宁夏石嘴山市引黄灌区地下水时空变化特性及影响因素

Temporal and spatial characteristics of groundwater and its influencing factors in the Yellow River diversion irrigation area of Ningxia Shizuishan

以宁夏石嘴山市引黄灌区为研究对象,基于灌区内76眼长序列地下水监测井,利用经典统计与地统计相结合的方法,对灌区地下水埋深的时空分布进行分析,并通过偏相关分析确定其影响因素。结果表明:(1)近20 a地下水埋深整体呈增大趋势,增大总幅度为0.09 m,可分为2个阶段:1997—2002年为逐渐减小趋势,年均减幅为0.037 m·a^-1;2002—2017年为增加趋势,年均增幅为0.019 m·a^-1;(2)地下水埋深空间上为扇形分布,以大武口区为原点,黄河为扇形弧段,从西往东逐渐减小,各月时空分布变化主要受区域灌溉水平影响;(3)地下水埋深空间结构均为高斯模型,块金系数分布在1.39%~3.08%,为强烈的空间自相关性,空间异质性主要受灌区本身的地质结构以及补给量和排泄量等因素影响,而影响程度依次为:农业灌溉取黄河水量>降雨量>蒸发量>人工开采。

Taking the Yellow River diversion irrigation area in Shizuishan City,Ningxia Province,as the research object,based on 76 long-term groundwater monitoring wells,this paper combines classic statistics and geostatistics to analyze the spatial-temporal distribution of the depth to groundwater in the irrigation area and determine its influencing factors by partial correlation analysis.The results indicate that(1)the depth of groundwater near 20 a shows an enlargement trend as a whole,with a total raise of 0.09 m,which can be divided into two stages:from 1997 to 2002,it gradually decreased,with an average annual decrease of 0.037 m·a^-1;from 2002 to 2017,it demonstrated an upward trend,with an average annual increase of 0.019 m·a^-1.(2)The groundwater depth is fan-shaped.With Dawukou District as the origin and the Yellow River as a fan-shaped arc,it gradually decreases from west to east.The spatial and temporal distribution of each month is mainly affected by the regional irrigation level.(3)The spatial structure of the depth to groundwater is a Gaussian model,and the nugget coefficient is distributed from 1.39%to 3.08%,which is a strong spatial autocorrelation.Moreover,spatial heterogeneity is mainly affected by the irrigation area’s geological structure andrecharge and excretion factors.The sequence of the impact degree is as follows:water taken from the Yellow River for agricultural irrigation>rainfall>evaporation>artificial exploitation.