Natural Sciences

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https://nru.uncst.go.ug/handle/123456789/151

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Browsing Natural Sciences by Author "Abebe, Adane"

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    Analyses of community willingness-to-pay and the influencing factors towards restoration of River Malaba floodplains
    (Environmental Challenges, 2021) Mubialiwo, Ambrose; Abebe, Adane; Onyutha, Charles
    The high productivity of soils along River Malaba floodplains and various functions (like, transport and recreation) increase the desire for humankind settlement adjacent to floodplain corridors. However, human life and property have unceasingly been destroyed by floods. Strategies have been established to deal with floods but the problem still exists. This study employed the double-bound dichotomous choice contingent valuation method to quantify the community willingness-to-pay (WTP) and associated influencing factors for restoration of River Malaba floodplains. Reconnaissance surveys, focus group discussions, key informant interviews, observations study, and household questionnaires from 498 out of the targeted 550 respondents were employed in data collection. Among the adaptation strategies at household and community level, the post-flood strategies were more efficient than those practiced before- and during-floods. Among the suggested structural and non-structural strategies, “embankment/river training structures” and “flood forecasting and early warning” were highly preferred, respectively. The results revealed that 55% of the households expressed WTP an individual amount between Uganda shillings (UGX) 5,000 (United States Dollar, US$ 1.35) to UGX 500,000 (US$ 135.14), with a monthly average of UGX 97,080 (US$ 26.24). Total monthly amount would be UGX 38,249,500 (US$ 10,333.70) considering the 498 households. Among the factors analysed, age, gender, marital status, education level, occupation, household income, business affected, lost property due to floods, flooding a major problem had significant (p<0.01) positive impact on WTP. This study findings are pertinent in supporting stakeholders’ decision regarding predictive planning of flood adaptation strategies in the study area.
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    Historical Rainfall and Evapotranspiration Changes over Mpologoma Catchment in Uganda
    (Advances in Meteorology, 2020) Mubialiwo, Ambrose; Onyutha, Charles; Abebe, Adane
    Changes in the long-term (1948–2016) rainfall and evapotranspiration over Mpologoma catchment were analysed using gridded (0.25° × 0.25°) Princeton Global Forcing data. Trend and variability were assessed using a nonparametric approach based on the cumulative sum of the difference between exceedance and nonexceedance counts of data. Annual and March-May (MAM) rainfall displayed a positive trend (p < 0.05), whereas October-December (OND) and June-September rainfall exhibited negative trends with p > 0.05 and p < 0.05, respectively. Positive subtrends in rainfall occurred in the 1950s and from the mid-2000s till 2016; however, negative subtrends existed between 1960 till around 2005. Seasonal evapotranspiration exhibited a positive trend (p > 0.05). For the entire period (1948–2016), there was no negative subtrend in the OND and MAM evapotranspiration. Rainfall and evapotranspiration trends and oscillatory variation in subtrends over multidecadal time scales indicate the need for careful planning of predictive adaptation to the impacts of climate variability on environmental applications which depend on water balance in the Mpologoma catchment. It is recommended that future studies quantify possible contributions of human factors on the variability of rainfall and evapotranspiration. Furthermore, climate change impacts on rainfall and evapotranspiration across the study area should be investigated.
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    Hydrodynamic Modelling of Floods and Estimating Socio‑economic Impacts of Floods in Ugandan River Malaba Sub‑catchment
    (Earth Systems and Environment, 2022) Mubialiwo, Ambrose; Abebe, Adane; Serre Kawo, Nafyad; Ekolu, Job; Nadarajah, Saralees; Onyutha, Charles
    River Malaba sub-catchment tends to experience dramatic flooding events, with several socio-economic impacts to the nearby communities, such as loss of lives and destructions of physical infrastructure. Analysis of spatiotemporal extents to which settlements, crops and physical infrastructures tend to be inundated are vital for predictive planning of risk-based adaptation measures. This paper presents a case study on flood risk assessment for Ugandan River Malaba sub-catchment. We applied the two-dimensional Hydraulic Engineering Center’s River Analysis System (2D HEC-RAS) for modelling of flooding extents. We considered extreme flow quantiles, lower and upper quantiles corresponding to the 95% confidence interval limits aimed at determining uncertainties in the flooding extents. Spatial extents of inundation on human settlement, land cover and infrastructure were analysed with respect to return periods of extreme flow quantiles. Finally, we estimated economic loss on infrastructure due to flooding. Results from the 2D HEC-RAS model were satisfactorily comparable with the results of observations. Amongst the land use types, cropland exhibited the highest vulnerability with at least 10,234.8 hectare (ha) susceptible to flooding event of 100-year return period (YRP). Inundated built-up land-use exhibited the highest vulnerability percentage increase (90%) between 2- and 100-YRP. In US Dollar, about US$ 33 million and US$ 39 million losses are estimated at 2- and 100-YRP, respectively, due to inundated rice gardens and these indicate a looming high risk of household food insecurity and poverty. Several infrastructure including 15 academic institutions, 12 health facilities, 32 worshiping places remain annually vulnerable to flooding. At least 6 km and 7 km of road network are also susceptible to flooding under extreme flows of return periods 2 and 100 years, respectively. Churches exhibited the highest economic losses of US$ 855,065 and US$ 1,623,832 at 2-YRP and 100-YRP, respectively. This study findings are relevant for planning the development of sustainable flood risk adaptation pathways given the established destructions within the sub-catchment due to flooding.