准确估计输水条件下河岸地下水埋深的动态变化,可以量化生态输水量与地下水埋深的响应关系,并由此估计自然河道所需输水量及持续时间,这对于干旱区水资源管理的可持续发展具有重要的科学意义。结合塔里木河下游20 a生态输水监测数据,用发展的包含地下水和土壤水的拟二维地下水模型,对输水条件下塔里木河下游上、中、下段3个断面（英苏、阿拉干和依干不及麻）的地下水埋深变化进行20 a长期模拟。通过率定期和后11 a（2010—2020年）的地下水埋深模拟结果与站点数据比较,发现两者较一致,证明该模型在塔里木河下游河岸断面地下水长期模拟上的合理性和适用性。然后根据3个断面20 a的模拟结果分析输水条件下地下水埋深和土壤水的长期变化及其对生态输水的响应。结果表明：经过20 a的生态输水,英苏、阿拉干和依干不及麻3个断面上的地下水位和土壤湿度都有明显的上升,地下水位埋深从输水前的8 m左右抬升到输水后的4 m左右,土壤湿度从最初的0.20上升到0.35以上,特别是自2009年以来,随年输水量增加,地下水位和土壤湿度增加幅度明显。生态输水与地下水的年际变化有一定的滞后性,由于土壤湿度和地下水位表现为正相关关系,这使得土壤湿度对输水量也有滞后性的特点。相比于河水流量,地下水水平传导率的取值对断面地下水埋深变化起着更重要的作用。另外,输水量与地下水的年际变化表明塔里木河下游河岸要想获得持续的生态效益,需要对河道提供间歇性的生态输水。

Accurate estimation of the groundwater table dynamic variation in a riparian zone under ecological water conveyance conditions is of great importance for the sustainable development of water resources management in arid areas. Based on the data of river discharges from ecological water conveyance and the groundwater tables of riparian monitoring wells from 2001 to 2020, this study simulated the dynamic variation of groundwater table at three sections of Yingsu, Alagan, and Yiganbujima in the lower reaches of the Tarim River, Xinjiang, China using a developed quasi-two-dimensional groundwater model, including the groundwater and soil water motion equations. In the calibration period, the observed groundwater table data was used to adjust the critical parameter (i.e., horizontal hydraulic conductivity) of the quasi-two-dimensional model, and the average simulation error of the monitoring wells at each of the three sections was approximately 0.2 m. In the validation period, the groundwater table data from 2011 to 2020 at the monitoring wells of the three sections were compared with the simulated results, and the average error at each of the three sections was approximately 0.5 m. Therefore, the simulated results of the groundwater table were acceptable under the lack of accurate river level data and the model was suitable for simulating the variation of the riparian groundwater table under ecological water conveyance in the lower reaches of the Tarim River. Thus, based on the simulation results from 2001 to 2020, the groundwater table and soil moisture variations were analyzed to demonstrate the response of riparian groundwater and soil moisture to the ecological water conveyance project. The results show that the groundwater table and soil moisture at the three sections evidently increased in 20 years of water conveyance periods. Specifically, the groundwater table increased from approximately 8 m before ecological water conveyance to nearly 4 m, and the corresponding soil moisture rose from 0.20 to 0.35 above. The increasing trend is more significant with the substantial increase of the annual water conveyance amount since 2009. Moreover, the variation of groundwater table presented a certain lag following the change in the water conveyance amount, and a positive correlation between soil moisture and groundwater table makes the soil moisture lags behind the water conveyance amount. Compared with the river discharge, the groundwater hydraulic conductivity plays a more important role in the variation of groundwater table at cross-section; thus, increasing the upswing amplitude of the groundwater table at Yiganbujima sections of the lower segment compared with that of the Alagan section of the middle segment in lower reaches of the Tarim River. Additionally, the inter-annual variations of groundwater and water conveyance amount also indicate that the intermittent ecological water conveyance is essential to achieve a sustainable ecological benefit in the lower reaches of the Tarim River.