盐碱地排水沟水体盐分变化规律

为了研究陕西卤泊滩盐碱地排水沟在排水出路受阻,上游灌区退水导致排水沟周期性较高水位运行条件下的水体盐分变化情况,选择研究区3条排水沟,进行野外水盐监测试验,测定了排水沟水体盐分随时间的变化规律.研究结果表明:在当前条件下影响研究区排水沟水量的主要因素为干旱蒸发和上游灌区退水.干旱期排水沟水量较少,上游灌区低含盐量的退水进入研究区排水沟内,致使水量显著增大,在研究区下游排水沟内水深达1.15 m;排水沟水体电导率值在干旱季节较高,盐分从上游至下游呈现出一定的富集现象;上游监测点位水体电导率基本维持在2~14 ms/cm,下游水体电导率值高达25.2 ms/cm;研究区上游灌区退水在排水沟内大量蓄积,使得排水沟水体电导率值降低至1.9 ms/cm,稀释率高达10倍,表明退水可以稀释排水沟中的盐分水平,维持排水沟水体盐分平衡,达到排盐效果.

Variation characteristics of salinity in water of drainage ditches in saline lands

The drainage ditches in the saline lands around Lupuotan Lake,Shaanxi Province are periodically full of water due to the blockage of drainage outlet and received huge amount of irrigation water returned from two upstream irrigation districts,causing a change in salinity concentration in the water body of the drainage ditches. To reveal the actual variation characteristics of salinity,the salinity in the water of three drainage ditches was monitored over two years. The results showed that the increase in salinity was apparent in the drainage ditches during the dry season from upstream to downstream in the studied lands,and the electrical conductivity of water in the upstream ditches was varied between 2 and 14 ms /cm,but it was as high as 25. 2 ms / cm in the downstream ditches. The fresh water from two upstream irrigation districts was recharged into the drainage ditches regularly,and the salt accumulation was destroyed. As a result,the salinity was diluted by more than 10 times and the electrical conductivity of that water was lowered down to 1. 9 ms / cm. Such periodic dilutions allow a relatively low salinity level to be kept and a salt balance to be maintained in the water body of the drainage ditches studied.