Assessment of Spatial-Temporal Lake Victoria Shoreline Variations Using Synthetic Aperture Radar

Abstract

Shorelines are one of the most important linear features on the earth’s surface, with a dynamic nature. They change shape and position over multiple spatial and temporal scales with water levels serving as a key indicator to characterize the expansion or shrinkage of lakes. There has been an uncontrolled increase in the water levels in Lake Victoria and this has ultimately contributed to the lake shoreline variation. This has in turn led to the occurrence of unpredictable flooding along the lake shores and bursting of the lake shoreline claiming people’s property. Therefore, Environment Management authorities such as NEMA require accurate and up-to-date information about the shoreline changes. The main objective of this study was to assess the spatial-temporal variations of the Lake Victoria shoreline in the Southern Buganda Sub-region for the period of 2015 to 2021 using microwave remote sensing. The study also assessed the performance of HH and VH polarizations in shoreline delineation. Different image processing techniques such as thresholding and band math were used in both SNAP and ArcGIS software. Based on the DSAS evaluation statistics, VH polarization performed a better delineation of the shoreline than HH polarization. The study also found that the Lake shoreline in Southern Buganda Sub-region generally underwent low erosion rates ranging from 0.5m/yr to 2m/yr, entirely observed in the sub counties of Buwunga, Kyanamukaaka, and Kabira. High erosion rates of above 5m/yr were observed in some areas in Bukakata and Kyebe Sub-County. This study recommends the utilization of VH polarization. Further studies can integrate predictive analytics to attain future shoreline positions.