Document Type : Research Paper
Authors
1 Technical Department, Nzoia Water Services Company, Webuye, Kenya.
2 2Department of Civil and Structural Engineering, School of Engineering and Built Environment, Masinde Muliro University of Science and Technology, Kakamega, Kenya.
3 Department of Civil and Structural Engineering, School of Engineering and Built Environment, Masinde Muliro University of Science and Technology, Kakamega, Kenya.
Abstract
Access to safe water and sanitation is a basic human right and is enshrined in the sustainable development goal 6. Consequently, resources have been channeled towards development and improvement of water sources. Unlike surface water, the demand for groundwater is increasing due to its preserved quality, affordable development capital and drought resilience. Population density has resulted into entry of pollutants into aquifers because of reduced distance between the pollutants and groundwater sources, human activities and hydrogeological conditions. The aim of this study was to carry out an assessment of groundwater vulnerability to contamination as a preventive approach. Webuye town is a service area of Nzoia Water Services which provides water and sewerage services. However, water and sanitation coverage in Webuye town still below 50%, a portion of residents rely on onsite sanitation systems and groundwater. This is due to costs of installation, topographical challenges and limited pipeline extensions. It was observed that areas where groundwater sources are predominantly used, human waste is managed onsite close to groundwater abstractions points. The methods used in this study included the application of DRASTIC model which was interfaced in ArcGIS version 10.3. Inverse distance weighted (IDW) interpolation technique was used to produce vulnerability maps. The model inputs were seven: depth, recharge, aquifer, soil properties, topography, impact of the vadose zone, hydraulic conductivity and Land use. The results show that North Eastern areas of the study area; Maraka (Township) and Muchi scored the highest DRASTIC-LU values, implying high chances of groundwater vulnerability to contamination. The shallow water table, groundwater recharge, the type of soil, slope and the land use activities in the study area resulted into increased vulnerability. The findings should inform the municipality management on water quality precautions to be undertaken while developing groundwater sources in the area and development of pollution control framework.
Keywords
Alasbahi, R.H., and Al-Hawshabi, O.S. (2021) ‘A review on some cultivated and native poisonous plants in Aden Governorate, Yemen’, Electronic Journal of University of Aden for Basic and Applied Sciences, 2(2), pp. 54–70. doi: https://doi.org/10.47372/ejua-ba.2021.2.91
Amanambu, A.C. et al. (2020) ‘Groundwater system and climate change: Present status and future considerations’, Journal of Hydrology, 589, pp. 125163–125181. doi: https://doi.org/10.1016/j.jhydrol.2020.125163.
Amin, H.M. et al. (2021) ‘Assessment of wastewater contaminant concentration through the vadose zone in a soil aquifer treatment system’, Applied Ecology and Environmental Research, 19(3), pp. 2385–2403. doi: https://doi.org/10.15666/aeer/1903_23852403
Chakraborty, M. et al. (2022) ‘Assessment of groundwater quality using statistical methods: A case study’, Arabian Journal of Geosciences, 15(12), pp. 1136–1136. doi: https://doi.org/10.1007/s12517-022-10276-2
Das, B., Dhorde, A., and Mitra, D. (2022) ‘Delineating saltwater intrusion zones and assessing its relation with mangrove species along the coastal tracts of Raigad district of Maharashtra, India’, Journal of Coastal Conservation, 26(6), pp. 78-88. doi: https://doi.org/10.1007/s11852-022-00926-8
Eftekhari, M., and Akbari, M. (2020) ‘Evaluation of the SINTACS-LU model capability in the analysis of aquifer vulnerability potential in semi-arid regions’, Journal of Applied Research in Water and Wastewater, 7(2), pp. 111–119. doi: https://doi.org/10.22126/arww.2020.4785.1151
Fankhauser, K. et al. (2022) ‘Estimating groundwater use and demand in arid Kenya through assimilation of satellite data and in-situ sensors with machine learning toward drought early action’, Science of The Total Environment, 831, pp. 154453–154468. doi: https://doi.org/10.1016/j.scitotenv.2022.154453
Gwara, S. et al. (2020) ‘Why do we know so much and yet so little? a scoping review of willingness to pay for human excreta derived material in agriculture’, Sustainability, 12(16), pp.6490–6515. doi: https://doi.org/10.3390/su12166490
