1. The potential benefits of Green Water Credits Part 1: Quantifying the role and advantages for upstream farmers Johannes Hunink Peter Droogers Wilco Terink Sjef Kauffman Godert van Lynden

2. First: the basic principles 1)Water always flows downhill 2)So do sediments and nutrients  It follows that land/water management upstream: a)Can positively influence food security upstream b)Can positively influence water supply downstream

3. Quantifying GWC Water Demand? Water Consumption? Water Supply? Impact Changes? Productive Use? Soil Water Conservation impact?

4. Example of potential benefits

5. WHAT to quantify? Supply  Biophysicial assessment Supply vs. Demand  Cost-benefit analysis

6. HOW to quantify? Observations in field (flows, erosion) – Precipitation dominant factor Large scale – experimental plots not possible – a lot of experimental data is already available Simulation model – experimental basin in PC – multiple options can be tested – various weather conditions (dry-wet)

7. RIVER BASIN SOIL AND WATER CONSERVATION

9. Methodology Hydrological models as a tool to simulate the paths of water and soil movement Upstream-downstream interactions

10. Methodology Soil and Water Assessment Tool (SWAT) Physically based Focus on water-erosion-land management processes Public domain Large user-group worldwide Successfully applied in many other studies worldwide as well as in Kenya

11. Data Elevation Landuse Soils Climate

12. Model Reliability

13. Selection of GWC options 11 options explored Bench terraces Conservation tillage Contour tillage Fanya Juu terraces Grass strips Micro-catchments for planting fruit trees Mulching Rangelands Ridging Riverine protection Trash lines Labor: intensive vs. extensive Investment: low vs. high Implementation on 20% of area ~ 100,000 farmers

14. Results: temporal

15. Results: spatial F.e. erosion rates may drop considerably in some areas Relative reduction depends on – location and – crop and land management

16. Results: Spatial

17. Results: Key Indicators Upstream – Crop transpiration – Soil evaporation – Groundwater recharge – Erosion Downstream – Inflow Masinga – Sediment load Masinga Climate – dry (2005) – wet (2006)

18. Results: Key Indicators

19. Results: Increase in Benefits

20. The potential benefits of Green Water Credits Part 2: Quantifying profits for downstream water users Peter Droogers Wilco Terink Johannes Hunink Sjef Kauffman Godert van Lynden