| dc.description.abstract | Wetlands are essential for the natural functioning of an ecosystem, by regulating floods and outstandingly being a source of water supply. However, land use changes are the main forces behind wetland deterioration worldwide. The status of wetlands coverage in Uganda is at 8.9% intact, 4.1% degraded and 2.6% completely lost.
One of the constraints for effective wetland management is lack of awareness among the land users about the existing land degradation already taking place in the different wetlands and their relationship with the declining ecosystem services provided by these wetlands.
This study focused on three specific objectives: (i) Assessing the land use changes that have occurred in Tochi wetland over the past twenty years that is, 2000-2020, (ii) Evaluating the effects of the land use changes on the water extent of Tochi wetland and (iii) Assessing the effects of the land use changes on vegetation productivity of Tochi wetland.
Land use land cover changes in Tochi catchment area, from 2000 to 2020 were analyzed using three satellite images; Landsat 8 OLI/TIRS combined, Landsat 5 Thematic Mapper, and Landsat 7 Enhanced Thematic Mapper acquired in the years 2020, 2010 and 2000 respectively. NDWI and NDVI were calculated using the respective bands of the downloaded satellite images using raster calculator in Arc GIS toolbox based on the formulae; (NIR- SWIR)/NIR+SWIR and (NIR-RED)/(NIR+RED), respectively.
The classified images for 2000, 2010 and 2020 had an overall accuracy of 90%, 88% and 88% while the kappa coefficients were 88.4%, 85.96% and 86%, respectively.
The image classification revealed eight major land use land cover types in Tochi catchment and these included; open water, dense forest, permanent swamp, seasonal swamp, built up areas, sparse forest, agricultural fields and grasslands. Land use land cover change detection also showed a significant change in the areal coverage of each of the land use land cover types; with a general increase in seasonal swamp (13.2%), agricultural land (5.5%) and built up areas (5.5%) and a decrease in forests (6.7%), grasslands (9.5%), open water(1.3%) and the permanent swamp (6.7%) for the 2000-2020 period. There was a general reduction in NDWI (58.1%) within Tochi catchment between 2000-2020, which means the catchment is becoming progressively drier. There was also a general reduction in NDVI (11.8%) within the catchment between 2000-2020, which means that vegetation biomass within the catchment is declining. There is, therefore, degradation in Tochi catchment as indicated by the declining moisture content and vegetation biomass for the 2000-2020 period. Stricter implementation of the existing laws on encroachment into the catchment and afforestation is recommended to curb the existing degradation within the catchment. | en_US |