Jamaa, H. et al. (2023) ‘Assessment of groundwater vulnerability to contamination using the drastic model and GIS functions in Doukkala Plain, Morocco’, Modeling Earth Systems and Environment, 10(1), pp. 1–17. doi: https://doi.org/10.1007/s40808-023-01789-0
Jat Baloch, M.Y. et al. (2021) ‘Shallow groundwater quality assessment and its suitability analysis for drinking and irrigation purposes’, Water, 13(23), pp.3361–3386. doi: https://doi.org/10.3390/w13233361
Kanda, E.K. et al. (2023) ‘Assessment of groundwater quality in Vihiga County, Kenya’, Progress in Sustainable Development, pp. 249–264. doi: https://doi.org/10.1016/b978-0-323-99207-7.00010-5
Kirlas, M.C. et al. (2023) ‘A GIS-based comparative groundwater vulnerability assessment using modified-drastic, modified-SINTACS and NV Index in a porous aquifer, Greece’, Environments, 10(6), pp. 95-95. doi: https://doi.org/10.3390/environments10060095
Liu, G. et al. (2019) ‘Transport of engineered nanoparticles in porous media and its enhancement for remediation of contaminated groundwater’, Critical Reviews in Environmental Science and Technology, 50(22), pp. 2301–2378. doi: https://doi.org/10.1080/10643389.2019.1694823
Talebi, M.S., and Fatemi, M. (2020) ‘Assessment of the quality and quantity of groundwater in Bahadoran plain using neural network methods, geostatistical and multivariate statistical analysis’, Journal of Applied Research in Water and Wastewater, 7 (2), pp. 144-151. doi: https://doi.org/10.22126/arww.2021.4367.1134
Maleki, S. et al. (2023) ‘Z-numbers based novel method for assessing groundwater specific vulnerability. Engineering applications of artificial intelligence, 122 (0952-1976), pp.106104–106119. doi: https://doi.org/10.1016/j.engappai.2023.106104
Malviæ, T. et al. (2020) ‘Application of the modified shepard’s method (MSM): A case study with the interpolation of Neogene Reservoir variables in northern Croatia’, Stats, 3(1), pp. 68–83. doi: https://doi.org/10.3390/stats3010007
Ni, C.-F. et al. (2023) ‘Stochastic-based approach to quantify the uncertainty of groundwater vulnerability’, Stochastic Environmental Research and Risk Assessment, 37(5), pp. 1897–1915. doi: https://doi.org/10.1007/s00477-022-02372-2
Novinpour, E.A., Moghimi, H., and Kaki, M. (2022) ‘Aquifer vulnerability based on classical methods and GIS-based fuzzy optimization method (Case study: Chahardoli plain in Kurdistan Province, Iran)’, Arabian Journal of Geosciences, 15(4), pp. 360-378. doi: https://doi.org/10.1007/s12517-022-09549-7
Nurfahasdi, M. et al. (2023) ‘Mapping groundwater vulnerability using drastic method’, E3S Web of Conferences, 434, p.03019. doi: https://doi.org/10.1051/e3sconf/202343403019
Oke, S.A. (2020) ‘Regional aquifer vulnerability and pollution sensitivity analysis of drastic application to Dahomey Basin of nigeria’, International Journal of Environmental Research and Public Health, 17(7), p. 2609. doi: https://doi.org/10.3390/ijerph17072609
Petryk, A. et al. (2023) ‘Comparison of pedotransfer functions for determination of saturated hydraulic conductivity for highly eroded loess soil’, Land, 12(3), pp. 610-635. doi: https://doi.org/10.3390/land12030610
Preisner, M., Neverova-Dziopak, E., and Kowalewski, Z. (2020) ‘An analytical review of different approaches to wastewater discharge standards with particular emphasis on nutrients’, Environmental Management, 66(4), pp. 694–708. doi: https://doi.org/10.1007/s00267-020-01344-y
RagaPriya, A., Janaki, P., Arulmozhiselvan, K. (2020) ‘Effect of repeated atrazine and Pendimethalin application on their bound residues in long term fertilized soil of semi-arid tropic region in India’, Journal of Applied and Natural Science, 12(4), pp. 471–477. doi: https://doi.org/10.31018/jans.v12i4.2367
Rama, F., et al. (2022) ‘Assessment of intrinsic aquifer vulnerability at continental scale through a critical application of the drastic framework: The case of South America. Science of the total environment’ Science of the Total Environment, 823, p. 153748. doi: https://doi.org/10.1016/j.scitotenv.2022.153748
Salomó-Coll, O. et al. (2020) ‘Influence of bone density, drill diameter, drilling speed, and irrigation on temperature changes during implant osteotomies: An in vitro study’, Clinical Oral Investigations, 25(3), pp. 1047–1053. doi: https://doi.org/10.1007/s00784-020-03398-y
Shah, S.H. et al. (2021) ‘Classification of aquifer vulnerability by using the drastic index and geo-electrical techniques’, Water, 13(16), pp. 2144–2144. doi: https://doi.org/10.3390/w13162144.
