Effect of land use activities on water quality, soil and vegetation cover for conservation of river wambabya catchment, hoima district

Abstract

Increasing land use activities are greatly decreasing environmental quality of River catchments thus, making them susceptible to pollution and depletion. The land use activities such as human settlements, massive deforestation, oil infrastructural developments, conversion of wetlands into subsistence farmland, and agroforestry were increasing within River Wambabya catchment. However, there was no empirical evidence of the present status of the water quality, soil and vegetation cover in the river catchment hence necessitating a research study. The overall objective of the research study was to evaluate the effect of land use activities on the water quality, soil and vegetation cover for conservation of River Wambabya catchment, Hoima District. The specific objectives of the study were; to determine the effect of land use activities on the water quality (pH, EC, COD, BOD, Total phosphates, nitrates, Pb, Escherichia coli, and total coliforms) of River Wambabya catchment; to assess the effect of land use activities on the soil (pH, EC, Heavy metals-Pb, Fe, Mn, Zn, Ni, Cd) of River Wambabya catchment; and to determine the effect of land use activities on the vegetation cover of River Wambabya catchment over a period of 20 years (1998-2018). The study used a simple random sampling technique during collection of water and soil samples. Water quality and soil parameters were analyzed using American Public Health Association (APHA) standard analytical procedures. Heavy metals in water were analyzed using an Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) while soil heavy metals were analyzed using Mehlich- 3 extraction method buffered to pH 2.5. Vegetation cover change of 20 years (1998-2018) was analyzed using Landsat 8 images and ArcMap 10.8 version. Results showed that land use activities had significant effect on water quality BOD (p value of 0.021) at p<0.05. Subsistence farmland (7mg/l), and wetland (6mg/l) activities were the major contributors of high BOD levels. Land use activities also had a significant effect on the concentration levels of soil Zn (p value of 0.048), Ni (p value of 0.020), and Pb (p value of 0.037) at p< 0.05. Subsistence farmland, and agroforestry were the major sources of high Zn, Ni and Pb concentrations. lastly, land use activities had a significant effect on the vegetation cover of river Wambabya catchment. There was a drastic increase in built-up areas (5.38%), and subsistence farmland (1.04%) with a reduction in vegetation cover under Bushland (1.97%), forests (2.58%), grasslands (7.56%), open water (1.23%), wetlands (1.42%) and woodland (1.39%) over the 20-year period. Subsequently, natural resources conservation efforts are required in river Wambabya catchment area so as to improve its sustainability and co-existence with human livelihoods. Particularly, more conservation efforts are needed to halt the deteriorating water quality and reducing vegetation coverage of the catchment. Further in-depth studies can be conducted on the temporal variations of vegetation cover and bioaccumulation of heavy metals in the soils of the RWC due to the increasing mining and oil and gas development.