Simulation and Evaluation of Ecohydrological Effect of Water Transfers at Alagan in Lower Tarim River

Abstract

The riparian vegetation is highly dependent on the groundwater which is recharged by the river in arid regions. Water is the most important limiting factor for riparian vegetation in arid regions. From 1970s to 2000, the lower Tarim River almost dried up and the groundwater table fell down obviously. The riparian vegetation degraded seriously due to the low groundwater table. From 2000 to 2006, water transfers were implemented in the lower Tarim River to restore the ecological environment. Although the observation of groundwater and vegetation was carried out along lower Tarim River, the dynamics of the groundwater and vegetation along the cross section of the river were unknown. Ecohydrological evolution model on Riparian Vegetation in hyper-arid regions (ERV model) is a distributed ecohydrological model and has been validated at Yingsu in lower Tarim River. In this paper, the ERV model is applied to analyze the ecohydrological effect of water transfers at Alagan in lower Tarim River. At the same time, the ERV model is further validated. The simulation result is validated by observed groundwater table and vegetation coverage computed from remote sensing data. The result shows that the average groundwater table at Alagan increased by 4.74m from 2000 to 2006 and the average groundwater depth reached 6.36m. The average vegetation coverage increased from 0.130 to 0.194. In order to recover the green corridor, the further water transfers are required. The results are helpful for the ecohydrological research and water resources management in lower Tarim River.