Characteristics of water consumption and the evolution of water delivery methods in the lower reach of the Tarim River

ZHOU Long;YANG Pengnian;WANG Yongpeng;Alishir Kurban;WANG Guangyan;College of Water Conservancy and Civil Engineering, Xinjiang Agricultural University;Xinjiang Key Laboratory of Water Conservancy Engineering Safety and Water Disaster Prevention;Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences;Xinjiang Tarim River Basin Mainstream Management Bureau;

ditch river water delivery;;vegetation water consumption;;ecological gate regulation;;the lower reaches of the Tarim River

The water consumption rate of the lower reaches of the Tarim River and the water permeability of the riverbed after water transfer were analyzed in this study, and the Modified Normalized Difference Moisture Index(MNDWI) change characteristics under the near-natural overflow behind the ecological gate were revealed. The results were as follows.(1) Continuous water delivery reduced the water consumption rate per unit river length and reduced the replenishment of soil water and groundwater.(2) Randomized water delivery behind the ecological gate represented by Kumtuge lacked orderly regulation and formed a constant river flow section; this led to excessively high groundwater levels in some areas and increased the ineffectiveness of evaporation.(3)Ditch overflow under near-natural conditions represented by Bozkule played an important role in the groundwater level and vegetation restoration in the area, but the solidification of ditches and formation of low-lying water areas tended to facilitate evolution of vegetation in dry areas into a single type of water-loving vegetation; this increased ineffective evaporation and luxury transpiration.(4) The ecological gate lacking regulation as well as the control and near-natural water delivery produced excessive surface water and wetland vegetation, which is in conflict with river ethics for the arid Tarim River Basin. Adjusting and regulating water delivery with manual intervention, i.e., using a combination of infiltration and flooding via a river wheel, should be considered the main method of water delivery in the future. This will not only improve the utilization efficiency of the discharged water and further expand the ecological restoration area but also facilitate the regulation and control of water dissipation in different restoration target areas, which would maximize the vegetation in these restoration areas.