Shaji, E. et al. (2021) ‘Arsenic contamination of groundwater: A global synopsis with focus on the Indian Peninsula’, Geoscience Frontiers, 12(3), pp. 101079–101079. doi: https://doi.org/10.1016/j.gsf.2020.08.015.
Sharma, K., Rajan, S. and Nayak, S.K. (2024) ‘Water pollution: Primary sources and associated human health hazards with special emphasis on rural areas’, Water Resources Management for Rural Development, pp. 3–14. doi: https://doi.org/10.1016/b978-0-443-18778-0.00014-3
Siganga, C.A., Ong’or, B.T.I., and Kanda, E.K. (2023) ‘Water quality index for assessment and mapping of groundwater quality in Webuye municipality, Kenya’, Harbin Gongcheng Daxue Xuebao/Journal of Harbin Engineering University, 44(11), pp.1239–1247. Available at: https://harbinengineeringjournal.com/index.php/journal/article/view/2177 (Accessed:13 March 2024).
Spijkers, O. (2020) ‘The no significant harm principle and the human right to water’, International Environmental Agreements: Politics, Law and Economics, 20(4), pp. 699–712. doi: https://doi.org/10.1007/s10784-020-09506-3
Usowicz, B. and Lipiec, J. (2021) ‘Spatial variability of saturated hydraulic conductivity and its links with other soil properties at the regional scale’, Scientific Reports, 11(1), pp. 8293–8301. doi:10.1038/s41598-021-86862-3.
Wang, Z. et al. (2023) ‘Assessment of groundwater vulnerability by applying the improved drastic model: A case in Guyuan City, Ningxia, China’, Environmental Science and Pollution Research, 30(20), pp. 59062–59075. doi: https://doi.org/10.1007/s11356-023-26763-2.
Xin, J. et al. (2019) ‘The missing nitrogen pieces: A critical review on the distribution, transformation, and budget of nitrogen in the Vadose Zone-Groundwater System’, Water Research, 165(0043–1354), pp. 114977–114977. doi: https://doi.org/10.1016/j.watres.2019.114977.
Xiong, H. et al. (2022) ‘Current status and future challenges of groundwater vulnerability assessment: A Bibliometric analysis’, Journal of Hydrology, 615(0022–1694), pp. 128694–128694. doi: https://doi.org/10.1016/j.jhydrol.2022.128694.
Yang, X. et al. (2020) ‘NET nitrogen mineralization delay due to microbial regulation following the addition of granular organic fertilizer’, Geoderma, 359(0016–7061), pp. 113994–113994. doi: https://doi.org/10.1016/j.geoderma.2019.113994.
Yi, X. et al. (2022) ‘Effects of concentrated flow changes on runoff conversion and sediment yield in gently sloping farmland in a karst area of SW China’, CATENA, 215(114977), 215, pp. 106331-106331. doi: https://doi.org/10.1016/j.catena.2022.106331
)