Understanding Volume Estimation Uncertainty of Lakes and Wetlands Using Satellites and Citizen Science

Abstract

Despite lakes and wetlands being critical indicators of climate change, there is limited knowledge of their volumetric change around the world. We studied the variations in the volume of water stored in small lakes and wetlands using satellite remote sensing and lake water height data contributed by citizen scientists. A total of 106 water bodies across the globe were studied using satellite data in the optical and microwave wavelengths from Landsat 8, Sentinel-1 and Sentinel-2. The uncertainty in volume estimation as a function of geography and geophysical factors such as cloud cover, precipitation and water surface temperature, was studied. The key finding that emerged from this global study is that uncertainty is highest in regions with a distinct precipitation season such as in the monsoon dominated South Asia or the Pacific Northwestern region of the US. This uncertainty is further compounded when small lakes and wetlands are seasonal with alternating land use as a water body and agricultural land, such as the wetlands of Northeastern Bangladesh. On an average, 45% of studied lakes could be estimated of their volume change with an uncertainty less than the expected volume in South Asia. In North America, uncertainty in volume estimation was to found to be around 50% in lakes eastward of the 108th meridian with lowest uncertainty found in lakes along the East coast of the US. The study provides a baseline for understanding the current state of the art in estimating volumetric change of lakes and wetlands using citizen science in anticipation of the planned Surface Water Ocean Topography (SWOT) Mission.