International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438 Volume 4 Issue 9, September 2015 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Hydrogeochemical Assessment of Groundwater Quality in Salima and Nkhotakota Districts, Malawi Tananga Mathews Nyirenda 1 , Harold Wilson Tumwitike Mapoma 2 , Aaron Msiska 3 , Junice Dzonzi-Undi 4 , Sella Jumbo 5 1, 3, 4 School of Environmental Studies, China University of Geosciences (Wuhan), Lumo Road 388, Wuhan, Hubei 340074, P. R. China. 2 School of Environmental Studies, China University of Geosciences (Wuhan), Lumo Road 388, Wuhan, Hubei 340074, P. R. China and Polytechnic, University of Malawi, Private Bag 303, Blantyre, Malawi 5 WaterAid, Malawi Country Programme, Private Bag 364, Lilongwe, Malawi Abstract: This paper investigated the hydrogeochemical characteristics influencing water quality, and assessed the groundwater quality for domestic and irrigation purposes in two districts of Salima and Nkhotakota in Malawi. Data was compiled from water quality surveillance reports of water sources constructed by sponsorship from WaterAid Malawi programme. A water quality index (WQI) was used to measure suitability of groundwater for domestic purposes. Electrical conductivity, total dissolved solids and various indices were used to measure quality of water for irrigation. Anion chemistry showed a general dominance of  3 HCO , while Ca 2+ was the dominant cation. The pH of groundwater in Salima was neutral and of Ca-HCO 3 /Na type; while in Nkhotakota it was slightly acidic and of Ca- Na/Mg type. It was determined that Ca 2+ , Mg 2+ ,  2 4 SO and  3 HCO originated from release of carbonates (calcite or dolomite) in both districts and from gypsum in Salima district only. Although turbidity, pH and EC exceeded drinking water standards, the WQI showed the water to be suitable for consumption. It was therefore recommended to educate communities on household water treatment methods. Continual monitoring of these water sources with unacceptable standards was also proposed to be a priority. Keywords: Hydrogeochemistry; Groundwater; Water-rock interactions; Water quality index; Malawi 1. Introduction Groundwater is important for domestic and irrigation uses in rural parts of Malawi. Rural communities in Malawi do not access safe drinking water easily, despite abundant water resources and a wide network of surface water (Palamuleni 2002). Surface water is easily accessible but it is prone to contamination from farming and household activities. Alternatively groundwater can be made available to rural communities cheaply, is not contaminated, and can be available regardless of season (McDonald and Calow 2009). However, any disturbance to the water-rock interactions can negatively affect groundwater quality. Therefore, knowledge of groundwater hydrogeochemical evolution is vital for water quality management. The demand for safe water in Malawi has prompted WaterAid to venture into promoting water supply and sanitation in the country. WaterAid is an international non- governmental organization that focuses on provision of portable drinking water, improved hygiene and sanitation in rural areas across the world (WaterAid 2015). WaterAid Malawi programme operates by funding its partners to construct boreholes and shallow wells, supports communities to repair broken wells and hand-pumps and trains them to maintain their own facilities in the long term. WaterAid aims to deliver quality drinking water to project beneficiaries, which conforms to quality standards of the country (WaterAid 2009). The objectives of this study were to (1) investigate groundwater hydrogeochemical characteristics; (2) determine water-rock interaction influencing water quality and; (3) assess groundwater quality for use in households and agriculture lands under irrigation. To achieve the set objectives the study used scatter plots, USGS geochemical code PHREEQC (Parkhurst and Appelo 2013) and piper diagram as complementary tools. A water quality index (WQI) was used to determine the safety of the groundwater for human consumption (Yidana 2010). The groundwater electrical conductivity (EC) together with recommended irrigation water quality (sodium adsorption ratio (SAR), percent sodium Ion (% Na + ) and residual sodium carbonate (RSC)) and total dissolved solids (TDS), were calculated to evaluate the suitability of groundwater for irrigation activities. 2. Materials and Methods Study Area Salima and Nkhotakota districts boarder each other and are located in the central region of Malawi, south of Lilongwe the country’s Capital (Fig 1). The two districts are located along Lake Malawi to the east. Salima district covers a land area of approximately 2,200 km 2 while Nkhotakota covers about 4,260 km 2 (Government of Malawi (GoM) 2006; GoM 2010). These districts experience a warm tropical climate, which is characterized by the rainy and dry seasons that occur from November to April and May to October, respectively. The mean annual temperature for Salima district is about 22 o C. The highest temperatures in Salima are experienced in October, which at times might go as high as 33 o C. The lowest temperatures are experienced between June and July. For Nkhotakota district the maximum and minimum temperatures have an average of 28.7 o C and 20 o C Paper ID: SUB158437 1568