Abstract
Hongjiannao groundwater exchange was the largest desert freshwater lake in China (57.25 km2 in 1986). However, it shrank sharply over the past 34a (1986-2019), with the smallest lake area 31.41 km2 in 2015. The objective of this study was to use the Landsat images, ASTER GDEM V2 data, and meteorology and statistics data, in combination with the water balance model to calculate the dynamics of water balance elements, quantify and characterize the interannual variations in lake-groundwater exchanges, and analyze its influencing factors by using the geographical detector. The results showed that in the stable stage (1986-1997), the average rate of the lake area, water level, and lake volume change was -0.26 km2/a, -0.0483m/a, and -0.0009 km3/a, respectively. Precipitation, river inflow, and groundwater were 0.0203 km3, 0.0485 km3, and 0.0098 km3, which accounts for the whole input were 25.83%, 61.70%, and 12.47%, respectively; evaporation was 0.0786 km3. In the reduction stage (1998-2015), the average rate of the lake area, water level, and lake volume change was -1.21 km2/a, -0.2422m/a, and -0.0101 km3/a, respectively. Before 2006, precipitation, river inflow, and groundwater were 0.0154 km3, 0.0475 km3, and -0.0025 km3, respectively; from 2006 to 2009, precipitation, river inflow, and groundwater were 0.0143 km3, 0.0334 km3, and 0.0058 km3, respectively; after 2009, precipitation, river inflow, and groundwater were 0.0139 km3, 0.0199 km3, and 0.0085 km3, respectively. Evaporation decreased from 0.0714 to 0.0480 km3 from 1998 to 2015. In the growth stage (2016-2019), the average rate of the lake area, water level, and lake volume change were 1.38 km2/a, 0.27m/a, and 0.0088 km3/a, respectively. Precipitation, river inflow, and groundwater were 0.0209 km3, 0.0005 km3, and 0.0373 km3, which accounts for the whole input were 46.63%, 52.12%, and 1.25%, respectively; evaporation was 0.0187 km3. Compared with the stable stage, groundwater in the growth stage reduced from 12.47% (0.0098 km3) to only 1.25% (0.0005 km3). From 1998 to 2004, Hongjiannao Lake experienced continuous losing conditions (discharge from the lake to groundwater), with a variable exchange volume of up to -0.01582 km3 in 1999. Through geographical detector analysis, it was found that temperature was the dominant factor from 1988 to 1997, while human factors were the dominant factors from 1998 to 2015.
Highlights
Inland lakes are an important part of water resources in arid or semi-arid regions, which has an important impact on the balance of the local ecosystem and human production and life (Sheng et al, 2016; Gal et al, 2016; Zhang et al, 2017; Yang et al, 2020)
The objectives of this study were as follows: (1) based on the hydrogeological model of Hongjiannao Lake, we calculated the dynamics of water balance elements, including precipitation, evaporation, lake volume change, river inflow, and runoff change; (2) to quantify and characterize the interannual variations in lake-groundwater exchanges based on water balance model ; (3) to comprehensively explore the dominant factors affecting the lake area, water level, and water volume change of Hongjiannao Lake in terms of NDVI (Normalized Difference Vegetation Index), sheep population (SP), human population (HP), the industrial output value (GVIO), annual average temperature (AT) and precipitation (AP)
After the groundwater is replenished by the atmospheric precipitation, it moves from the watershed to the lake along the terrain, and discharges into the Hongjiannao Lake, the infiltration of atmospheric precipitation forms phreatic water and shallow confined water, and supplies surface water (Yin et al, 2008)
Summary
Inland lakes are an important part of water resources in arid or semi-arid regions, which has an important impact on the balance of the local ecosystem and human production and life (Sheng et al, 2016; Gal et al, 2016; Zhang et al, 2017; Yang et al, 2020). Due to the impact of climate change and human activities, the area of some lakes in northern China has shrunk or disappeared (Ma et al, 2011; Liu et al, 2013; Yang and Lu, 2015; Liu and Yue, 2017). Hongjiannao Lake is located at the junction of Shaanxi and Inner Mongolia in the arid and semi-arid regions of Northwest China. It is currently the largest desert freshwater lake in China, which plays an indispensable role in regulating the local climate, maintaining the balance of water resources, and biodiversity.
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