干旱区冲洪积扇-冲积平原绿洲浅层地下水质时空变化初步分析——以三工河流域绿洲为例

Study on the Temporal and Spatial Change of Shallow Groundwater beneath the Alluvial-diluvial Plain Oasis in Arid Regions——A Case Study in the Oasis in the Sangong River Basin

以三工河流域绿洲为例,分析了干旱区平原绿洲浅层地下水水质的时空变异性。结果表明,该区域地下水质不仅在空间上存在着显著的差异,而且年内及年际差异也很明显:1)冲洪积扇区域地下水质显著优于冲积平原区水质;2)春季地下水质总体好于秋季,且冲积平原区水质恶化程度要快于冲洪积扇区域;3)绿洲地下水质总体呈现下降的趋势,尤其是农业活动强烈且地下水埋深浅的冲积平原区域;4)水文地质条件是造成地下水质时空变异的主要原因,土地利用加剧了其变异性。

In this paper, a case study on the temporal and spatial variability of shallow groundwater beneath the alluvial-diluvial plain oasis in the Sangong River Basin is carried out.The Sangong River Basin is located in the middle section of northern slope of the Tianshan Mountains and the southern marginal zone of the Junggar Basin, Xinjiang,and it belongs to an inland arid region.The annual precipitation and potential evaporation in the plain are 220 mm and 1 817 mm respectively,and the annual air temperature is 6.9℃.The results show that the temporal and spatial variability of groundwater quality is remarkable in the oasis in the Sangong River Basin.The conclusions are as follows:(1) The groundwater quality beneath the alluvial-diluvial oasis is better than that beneath the alluvial plain;(2)The groundwater quality in autumn is worse than that in spring,and the deterioration of groundwater quality beneath the alluvial plain is more serious than that beneath the alluvial-diluvial fans;(3)The groundwater quality beneath the different regions of the oasis is generally deteriorated,especially beneath the alluvial plain where agriculture activities are strong and the groundwater depth is shallow.Moreover,the causes of variability of groundwater quality are briefly explained;(4)Land use results in a great effect on the temporal and spatial variability of groundwater quality, which is different from the different alluvial-diluvial fans and alluvial plain.It is considered that the hydrogeologic conditions are the main causes resulting in the variability of groundwater quality.