Contribution of the Reconstruction of the Area of Seling Co Lake Using DEM Data and Analysis of Spatio-Temporal Variations

Abstract

Seling Co Lake, located on the Qinghai-Tibet Plateau, has been expanding rapidly since the 1980s and, in 2008, surpassed Namtso Lake to become the largest lake in Tibet. Additionally, this rapid expansion has significantly impacted the ecological environment, and human activities surround the lake. Thus, it is of great importance to reveal the expansion pattern of Seling Co Lake for a long time-series. Previous studies always contained errors when exploring this subject due to the limitations associated with the quality of remote sensing images. To overcome the existing deficiency, a method based on the SRTM1 DEM and a water frequency Landsat-series dataset is developed to reconstruct the complete inundation area of Seling Co Lake from 1987 to 2021 while taking full advantage of the relationship between the water frequency and terrain. The results show that the water frequency reconstruction model proposed in this study has a significant optimization effect on the restoration of the permanent and seasonal water areas of Seling Co Lake. In particular, the proposed method can effectively improve the underestimated water-frequency pixel values of the seasonal waters located on the southern and northern shores of Seling Co Lake. The water-inundation area of Seling Co Lake showed an overall increasing trend with a rate of 26.02 km2∙year−1 (p < 0.01), and this expansion trend was mainly concentrated in the southern and northern parts of the lake. This study cannot only provide an efficient and feasible remote sensing means of reconstructing the water-inundation area for lakes in complex terrain according to topographic conditions but also greatly refines our understanding of the annual variations in the water-inundation area of Lake Seling Co.