need often be considered as kinetically controlled. Characterisation of such kinetic processes is needed to determine the present extent of contamination and future behaviour of the contaminant. Determination of the fate of contaminants at the contaminated sites requires the application of a diverse array of characterisation and prediction techniques. Contributions are welcomed regarding field characterisation, laboratory characterisation and mathematical modelling techniques.

S4.3 Dynamics of microbially mediated hydrogeochemical processes in aquifers

Many redox reactions in the subsurface are microbially mediated and other reactions as well. Degradation of organic contaminants is not a one-step process, but a sequence of redox processes. Disturbance of the redox system also induces other chemical processes. The rate of these microbially mediated reactions is the result of a complex interplay between amongst others mass transfer into biofilms, availability of reductants and oxidants, and competition among (groups of) bacteria. Many process parameters and variables are involved in describing this complex interplay. Proper description of the complex interplay depends on the time and space scale of interest; less mechanistic descriptions are allowed at increasing scale. Studies that deal with validation of conceptual and mathematical models at the field scale are welcomed together with studies about the interplay between hydrological and biogeochemical processes.

S4.4 Process concepts behind in-situ remediation

The threat of contaminated groundwater to human and ecosystem health necessitates remediation of sites. Conventional "pump and treat" technologies are, in general, economically unfeasible due to the extent of the contamination. Remediation of regional scale contamination is often done by water treatment at groundwater pumping locations, i.e., end-of-pipe techniques. Remediation of (local-scale) contamination, therefore, requires the implementation of innovative technologies. The potential costs of remediation have increased the emphasis on developing passive, low maintenance remedial measures. The potentials and limitations of innovative techniques need to be realised for successful implementation in the field. Papers are welcomed that deal with the process concepts behind in-situ remediation techniques and which also address data needs and availability.

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S5 Soil-Vegetation-Atmosphere Transfer schemes and large scale hydrological models

Leading Organizations: ICASVR and the IAHS Working Group on Experimental and Theoretical Hydrology at all Scales

Co-operation with: GEWEX, IAHS/WMO Working Group on GEWEX, ICRS, ICSI Working Group on Snow-Vegetation Interactions

Convenor: Han Dolman dolman@sc.dlo.nl

Various Soil-Vegetation-Atmosphere Transfer (SVAT) schemes have been developed for use with General Climate Models (GCMs), Regional Climate Models (RCMs), Numerical Weather Prediction Models (NWPMs), coupled atmospheric-hydrological models and large-scale hydrological models. However, SVAT models face various difficulties that include:

comparable complexity between system components;
scaling incongruities between atmospheric, hydrological, cryospheric and terrestrial components;
advection, mixing and redistribution of mass and energy at sub-grid scales;
validation of SVATs at appropriate space and time scales. The need for improved characterisation of soil and land surface properties at regional and global scales is generally recognised. This involves aggregation over heterogeneous surfaces;
General lack of understanding of the SVAT processes and associated models in snow-covered areas, particularly as affected by the evolution of vegetation communities
Current soil-vegetation-atmosphere transfer (SVAT) schemes include increasingly complex descriptions of the physical mechanisms governing land surface processes. These schemes require large numbers of soil and land surface parameters controlling the vertical fluxes. The underlying rationale is that improved process representation will result in parameters which are easier to measure or estimate and in improved model performance and robustness. However, this is not necessarily so, mainly because SVAT models require effective values for the various parameters at patch, regional or larger scales, which are not easily estimated and because redistribution of water and energy at sub-grid scales can alter surface properties. Surface energy fluxes can vary significantly in space and time due to the variability in land surface properties and to local scale advection. Recent studies have shown that characterising such properties is fraught with difficulties, as determining representative parameterisations is non-trivial due to our inability to accurately measure land-surface properties. These issues are particularly difficult to address for snow-covered areas, where vegetation communities are strongly coupled with patterns of snow accumulation and melt. The snow and vegetation interactions influences mass, chemical and energy exchanges. Furthermore, the vegetation is affected by the sensitivity of the vegetation to snow thermal insulation and spring time inputs of meltwater, nutrients and latent heat. Current snow models and parameterisations presume stationary plant communites as part of their regional calibrations.

