Abstract:
Abstract: Existing canal-system water use efficiency (CSWUE) specifically reflects canal engineering conditions impacts on water conveyance efficiency, including the influences of engineering conditions and management level to water use efficiency of canal-system, namely can't distinguish the impacts between engineering conditions and management level to water use efficiency. So, the existing assessment indicator may lead to an excessive emphasis in engineering measures (such as channel lining), such as rational water allocation to raise CSWUE and cannot be scientific developing water-saving irrigation strategy, while ignoring the management measures. In order to analysis the influence factors of engineering conditions and management level respectively to CSWUE, a new assessment indicator system of CSWUE is proposed based on the modified assessment indicators. The new assessment indicator system including canal conveyance efficiency (Eca), canal-system conveyance efficiency (EC), canal-system distribution efficiency(Ed) and water use efficiency of canal system (Ecs). The definitions, connotations and the determine methods for these indicators are given. The rationality of the assessment indicator system is also tested by case study. Eca is the ratio of net outflow to gross inflow of a certain canal under normal operation conditions. EC is the ratio of net outflow to gross inflow of a canal-system under normal operation conditions during an irrigation period. Ed is the ratio of net inflow to the fields to net outflow from a canal system under normal operation conditions during an irrigation period. Ecs is the ratio of net inflow to the fields to gross inflow from a canal system under normal operation conditions during an irrigation period. Eca and EC revealed the impacts of engineering conditions to water use efficiency, and can be determined by still water measurement or dynamic water measurement methods. Ecs revealed the impacts of engineering conditions and management level to water use efficiency, and can be determined by the ratio of net outflow and gross inflow of a canal-system, or determined by irrigation efficiency divided by field water use efficiency. Ed revealed the impacts of management level to water use efficiency, and can be determined by Eca divided by Ecs. The new assessment indicator system can satisfy the needs of different development stages of irrigation system and different purposes of canal-system water use efficiency assessment, and propose the guide for irrigation project investment allocation, engineering operation and water management assessment.