Groundwater Numerical Simulation and Water Source Allocation of Paddy Field Irrigation Area in Northeast China Based on Water Consumption Balance

Abstract

【Background】 With the development of society and the increasing of global food demand, irrigation water for agricultural production plays a more important role. According to statistics, 90% of the world’s freshwater resources are used for agricultural irrigation. At present, the supply and demand of surface water resources are unbalanced in many areas. Groundwater resources have become the main water source for agricultural water. With the increasing of grain production, the problem of overexploitation of groundwater is becoming more serious, which leads to over-exploitation of groundwater and huge underground funnel. 【Objective】 In order to alleviate groundwater overexploitation in the main grain production areas of Northeast China and promote scientific allocation of surface water and groundwater resources. 【Method】 Taked Qingan County and Heping Irrigation Area in Heilongjiang Province as typical irrigation areas, this paper used a groundwater numerical simulation model based on water consumption balance, and validated and identified the model with measured data. On this basis, 22 scenarios under two irrigation modes were simulated with the model. 【Result】 ①Under constant irrigation mode, when groundwater proportion is less than 66%, groundwater level in irrigation area rises and can be restored; when groundwater proportion equal to 66%, the irrigation area is in equilibrium; when it more than 66%, groundwater level in irrigation area keeps decreasing.②Under water-saving irrigation mode, when the groundwater proportion is less than 68%, the groundwater level in the irrigation area will rise and recover; when groundwater proportion equal to 68%, the irrigation area will be in equilibrium; when it more than 68%, the groundwater level in the irrigation area will decrease continuously. Water-saving irrigation mode is less fluctuation of groundwater level under each proportion scenario than constant irrigation mode. 【Conclusion】 The proportion of groundwater resources in irrigation water has a significant influence on the water consumption equilibrium state of the irrigation area. With the increasing of groundwater resources, the total amount of recharge and discharge difference in the irrigation area has gradually decreased to negative value in 20 years. Both irrigation modes can achieve water consumption equilibrium when groundwater accounts for 66% and 68%.

Keywords

• paddy field
• water saving irrigation
• groundwater model
• water consumption balance