Abstract
Global measurements of reservoir water levels are crucial for understanding Earth’s hydrological dynamics, especially in the context of global industrialization and climate change. Although radar altimetry has been used to measure the water level of some reservoirs with high accuracy, it is not yet feasible unless the water body is sufficiently large or directly located at the satellite’s nadir. This study proposes a gauging method applicable to a wide range of reservoirs using Sentinel–1 Synthetic Aperture Radar data and a digital elevation model (DEM). The method is straightforward to implement and involves estimating the mean slope–corrected elevation of points along the reservoir shoreline. We test the model on six case studies and show that the estimated water levels are accurate to around 10% error on average of independently verified values. This study represents a substantial step toward the global gauging of lakes and reservoirs of all sizes and in any location where a DEM is available.
Highlights
The search for renewable energy has resulted in a global proliferation of hydroelectric dams
A Reported values are calculated as water surface slope averaged over the investigated period (2014–2018). b Water level range after the reservoir filling calculated from altimetry data (2014–2018). c Altimetry series dated within one week of the Sentinel–1 data collection were used for calculation. d Calculated as Root mean square errors (RMSE)/water level (WL) variations. e Year construction started
Extreme and unpredictable flooding, the relationship between physical habitat and water availability, and the global increase in demand for hydroelectric power are all magnified in a changing climate
Summary
The search for renewable energy has resulted in a global proliferation of hydroelectric dams. Approaches intersecting the lake surface extent with DEMs to extract elevation information have been published, they were focused either on a specific arid environment [35,36] or on a local scale based on airborne LiDAR or interferometric DEM processing [37,38,39] In this case, we propose a method that allows users to estimate WL dynamics at nearly global scales by using a relatively simple geographic information science (GIS) workflow (included as Figure S1) solely based on operational remote sensing data. We propose a method that allows users to estimate WL dynamics at nearly global scales by using a relatively simple geographic information science (GIS) workflow (included as Figure S1) solely based on operational remote sensing data This method should be an attractive option for environmental managers without expertise in remote sensing and will complement studies on flood mapping, nutrient and sediment storage, and human impacts on water supply. Our method is not spatially limited to below–nadir water bodies and can be used for Remote Sens. 2020, 12, 1353 lakes of almost any size and in any location as long as it is covered by a DEM (approximately 86% of the global surface in the case of the Shuttle Radar Topographic Mission (SRTM))
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