Reconstruction of the depletion process of lake water resources in semi-arid areas under strong human activities—Taking Lake Daihai as an example

Abstract

湖泊水资源持续损失已经成为影响半干旱地区经济社会发展的主要问题之一.然而，由于缺少长期连续的湖泊动态监测数据，该地区湖泊水资源损失过程及其与气候变化和经济社会发展之间的关系没有得到详细的评估.针对此问题，本文以位于半干旱地区的岱海为研究对象，利用改进型归一化差异水体指数从1986—2020年258景Landsat遥感影像中提取湖泊水体边界，结合湖泊水位数据，重建了近60 a岱海水资源量动态变化过程.结果表明：1961—2019年期间，岱海急剧萎缩，湖泊水量共减少9.88×10⁸ m³.同时水量变化趋势分段函数拟合结果表明，岱海水量变化可分为3个阶段：1961—1978年，水量损失速率为0.726×10⁷ m³/a的缓慢损失阶段；1979—2004年，水量损失速率为2.10×10⁷ m³/a的快速损失阶段；2005—2019年，水量损失速率为3.39×10⁷ m³/a的加速损失阶段.相关分析表明：岱海水量损失与流域经济社会发展密切相关.其中，改革开放后流域农业开发利用规模和强度的提高是导致岱海水量损失的主要原因；“西部大开发”战略实施后工业经济的兴起则加速了岱海水量的损失.据此，本研究建议干旱半干旱地区湖泊流域经济社会的发展应与其水资源承载力相协调.;The continuous loss of lake water resources has become one of the main problems affecting the economic and social development in semi-arid areas. However, due to the lack of long-term continuous monitoring data of lake dynamics, the process of lake water resources loss and its relationship with climate change and economic and social development in this area have not been evaluated in detail. To solve this problem, this paper takes Lake Daihai, which is located in a semi-arid area, as the research object, using the improved normalized difference water body index to extract the boundary of lake water body from 258 Landsat remote sensing images from 1986 to 2020, and reconstructs the dynamic change process of water resources in Lake Daihai for last 60 years by integrating lake water level data. The results show that from 1961 to 2019, the Lake Daihai shrank sharply, and the lake water volume decreased by 9.88×10⁸ m³. At the same time, the fitting results of the piecewise function of the water volume change trend show that the water volume change of Lake Daihai can be divided into three stages:from 1961 to 1978, the slow loss stage with the water loss rate of 0.726×10⁷ m³/a; from 1979 to 2004, the rapid loss stage with the water loss rate of 2.10×10⁷ m³/a; from 2005 to 2019, the accelerated loss stage with the water loss rate of 3.39×10⁷ m³/a. Correlation analysis shows that the loss of water volume of Lake Daihai is closely related to the economic and social development of the river basin. Among them, the increase in the scale and intensity of agricultural development and utilization in the watershed after the reform and opening-up is the main reason for the loss of water volume of the Lake Daihai; the rise of the industrial economy after the implementation of the Western Development strategy accelerated the loss of water volume of the Lake Daihai. Accordingly, this study suggests that the economic and social development of lake basins in arid and semi-arid regions should be coordinated with their water resource carrying capacity.