METHOD FOR ESTIMATING EFFICIENCY IN SPANISH IRRIGATION SYSTEMS

The investigation deals with conveyance efficiency and global hydrauli c efficiency in Spanish irrigation systems. The values of conveyance e fficiency are calculated for five channels. As the lack of reliable da ta makes it impossible to calculate global efficiency, a method is dev eloped that is based on the comparison between the theoretical crop wa ter requirements and the volume released at the head of the main chann el. The so-defined net demand/release ratio marks the upper limit of g lobal efficiency. Values are calculated in 38 irrigation systems that represent about a fifth of the total irrigated surface in Spain. It is demonstrated that the most water loss occurs in distribution and appl ication. Analysis of the influence of diverse system characteristics, such as irrigation method, gross supply, water prices, and tariff type s shows the importance of these aspects on irrigation efficiency.