Abstract
Quantifying terminal-lake dynamics is crucial for understanding water-ecosystem-economy relationship across endorheic river basins in arid environments. In this study, the spatio-temporal variations in terminal lakes of the lower Heihe River Basin were investigated for the first time since the Ecological Water Diversion Project commenced in 2000. The lake area and corresponding water consumption were determined with 248 Landsat images. Vital recovery of lakes occurred two years after the implementation of the project, and the total lake area increased by 382.6%, from 30.7 to 148.2 km2, during 2002–2017. East Juyan Lake (EJL) was first restored as a project target and subsequently reached a maximum area of 70.1 km2. Water dispersion was initiated in 2003, with the East river prioritized for restoration. Swan Lake in the East river enlarged to 67.7 km2 by 2017, while the other four lakes temporarily existed or maintained an area < 7 km2, such as West Juyan Lake. Water consumed by lakes increased synchronously with lake area. The average water consumption of the six lakes was 1.03 × 108 m3/year, with 63% from EJL. The increasing terminal lakes; however, highlight the seasonal competition for water use between riparian vegetation and lake ecosystems in water-limited areas.
Highlights
Endorheic basins, which retain water and allow no outflow to other external water bodies, occupy approximately 21% of Earth’s land [1]
The results of this study indicated that the Ecological Water Diversion Project (EWDP) in the Heihe River Basin (HRB) has effectively reallocated the surface water resources, replenished the targeted East Juyan Lake (EJL), and facilitated the recovery of five other lakes in the area
With the recovery of un-targeted lakes in 2003, the total lake area of the lower HRB increased to 148.2 km2 by 2017, representing a 382.6% increase
Summary
Endorheic basins, which retain water and allow no outflow to other external water bodies, occupy approximately 21% of Earth’s land [1]. The ecosystems in the downstream areas of theses river basins are supported mainly by runoff generated from upper mountain regions because the precipitation in the downstream areas is very low [3]. The vast decline in both area and ecological condition of terminal lakes has led to efforts across the world to promote their protection or restoration [11]. River regulation by controlled water allocation has been carried out widely to restore the degraded lake ecosystems. To quantify the ecological restoration efforts, it is important to estimate the spatio-temporal dynamics of terminal lakes on the basin scale. A better understanding of water use of lakes is needed for better water allocation and conservation promotion in the water-deficient endorheic river basins [2,11]
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