Browsing by Author "Kitaka, Nzula"

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  • Publication
    Publication
    Assessing Future Water Demand and Associated Energy Input with Plausible Scenarios for Water Service Providers (WSPs) in Sub-Saharan Africa
    (Multidisciplinary Digital Publishing Institute, 2021-04-13) Macharia, Pauline; Kitaka, Nzula; Yillia, Paul; Kreuzinger, Norbert
    This study examined the current state of water demand and associated energy input for water supply against a projected increase in water demand in sub-Saharan Africa. Three plausible scenarios, namely, Current State Extends (CSE), Current State Improves (CSI) and Current State Deteriorates (CSD) were developed and applied using nine quantifiable indicators for water demand projections and the associated impact on energy input for water supply for five Water Service Providers (WSPs) in Kenya to demonstrate the feasibility of the approach based on real data in sub-Saharan Africa. Currently, the daily per capita water-use in the service area of four of the five WSPs was below minimum daily requirement of 50 L/p/d. Further, non-revenue water losses were up to three times higher than the regulated benchmark (range 26–63%). Calculations showed a leakage reduction potential of up to 70% and energy savings of up to 12 MWh/a. The projected water demand is expected to increase by at least twelve times the current demand to achieve universal coverage and an average daily per capita consumption of 120 L/p/d for the urban population by 2030. Consequently, the energy input could increase almost twelve-folds with the CSI scenario or up to fifty-folds with the CSE scenario for WSPs where desalination or additional groundwater abstraction is proposed. The approach used can be applied for other WSPs which are experiencing a similar evolution of their water supply and demand drivers in sub-Saharan Africa. WSPs in the sub-region should explore aggressive strategies to jointly address persistent water losses and associated energy input. This would reduce the current water supply-demand gap and minimize the energy input that will be associated with exploring additional water sources that are typically energy intensive.
  • Publication
    Publication
    Potential Risks of Agricultural Intensification in Tropical Catchments: the Case of Lake Naivash
    (Reseach Square, 2022-02-28) Onyango, Joel; Kitaka, Nzula; Bruggen, J.A. Van; Irvine, Kenneth; Simaika, John
    The use of both fertilizers and pesticides in the Lake Naivasha Catchment, is associated with agricultural intensification and has resulted in enrichment of aquatic ecosystems with nutrients, coupled with exposure of aquatic biota to pesticide residues affecting aquatic ecosystem structure and function. This study explored the changes in land use and related it with the concentrations of nutrients and selected pesticides, to show the potential of combined (nutrients and pesticides) risks associated with agricultural intensification in Lake Naivasha catchment, a tropical catchment in Kenya. The results indicate that between 1989 and 2019 there was an increase of cropland by 623 km 2 , a reduction of forest cover by 200 km 2 , increase of grasslands by 534 km 2 , a reduction in bare soils by 100 km 2 , and an increase of 540 km 2 of built area. The land cover changes were correlated with increased concentrations of nutrients and pesticides in surface waters across sampling sites monitored in 2015. The results further indicated that while the concentrations of nitrogen and phosphorus indicated a potential stoichiometric nitrogen limitation, increase in forest cover resulted in decreased nutrient concentrations in the river water. Concentrations of DDT and technical HCH active ingredients indicated significant relationships between land use changes and intensification. Areas with extensive farming systems were associated with higher concentrations of TP and ∑DDT compared with areas of high intensification, which may reflect high connectivity between intensive agricultural systems and river ecosystems. When combined nutrients and pesticides were considered, most of the lower reaches of the rivers draining to L. Naivasha were of poor water quality status as defined by Kenyan water quality regulations. The changes in land cover and agricultural intensification in the Naivasha catchment needs management and policy frameworks that manage the combined contamination from nutrients and pesticide residues. Enhanced investment in institutional and policy reforms, and an integrated review of water quality standards and monitoring indicators that combine biological, physical, and chemical monitoring, is necessary for future management of the catchment.