Scale Effect of Water Saving in Agriculture

摘要

This paper discusses the issues of scale effect of water saving,which was caused by the return flows and their reuse in water resources system.We analyzed the components of water balance and their roles at different scales,and pointed out the situation would be becoming more complicated and scale effect could be larger with scale going up.The classical concepts of irrigation efficiency,which ignored the existence of scale effect,had limits and constraints in their usefulness in the field of water resource managements and assessments,so some new definitions and indicators introduced recently have been reviewed.The issues and methodology for the research on the scale effect of water saving in agriculture have been discussed through the analysis and comparison of several cases.