Ecological water requirements are an important component of basin-scale water resources allocation

and meeting these requirements is a prerequisite for high-quality river basin development. Ecological water conveyance to the lower reaches of the mainstream Tarim River has continued for 25 years

making it necessary to determine whether current ecological water requirements are consistent with the planned downstream water-release target. Based on the current area of natural vegetation

groundwater depth

and river-channel morphology

this study applies the phreatic evaporation method

areabased quota method

and wetted-perimeter method to estimate the ecological water requirements of natural vegetation

the water requirement for groundwater recovery

the ecological baseflow requirement

and evaporation from the river water surface. The

estimated amounts are 1. 64 × 10

8

0. 65 × 10

8

0. 04 × 10

8

and 0. 08 × 10~8m

3

respectively. Under the objective of ensuring that water reaches Taitema Lake

the total ecological water requirement of the lower Tarim River is estimated at 2. 55 × 10~8m

3

which is 0. 95 × 10

8

m

3

lower than the planned downstream release target of 3. 50 × 10~8m

3

. Under long-term ecological water conveyance

groundwater conditions in the lower Tarim River have improved significantly and the area of natural vegetation has gradually increased. Under current conditions

ecological water demand is dominated by the water requirement of natural vegetation. The findings provide a scientific basis for optimizing ecological water conveyance schemes and improving ecological water-use efficiency.