Determining Bathymetry of Shallow Ephemeral Desert Lakes Using Satellite Imagery and Altimetry

Abstract:

Drylands around the globe are characterized by interior drainage systems terminating at shallow desert lakes or playas. These remain mostly dry but fill up on episodic floods. Their floor topography is the basis for water volume estimates, water balance calculations, water resource management, and a key in understanding paleohydrology/climatology of such regions. However, being shallow, ephemeral, and remote, bathymetric surveys are scarce and radar-based remote sensing is practically inappropriate in such lakes. This study shows a new, remote‐sensing‐based method that derives bathymetry of shallow and ephemeral desert lakes from freely available and global datasets. We associate between frequencies 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. The bathymetries of these lakes are now mapped with ~0.3 m error, whereas the Shuttle Radar Topography Mission (SRTM) yields an error of ~2.5 m. 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 data sets.