Bathymetric and contemporary sediment quantity assessment for the Lukanga Swamps in central Province, Zambia

Abstract

Globally, wetlands are under threat and Lukanga Swamps (14,000 km²), a wetland of international significance and a Ramsar site, is one of them. This study aimed to assess the bathymetry and sediment quantity of the Lukanga Swamps, identify associated threats, and compare sedimentation with similar wetland case studies. A Hydrographic Survey Boat Sonar Model RC-S2 mounted with a Trimble Hemisphere OmniSTAR Virtual Base Station for Differential Geographic Positioning System was used to measure water depths across Lukanga Swamps (here referred to as the Swamp). Data on sediment depth was collected using a sediment coring method with the aid of a Graduated Sediment Depth Rod. Bathymetric and sediment data were analysed using the Inverse Distance Weighted interpolation method in ArcMap 10.4 Environment. The findings showed that at the time of survey, the water stored in the Swamp was about 2918 million cubic metres (MCM), and about 1200 MCM of the Swamp’s capacity was lost to sedimentation. The study concludes that the Swamp has lost the original storage capacity and Nature-based Solutions are recommended to preserve it. Although other studies have been done on the Lukanga Swamps, we are of the view that this study is a novel contribution to the understanding of the Lukanga Swamps’ storage capacity and sedimentation dynamics by producing, for the first time, a comprehensive bathymetric map and sediment distribution map for the Swamp, which provide firsthand scientific baseline data that allows for future monitoring of the Swamp’s sedimentation rates and storage capacity over time.