Monitoring water depth, surface area and volume changes in Lake Victoria: integrating the bathymetry map and remote sensing data during 1993–2016

Abstract

In this study, a framework to monitor the volumetric fluctuation of the inland water body by the combination of a bathymetry map, an optical satellite imagery & multiple satellite altimetry measurements is presented. In spite of the recent studies in monitoring water level changes in lakes using satellite altimetry & optical satellite imagery, it’s still evident that these methods are limited to the water level, surface area and volume changes. However, to effectively study the lakes, it’s important to quantify the total lake volume. This hasn’t been possible as the existing satellite methods cannot estimate the bathymetry depth. The methodology was developed over Lake Victoria during 1993–2016. The results indicate that the water level, area, and volume of Lake Victoria decreased over the past 23 years. The water level shows a slight decrease (−0.005 m/year) of a total of −0.115 m from 1993 to 2016. The changes in water level translates to a reduction in lake area (−100 km2) and volume (−5 km3). Despite the inconsistent changes in area and volume, significant reduction occurred between 1998 and 2006 where (3484 km2) and (122.87 km3) reduction in area and volumes respectively were observed.