A systems approach to the assessment and improvement of water use efficiency in the North China plain

Abstract

The ways in which the total yield of crops in the North China Plain can be improved by optimizing the use of water are explored. The approach differs from many current ones in that, firstly, only the water entering the system as precipitation and inflow is considered water income, and only the water leaving the system through evapotranspiration and into the sea is considered lost; secondly, the dependence of yield on water supply is analyzed on the basis of physical and physiological mechanisms involved in water transport and yield formation, instead of on empirical relations. The whole Plain is divided into three main categories, and different strategies are suggested for them, i.e., (1) Areas with poor water supply, in which the limited amount of water recharge is to be optimized; (2) Areas with considerable surface water supply, where allocation of incoming water to fields with different distances from the water sources is to be optimized; (3) Areas with abundant water supply, means are to be found to excavate the underground free space to accommodate the excess water during the rain season.