Assessment of Water Supply and Demand in Walatsi Sub-Catchment, Busia County, Kenya
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Date
2024-10
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Kenyatta University
Abstract
Many governments around the world are confronting serious problems in freshwater
management because of growing competition for the dwindling natural resource.
Overexploitation of water supplies remains the most serious constraint on its
sustainability. Water resources in Sub-Saharan Africa (SSA) are highly varied, with
on average a relatively low supply per capita. In Kenya, inadequate water supply
management, years of frequent droughts, pollution of existing water, and a fast growth
in water demand due to a relatively rapid population increase have all contributed to
water scarcity, which is a serious issue. This study was conducted in Walatsi sub catchment, traversing Busia and Bungoma counties in Western Kenya. Increasing
demand for water in the sub-catchment and unsustainable use are substantially putting
pressure on water volume, jeopardising the livelihoods of growing populations, in
particular during dry seasons. The study addressed the following objectives: to
determine the available water supply in Walatsi sub-catchment; to establish the current
and future water demand in the sub-catchment; and to develop and simulate the water
balance in the sub-catchment. This study therefore adopted a Decision Support System
(DSS), the WEAP model, for scenario analysis and simulations to assess water supply
and demand in the sub-catchment from the year 2022 up to 2030. This was used to
determine the available water supply, establish the current and future water demand,
and simulate and develop the water balance for the sub-catchment. The study utilised
data from key informants, experiment, direct observations, and GIS analyses. QGIS
software was used for GIS analyses and mapping, and Microsoft Excel for data and
statistical analyses (including correlation and regression). The outcome of the analyses
was fed into the WEAP software for its calibration and validation and as a parameter
for water supply, demand scenario, and balance analysis. By using a built-in supply
and demand database, available water supply, present and future water demand, and
water balance were determined in monthly and annual timesteps with a projection done
after 3 years and 5 years for 8 years to the year 2030. The results from the study
indicated an annual supply of between 31.63 and 31.65 Mm3
and a monthly supply
ranging from 0.48 to 6.80 Mm3
. There was an upward annual spiral in water demand
in both scenarios and overall, by 9.87% and 27.59% in 2025 and 2030 from 6.45 Mm3
in 2022.The outcome further revealed a declining annual water balance in the scenarios
and overall, by -2.54% and -7.07% in 2025 and 2030 from 25.18 Mm3
in 2022 and an
increasing annual monthly water deficit in February (driest month) from -0.02 to -0.06
and -0.15 Mm3
. The strong negative correlation (r = -0.999, p < 0.001) explained the
increasing deficit as due to growing demand and was confirmed by the widening gap
in unmet demand by 0.91% and 1.85% in 2025 and 2030 from 0.24% in 2022. The
variations in monthly supply annually are due to the bimodal dry and rainy seasons (r
= 0.73, p < 0.01) and annual supply due to normal and leap years. The positive trend
in demand is likely to put pressure on available water supplies. The increasing deficit
indicates pressure on water sources and exploitation of the reserve. This study
indicates a water scarcity sub-catchment and recommends, among other interventions,
the protection and conservation of water resources and the exploitation of alternative
sources; the adoption of best demand management practices, including economical and
efficient water use technologies to satisfy the needs; and the development of a water
allocation and monitoring plan to sustainably manage the resource
Description
A Thesis Submitted in Partial Fulfilment of the Requirements for the Award of the Degree of Master of Science (Integrated Watershed Management) in the School of Pure and Applied Sciences, Kenyatta University October, 2024
Supervisor:
1.Kennedy Obiero
2.Mary Makokha