Browsing by Author "Mwololo Waema, Tim"

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    Effects of heterogeneous land use/cover types on river channel morphology in the Solo River catchment, Eastern Uganda
    (Geocarto International, 2015) Barasa, Bernard; Kakembo, Vincent; Mwololo Waema, Tim; Laban, Macopiyo
    In the tropics, unmonitored land use/cover types cause significant effects on the narrowing and widening of river channels which affects the integrity of water resources. River channel planform extent was characterised using Landsat images while water and bedload samples were collected and analysed for a period of one year. The results revealed that in 1986 the channel planform covered 3.7sq.km in length than in 2013 where it increased to 4.2sq.km. Wetland (537.1mgl-1) and bushland (186.3mgl-1) cover types had the highest concentration of suspended sediments. Fine-sand (0.25mm), silty-sand (1mm) and silty-clay (0.125mm) bedload particle types dominated the riverbed along the channel from the sampled land use/cover types. The high concentration of sediments, bedload materials, bank-instability, and stream-flow were significant contributors to the narrowing and widening of the channel (P<0.05). Agricultural landuse was the major contributor of channel aggradation (0.8m) and degradation (0.25m) compared to treeplantations, bushlands, forest and wetland cover types.
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    Streamflow responses to changes in land use and climate in a tropical catchment: Malaba River Catchment, Eastern Uganda
    (Geosciences, 2018) Barasa, Bernard; Kakembo, Vincent; Mwololo Waema, Tim; Macopiyo, Laban
    The hydrological cycle over most tropical catchments is mainly influenced by changes in land use and climate. This study explored the trend of precipitation and streamflow to evaluate the sensitivity of the catchment to land use and climate. A Mann-Kendall test and the concept of streamflow elasticity were adopted to determine the trend of precipitation and sensitivity of the catchment to climate. Changes in land use on the streamflow were evaluated using a spatially distributed SHETRAN hydrological model. The model calibration period was 1995-1998, while 2009-2012 was the validation period. The highest change in the gain of land were mainly experienced from the agricultural land use (crop growing) (36.7%) and tropical forest-regeneration (2.2%); while the highest loss in land were experienced from the wetlands (24.6%) and bushlands and thickets (15.3%) land cover types. The calibration period had a Nash-Sutcliffe Efficiency (NSE) of 0.78 whilst 0.81 during validation. The high frequency of flood re-occurences and growth in agricultural land use were the major contributors of streamflow in the catchment.