Comparison of methods to derive the height-area relationship of shallow
lakes in West Africa using remote sensing
Abstract
In West Africa, lakes and reservoirs play a vital role as they are
critical resources for drinking water, livestock, irrigation and
fisheries. Given the scarcity of in situ data, satellite remote sensing
is an important tool for monitoring lake volume changes in this region.
Several methods have been developed to do this using water height and
area relationships, but few publications have compared their performance
over small and medium-sized lakes. In this work we compare four methods
based on recent data from the Pleiades, Sentinel-2 and -3, ICESat-2 and
GEDI missions over 16 lakes in the Central Sahel, ranging in area from
0.22 km² to 21 km². All methods show consistent results and are
generally in good agreement with in situ data (height RMSE and volume
NRMSE mostly below 0.30m and 11% respectively). The obtained
height-area relationships show very little noise (fit RMSD mostly below
0.10m), except for the Sentinel-3-based method which tends to produce
higher dispersion. The precision of the estimated water height is about
0.20m for Pleiades Digital Surface Models (DSMs) and less than 0.13m for
the other methods. In addition, fine shape patterns are consistently
observed over small height amplitudes, highlighting the ability to
monitor shallow lakes with non-linear bathymetric behavior. Inherent
limitations such as DSM quality, temporal coverage of DSM and lidar
data, and spatial coverage of radar altimetry data are identified.
Finally, we show that the combination of lidar and radar altimetry-based
methods has great potential for estimating water volume changes in this
region.