GENERAL IRRIGATION EFFICIENCY FOR FIELD WATER MANAGEMENT

On-farm water management systems are traditionally evaluated using a s et of performance indices which are inconvenient for evaluation and co mparison. We propose a general efficiency (E(g)) which is defined as t he ratio of crop transpiration to the sum of the volume of applied wat er and the volume of deficit. E(g) combines the characteristics of tra ditionally used irrigation efficiencies: application efficiency (E(a)) , storage efficiency (E(s)) and the Christiansen's coefficient of unif ormity (U-c). Thus, it is possible to compare the performance of diffe rent water application systems and/or design and management scenarios using a single index. The relationships of E(g) vs. E(a), E(s) and U-c are also presented using a transpiration fraction (alpha) which is de fined as the ratio of transpiration to evapotranspiration.