Relationship between Water Surface Area of Qingtu Lake and Ecological Water Delivery: A Case Study in Northwest China

Abstract

Qingtu Lake is located between Tengger Desert and Badain Jilin Desert, Gansu Province, Northwest China. It is the terminal lake of Shiyang River. In recent years, Qingtu lake has maintained a certain area of water surface and vegetation by artificial water conveyance. It is of great significance in preventing the convergence of the two deserts and restraining the trend of ecological deterioration of Shiyang River Basin. The relationship between the water surface area and the ecological water conveyance have not been thoroughly investigated. This study analyzed the spatial and temporal distribution of water surface area of Qingtu Lake and surrounding reeds by interpreting remote sensing data; the change of water surface area under the influence of meteorological factors and water conveyance by linear regression; the water conveyance to maintain current water surface area by water balance method, as well as the reasonable ecological water delivery in high flow year, normal flow year and low flow year by the means of analyzing the upstream inflow and water consumption in Minqin Basin. The results showed that there is a significant correlation between the water surface area of Qingtu Lake, evaporation and ecological water conveyance, and the minimum and maximum water surface areas generally appear before and after water delivery, indicating that the ecological water delivery and evaporation are the two main factors affecting the water surface area change of Qingtu Lake. The result calculated by linear regression indicated that the ecological water delivery volume to maintain current water surface area of Qingtu Lake is 3.146 × 107 m3/yr, while the value was 3.136 × 107 m3/yr calculated by water balance method. These two results are similar and can be verified with each other. Reasonable ecological water conveyance of Qingtu Lake in high flow year, normal flow year and low flow years were 4 × 107 m3/yr, 3.2 × 107 m3/yr and 2.3 × 107 m3/yr, respectively.

The potential risk of soil salinization on vegetation restoration by ecological water conveyance project in Qingtu Lake Wetland, northwestern China

“…If the water including both surface water and groundwater in QLW becomes saltier, the risk of soil salinization will naturally increase; 2) as a terminal wetland in the inland river basin, there is no natural salt removal mechanism in QLW (Jolly et al, 2008). As a result, the soil in QLW is always at risk of salinization; 3) the vast majority of ecological water in QLW was stored in groundwater and lake and then lost through evaporation (Guo et al, 2021; Huang et al, 2021). Low GWD by EWCP and high evaporation by dry climate provide the prerequisites for secondary soil salinization in QLW.…”

“…The restorations of seasonal water surface and vegetation in QLW have received extensive attention since the implementation of EWCP in 2010. Guo et al (2021) suggested the ecological water volume needed to maintain the water surface area by investigating the relationship between water surface area and conveyed ecological water volume. Chunyu et al (2019) distinguished the dominant plant species using satellite remote sensing images and analyzed the relationship between plant species and groundwater depth based on a field survey at the edge of QLW.…”

A new model for simulating root water uptake by vegetation under the impact of a dynamic groundwater table in arid regions

“…Qingtu Lake, which is the largest lake in the Shiyang River Basin, covering an area of 400 km 2 during the Ming and Qing Dynasties, dried in 1959 (Hu et al, 2021) due to the unreasonable exploitation of water resources and construction of the Hongyashan Reservoir (Guo et al, 2021). The drying of Qingtu Lake resulted in severe eco-environmental problems such as a decline in groundwater depth, vegetation degradation, and soil salinization (Zhang et al, 2019).…”

Environmental flow mechanism and management for river–lake‐marsh systems

“…For lakes, the e‐flow calculation methods are established from the hydrological or ecological perspectives (Gleick, 1998; Liu & Yang, 2002). Based on the hydrological perspectives, Guo et al (2021) combined water balance method and linear regression method and calculate the e‐flow delivery volume to maintain current water surface area of Qingtu Lake. In the absence of specific river‐bio data, Yasi and Ashori (2017) used multiple hydrological methods to calculate the e‐flows of rivers around the Urmia Lake, and took the results as the e‐flow requirement of the lake.…”