Forests and agroforestry systems improve the amount of water in the soil, retards surface runoff and reduces soil erosion. They also help increase and regulate base water flow.

1. Evidence that land use interventions including Agroforestry can deliver quantifiable environmental services – case studies from Kenya and Asia John K. Mwangi John M. Gathenya PES Training Workshop 8th - 9th August, 2011

3. Land management

4. Soils and Geology

5. Rainfall

6. Climate / Weather

7. Topography

8. Drainage pattern

10. Land form

11. Soil type

12. Rooting depth (natural vegetation)

13. Downstream water users,

14. esp. living in flood plains & river beds,

15. esp. without storage

16. or purification

19. What influences watershed services? Non structural (Vegetative) : Use vegetation to control erosion. Examples: Grass strips, hedge barriers, contour farming and agroforesty systems. Structural: Design and construction of erosion control structures. Examples: Terraces, waterways, grade stabilization structuresand cut off drains

20. Case study: 1 Kapingazi KAPINGAZI CATCHMENT

21. Impacts of land use change - Kapingazi Impact of land use change on water yield is generally low.

22. Case study 2: Mara River basin Amala and Nyangores Satellite image analysis showed forest in MRB has declined by almost 60% over the 25 years between 1975 and 1999

23. Mara river basin Using Genriver, two scenarios were tested in Amala and Nyangores: 1. Base case 2. Complete forest cover Result: Restoring forest cover may not necessarily increase water yield

24. Case study: 3 Kejie watershed Dramatic change in land cover has occurred in the last 40 years

25. Land use change and water balance Watershed scenarios Land cover: forest+, grassland+, crop+, urban+

26. Case study: 4 Sasumua Catchment 10 m DEM Area = 107 km2 , 50% under agriculture Population = 17,500 growing at 3.5% Households ca = 3,700 Average farm size = 2.5 acres

27. What are the problems? Clogging of intakes Lowered water quality Dried up streams and rivers Increased water treatment cost Frequent de-silting of intakes Reduced dry weather flow

28. Effect on water balance components Quality:Surface runoff reduction significant Regulated flow: base flow increase is significant Quantity : Impact on water yield is insignificant

30. High rates in cultivated areas, exceeding 11.2 tons/ha per year

31. A- Steep cultivated areas

33. Filter strips/terraces ideal in ARequired in Sasumua - flow regulation and improved water quality.

34. Sediment yield reductions at reservoir inlet (tons/year)

36. Identify critical source areas

37. Identifying appropriate land uses

38. Quantifying the ES being provided

39. Predict impact of interventions before / After implementation

41. Monitor environmental impacts water quantity and quality

42. Monitor impact of payments on the community

43. Gender analysis of HH benefits

44. Monitoring at community level

45. Measurement of river flow

46. Sediment sampling

47. Water quality analysis

50. Labour and grassYear 2 onwards: Benefit to Nairobi Water Company Reduction in cost of alum: Reduction in cost of de-silting intakes 1,725,000 2,000,000 283,200 Maintenance only Net annual earning per household: This does not include effect of other interventions 566.4 (Values in Kenya Shillings)

51. Institutional and regulatory framework 6-Basins xxx- farmers WRUA xxx KFS

53. Potential sellers of these watershed

54. Potential buyers – basically NWC

55. Engaged sellers

56. Attempting to engage buyers

57. WTA study of sellers of ESChallenges: Multiple sellers available Lack of multiple buyers

59. improve water quality

61. retards surface runoff and reduces soil erosion

62. Increase base flow and regulate flow.Water quality improvement impacts are more “tangible”

63. Thank You

64. Acknowledgement This research is being implemented by PRESA, a research project of World Agroforestry Centre (ICRAF) Web site http://presa.worldagroforestry.org.