2 MATERIALS AND METHODS

2.1 Study area

The EIB is located in the core part of Eurasia (Figure 1), spanning an area of 1.15 × 107 km2; it includes 16 closed inland basins and 23 sub-basins, which are shown in Figure 1 and Table 1. Notably, the AET simulation based on the hydrologic budget method is targeted at closed inland basins. Glaciers are distributed throughout the mountainous areas of the central and eastern basins, being mainly located in the Qinghai-Tibetan Plateau. Due to the inland location of the EIB, its climate is characterized by low precipitation and high evaporation, and the mean annual precipitation and AET are 353.4 and 358.8 mm, respectively. The mean annual precipitation, AET, and coefficient of variation for the monthly precipitation series in each basin are shown in Table 1. There are nine closed basins in the EIB with a mean annual precipitation <200 mm; these basins are predominantly located in the eastern and southern regions. The highest mean annual precipitation occurs in the CSB, exceeding 500 mm, while lowest occurs in the TB, being <100 mm. The coefficient of variation for monthly precipitation in the EIB is 0.20; it is highest in the QPB (1.34) and lowest in the CSB (0.21).