生态输水后塔里木河下游合理水位探讨

塔里木河下游应急生态输水工程改善了该区水资源匮乏的现状,地下水的平均水位从输水前的8.25m升至输水后的4.13m。相应地,地表植被也出现明显的响应。但是,在不同河段由于过水时间、耗水量等因素的差异,造成输水后水位差异较大。以既能减少地下水强烈蒸发返盐,又不造成土壤干旱而影响植物生长的合理生态水位作为评价标准,对输水后不同河段的地下水位进行分析。结果显示,目前英苏—阿拉干段的地下水位2.97～4.8m是比较理想的水位;大西海子—英苏段水位较高,可能出现次生盐渍化;阿拉干—台特玛湖段地下水位太低,不利于植被的自然恢复。

Reasonable Ground-water Level at Lower Reaches of Tarim River After Water Transfer

According to monitoring and analysis of ground-water and vegetation response at the lower reaches of Tarim river in the last 3 years, the water resource deficit situation changed after the project of transferring water. It was found that the average ground-water level rose from 8. 25 m below ground surface before water transfer to 4. 13 m below ground surface after water transfer. Correspondingly, the vegetation health improved in this region. However, due to differences in timing and quantity of water transfer to different parts of the lower reaches of the Tarim river, the ground-water level varies in the region. Judging by the criteria for ecologically sound ground-water levels, which indicate conditions to prevent salinization, desertification and damage to the growth of some xerophytic trees and bushes in this region. The problem, whether the ground-water level in different parts at the lower reaches of the Tarim river reasonable is analyzed. The results show that the ground-water level (between 2. 97 and 4. 8 m below ground surface after water transfer) from Yingsu to Alagan is comparatively reasonable. The ground-water level (between 0. 1 and 2. 47 m below ground surface after water transfer) from Daxihaizi reservoir to Yingsu is too high and may cause salinization. Conversely, the ground-water level at the downstream part from Alagan to Taitema lake is too low to prevent land from desertification and to improve vegetation restoration. Therefore going on translating water to raise the ground-water level is necessary.