Risk Prevention Of Agricultural Drought Based On Water Overdraft Index

The severe shortage of water resources is a bottleneck factor restricting the sustainable development of the region.As a large agricultural province,Hebei Province is deeply affected by agricultural drought due to the large variability of precipitation.The continuous over-exploitation of groundwater for agricultural drought resistance in Hebei Province has caused a series of environmental problems and affected regional sustainable development.This paper selects Xingtai City,the most serious agricultural mining funnel in Hebei Province,as the research area.Based on the meteorological data,agricultural data,and water conservancy data of Xingtai City,the theoretical theoretical water demand and actual irrigation water for crops under the conditions of unit yield and total output are estimated.To build a water resources overdraft index,analyze the water resources overdraft situation caused by the imbalance of agricultural water resources supply and demand in Xingtai City from the spatiotemporal point of view,combined with the analysis of the groundwater overrun situation in Xingtai City,make reasonable suggestions for Xingtai City to further adjust the planting structure,alleviate the water resources overdraft situation,and reduce the risk of agricultural drought.Research indicates:1)The theoretical water demand for winter wheat,summer corn,and cotton in Xingtai City is rising on the basis of the general increase in yield.Summer maize and cotton growth season precipitation can basically meet the needs of crop growth,winter wheat has a serious water deficit,the actual irrigation water used to obtain the total output of winter wheat in Xingtai City from 1984 to 2017 was between3.6×10~8-19.2×10~8 m3,with an average of 11.8×10~8 m3,the total actual irrigation water consumption of the three crops in Xingtai City is between 3.6×10~8-24.3×10~8 m3,with an average value of 12.3×10~8 m3.The actual irrigation water consumption in Xingtai area is greatly affected by the winter wheat planting area and precipitation.Under different precipitation types,the actual irrigation water consumption increases with the decrease of precipitation.In terms of counties,Ningjin County in the central plain,Longyao County,Ren County,Nanhe County,and Wei County,Nangong City,Linxi County,and Qinghe County in the eastern plains have large winter wheat planting areas,and the actual irrigation water consumption is the largest.2)Based on the estimation results of actual irrigation water consumption and the available agricultural water resources in Xingtai,construct a water resources overdraft index,and analyze the water resources overdraft situation in Xingtai:the winter wheat planting area in the western mountain area is small,the irrigation water is small,and the water The condition is good,only a slight overdraft will occur in the dry season;the winter wheat is the most widely sown in the central plains,and the amount of irrigation water is large.There are different levels of water overdrafts in high,flat,and dry years.Among them,Ningjin County,Baixiang County,Longyao County,Ren County,and Nanhe County have the most severe overdrafts of water resources.In the Eastern Plains,due to the small area of winter wheat planted in Guangzong County,the overdraft of water resources is relatively light.County,Nangong City,Linxi County,and Qinghe County have overdrawn water resources.3)Based on the average exploitable groundwater in the plain area of Xingtai City for many years and the actual groundwater exploitation in 1984-2017,the over-exploitation of groundwater in various counties(cities)was calculated,and a spatial-temporal analysis was conducted.In 1984-2017,the groundwater over-exploitation in Xingtai City was between 4.2×10~8-14.8×10~8 m3,with an average over-exploitation of 6.9×10~8 m3per year.In terms of the average status over many years,the groundwater extraction in Ningjin County,Baixiang County,Longyao County in the central plain and Nangong City in the eastern plain is the largest,respectively 0.9×10~8 m3,0.7×10~8 m3,0.9×10~8 m3,0.6×10~8 m3,It is also the area where Ning Bailong's underground funnel and Nangong funnel are located in Xingtai City.The groundwater over-exploitation status has a high correlation with the water resources overdraft status.Areas with large water overdrafts also have large amounts of groundwater overdraft.Therefore,the implementation of groundwater pressure extraction measures can reduce the water resources in Xingtai City to a certain extent Overdraft status.4)According to the overdraft situation of water resources under different precipitation years in Xingtai area,the plan of planting structure adjustment based on the balance of regional agricultural water resources is discussed.According to the water adaptability of crops,reducing the planting area of winter wheat and expanding the planting area of summer maize and soybean with better water adaptability in the water resources overdraft area can effectively reduce the local irrigation water consumption and appropriately increase the drought-resistant sweet potatoes,cotton and The planting area of peanuts can improve local economic benefits.The water resources in the western mountainous areas are in good condition,which can save more than 80%of the irrigation water after adjustment;the central and eastern plains have serious water overdrafts and large winter wheat cultivation,which is the main area for planting structure adjustment.The central plain can save more than 80%of the irrigation water during the high and low water yearst,and can save more than 60%of the irrigation water during the dry season.The eastern plains can save more than 80%of irrigation water during high and low water years,while Guangzong County and Wei County only save about 50%of irrigation water during dry years,and other regions can save more than 60%of irrigation water.