The objective of the symposium is to present progress in SVAT modelling and large-scale hydrological modelling, with some emphasis on the processes and model development in snow-covered areas. Suggested subtopics for the symposium include:

S5.1 SVAT and precipitation-runoff process modelling at large catchment ( >1000 km2) , regional and continental scales

The modelling of SWAT, water balance and precipitation-runoff processes at a range of space and time scales are key issues for the integration of landsurface process models in atmospheric models and hydrological processes in large catchments. Distributed hydrological models are required to accommodate spatial information on the heterogenity of land surface characteristics and nonlinearity both in the component hydrological processes as well as their interaction with atmospheric processes. Papers are sought on physically based, distributed modelling of scaling of hydrological processes in space and time, starting from the catchment scale opto the continental scale. Papers on the sub-grid scale of hydrological parametrization (such as hillslope runoff processes and soil water flow processes) within catchment and larger-scale distributed precipitation-runoff and SVAT models are encouraged.

S5.2 Parameter estimation of large-scale hydrological models

Land surface characteristics are heterogeneous at all scales including at the scale of the land surface discretization in a distributed catchment model. Within a numerical grid element topography, vegetation characteristics (LAI, vegetation height, root depth) and soil characteristics (retention and hydraulic conductivity functions) will exhibit spatial variation. Effective parameters representing the integrated behavior of the processes over the scale of a numerical unit are thus required. Derivation of effective land surface parameters is inevitably very complicated due to the non-linear and interacting processes involved. Papers are invited dealing with theoretical derivation of effective parameters (deterministic and stochastic averaging) and inverse identification based on field observations.

S5.3 Data assimilation in large-scale hydrological models

Distributed catchment models requires specification of the relevant parameters at every spatial unit included in the model. Obviously, this information can rarely be established from traditional point measurements and monitoring networks. Therefore satellite and radar derived spatially distributed data on vegetation characteristics, soil moisture and precipitation will constitute valuable information that may be used as either input to the model or for updating. Papers are invited dealing with data assimilation of traditional and remote data in distributed hydrological models.

S5.4 Snow-vegetation interactions

High latitude and altitude vegetation communities are strongly linked to patterns of snow accumulation and melt at local, basin and continental scales. Processes driving this linkage involve mass and energy exchange through the snow and from the snow at the time of seasonal melt. Many snow models and parameterisations presume stationary distributions of plant communities as part of their regional calibrations. With global change the stability of the interaction of vegetation communities and snow phenomena needs to be examined. Papers are solicited that help to explain current snow-atmosphere exchange and snow hydrology as affected by vegetation community, express available data for addressing this issue and suggest means of anticipating changes in this interaction under environmental stress.

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Workshops

W1 Flood forecasting with reference to global change

Leading Commission: ICSW

Co-operation with: ICSI, ICRS, WMO

Convenor: Paul Pilon Paul.Pilon@ec.gc.ca

The objective of this workshop is to evaluate recent advances in the science and technology of forecasting floods. There are several sub-topics to this (regional) flood forecasting theme that are of interest to the scientific community. Some of these topics include quantitative precipitation estimation and forecasting, ensemble forecasting in hydrology, coupling of atmospheric and hydrological models, snow and ice related floods and the capabilities of distributed and semi-distributed hydrological process models.

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W2 Hydrological impacts of long-term exploitation and climatic evolution: contributions of studies based on tracers and modelling

Leading Commission: ICT

Cooperation with: ICGW, IAEA

Convenor: Anne Coudrain-Ribstein coudrain@biogeodis.jussieu.fr

In many aquifer systems, present observations of dissolved element concentrations, of isotopic ratios, of temperature or of hydraulic heads cannot be explained by the average conditions that are prevailing inside or at the boundaries of these systems. These data highlight a transitory state whose initial conditions are to be found in a more or less distant past. Do these current data allow reconstruction of the past conditions? How do they contribute to the knowledge of the influence of the long-term exploitation and climatic or geological evolution on aquifer systems? What are the possible contributions of hydrological models, calibrated/validated on tracers and isotopic results, to predict the impact of climatic change on the hydrological cycle?

