DRAFT Exploring the Potential Impact of Reforestation on the Hydrology of the Upper Tana River Catchment and the Masinga Dam, Kenya
DRAFT Exploring the Potential Impact of Reforestation on the Hydrology of the Upper Tana River Catchment and the Masinga Dam, Kenya Jennifer Jacobs, Jay Angerer, Jeff Vitale Raghavan Srinivasan, Robert Kaitho, Jerry Stuth, Texas A&M University ABSTRACT The Upper Tana River Basin is strategically one of the most critical resource areas of Kenya. The Masinga Reservoir, at the outlet of the basin, provides water and hydroelectric power for 65% of the Nation. Unregulated deforestation and expansion of cultivation practices onto marginal soils in this critical river basin has resulted in significant reservoir siltation, reduced ecosystem function and more erratic downstream flows. Using a participatory process, collaborating technical policy analysts working for key government institutions in Kenya identified the need to assess the impact of meeting a national goal for reforestation of 30% of deforested lands with the infusion of new agro-forestry technologies and land tenure laws through the consideration of population expansion to 2015. Using a rapid rural appraisal methodology, it was determined that reforestation below 1,850 m would be difficult to achieve. However, reforestation at elevation increments of 2,000 m, 1,950 m, 1,900 m and 1,850 m would represent a 30 to 55% increase in reforested area in the Upper Tana River catchments. In addition, the results of this analysis show that full implementation of reforestation to 1,850 m would result in a 7% decrease in sediment loading in the Masinga Reservoir. Runoff yields would be similar to baseline conditions but peak annual flows would increase approximately 3% with less inter-annual variability, resulting in greater stability of water levels in the reservoir.
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