第二松花江流域平原区浅层地下水脆弱性时变特征分析

Time-varying Characteristics of Shallow Groundwater Vulnerability in the Plain Area of the Second Songhua River Watershed

以第二松花江流域平原区为研究区,选择了地下水埋深、净补给量、含水层介质、土壤介质、地形坡度、包气带影响、渗透系数7个指标,运用DRASTIC评价方法对浅层地下水脆弱性进行了评价,进一步分析了地下水脆弱性评价结果的影响因素。结果表明:(1)地下水脆弱性分区在整体上具有空间分带特征性,并与地貌分区具有良好的一致性,其中河谷平原区由于地下水埋藏较浅,地下水脆弱性较高,污染风险大;(2)受地下水位变动以及净补给量的影响,具体地段的地下水脆弱性等级也具有较为明显的年际与年内变化特征,但整体区域上的地下水脆弱性的相对级别仍受地貌格局的控制。在开展区域地下水脆弱性评价时,应注意选择具有代表性的时段数据进行评价。

With the plain area of the second Songhua River watershed as study area,we selected seven indicators including depth of water-table,net recharge,aquifer media,soil media,topography,impact of vadose zone and hydraulic conductivity of the aquifer to evaluate the shallow groundwater vulnerability using DRASTIC index method and to further analyze the influential factors of assessment results.Results suggest that groundwater vulnerability distribution in the study area can be partitioned in space and is in good consistency with landform division,among which river valley plain is of high groundwater vulnerability and high risk of contamination due to shallow groundwater.Moreover,influenced by groundwater table variation and net recharge,the level of groundwater vulnerability in particular area has obvious annual and inter-annual change characteristics;whereas in the whole area,the relative level of groundwater vulnerability is still controlled by landforms pattern.In the assessment of regional groundwater vulnerability,more attention should be paid to the selection of representative time data.