Evaluation of Hydraulic Performance: A Case Study of Etana Small Scale Irrigation Scheme: Wolaita Zone, Ethiopia

Abstract

The conventional furrow irrigation system is inherently inefficient in wolaita zone, while the suboptimal management and operation (inflow discharge and cutoff time) are considered as one of the main reasons for satisfactory hydraulic performance. Addressing these issues, the furrow irrigation system which is only practiced in the study area was evaluated on three fields under routine farmer management in wolaita zone. The study consisted of field experiments and simulation modeling. Irrigation performance including application efficiency, Potential Application Efficiency, Adequacy and distribution uniformity, runoff ratio and deep percolation ratio of two irrigation events were evaluated using surface irrigation evaluation and simulation Model WinSRFR 4.1.3. The study revealed satisfactory irrigation efficiencies, with higher distribution uniformity and water losses. Therefore, hydraulic performance of the study area had a value of application efficiency (55% to 73%), low quarter adequacy (0.96 to 1.28) and low quarter distribution uniformity (0.89 to 0.96), runoff ratio (7% to 38%) and deep percolation ratio (1% to 25%) on farms. In addition, irrigation over irrigation status practiced was found in study area with the average low quarter adequacy of 1.14. The existing irrigation application efficiencies of irrigated fields at ETANA SSIS were poor.  

Keywords: Infiltration parameter; Irrigation performance; Furrow; WinSRFR; Etana