基于供需水量平衡分析的灌区机井布局模式

Wells distribution layout in irrigation district based on water supply and demand balance analysis

针对机井布局缺乏合理科学规划,造成的北方灌区地下水采补失调问题,以宝鸡峡灌区为研究区,在灌区地下水资源综合评价的基础上,划分地下水开发利用类型区;以充分灌溉和非充分灌溉条件下的灌区供需水量平衡分析为依据,拟定不同的井灌地下水开采规模方案,并通过地下水数值模拟计算,确定合理的地下水开采规模;运用传统计算方法和基于遗传算法的优化方法计算灌区规划机井数,单井灌溉面积及井距,确定灌区机井合理布局模式.计算结果表明:开采方案Ⅱ(采补平衡)条件下,灌区地下水位埋深年内变幅最小,且呈微小上升趋势,地下水采补基本平衡,缺水率可控制在1%左右,利于涵养地下水源.针对现有机井数量,灌区需做如下调整:塬上灌区需新建机井53眼,塬下灌区需减少机井242眼,以利于灌区合理开发利用地下水资源.

Lack of reasonable and scientific planning of well layout is one of the most important reasons for the imbalance problem of groundwater supply and demand in the north irrigation districts of China.Baojixia irrigation district was used as the study model and based on its comprehensive groundwater resources,the types of groundwater development and utilization were classified.According to water supply and demand balance analysis under both sufficient insufficient irrigation conditions,the various schemes of groundwater extracting scale were figured out.A reasonable groundwater mining scale was determined based on the numerical simulation of groundwater to reduce the shortage rate of irrigation water and to balance the extraction and supply.Two methods,namely traditional method and GA optimization method,were applied to calculate the number of pumping wells,single well irrigating area and distance between two wells so as to determine a reasonable layout of well distribution in the irrigation district.The results showed that in the second scheme not only the less change in the groundwater level is obtained,but also extraction almost equals to infiltration of water and the water shortage rate is controlled in around 1%,and subsequently a sustainable groundwater utilization will be realized.According to the current number of wells,additional 53 wells should be drilled in the highland and the 242 wells should be reduced in the lowland in that irrigation district.