Mitigation of Environmental Problems in Lake Victoria, East Africa: Causal Chain and Policy Options Analyses

Odada, Eric O.; Olago, Daniel; Kulindwa, Kassim; Ntiba, M. J.; Wandiga, Shem O.

doi:10.1579/0044-7447-33.1.13

Cited by 119 publications

(82 citation statements)

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“…Eutrophication related to anthropogenic activities has become a serious issue in SSA and has in some cases resulted in drastic reduction of dissolved oxygen and fish populations, and proliferation of toxic cyanobacteria blooms (Nyenje et al 2010). As reported for Lake Victoria (Kishe 2004;Odada et al 2004), eutrophication in SSA is mainly a result of soil erosion, nutrient leaching, atmospheric N deposition, runoff of organic wastes, and poor recovery of nutrients from wastewater among other sources. Reliable estimates of the contribution of each of these sources to N load into water bodies in SSA are generally yet to be determined to better inform policy decisions intended to reduce N losses to the environment.…”

Section: High N Loss To the Environmentmentioning

confidence: 99%

Dilemma of nitrogen management for future food security in sub-Saharan Africa – a review

et al. 2017

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Abstract. Food security entails having sufficient, safe, and nutritious food to meet dietary needs. The need to optimise nitrogen (N) use for nutrition security while minimising environmental risks in sub-Saharan Africa (SSA) is overdue. Challenges related to managing N use in SSA can be associated with both insufficient use and excessive loss, and thus the continent must address the 'too little' and 'too much' paradox. Too little N is used in food production (80% of countries have N deficiencies), which has led to chronic food insecurity and malnutrition. Conversely, too much N load in water bodies due mainly to soil erosion, leaching, limited N recovery from wastewater, and atmospheric deposition contributes to eutrophication (152 Gg N year -1 in Lake Victoria, East Africa). Limited research has been conducted to improve N use for food production and adoption remains low, mainly because farming is generally practiced by resource-poor smallholder farmers. In addition, little has been done to effectively address the 'too much' issues, as a consequence of limited research capacity. This research gap must be addressed, and supportive policies operationalised, to maximise N benefits, while also minimising pollution. Innovation platforms involving key stakeholders are required to address N use efficiency along the food supply chain in SSA, as well as other world regions with similar challenges.

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Section: High N Loss To the Environmentmentioning

confidence: 99%

Dilemma of nitrogen management for future food security in sub-Saharan Africa – a review

et al. 2017

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“…Currently, ~90% of the basin's inhabitants rely on subsistence agriculture and livestock for their livelihood [20], resulting in over 40% of the land within the basin classified as cropland (based on the International Geosphere-Biosphere Programme classifications). The Nzoia Basin expects urban growth and has a medium to high potential for industrial agricultural schemes [21] despite its significant population of more than 3 million inhabitants [22]. Unfortunately, this growth is also paired with projected water scarcity.…”

Section: Study Areamentioning

confidence: 99%

Increasing the Accuracy of Runoff and Streamflow Simulation in the Nzoia Basin, Western Kenya, through the Incorporation of Satellite-Derived CHIRPS Data

Pricope

2017

Water

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Hydrologic models will be an increasingly important tool for water resource managers as water availability dwindles and water security concerns become more pertinent in data-scarce regions. Fortunately, newly available satellite remote sensing technology provides an opportunity for improving the spatial resolution and quality of input data to hydrologic models in such regions. In particular, the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) dataset provides quasi-global high resolution precipitation information derived from a blend of in situ and active and passive remote sensing data sources. We piloted the incorporation of the CHIRPS dataset into the Soil and Water Assessment Tool (SWAT), a hydrologic model. Comparisons of results between estimation of streamflow using in situ rainfall gauge station data, the Climate Forecast System Reanalysis (CFSR) dataset, and the CHIRPS dataset in the data-scarce Nzoia Basin in western Kenya over the temporal range 1990-2000 were reported. Simulated streamflow estimates were poor with rainfall gauge station data but improved significantly with the CFSR and CHIRPS datasets. However, the use of the CHIRPS dataset in comparison with the CFSR dataset provided an improved statistical performance following model calibration with the exception of one streamflow gauge station in higher elevation regions. Overall, the use of the CHIRPS dataset had the greatest linear correlation, relative variability, and normalized bias despite overall average Nash-Sutcliffe Efficiency (NSE) and R 2 values.

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“…In the past decades, population increase and the migration of people to the lake region have led to wetland destruction and degradation. Over-exploitation and destruction of wetland vegetation curtail the filter function of wetlands as pollutants and nutrients are carried directly into the lake when the vegetation of wetland macrophytes is destroyed (Okeyo-Owuor 1999;Odada et al 2004). To formulate sustainable management strategies, trade-offs between socio-economic and ecological indicators need to be made (McCartney et al 2005) based on a good understanding of the hydrological and ecological (including nutrient retention and buffering) mechanisms underlying wetland functioning.…”

Section: Introductionmentioning

confidence: 99%

A simulation model for nitrogen retention in a papyrus wetland near Lake Victoria, Uganda (East Africa)

Dam

Dardona

Kelderman

et al. 2007

Wetlands Ecol Manage

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Papyrus wetlands around Lake Victoria, East Africa play an important role in the nutrient flows from the catchment to the lake. A dynamic model for nitrogen cycling was constructed to understand the processes contributing to nitrogen retention in the wetland and to evaluate the effects of papyrus harvesting on the nitrogen absorption capacity of the wetlands. The model had four layers: papyrus mat, water, sludge and sediment. Papyrus growth was modelled as the difference between nitrogen uptake and loss. Nitrogen uptake was modelled with a logistic equation combined with a Monod-type nitrogen limitation. Nitrogen compartments were papyrus plants, organic material in the floating mat; and total ammonia, nitrate and organic nitrogen in the water, sludge and sediment. Apart from the uptake and decay rates of the papyrus, the model included sloughing and settling of mat material into the water, mineralization of organic matter, and nitrification and diffusion of dissolved inorganic nitrogen. Literature data and field measurements were used for parameterization. The model was calibrated with data from Kirinya wetland in Jinja, Uganda which receives effluent from a municipal wastewater treatment plant. The model simulated realistic concentrations of dissolved nitrogen with a stable biomass density of papyrus and predicted accumulation of organic sludge in the wetland. Assuming that this sludge is not washed out of the wetland, the overall nitrogen retention of the wetland over a three-year period was 21.5 g N m À2 year À1 or about 25% of input. Harvesting 10, 20 and 30% of the papyrus biomass per year increased nitrogen retention capacity of the wetland to 32.3, 36.8 and 38.1 g m À2 year À1 , respectively. Although the nutrient flows estimated by the model are within the ranges found in other papyrus wetlands, the model could be improved with regard to the dynamics of detrital nitrogen. Actual net retention of nitrogen in the sludge is likely to be lower than 21.5 g N m À2 year À1 because of flushing out of the sludge to the lake during the rainy season.

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Mitigation of Environmental Problems in Lake Victoria, East Africa: Causal Chain and Policy Options Analyses

Cited by 119 publications

References 0 publications

Dilemma of nitrogen management for future food security in sub-Saharan Africa – a review

Dilemma of nitrogen management for future food security in sub-Saharan Africa – a review

Increasing the Accuracy of Runoff and Streamflow Simulation in the Nzoia Basin, Western Kenya, through the Incorporation of Satellite-Derived CHIRPS Data

A simulation model for nitrogen retention in a papyrus wetland near Lake Victoria, Uganda (East Africa)

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