Water Productivity Over Scales in Zhanghe Irrigation System

摘要

China has pioneered the water saving irrigation (WSI) techniques for rice and the techniques have been widely adopted over large areas. However, a question of global interest is whether this on-farm practice has led to water "real" savings, which can be transferred to other agricultural and non-agricultural uses. By better understanding how farmer practices and other interventions "scale up", a typical large-sized irrigation system, Zhanghe Irrigation System (ZIS), located in the Hubei Province north of the Yangtze River was selected for the research and we considered water use at different scales- farmers' fields, a mezzo scale, a main canal command scale and, finally at the irrigation system or sub-basin scale. Based on the analysis of two years' experimental data and long-term data on flow records, cropping area and crop yield in various sections of ZIS, the paper quantified the water productivity with and without WSI techniques at different scales and described the trend of water productivity over time. The factors behind the increase in water productivity at ZIS were explored. The water accounting methodology and related indicators developed by the International Water Management Institute (IWMI) were applied to ZIS to evaluate the status of water use and productivity at different scales.