Contributions on the following will be particularly welcomed:

synthesis of different approaches
mathematical and numerical modelling
inscription of recent and exceptional hydrologic events in continental archives
dating the initial state to be considered to explain present observations
methodological developments of underground circulation dating
ability of models calibrated/validated on extreme events of the past to simulate future impact of climate change on the hydrological cycle.
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W3 The role of Information Technology in sustainable water resources management: case studies from developed and developing regions

Leading Commission: ICWRS

Cooperation with: ICRS, WMO

Convenor: Dr. Slobodan P. Simonovic, Natural Resources Institute, University of Manitoba, Winnipeg, Canada, R3T 2N2, phone (+1) 204 474-8375; fax (+1) 204 261-0038, slobodan_simonovic@umanitoba.ca

Possible co-convenor: Dick van Doorn, Tjeerd Willem Hobma, Gheorghe Stancalie, Richard Hooper, George Leavesley

Throughout the world, large investments have been made in the development of computer technologies and tools to support hydrological research and operational planning. The objective of this workshop is to provide forum for the discussion of ‘good modelling practice’. Improvements in information technology have had a positive impact on hydrological research. Several decision support systems (DSS), geographical information systems (GIS) and Remote Sensing database systems have been developed for integrated water management. These systems improve the supply and communication of information among the water managers and among water managers, private interests and the public. However, despite these improvements, the hydrological system modelling has become increasingly more complex. Several attempts have been made to develop re-usable hydrologic code as well as mechanisms to integrate component models into complete systems (modular modeling systems). New key words are, for example, object-oriented modelling and neural networks. This workshop will address these and other recent advances in information technology as well as aspects related to these developments such as quality assurance and the development of validation/verification standards for hydrologic modelling.

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W4 High-mountain regions: hydrological processes and cryospheric processes, models and the variability of available water resources; in anticipation of the ‘Year of the Mountains 2002’

Leading Commission: ICSI

Co-operation with: ICSW, ICCE, IAMAS, WCRP/CLIC, IGBP/BAHC, GCTE

Convenor: Herbert Lang lang@geo.umnw.ethz.ch

The already detectible indications of global warming, its effects on precipitation, on the retreat of glaciers and on seasonal snowcover and its possible impact on hydrology and water resources in high-mountain regions will affect millions of people in the downstream river basins. Similarly, erosion and sediment transport as well as transport of nutrients and other substances from mountain regions form an essential component in regional and global biogeochemical cycles and in the control of water quality and hydroecology of mountain rivers and lakes. Therefore special attention is required to the water, snow and ice-related aspects of high-mountain regions, including interactions with the atmosphere and interrelations with ecological and socio-economic conditions.

In many high-mountain regions of the world, communities are poor and marginalised and water-related issues have not received enough scientific and political attention. Many of these regions are particularly vulnerable to possible impacts of global change in terms of climate and land use changes. Furthermore, various aspects of the hydrological cycle including snow and ice in high-mountain areas are not sufficiently understood and this is further aggrevated by the lack of long-term data and the difficulties of collecting observational data in these areas.

The main issue of the workshop is to point out on the high-mountain regions and their great importance as source areas of rich water resources. Particular foci of the workshop will be on:

High-mountain snow and ice as indicators of climate change and as substantial components of the hydrological cycle
Interaction between the orography and the atmosphere and spatial distributions of precipitation, snow, glaciers and water resources
Glacier hydrology
The water balance and its components in high-mountain regions of different climatic zones
Ecohydrological issues
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W5 Application of Geographic Information Systems and Remote Sensing for quantifying patterns of erosion and water quality

Leading Commission: ICRS

Co-operation with: ICCE, ICWQ

Convenor: Jerry C. Ritchie jritchie@asrr.arsusda.gov

The objective of this workshop will be to provide participants with the basic knowledge for the application of Geographic Information Systems (GIS) and Remote Sensing tools for quantifying the spatial and temporal patterns of erosion and water quality across the landscape. Techniques for combining satellite and aircraft remotely sensed data with Digital Elevation Modelling (DEM) and ground data in a GIS will be discussed to show ways to extend point data to field and regional scales. Case studies will be provided to let the participants follow the sequence of events from measurements to maps of soil loss and water quality.

