BATHYMETRY OF SHALLOW EPHEMERAL DESERT LAKES DETERMINED BY SATELLITE IMAGERY AND ALTIMETRY

Drylands around the globe are characterized by interior drainage systems terminating at shallow ephemeral desert lakes or playas, which fill up on episodic floods. Their floor topography (or bathymetry) is the basis for water balance calculations, water resource management, and a key in understanding paleohydrology of drylands. However, being shallow, ephemeral, and remote, bathymetric surveys are scarce. Unfortunately, radar-based remote sensing, such as the Shuttle Radar Topography Mission (SRTM), is inaccurate in such lakes. This study shows a novel, remote‐sensing‐based method that derives bathymetry of shallow ephemeral desert lakes from freely available global datasets. We associate the frequency of water occurrence, at 30 m pixel resolution, based on optical satellite data for >30 years and accurate elevation measurements from the new Ice, Cloud, and Land Elevation Satellite‐2 (ICESat‐2). We demonstrate the success of our method at three different desert lakes: (a) Lake Eyre (Australia), representing a complex lake system with multiple subbasins, (b) Sabkhat El-Mellah (Algeria), a much smaller lake in the Sahara never mapped for bathymetry, and (c) Lago Coipasa (Bolivia), which we mapped both before and during its inundation. Using our method, the bathymetries of these lakes are mapped with an error smaller than the SRTM error by ~85%. Our method complements other remotely sensed, bathymetry‐mapping methods as it can be applied to remote lakes with no in-situ records, lakes consisting of subbasins, and flooded lakes. The proposed method can be easily implemented in other shallow lakes as it builds on publicly accessible global datasets.