An optimization model of groundwater resources allocation for agriculture in well irrigation district of North China

Due to excessive exploitation of groundwater resources to meet crop irrigation requirement, shallow groundwater table is falling at the rate of about 1m/y for the last 20 years in North China plain, which has caused many ecological and environmental problems. A kind of non-linear multi-year optimization model of groundwater resources allocation (MOGA) has been developed to decrease groundwater exploitation as well as keep high yield of crops at the same time. The model has been applied for agricultural water supply in Huantai County, a well known irrigation district in north China, and achieved good fruits. In the model, average crop yield in optimization period was maximized as objective function and crop optimal irrigation regime based on Jensen function were coupled in the constraints to construct a non-linear optimization model with reliable precision and practicability. According to the characteristics of precipitation in studied area, combination of three hydrological years, namely wet year (P = 25%), average year (P = 50%) and dry year (P = 75%), were presented as an optimization period in the model parameter set. Through four planned scenarios, optimized planting areas, irrigation quota and grain yields for different crops in three hydrological years could be calculated optimally, respectively, using LINGO optimization software. The result indicates that high food crop yield could be obtained with 80% of total available groundwater resources, almost same as crop yield when irrigating with total available groundwater. The optimization model and optimal scheme provide decision makers a theoretical way to implement deficit irrigation and manage groundwater resources in well irrigation district, coping with the problem of extensive exploitation of groundwater from the aspect of water resources allocation.