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W6 Hydrogeological evolution in coastal lowlands: role of density- and compaction-driven groundwater flow

Leading Commission: ICT

Co-operation of: ICGW, ICCE

Convenor: Jacob de Vries vrij@geo.vu.nl

The groundwater and surface water characteristics in lowlands are normally strongly related to paleo-conditions characterised by marine transgressions and regressions, sedimentation and erosion, and human influence during the Quaternary. Salinisation, eutrophication, and sedimentation are all major management problems costing communities millions of dollars per annum. Reconstruction and prediction of the hydrogeological evolution is a prerequisite for understanding problems of salinisation and land subsidence. Tools for a palaeohydrological study are: reconstruction of the Quaternary geological and geomorphological evolution, groundwater flow modelling with density and compaction flow components, and especially hydrogeochemical (isotope) transport and process modelling.

Combined description of the geochemical and hydraulic processes, reconstruction of coastal development, groundwater abstraction, and salt water intrusion resulting from sea-level rise are some of the problems for which groundwater flow modelling should include density-driven flow simulation. In addition, the subsurface in coastal areas often consists of young compressible sediments, in which compaction is still active. Several computer codes include density-driven flow simulation, some of which are more complex than others. All of these codes still have shortcomings or simplifications of the complex processes. Papers are welcomed that address:

new developments in both numerical and analytical methods of transient, density-driven and compaction-driven flow simulation.
the reconstruction and/or prediction of the hydrogeological evolution of coastal lowland areas.
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W7 Optimisation of monitoring strategies for groundwater quantity and quality

Leading Commission: ICGW

Cooperation with: ICWQ, ICWRS, WMO

Convenor: Steve Gorelick or Frans van Geer f.vangeer@nitg.tno.nl

The strategy of data gathering or monitoring determines the available information on our groundwater systems. The management objectives underlying the monitoring network have gradually changed from rather general state descriptions a few decades ago to quite specific problem-oriented information today. The monitoring strategy therefore may have to change as well. The design of groundwater monitoring networks is often based on quantifiable technical criteria, such as the kriging interpolation standard error as a measure of uncertainty for spatial interpolation of groundwater heads. These criteria are usually of a purely statistical nature, having no direct relation with the physics that determine the variable being monitored. In principle, monitoring strategies could be more effective and perhaps based on more available information if monitoring networks were designed on the basis of more physically-based, but still quantifiable criteria. These criteria could be based on the physics of the hydrological system, incorporating information on topography, land use, soil type, geology, etc. In line with a more physically-based approach is the aspect of integration of different networks. Papers are invited that deal with new methods and examples of monitoring strategies, with quantifiable, preferably physically-based, technical criteria. Of special interest are contributions on the integration of monitoring networks and the coupling of monitoring strategy with the information needed for the calibration of groundwater models. To aid the discussion, presentations of existing network data and its availability are also welcomed.

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CONCLUDING GENERAL SESSION

Threats and challenges to water quantity and quality on a thirsty planet

Leading Commission: all commissions involved

Convenor: Reinder Feddes Reinder.Feddes@USERS.WHH.WAU.NL

From the early civilizations, the irregular pattern in the availability of water in space and time has been a challenge to mankind to regulate the distribution of water. Often the remedy became worse than the problem, because of a lack of knowledge on the long term impact. Very few problems have been solved in a sustainable way; often solutions were of a technical nature and solved the problems only temporarily. New threats are especially related to disasters caused by a reduction of the buffer capacity of the system through a disappearance of storage by depletion and /or storage space. The problems of water quantity go hand in hand with the degradation of water quality.

Existing and future threats include:

diffuse and point source pollution threats
aquifer depletion by over-production; exploitation of fossil groundwater reserves
groundwater abstraction, land subsidence and salinisation.
effects of land use change on water and sediment regimes
water quality and sedimentation threats to water supply reservoirs and lakes.
irrigation, problems of salinisation and water logging
growing of crops that have a low water use efficiency
loss of river bed space
environmental change and overpopulation
impact of political conflicts on water resources management
The aim of this general concluding session is to evaluate the outcome of all symposia and workshops of the Maastricht Assembly with respect to the main theme of water related threats and challenges. Contributions are welcomed from convenors or rapporteurs of the symposia and workshops that discuss one or more of the formulated problems and how they evolved, past measures (successful as well as failures), and possible solutions in the future. Special attention should be given to the question how hydrological sciences can contribute to better water management practice and can help society and policy makers to deal with conflicting interests in a sustainable way.

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