COMPARATIVE EVALUATION OF LOCAL WATER MANAGEMENT PRACTICES IN TWO COMMUNITIES MANAGED SMALL-SCALE IRRIGATION SCHEMES: CASE STUDY OF GATTO AND ARGUBA IN DERASHE IN SNNPR, ETHIOPIA

Abstract

This study analyses the comparative evaluation of local water management practices in two communities managed small-scale irrigation schemes: case study of Gatto and Arguba in SNNPR. Primary and secondary data were collected from farmers‟ field and from Derashe Woreda irrigation district. All the data for the community managed small scale irrigation schemes includes area for both irrigation schemes, agricultural production for both schemes, irrigation water related data and others. Community-managed irrigation schemes are managed, maintained and operated by farmers themselves. This activity includes water diversion, conveyance, and maintenance of infrastructure, sanctions for misbehaving and others. Gatto irrigation Scheme designed to irrigate the command area of 200ha and Arguba irrigation scheme was also designed to irrigate the command area of 150ha. Three groups of comparative performance indicators were used to asses both irrigation schemes. This includes three water supply indicators such as (Annual irrigation water delivery per unit irrigated cropped area, Annual relative water supply and Annual relative irrigation supplies), four agricultural output indicators such as (Output per unit irrigated cropped (harvested) area, Output per unit command area, Output per unit irrigation water supply and Output per unit water consumed) and two physical indicators such as (Irrigation ratio and Sustainability of irrigated area ) were used to evaluate the performance of the schemes. The results obtained show the irrigation sustainability of Gatto was 0.7867 and that of arguba was 0.881. For irrigation ratio the result for both schemes was 0.967 and 0.88 for Gatto and Arguba irrigation scheme respectively. In this result it shows that the value of indicators of Arguba irrigation scheme was Higher than that of Gatto irrigation scheme. For water supply indicators the result for Annual relative water supply was 1.871 and 1.624 for Gatto and Arguba irrigation scheme respectively. For Annual relative irrigation supply the result was 1.52 and 1.63 for Gatto and Arguba irrigation scheme respectively. The values of annual relative irrigation supply for both schemes were higher than one this shows that there were over supply of water in both irrigation schemes and For agricultural indicators the result for output per unit irrigated cropped area was 18633.95 birr/ha and 16828.20 birr/ha respectively for Gatto irrigation schemes, output per unit command area was 1639.88 birr/ha and 13238.18 birr/ha respectively for Gatto and Arguba irrigation schemes, for output per unit irrigation water supply was 2.3 birr/m3 and 2.32 birr/m3 for Gatto and Arguba irrigation schemes respectively and for output per unit consumed was 3.24 birr/m3 and 3.44 birr/m3. For this result the land productivity of Gatto irrigation was higher than Arguba irrigation scheme and the water productivity of Gatto irrigation was lower than that of Arguba irrigation scheme. For irrigation efficiencies the application and storage efficiency for the three fields for Arguba irrigation scheme were higher than that of Gatto irrigation scheme but the distribution efficiencies for field 2 and 3 in Gatto irrigation scheme were higher than that of Arguba irrigation scheme but field 1 of Gatto irrigation scheme has distribution efficiency than that of Arguba irrigation scheme. In general the variation in efficiency illustrates the fact that application efficiency varies with every irrigation event, depending on how the water is applied and the conditions existing at the time of the irrigation event.