生态输水影响下地下水化学特征的时空变化分析

Spatial and Temporal Variations of the Groundwater Chemical Characteristics under Ecologic Water Conveyance in the Lower Reaches of Tarim River

对塔里木河下游自2000年以来的4次生态输水的地下水位变化与地下水监测井的水化学资料比较分析,结果表明:地下水化学特征随4次生态输水,在时间与空间上发生明显变化.沿输水河道方向(纵向),下游上段的监测断面的地下水化学特征受输水的影响明显早于下游下段的水化学特征,且变化幅度也较大.沿垂直河道的方向(横向),距输水河道不同距离处的地下水化学特征先后呈现相似的变化规律,即:在受输水影响的初期,地下水化学成分中的主要离子含量和矿化度都明显上升,随着生态输水的继续进行而逐步下降.同时,地下水化学的变化特征反映出生态输水的影响范围在逐渐扩大,4次输水后地下水的响应范围在距离输水河道1 000 m左右.生态输水虽然对地下水中盐分浓度起到了暂时冲淡和区域盐分再分配作用,但要使下游水质真正好转只有采取一系列工程和管理措施.

Based on the monitoring data of groundwater chemistry and groundwater level influenced by the intermittent water conveyance in the lower reaches of Tarim River from May 2000 to November 2002, the variation of the groundwater chemistry was studied in this paper. It is found that the groundwater chemistry in the whole lower reaches has changed a lot. The groundwater chemistry at the sections near the Daxihaizi Reservoir was influenced earlier than that beyond it. The varying scope of the total dissolved solid （TDS） and the major ions in groundwater is obvious near the Daxihaizi Reservoir. At Yinsu Section, the range influenced by the water conveyance was continual enlarged, it was about 200m from the channel during the first water conveyance, about 400m during the second conveyance, about 700 m duringthe third conveyance, and about 1000 m during the fourth conveyance. As for the groundwater chemistry in a certain site, TDS and the major ions in groundwater increased at the beginning of the conveyance, then it can be interpreted as follows, at the beginning water brought the salt to channel from the place nearby, when more and more water came, the solute was diluted, so TDS and the major ions in groundwater decreased, and the decreasing process was fast in speed at the beginning, then slowed down. In addition, it is assumed that the water conveyance has not removed any salinity in this region, but diluted it. To reduce the salinity in the groundwater and soil, a series of measures on ecology, engineering and management should be carried out.