三江平原地下水流场演化趋势及影响因素

An analysis of the evolution trend and influencing factors of the groundwater flow field in the Sanjiang Plain

近年来,三江平原部分区域地下水位呈持续下降的态势,引起广大学者和相关部门的高度关注,为了查明三江平原地下水流场时空演化规律,揭示其主要影响因素,以三江平原1980年72组及2019、2020年同期1092组地下水位统测数据和44组国家地下水监测数据为基础,应用ArcGIS插值分析、栅格代数运算、对比分析等方法,查明了三江平原地下水流场时空演化特征,阐明了不同影响因素对地下水流场演化的控制作用。结果表明:与1980年相比,三江平原地下水位整体呈下降趋势。西部平原区地下水位累计降幅1~5 m的区域面积2.6×104 km2;东部建三江垦区累计降幅大于5 m的区域面积为1.17×104 km2,其中,累计降幅大于10 m的区域面积为3400 km2,地下水位年均降幅约0.29 m。地下水开采引起地下水流场变化,“西砂、东黏”的水文地质条件促使区域地下水降幅的时空演化差异;水田种植规模的不断扩大引起地下水超采,浅地表黏土层阻挡降水入渗补给,地下水无法实现以丰补欠自平衡,造成了建三江垦区地下水位的持续下降。本研究成果为进一步查清三江平原地下水变化规律和现状特征奠定了基础,为科学指导地下水资源合理开发利用和管理提供了技术支持。

In recent years,groundwater levels in parts of the Sanjiang Plain has continuously decreased,which attracts great attention from scholars and related departments.In order to find out the temporal and spatial evolution of the groundwater flow field in the Sanjiang Plain and reveal its main influencing factors,in this paper the ArcGIS interpolation analysis,grid algebraic operations,comparative analysis and other methods are used to analyze the 72 groups of data in the Sanjiang Plain in 1980 and 1092 groups of groundwater level data and 44 groups of national groundwater monitoring data in the same period in 2019 and 2020.The spatio-temporal evolution characteristics of the groundwater flow field in the Sanjiang Plain are ascertained,and the control effects of different influencing factors on the smooth evolution of groundwater are clarified.The results show that,compared with 1980,the groundwater levels of the Sanjiang Plain showed an overall decreasing trend.The groundwater levels of the western plain area cumulatively decreased by 1 to 5 m,with an area of 2.6×104 km2,and most areas of the eastern Jiansanjiang reclamation area fell greater than 5 m with an area of 1.17×104 km2.Among them,the area where the cumulative drop of groundwater levels is greater than 10 m is as high as 3400 km2,and the average annual drop of groundwater levels is about 0.29 m.Groundwater exploitation causes the changes in the groundwater flow field,and the hydrogeological conditions of"West Sand and East Stick"promote the temporal and spatial evolution of the regional groundwater level decline.The continuous expansion of the scale of paddy fields has caused over-exploitation of groundwater.The shallow surficial clay layer blocks replenishment from rainfall infiltration,and the groundwater cannot achieve self-balance with abundance to compensate for the shortage,resulting in the continuous decline in groundwater levels in the Jiansanjiang Reclamation Area.The results of this research lay a foundation for further investigation of the groundwater change laws and current characteristics of the Sanjiang Plain,and also provide technical support for scientifically guiding the rational development,utilization and management of groundwater resources.