Abstract
The spatio-temporal change of the surface water is very important to agricultural, economic, and social development in the Hetao Plain, as well as the structure and function of the ecosystem. To understand the long-term changes of the surface water area in the Hetao Plain, we used all available Landsat images (7534 scenes) and adopted the modified Normalized Difference Water Index (mNDWI), Enhanced Vegetation Index (EVI), and Normalized Difference Vegetation Index (NDVI) to map the open-surface water from 1989 to 2019 in the Google Earth Engine (GEE) cloud platform. We further analyzed precipitation, temperature, and irrigated area, revealing the impact of climate change and human activities on long-term surface water changes. The results show the following. (1) In the last 31 years, the maximum, seasonal, and annual average water body area values in the Hetao Plain have exhibited a downward trend. Meanwhile, the number of maximum, seasonal, and permanent water bodies displayed a significant upward trend. (2) The variation of the surface water area in the Hetao Plain is mainly affected by the maximum water body area, while the variation of the water body number is mainly affected by the number of minimum water bodies. (3) Precipitation has statistically significant positive effects on the water body area and water body number, which has statistically significant negative effects with temperature and irrigation. The findings of this study can be used to help the policy-makers and farmers understand changing water resources and its driving mechanism and provide a reference for water resources management, agricultural irrigation, and ecological protection.
Highlights
As an important part of the land–water cycle, surface water resources play an important role in promoting national economic development and maintaining the balance of terrestrial and aquatic ecosystems, agriculture, and the ecological environment [1]
The surface cover was divided into water bodiesbodies and non-water bodies, 1500 random points of water bodies and non-water bodies were generated in the Hetao Plain, and a total of 3000 verification points were uniformly distributed in the study area [62,63] (Figure 3)
water frequency (WF) is the frequency of the water body, NWater represents the number of times that all were identified as water bodies during the year, and NGood represents the number of high-quality images during were identified images the year. as water bodies during the year, and N G ood represents the number of highquality images during the year
Summary
As an important part of the land–water cycle, surface water resources play an important role in promoting national economic development and maintaining the balance of terrestrial and aquatic ecosystems, agriculture, and the ecological environment [1]. In the past hundred years, due to the intensification of human activities and global climate change, surface water resources have generally experienced problems such as a sharp decline in the water volume, deterioration of the water quality, and area shrinkage, which have changed the form of the surface water hydrological cycle and hydrological dynamics [2,3] These problems have caused huge losses to the life and agricultural production of the residents in the Hetao Plain and greatly affected the development of the local economy. Previous studies have frequently selected a single remote sensing image in a year or in different years at the same time to represent the surface water area and interannual variation [8,9,31,32]. Changing trend of surface water and the major driven factors was discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
