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The World Water Quality Assessment Large-scale water quality modeling Hot spots and causes of water pollution.

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Presentation on theme: "The World Water Quality Assessment Large-scale water quality modeling Hot spots and causes of water pollution."— Presentation transcript:

1 The World Water Quality Assessment Large-scale water quality modeling Hot spots and causes of water pollution

2 The World Water Quality Assessment The modeling framework Model results for Africa – Progress since October 2013 Hot spots of water pollution – Fecal Coliform bacteria Risk to human health – BOD Threat to inland fishery Causes of water pollution – Main sectors contributing to pollution Conclusions & preliminary findings Next steps Outline

3 The World Water Quality Assessment Modeling framework WaterGAP3 Water Use Models agriculturedomesticmanufacturing electricity production consumptive water use return flow WaterGAP3 Hydrology Model spatial: 5 temporal: daily results: daily/monthly WorldQual Water Quality Model spatial: 5 temporal: daily results: daily/monthly/yearly spatial: 5 temporal: monthly results: monthly discharge, runoff, flow velocity

4 The World Water Quality Assessment Progress since October 2013 agriculture (industrial fertilizer) natural back- ground agriculture (organic fertilizer) diffuse sources domestic –septic tanks –pit latrines –inadequate sanitation manufacturing (wastewater) urban surface runoff domestic (urban) –sewage point sources domestic (rural) –sewage –hanging latrines scattered settlements Data from Joint Monitoring Programme; country files ( )

5 The World Water Quality Assessment Connectivity & treatment

6 The World Water Quality Assessment Loadings: Fecal coliform bacteria Human and animal input 2010

7 The World Water Quality Assessment Dilution capacity Climate normal period ( ) Example: Modeled FC concentration at Mhlatuze River, South Africa January to December 2010

8 The World Water Quality Assessment FC in-stream concentration February 2010

9 The World Water Quality Assessment Comparison: FC in-stream concentration February 2010August 2010

10 The World Water Quality Assessment Sensitivity analysis: Assuming 100% connectivity… …but no improvement of treatment levels February 2010

11 The World Water Quality Assessment Total BOD loads in 2010 ~ 8.5 million tons BOD loadings in 2010

12 The World Water Quality Assessment BOD in-stream concentration February 2010August 2010

13 The World Water Quality Assessment Uncertainty of model assumptions High: assuming 7.5% of washed-off manure contributes to BOD load Low: assuming 3% of washed-off manure contributes to BOD load

14 The World Water Quality Assessment Sensitivity analysis for BOD: low rate assumption Total BOD loads in 2010 ~ 5 million tons

15 The World Water Quality Assessment Hot spots of BOD for low rate assumption February 2010August 2010

16 The World Water Quality Assessment Model validation High: assuming 7.5% of washed-off manure contributes to BOD load Low: assuming 3% of washed-off manure contributes to BOD load

17 The World Water Quality Assessment Cause of water pollution: sources of BOD loads

18 The World Water Quality Assessment Transboundary river basin scale Example: Total BOD loads in the Nile river basin contributing loads per country [%]

19 The World Water Quality Assessment First time: Synthesize information about population, sanitation and connectivity and make spatially explicit for all of Africa Compute loads of organic pollution and bacterial contamination for each river basin in Africa (grid cell basis) Geographic comparison of BOD and fecal coliform loadings in Africa Calculation of BOD and coliform levels for all rivers in Africa Estimation of hot spot water pollution areas in Africa Conclusions

20 The World Water Quality Assessment Hot spot areas: 17% of population living at big rivers with bacterial contamination >1000cfu/100ml in Africa Hot spot areas: Dilution capacity + magnitude of loadings Magnitude of BOD loading uncertain (manure runoff) Most important source of BOD: manure runoff; least important: urban surface runoff Source profile of BOD loadings vary greatly between countries (e.g. Somalia: manure runoff; Egypt: urban domestic) Total BOD loads steadily increased in Africa between 1990 and 2010 (increasing population, livestock, connectivity) High potential to provide policy-relevant overview of water quality issues for Africa and other regions Preliminary findings

21 The World Water Quality Assessment Further improvement of estimates for Africa –getting regional feedback Extension of estimates to Asia and Latin America Extension of estimates to include: –other water quality parameters (total dissolved solids, total N, total P, water temperature) –lakes Apply water quality guidelines as thresholds Merger of model-driven & data-driven analyses: threats to human health & inland fisheries (food security) and policy responses Next steps


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