Bugenimana, Eric Derrick
(2017)
Assessment of Technical Efficacy and Economic Impact of Bench Terraces used in Soil Erosion Control in Eastern Rwanda.
["eprint_fieldopt_thesis_type_phd" not defined] thesis, The Open University of Tanzania.
Abstract
Soil erosion is one of the most serious problems challenging the wellbeing of the human beings and environmental sustainability. In developing countries like Rwanda, in order to combat soil erosion, conservation practices should be implemented. This research evaluated the technical conformity and cost effectiveness of bench terraces in Rwanda. The Eastern Province of Rwanda was selected for this study as it is the largest, and has a combination of the most populous and the least densely populated areas and compares well with other five provinces. This province experiences insufficient rainfall and serious erosion problems because of its hilly nature and frequent rainstorms. The technical standards and models provided by MINAGRI and FAO were tested on 180 terraces taken as a sample against the current terracing practice. The results showed that many sites have been constructed without consideration of the technical guidelines. In fact, some land slopes are below the 10.7% standards; others are above 44% instead of 15-40% and slope risers of 90% and height of 2.9m. The correlation between vertical interval measured on the field and vertical interval given by FAO formula indicated weak correlation (r=0.314; P<0.01) and very weak correlation between width measured on the field and width given by FAO formula (0.194;P<0,05). Furthermore, some plots have been abandoned and used as pastures and some farmers destroyed the embankment for increasing the cultivable area. The benefit analysis showed that whether farmers use all agricultural technology of farming management the terraces can be economically benefit in second year with 1.15 BCR. Farmers’ preferences were investigated through pair-wise ranking approach. The farmers ranked the increasing fodder and soil erosion control at the first rank. If no remedial measures are taken soon to some terraces, landslides and erosion will be carrying more soil than before the construction of bench terraces. The remaining subsoil will not suitable for growing crops; and the increase in agriculture productivity, which was a target while implementing bench terraces will not be met. Therefore, special emphasis should be placed on it by increasing the supervision of implementation on field. MINAGRI should make its effort on construction of them during and after even should continue the monitoring and evaluation till at least 5 years and handover with both implementers and farmers.
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