SYSTEM ANALYSIS OF ADIGELA IRRIGATION PROJECT, TIGRAY, ETHOPIA

Abstract

System Analysis of Adigela Irrigation Project, Tigray, Ethopia is an attempt made to tackle the problems encountered in sizing of reservoir so that Safe yield is obtained from the reservoir to the Irrigation area and water supply. In the present study for optimal sizing of Adigela dam, which is to serve for irrigation and community water supply two models i.e. liner programming and simulation model are considered. The objective of the study is to find out optimal size of reservoir which has maximum annual benefit for the present and optimized cropping patterns. Further more the 75% dependable release for the present size of reservoir 1.25 x 106 m3 is computed using the above meM,tioned models. The sizes obtained in linear programming for present and optimized cropping pattern are 1.23 x 106 ►n3 and 1.2345 x 106 m3 and. the benefit obtained are 86911 Birr/year and 96868 for the present and optimized cropping pattern respectively. The releases obtained from the above two sizes are further screened by simulation model using 25 years generated flow by trial and -error. and turned out to be 0.98 x 106 ►n3 and 0.99 x 106 m3 from the results obtained in LP as 1.09077 x 106 rn3 and 1.087997 x 106 m3 for the optimized and present cropping pattern. However, since the dam is constructed at present with capacity of 1.25 x ' 106 m3, a linear programming model in tested : for the release expected from this size for the present and optimized cropping pattern and obtained s 1.09077 x 106 and 1.087997 x 106 m3 By further screening the releases by simulation the result obtained are 0.995 x 106 m3 for present and optimized cropping patterns which shows a reduction in area to be irrigated from 51 ha. found in LP for both to 46.5 ha. and 46.6 -ha. for the present and optimized cropping patterns respectively.