Abstract
Urbanization has caused limitations on water resources, while climate change has reduced amounts of surface water in some parts of the world. Kikuyu, a suburban area in Kiambu county, Kenya, is facing this challenge. The major challenge in the study is scarcity of potable water, resulting in inadequate water supply to Kikuyu residents. Currently, only 63.6% of the population is being supplied with water by Kikuyu Water Company, the company mandated to supply water to the area. Water demand was 2972 m3/day in 2015 and was projected to be 3834 m3/day by 2025. This has put pressure on the already exploited clean water resources, making it necessary to seek additional sources of domestic water. Storage capacity and water quality of surface water bodies, especially small reservoirs whose water can be used to ease the demand, need to be assessed for supplemental water supply. This study aimed at assessing the suitability of the abandoned quarry reservoir as a source of potable urban water by determining its storage capacity characteristics and water quality status. Volume characteristics were determined using bathymetry survey in January 2019. Water samples were collected in January and August 2019 and analyzed for chemical, physical, and bacteriological quality, as per the American Public Health Association (APHA) standard methods for water and wastewater. Parameters were evaluated based on World Health Organization (WHO) and Kenya Bureau of Standards (KEBS) guidelines for drinking water, and rated based on the drinking water quality index (WQI). The reservoir’s maximum storage capacity was found to be 128,385 m3, the surface area was 17,699 m2, and the maximum depth was 15.11 m. Nineteen of the twenty-five investigated parameters were within the acceptable standards. However, the concentrations of manganese (Mn), cadmium (Cd), iron (Fe), turbidity, total coliforms, and Escherichia coli (E. coli) were above the acceptable limits. Manganese and iron levels increased with depth. The overall WQI of the reservoir was 82.51 and 85.85 in January and August, respectively. Therefore, based on WQI rating, the water scored a good quality rating and could be used for domestic supply upon treatment. The original achievement of this study is establishment of the volume of the water in the quarry as an additional source of water to the nearby community, along with water quality status.
Highlights
Urbanization has led to constraint of water resources, while climate change has reduced amounts of surface water in some parts of the world [1]
It was established that the storage capacity and surface area of the reservoir were 128,385 m3 and 17,699 m2, respectively
The study revealed that the storage capacity of the reservoir is 128,385 m3, the surface area is
Summary
Urbanization has led to constraint of water resources, while climate change has reduced amounts of surface water in some parts of the world [1]. Underground mine galleries and open-pit mines are flooded by natural groundwater, surface water inflow, and water pumped from dewatering systems, and can be used as strategic reservoirs for water storage. Water in quarry reservoirs can be used for irrigation, domestic supply, industrial supply, and aquifer recharge, amongst other uses [2]. The Hallett quarry gravel pit lake system in Ames City, Iowa, United States, is one of the quarry pits that was assessed for water storage and domestic supply to the city [3]. The quarry pit system water was analyzed together with the effect of storm water. Storm water elevated concentration of parameters such as fecal coliforms in the quarry pit system [3]. Bellwood quarry in Atlanta, Georgia, is used for raw water storage to supplement existing water supply [4]
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