Evaluation of sediment trapping efficiency of a settling basin at Finchaa Sugar Estate, Ethiopia

The efficiency of an irrigation system greatly depend on the quality of water it is using. The suspended solids (amount and nature) found in irrigation water has a significant effect on irrigation water supply, especially on sprinkler and drip irrigation systems. In such irrigation systems, sediment in canal structures has both technical and economic implications in the development and utilization of water resources and hence, its control is very essential. Therefore, assessing the performance of irrigation structures and infield irrigation equipments is important for better management of an irrigation system. The objective of this study was to evaluate the sediment trapping efficiency (TE) of the settling basin at Finchaa Sugar Estate under present sediment load. Suspended sediment samples were collected from inlet and outlet of settling basin using US D-74 suspended sediment sampler. The samples were analyzed in laboratory for sediment concentration and particle size distribution to assess the efficiency of the silt basin. The TE was determined for different flushing intervals (per week, per two week, per three week and per one month). The result indicated a TE of 30.15%, 13.9%, 4.47% and −1.05%, for the respective flushing intervals. The average TE for the test period was found to be 9.92%. In general, the performance of the settling basin is not bad under the existing sediment load. On the bases of the above TE result, this study recommended an optimum flushing interval of one week for the settling basin.