Abstract: The Yarkand River is one of the main tributaries of the Tarim River. Understanding the water balance in its lower reach and the water consumption by riparian forests and grasses is greatly significant to the allocation of water resources in the basin. This paper develops a water balance model to describe water loss and water transformation and their variations based on the relationship between groundwater and vegetation. A phreatic water evaporation model and a groundwater transport model are coupled to construct a water consumption model of riparian forest and grass that is applied in a case study of the lower Yarkand River in 2000-2020. The results show that in this reach, most of the river water loss comes from leakage, which is more than 95% of the total water loss; multiyear average water consumption by forest and grass is 128 mm, with the left bank of 226 mm that is greater than 93 mm on the right bank. This model gives satisfactory calculations of the water balance components and the water consumption by forest and grass for the study river reach, and thus it would be applicable to other northwest inland rivers where riparian froest and grassland depend on river leakage recharge.

Key words: Yarkand River, water balance, water consumption of forest and grass, model simulation