Simulation of Deep Percolation in Fields with Greater Depth of Groundwater

摘要

The rules of deep percolation produced by irrigation under maize in the field with greater depth of groundwater are studied. With the maize cultivation in Dalian as an example, 1-D finite element model is built by VADOSE/W using the daily meteorological data in the years with guaranteed rainfall frequency of 75%, 50% and 25% through analyzing the years-long period regional meteorological data. By this model, the field soil water flow in a whole year under the rain-fed, sprinkler irrigation and border irrigation is simulated respectively, and the water balance of 1 m-deep root zone is analyzed. The simulation shows that the ratio of deep percolation to the sum of net precipitation and net irrigation water amount is less than 5% under the rain-fed, 5%～9% under the sprinkler irrigation, 7%～13% under the border irrigation respectively. 70%~95% of deep percolation is produced by irrigation and about 13%～28% of net irrigation water amount is lost as deep percolation, as a result, the main reason for deep percolation can be concluded as irrigation in fields.