Hydrogeochemical characteristics and evaluation of groundwater quality for domestic and irrigation purposes: a case stud
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Hydrogeochemical characteristics and evaluation of groundwater quality for domestic and irrigation purposes: a case study of the Heuningnes Catchment, Western Cape Province, South Africa Portia Mokoena1 · Thokozani Kanyerere1 · Jan van Bever Donker1 Received: 22 April 2020 / Accepted: 13 August 2020 © Springer Nature Switzerland AG 2020
Abstract Knowing the quality of water is imperative if the water is meant for drinking or agricultural purposes. The spatial and temporal groundwater quality in the Heuningnes Catchment was investigated, and its appropriateness for irrigation and drinking purposes was considered. Thirty-one samples were collected and analysed for physical (pH, EC, TDS) and chemical (Na+, K+, Ca2+, Mg2+, HCO3−, Cl−, SO42−) parameters. Maps demonstrating the spatial and temporal distribution of groundwater quality were constructed using Geographical Information System software. These maps indicate variations in the concentration of various water quality parameters in the region. Groundwater in the region is mostly alkaline and is categorised as either fresh, brackish or saline based on TDS classification. Using Piper diagrams, it is shown that Na+–Cl− water type is the main water type in the area. The quality is mostly influenced by chemical weathering of rockforming minerals. Over 50% of groundwater in the region is not fit for drinking purposes as established from WHO (2011) and SANS241 criteria. Following SAR criteria, looking at Na%, PI, MH, KR and salinity hazard for irrigation assessment, it was discovered that shallow groundwater in the region was not fit for irrigation purposes. However, groundwater from deeper boreholes proved otherwise. The study has shown that not all-available groundwater is suitable for either drinking or irrigation. Therefore, it recommends to plant crop varieties that are highly salinity tolerant, as treating the water prior to irrigation would not be economically viable, and it also recommends further exploration to make the available 50% of groundwater drinkable and to make the shallow groundwater fit for irrigation. Keywords Groundwater quality · Irrigation · SAR · Salinity · Coastal aquifer
1 Introduction Groundwater has become the major source of freshwater supply for many uses such as domestic, irrigation, industrial and ecosystem support across the world [12, 22, 33, 41], and this is especially true in coastal areas where the water demand is high because of the increasing population and agricultural activities. Groundwater is important
for the Heuningnes community who requires it for domestic usage and irrigation purposes. Therefore, groundwater quality is as essential as its quantity especially because the water quality informs the aptness of groundwater for various uses. The type and concentration of dissolved minerals determine the aptness of water for different uses. A number of factors are considered to have an effect on the chemistry of groundwater thus influencing its quality.
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