Project Number: 6218-13000-011-04
Start Date: Oct 01, 2013
End Date: Sep 30, 2018
The Masinga Reservoir Watershed, located in Nairobi, Kenya, will be evaluated using standard rapid geomorphic assessment techniques to determine sources of sediment. A vibracoring system, boats, and outboard motor, gas tank, and a submerged jet purchased by Jomo Kenyatta University of Agriculture and Technology (JKUAT) and the multifrequency acoustic profiling system (APS) purchased by USDA ARS will be used. Reservoir water storage capacity and long-term average annual sedimentation rates will be quantified using the APS. One to two sediment cores will be taken from the reservoir using the vibracore and analyzed for sediment texture and bulk density. In addition, 137Cs analysis will be performed to determine past and recent sedimentation rates. Overland and channel stream sediment budget will be determined using the submerged jet. A digital elevation model, soils, land use and land management, weather, and streamflow data will be obtained and used for modeling. A Soil and Water Assessment Tool (SWAT) model project will be built, calibrated, and validated for streamflow and sediment using sediment budget data and reservoir sedimentation rates. SWAT will be used to identify "hot spots" within the watershed, determine the impacts of climate change on reservoir/stream sedimentation rates, and evaluate alternative conservation scenarios to enhance water sustainability under climate change and a growing population. ARS will work with the International Center for Research in Agroforestry (ICRAF) on details to establish an East Africa reservoir and watershed management and education center (RWMREC) to be run by ICRAF. A board, which involves members from ICRAF, ARS, and other interested parties, will be formed. The board will draft the mission and vision of the center and develop ideas to raise funds to sustain the center. All equipment used during the proof of concept study will be made available to ICRAF through a cooperative agreement with JKUAT and donation by ARS to help with establishment of the center. A suite of models including SWAT will be adopted to evaluate the impacts of land use and management, climate change, and agroforestry on water resources, soil health, and food security for growing populations and to determine suitable conservation practices to mitigate negative impacts. Economic analyses of the impacts of reservoir sedimentation and unmanaged watershed will be carried out by ICRAF. We envision JKUAT offering academic training on reservoir and watershed management through a graduate-level degree program. The RWMREC will be used for academic and non-academic research and for other applications as decided. As the first step, ICRAF will organize a proof of concept workshop in Nairobi, Kenya, once the proof of concept study is completed. The main goal of the workshop will be to gather stakeholders and funding agencies to showcase what the center will offer. Complete results and products of the proof of concept study and estimates of economic impacts of unmanaged reservoirs and watersheds will be presented, and demonstrations of how the APS and vibracore for bathymetric survey and submerged jet for sediment budgets will be provided.