Analysis of suitable irrigation water ratio of well to channel based ongroundwater model

In order to obtain the suitable irrigation water ratio of well and channel to determine scientific and reasonable agricultural water saving scheme in the Jinghui Canal Irrigation District, the ArcGIS and PMWIN software were integrated together to establish the groundwater distribution simulation model of the irrigation area. The EVT evapotranspiration subroutine of PMWIN was rewritten with the VB programming language so that it can simulate the nonlinear evaporation. The simulation accuracy of evaporation was greatly improved. According to the actual situation of agricultural irrigation, 10 kinds of water-saving irrigation simulation scenarios were set up to simulate the change of groundwater depth. Then the suitable irrigation water ratio of well to channel was obtained through the groundwater equilibrium analysis. The results show that: 1) It can keep a balance between groundwater supply and drainage when the irrigation water ratio of well to channel is at 0.35-0.55 with irrigation intake water amount of 0.37-0.41 billion m3 from canal head; 2) It is possible to keep a balance between groundwater supply and drainage when the irrigation water ratio of well to channel is at 0.5-0.7 with irrigation intake water amount of 0.15-0.2 billion m3 from canal head; 3) The current well and canal irrigation ratio of 0.9-1.2 has led to excessive extraction of groundwater. It is recommended that the ratio of well to canal irrigation should be controlled at 0.5-0.7 through agricultural water-saving efforts, increasing financial subsidies to water price and artificial regulation of groundwater storage, so as to achieve the efficient and sustainable use of water resources in the irrigation district.