Development of Water Allocation Strategy to Increase Water Use Efficiency of Irrigation Project

Abstract

In development of water allocation strategy to meet crop water requirement and to utilize rainfall effectively, a computerized water allocation scheduling and monitoring system named WASAM 2 was developed. Song Phi Nong irrigation project was selected as a case study. WASAM 2 was used for water allocation scheduling in Song Phi Nong project for 3 cultivation seasons of 1994 dry and wet seasons and 1995 dry season. The discharge at 5 key regulators which are the entrance to 5 water masters were monitored on daily basis. The actual delivery performance of the 3 studied seasons indicated that the actual measured discharge was about 20-30% higher than the recommended WASAM 2 discharge because Song Phi Nong project was the downstream project and had to take all the remaining water from the upstream Phanom Tuan project. It is recommended that the water allocation scheduling system of Song Phi Nong and Phanom Tuan projects will be combined into one system to increase the efficiency in water allocation. The average irrigation efficiency of Song Phi Nong was 37.6% in dry season and 28.5% in wet season. WASAM 2 increased the wet season efficiency by 3-5%. The irrigation efficiency in the dry season was on the average 7.7% higher than that in the wet season. Some water master has the efficiency up to 46.9% in dry season. The irrigation efficiency of the project is still low by two reasons : (1) being unable to completely control the discharge, and (2) high seepage loss in the canal system.