Application of SWAT to Assess the Effects of Land Use Change in the Murchison Bay Catchment in Uganda

Abstract

The Soil and Water Assessment Tool (SWAT) is a versatile model presently used worldwide to evaluate water quality and hydrological concerns under varying land use and environmental conditions. In this study, SWAT was used to simulate streamflow and to estimate sediment yield and nutrients loss from the Murchison Bay catchment as a result of land use changes. The SWAT model was calibrated and validated for streamflow for extended periods. The Sequential Uncertainty Fitting (SUFI-2) global sensitivity method within SWAT Calibration and Uncertainty Procedures (SWAT-CUP) was used to identify the most sensitive streamflow parameters. The model satisfactorily simulated stream discharge from the catchment. The model performance was determined with different statistical methods. The results showed a satisfactory model streamflow simulation performance. The results of runoff and average upland sediment yield estimated from the catchment showed that, both have increased over the period of study. The increasing rate of runoff can lead to severe and frequent flooding, lower water quality and reduce crop yield in the catchment. Therefore, comprehensive water management steps should be taken to reduce surface runoff in the catchment. This is the first time the SWAT model has been used in the Murchison Bay catchment. The results showed that, if all uncertainties are minimised, a well calibrated SWAT model can generate reasonable hydrologic simulation results in relation to land use, which is useful to water and environmental resources managers and policy and decision makers.

The impact of future climate and land use/cover change on water resources in the Ndembera watershed and their mitigation and adaptation strategies

“…The sensitivity analysis from other watersheds in the East African region had, among the top six sensitive parameters, few parameters similar to the one found in the Ndembera watershed. For example, in Murchison Bay Catchment, Uganda, the CN_2, GW_DELAY and GW_REVAP were among the top six sensitive parameters to river discharge (Anaba et al 2017). The CN_2 and SOL_AWC were also among the most sensitive parameters reported in the Simiyu river Catchment in Tanzania (Mulungu and Munishi 2007).…”

Assessing Land Use and Land Cover Changes in the Murchison Bay Catchment of Lake Victoria Basin in Uganda

“…Urbanisation has caused a significant negative impact on the environment in the catchment as it has created permanent impervious layers which reduces infiltration and percolation of water to the underground increasing surface runoff and causing perennial flooding within the catchment. Wastewater and other pollutants discharged from industrial setup have also increased the quantity of sediments and nutrients transported into the Lake Victoria from the catchment studied (Anaba et al, 2017). Encroachment on wetlands that have for long acted as filters and traps pollution discharges from the catchment (JTR, 2015; Kansiime & Nalubega, 1999) area have lost its function as a buffer zone.…”

Sensitivity test of the Hydrological Model of Large Basins (MGB-IPH) in scenarios of extreme changes in soil use and occupation, precipitation regime and mean air temperature.

“…As a consequence, the runoff is intensified towards drainage lines. Anaba et al (2017) used the SWAT model in various land use scenarios and found that The model satisfactorily simulated stream discharge from the catchment. The model performance was determined with different statistical methods.…”