WorkBlock 6 - Assessing the vulnerability of global water resources

Co-ordinator: Pavel Kabat, Wageningen University
Deputy co-ordinator: Joseph Alcamo, Kassel University

The main objective of Workblock 6 is to assess the vulnerability of the water resources to global environmental, social, and economic change, with a special attention to effects of climate change and related extreme events. The Work Block aims at evaluating current vulnerability of water resources and related systems, and projecting future vulnerabilities in order to predict and prevent adverse changes. To reach this objective, WB 6 develops and tests new modelling framework and methodologies to assess vulnerability of (global) water resources, and predict the possible responses and feedbacks under increasing complexity and uncertainty.

This Work Block will make use of the results and outputs from all previous Work Blocks to quantify water resources availability, and implications of floods and droughts worldwide, imbedded in the needs and risks of the selected sectors of the economy and the society. The analysis will be conducted both for the 20th century and for the next 100 years (following a range of emission, land use change and demographic/economical scenarios). It will assess the uncertainties in these estimates and, finally, identify regions where changes, due either to climate, land use or population growth, are likely to lead to serious water shortages or risk. To test the “relevance” of the global/continental scale analysis for water resources strategic planning and management down to the regional and river catchments scales, WB 6 will conduct a number of exploratory scaling and dis-aggregation and “matching” studies, for selected smaller areas, located with the WATCH special focus regions.

Work Block 6 is organised in 4 Work Packages:

• WP 6.1 focusses on developing a new integrated quantitative modelling framework for analysis of the global water resources and their vulnerability. The two main issues in this work package are a comparison of Global Hydrological Models and the improvement of model components
• WP 6.2  focusses on the evaluation of water resources for 20th century. Using forcing data generated by WB1 this work pack looks at the human and climate impacts on the water resources in the last century. This work will also the basis for the water resources assesment of the 21th century which is the focus of
• WP 6.3. The theme of this third work package is a vulnerability assessment of water resources for 21th century with a focus on water for food, ecoystems and utliities.

Work Performed and Results achieved during Year 2 (February 2008 – 31 January 2009)
Work Block 6 has focused on comparing and improving Global Hydrological Models, evaluating water resources of the 20th century and assessing the vulnerability of water resources within the next century. Work on developing a new global water resources assessment modelling framework focused on describing and designing the modelling framework, improving the different components especially in terms of water availability. Considerable progress has been made on the WATCH/GSWP
intercomparison of global hydrology and land surface hydrology models, this now includes 12 models from over Europe, N America and Japan. In addition estimates of global ground water availability have been produced and a global surface water quality model set up and tested in European river basins. A set of scenarios and procedure for developing climate forcing data has been agreed upon with work blocks 2 and 3. A range of model improvements have been made to improve water resources analyses related to water for food, nature and utilities. A protocol has been developed for uncertainty analyses, distinguishing between uncertainty related to Climate model (global circulation models), hydrological models and emission scenario. All test basins have developed methods and tools to study climate change impact on water resources in their basins.

Achievements have included:

• The WATCH Modelling Framework developed (Technical Report Number 12)
• Initial analyses of 20th century global water cycle through the WATCH/GSWP model intercomparison (Technical Report Number 1 First results from intercomparison of surface water availability modules (WATCH deliverable 6.1.2))
• Protocol for 20th analyses, validation and calibration has been developed and agreed upon during two intercomparison workshop 
• Decision upon which model to use for which water resources has been made 
• Preliminary Water Assessment Reports of the test basins published (Technical Report number 10).
• WATCH Technical Report Number 18: Preliminary water quality module: state of development and plan for linkage to the overall modelling framework (WATCH deliverable 6.1.4)