Surface Water Extraction and Dynamic Analysis of Baiyangdian Lake Based on the Google Earth Engine Platform Using Sentinel-1 for Reporting SDG 6.6.1 Indicators

Weiguo Jiang,Zijie Jiang,Xiaoya Wang,Chunlin Wang,Ziyan Ling,Kaifeng Peng

doi:10.3390/w13020138

Abstract

Surface water is an essential element that supports natural ecosystem health and human life, and its losses or gains are closely related to national or local sustainable development. Monitoring the spatial-temporal changes in surface water can directly support the reporting of progress towards the sustainable development goals (SDGs) outlined by the government, especially for measuring SDG 6.6.1 indicators. In our study, we focused on Baiyangdian Lake, an important lake in North China, and explored its spatiotemporal extent changes from 2014 to 2020. Using long-term Sentinel-1 SAR images and the OTSU algorithm, our study developed an automatic water extraction framework to monitor surface water changes in Baiyangdian Lake at a 10 m resolution from 2014 to 2020 on the Google Earth Engine cloud platform. The results showed that (1) the water extraction accuracy in our study was considered good, showing high consistency with the existing dataset. In addition, it was found that the classification accuracy in spring, summer, and fall was better than that in winter. (2) From 2014 to 2020, the surface water area of Baiyangdian Lake exhibited a slowly rising trend, with an average water area of 97.03 km2. In terms of seasonal variation, the seasonal water area changed significantly. The water areas in spring and winter were larger than those in summer and fall. (3) Spatially, most of the water was distributed in the eastern part of Baiyangdian Lake, which accounted for roughly 57% of the total water area. The permanent water area, temporary water area, and non-water area covered 49.69 km2, 97.77 km2, and 171.55 km2, respectively. Our study monitored changes in the spatial extent of the surface water of Baiyangdian Lake, provides useful information for the sustainable development of the Xiong’an New Area and directly reports the status of SDG 6.6.1 indicators over time.

Highlights

Water resources are one of the basic materials needed for the survival of natural ecosystems and human society
To explore the accuracy of the surface water extraction results based on the Sentinel-1 and OTSU automatic threshold algorithm, the water body extraction results in this study were compared with an existing Landsat-SMDPSO water dataset for Baiyangdian Lake
The results of the two water bodies have a higher consistency in the overall distribution of Baiyangdian Lake; C1 and C2 are a partial enlargement of the original image, and the location is near the junction of subregions D and E, including towns, roads, ponds, and farmland

Summary

Introduction

Water resources are one of the basic materials needed for the survival of natural ecosystems and human society. Water supports multiple ecosystem services and provides diverse ecological functions for human activities and biological reproduction and habitat. Due to climate change and other “global megatrends” such as population increase and urbanization, between 1970 and 2015, inland and marine/coastal wetlands both declined by approximately 35% where data are available, three times the rate of forest loss. Over the past 30 years, due to the impact of human activities and climate change, the global permanent water area has decreased by 90,000 km , which includes the artificially increased area of reservoirs [2]. The adverse impacts on ecology will significantly deteriorate ecosystem service functions.

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Conclusion