Standard Base Evaluation of Qualities of Soil and Water Conservation Structures in Gutam Watershed, Gurage Zone, Ethiopia.

Abstract

This research is entitled Standard Base Evaluation of Qualities of Soil and Water Conservation Structures in Gutam Watershed, Gurage Zone, Ethiopia. The study included biophysical field surveys and household level survey. SWC structures were widely practiced such as level of soil bund terrace on cultivated lands and brush wood check dam on eroded and small gully areas in the watershed. A total of 20 level of soil bund terraces and 20 brush wood check dam that lie in three randomly selected transect lines on farm lands and small gully areas, respectively were investigated. Width of check dam and gully, height of check dam and gully (length for brush wood check dam) and canal, and base width, and canal depth, length of soil bund, leg width and distance between two consecutive soil bunds were measured against the standard values provided by MoARD. A total of 20 Household heads were interviewed through open-ended questionnaires to assess the community based watershed management practices and their associated attributes in Gutam watershed. Evaluation of SWC measures indicated that the quality of structures practiced in cultivated area was in good position compared to SWC structures implemented on eroded and small gully areas. Level of soil bund structures that were implemented on cultivated lands showed very significant differences in the height of soil excavated and top width is 10%. The existing level of soil bund structures meet 25%, 10%, 95% 10%, 50% and 35% with the recommended standard in the canal width, height of soil excavated from bund canal, length of soil bund, top width of soil bund, and base width of soil bund and depth of canal respectively. The qualities of brush wood check dam constructed on gully area were almost the same as the recommended standard. From the study it was possible to conclude that, since SWC conserved cultivated lands differentiated across the years of constructed structures (stabilized with differ tree), the measures had better hold the soil in- situ and improved inter-terrace soil physical and biological properties. This suggests that by applying soil conservation measures upstream, the erosion rate and the amount of silt entering streams has been reduced. Improving land productivity through SWC in the upstream areas is the means to cut the huge costs of silt cleaning in dams and irrigation canals of the downstream areas.