1. The World Water Quality Assessment Concept of the overall assessment and next steps

2. The World Water Quality Assessment Main issues Issue 1: From local to regional to global Issue 2: Scarce data, validity of data Issue 3: Linking water quantity, water quality and impact Issue 4: Are we measuring/modelling the right thing?  Assessment concept Issue 5: Networking, regional consultation

3. The World Water Quality Assessment Issue 1: From local to regional to global How do we come to a global assessment? Our concept of bringing top-down and bottom-up togetherconcept How can data driven and model driven analysis come together? Example of lakes: trophic level thresholds and loading to lakeslakes How do the deal with obstacles? Data gap (but for modelling and data driven analysis different) Assumptions (sensitivity analysis) Adapted management questions

4. The World Water Quality Assessment Issue 2: Scarce data, validity of data How to validate results and findings? Model validation (GEMS data, interpretation using explanatory variables O 2 /pH/  )validation What are the assumptions that need to be checked? Modelling scattered settlements (WWT): stage 1 European assumptions, stage 2 regional statistics What can be transferred from data rich areas? Example on the interaction of variables (example from India) to identify “useful” variablesexample from India Gradients: example on African citiesAfrican cities

5. The World Water Quality Assessment Issue 3: Linking water quantity, quality and impact Modelling concept WaterGAP & WorldQual integrates quantity & quality WaterGAP & WorldQual How do we deal with the health aspect?, How do we deal with the food security aspect? Indicators and thresholds

6. The World Water Quality Assessment Issue 4: Are we measuring/modelling the right thing Concentration of selected variables, describing water pollution:  FC => drinking, bathing, irrigation  BOD (&O2) => fishery  P => eutrophication (esp. fishery)  N => eutrophication (esp. fishery)  TDS => salinity (esp. irrigation, fishery)  Toxicants, emerging pollutants How to improve monitoring concepts and data basis Compendium and guidelines projects Compendium and guidelines

7. The World Water Quality Assessment Assessment concept Approach of three steps: 1.Analyzing variables separately 2.Data and model driven description: e.g. population per grid cell & dilution capacity as explanatory variables 3.Multivariate indicators in addition and/or instead of the short list variables Hypothesis: Use-specific water quality indices can be developed based on a limited number of variables by linking data driven and model driven analysis  “Water uses”: drinking, bathing, irrigation (human health related), fishery (food security related)  Requirement: joint definition of thresholds

8. The World Water Quality Assessment Issue 5: Networking, regional consultation Regional consultation Our experience on data accessibility: WWQA data request with NFPs in Africa Hubs, regional offices, case studies, … Join WP4 for regional consultation Approach international organisations International consultation of the Assessment results Assessment launch?