A THESIS SUBMITTED TO THE FACULTY OF HYDRAULIC AND WATER RESOURCES ENINEERING, ARBA MINCH WATER TECHNOLOGY INSTITUTE, SCHOOL OF GRADUATE STUDIES, ARBA MINCH UNIVERSITY, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN HYDRAULIC ENGINEERING

Abstract

Assessment of potential irrigable land and available water resources is an essential for the development of irrigated agriculture. Around 87% of the population in the Maze River catchment area still resides in rural regions and relies on traditional rain-fed farming, which is greatly affected by unpredictable rainfall patterns and climate change. The study is focused on assessing land and water resources potential of Maze river catchment and preparing geo-referenced maps of these resources using ARC GIS. Land suitability for irrigation development was identified by considering the irrigation suitability factors such as slope, soil and land use /land cover. The analysis result of these factors indicates that 90 % of slope, 75.2 % of soil and 79 % land use/land cover are in the range of highly to marginally suitable for surface irrigation. The irrigable land of the area was identified using weighted overlay analysis of the suitability parameters. The total irrigable land of watershed is about 76.75% which is potentially suitable for surface irrigation and 23.25% is classified as not suitable (N). Surface water potential of the study area was estimated through stream flow simulations by HEC HMS model. The model was calibrated and validated from observed stream flow data of the watershed using the periods of 1989-2021. During calibration and validation, the results of model performance indicators were in the acceptable range (Curve Number (CN) with range of (30 to 100), Soil Moisture Retention (SI) with range of (0.01 and 0.5) Time of Concentration (Tc) with range of (0.1 and 3 hours) Initial Abstraction (IA) (0.1 and 2 mm.) Constant Loss Rate (PL) (0.1 and 20 mm/h).Which indicated that a good agreement between observed and simulated values. Generally, irrigation potential of Maze watershed was estimated to be 82809.41 ha of land for surface irrigation system without considering any storage structures and annual surface water volume of 7170.15Mm3.. For sustainable irrigation development, other suitability factors such as soil chemical properties, socio-economic, environmental issues, and distance from water sources should be studied.