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Partnerships for enhanced engagement in research (PEER) SCIENCE Cycle 1 (2011 Deadline)
Reducing soil loss through effective soil and water conservation practices using hydrologic considerations and farmers’ participation in the Blue Nile Basin
PI: Seifu Tilahun, Bahir Dar University
US Partner: Christopher Barrett, Cornell University
Project Dates: May 2012 - June 2015
Soil erosion decreases food production and hampers poverty reduction efforts in the highlands of eastern Africa. Although intensive efforts have been underway both to reduce sediment production and to halt land degradation since the 1980s, erosion continues unabated and the already low crop yields are decreasing even further. Shallow soils are becoming shallower and are often abandoned, and gullies are swallowing up productive cropland. Finally, some of the lost soil fills up reservoirs and silts up downstream irrigation canals. Current measures to reduce soil loss are ineffective, and new approaches that both consider the hydrology of the whole landscape (instead of the current plot based erosion research) and use traditional farmer’s knowledge for locating erosion control practices are required. The goal of the proposed research is to develop appropriate watershed and farmer-based erosion control practices for the Ethiopian highlands in order to replace the well minded imported and inappropriate technologies from foreign donors.
A video summary of Dr. Tilahun's project and efforts to combat soil loss in the Blue Nile Basin.
These researchers will instrument the Debre Mawi (5.27km2) and Bir (64km2) watersheds in the headwaters of Blue Nile and to continue monitoring another instrumented by the International Water Management Institute (IWMI), the Mizewa watershed (27km2). Their efforts will be aimed at identifying erosion hotspots by measuring spatially distributed runoff and soil loss (from periodically saturated areas in the valley bottoms and areas with exposed subsoil that are severely degraded) and by participatory watershed methods approach and sediment tracers. They will also study the relationship between nutrient loss and soil loss by measuring soil nutrients (N, P, K, Mg, and Ca). Perched water table levels will be measured in the Bir watershed (~64km2) to identify saturated areas. Gullies will be monitored through areal and satellite images in addition to field measurement in the Bir and Debre Mawi watersheds. By locating the hotspot areas within the watershed, they will propose effective conservation practices. A simple physically-based hydrology model will be applied to locate the practices on the vulnerable areas. Their predictions will be compared with farmers’ knowledge including the location of the traditional practices. Finally, practices will be designed with the participation of farmers. Within the project period and beyond, some of the proposed practices will be installed with the farmers’ help in the Debre Mawi and monitored after the project. This research project will be carried out by the School of Civil and Water Resource Engineering as part of the newly implemented PhD program and an existing master’s graduate program on hydrology in close cooperation with faculty and students of an NSF IGERT program at Cornell. Most importantly, the international partnership will train future scientists and managers in managing the soil and water resources in Ethiopia.
Summary of Recent Activities
During January-March 2015, the main task for the research team was producing documentary film. In February 2015, filming of Anjeni, Ene-enchilala (in Birr), Tsegur Eyesus and Debbre Mawi watersheds was completed. The research team included in the documentary all three watersheds: in Anjeni area, hillslope conservation structures made in 1985 were targeted for filming, and active recent gully erosion sites were captured. One male farmer and one development agent was interviewed. In Ene-enchilala sub-watershed of Birr watershed, the research work of PhD students rehabilitating gullies was captured. Six farmers (including 2 women were interviewed as well. Getanhe (student benefited from PEER Science) was included in the interiew. Finally, one development agent from the district administration talked about the soil conservation efforts in the watershed. In Tsegur Eyesus watershed, previous gully rehabilitation works by NGO's such as GTZ were captured in the documentary as well. In this watershed, 2 men and 3 women farmers told stories about gully rehabilitation works and their limitations. Finally, in the Debre Mawi watershed, upland conservation structures of terraces integrated with biological measures, gully rehabilitation efforts made by PhD student from Cornell, and upslope failed conservation structures due to design problems were documented. In addition, the research team included in the documentary the irrigation reservoir to highlight the impact of erosion on water resources development. In March 2015, soil and water conservation expert from Bureau of Agriculture of Amhara Region was interviewed about soil erosion and conservation challenges, social mobilization, and gully erosion and rehabilitations. In addition, the PI and Tammo Steenhuis from Cornell were included in the documentary as well. The film is currently being edited and the producers will provide the first production to have comments from the group of PEER Science researchers.
The gully rehabilitation demonstration shows improvement through community participation in physical and biological conservation. (Photo courtesy Dr. Tilahun).
At the same time gully erosion expansion is severe in the control area (Photo courtesy Dr. Tilahun).
This past quarter has been prolific with publications as well. The group published an article "Impact of conservation practices on runoff and soil loss in the sub-humid Ethiopian Highlands: The Debre Mawi watershed" in the Journal of Hydrology and Hydromechanics 01/2015. A journal paper entitled "Non-point Source pollution of Dissolved phosphorus in the Ethiopia Highlands: The Awramba watershed near Lake Tana” has been submitted by the group to CLEAN – Soil, Air, Water. Another article was submitted to Frontiers in Earth Science, entitled "Improving efficacy of landscape interventions in the (sub) humid Ethiopian highlands by improved understanding of runoff processes". Five PhD students who were supported by PEER Science plan to present papers at the International Conference on the Advancement of Science and Technology (ICAST-2015) on 9 May 2015 at Bahir Dar University. The titles of the paper are: “Effect of community based soil conservation works on runoff and sediment loss in the Ethiopian highlands: The Birr Watershed”; “Effects of hardpan breaking on hydrological process in Birr watershed, Upper Blue Nile Basin, Ethiopia”; “Hydro-Geomorphological Features at gully headcuts the Humid Northern Ethiopian Highlands, Birr Watershed”, “Contributions of peak sediment events to annual sediment loads before and after BMP installation in the sub-humid Ethiopian highlands: the Debre Mawi watershed”, and “Hydrological Response based rainfall runoff modeling in the Upper Blue Nile Basin”. In order to allow the team to finalize production and editing of the documentary film, the grant has been extended until June 2015.