基于生态水文耦合模型的塔里木河下游人工输水优化方案研究

Study on optimal scheme of water transfer in the lower Tarim river based on ecohydrological evolution model

2000年开始,塔里木河下游实施了多次人工生态输水,下游植被得到显著恢复。为维持并进一步扩大生态水文恢复效果,在流域调控能力持续增强的条件下人工生态输水仍是重要的措施,为此需要分析确定人工输水的优化方案。根据实际操作的可能,设计了周期和自动两种输水模式,周期输水模式的输水周期为1年,设定不同的输水开始时间和持续时间,共有36个方案。自动输水模式设定地下水位的上下临界值自动控制输水的起止时间,共有10个方案。应用干旱区河岸植被生态水文演化模型分析了不同输水方案下塔里木河下游英苏断面的地下水和植被演化,结果显示各种方案经过长期实施后地下水和植被都能演化趋于稳定状态,地下水位和植被覆盖度都有较大的提高。以地下水位最高和植被覆盖度最大为输水的优化目标,对于周期输水模式,优化方案是在适宜输水的8-10月进行输水。对于自动输水模式,稳定期地下水位和植被覆盖度随着控制输水起止的上下临界水位的提高而提高,同时年平均输水天数和地下水补给量增大。在自动输水模式的10个输水方案中,优化方案是上下临界水位分别为832.0m和830.0m的方案。

Sincethe year 2000, ecological water transfers have been implemented in the lower Tarim river and most of the degraded vegetation restored. To maintain and further expand the ecohydrological effect, water transfer is still an important method in the existing situation that the regulation ability of the watershed is improving continually, and optimal schemes for water transfer should be studied. According to the feasibility of practical operation, two water transfer patterns were designed, i.e. periodic water transfer and automatic water transfer. The periodic pattem with a one year cycle was examined through totally 36 scenarios with different start time and transfer duration. In the automatic transfer scenarios, the start and pause were controlled by specifying a upper and lower bound on groundwater table and totally 10 scenarios were examined. For all the scenarios, an ecohydrological evolution model of riparian vegetation in hyper-arid regions （ERV model） was applied to simulation of the evolutionary features of groundwater and riparian vegetation at Yingsu section in the lower Tarim. The results show that in all the scenarios the groundwater and vegetation would tend toward an equilibrium stage after long-term implementation of the transfers but the restoration in groundwater and riparian vegetation would be different. With an optimization objective of maximizing water table and vegetation coverage, the optimal transfer is a scenario of implementation in the optimal period, i.e. from August to October. For automatic transfer, the water table and vegetation coverage at the equilibrium stage will rise with the upper and lower bounds, and the average annual transfer duration and required groundwater recharge would increase simultaneously. Among the 10 scenarios of automatic transfer, the one whose upper and lower bounds are respectively 832.0m and 830.0m is optimal.