渭干河―库车河三角洲绿洲地下水盐化特征及成因分析

Cause Analysis: Salinization Characteristics of Underground Water in Delta Oasis of the Weigan-Kuche River

在综合分析大量实测资料和参考资料的基础上,阐明了渭干河―库车河三角洲绿洲地下水不同埋深的分布面积、盐化特征、化学类型、补排量、含盐量的时空变化及成因。结果显示：（1）在绿洲平原区,地下水埋深3~6m范围最大,占总面积的39.68%;在灌区地下水埋深1~3m范围最大,占53.03%。在绿洲平原区,地下水矿化度小于1g/L范围最大,占总面积的91.98%;在灌区地下水矿化度小于1g/L的范围最大,占94.81%。从pH值来看,pH值7.5~8.0范围之间的面积最大,占总面积的90.25%。（2）冲积洪积扇北部属于淡水带,水化学类型为HCO3—Cl—SO4—Ca—Na;冲积洪积扇中部属于上咸下淡水带,水化学类型为SO4—Cl—Na—Mg;冲积洪积扇南部属于上咸下淡水带,水化学类型为Cl—SO4—Na—Mg。从水质上看,Ⅲ级地下水分布面积最大,占总面积的84.77%,其地下水资源量占61.89%。（3）地下水含盐量在时间尺度上,波动较大,1997、2000、2001年含盐量较高,均为3.7g/L以上,而1998、1999、2006年较低,为3.4g/L左右;在空间尺度上,研究区东部的地下水含盐量高于西部,南部高于北部,东南部高于西北部。（4）可溶性矿物的溶解、地下水水位抬升、强烈的蒸发、降水量的稀少、农业灌溉、化肥的使用是渭干河―库车河三角洲绿洲地下水含盐的主要原因。

Based on the observed and reference data,this paper analyzed the temporal-spatial changes of the different depth distribution area,salinization characteristics,chemical types,the supplement-discharge amount and salinity of the underground water in the delta oasis of the Weigan-Kuche River.The results show that（1） The depth of the underground water of the largest area is 3-4 m in the plain oasis,accounting for 39.68% of total area,and that the depth of the underground water of the largest area is 1-3 m in the irrigation district,accounting for 53.03%,and that the area of less than 1 g/L salinity of the underground water is the largest in the plain,accounting for 91.98%,and that it’s also the largest area in the irrigation district,accounting for 94.81%,and that the pH value of the of the largest area is 7.5-8.0,accounting for 90.25% of total area.（2）The upper of the alluvial-deluvial fan is the fresh water band,and the water chemical type is HCO3-Cl-SO4-Ca-Na,and the central area is a zone with salt water in surface and fresh water in subjacent,and the water chemical type is SO4-Cl-Na-Mg,and the lower is a zone with salt water in surface and fresh water in subjacent,and the water chemical type is Cl-SO4-Na-Mg,and the underground water of the largest distribution area is grade III,accounting for 84.77% of total area and 61.89% of the total underground water resources.（3） The salinity of the underground water have a larger fluctuation in the time scale,and the higher salinity is all above 3.7 g/L in 1997,2000,2001,while the lower is around 3.4 g/L in 1998,1999,2006,and in the spatial scale,the salinity of the underground water in the study area appears that the east is higher than the west,the south higher than the north and the southeast higher than the northwest.（4）The dissolving of the soluble minerals,the uplift of the underground water level,the strong evaporation,the scarce rainfall,the agricultural irrigation and the use of chemical fertilizers are the main reasons for the salinity of the underground water of delta oasis in the Weigan-Kuqa River.