ANALYSIS AND MAPPING OF GROUNDWATER SALINITY IN SHALLOW HAND-DUG WELLS IN T/A CHIMALIRO AREAS OF THYOLO, MALAWI

Access to portable water sources in rural and urban areas remains a serious challenge in many developing countries like Malawi. The present study was undertaken to analyze and map groundwater salinity in shallow hand-dug well in thyolo district T/A chimaliro. The purpose of the study was to map the hand-dug wells in the area, determine the groundwater flow direction and to analyze the Physio-chemical composition of groundwater salinity. Six shallow wells were identified and mapped in Arc GIS. At each well point, two sets of water samples were taken in 250ml sterilized glass bottles and analyzed for Physio-chemical parameters including temperature, pH, total dissolved solids, electrical conductivity, carbonate, sodium, potassium, magnesium, chloride, sulfate, carbonate, and bicarbonate. From the results, it is clear that water is flowing from southwest going towards the northeast in the study area. The results further demonstrate three things; first 33.3% of the samples are characterized by relatively low salinity, second 50% are characterized by medium salinity, and thirdly 16.6% of all samples, are characterized by relatively high values of salinity and the water is brackish saline. Despite the classification, well 6 registered the highest salinity and exceeded the WHO and MBA guidelines for drinking water. The implications of these findings indicate that well (W6) is not good to draw water for household or irrigation while most of the Wells their Physio-chemical parameters fell within the acceptable range of World Health Organization and Malawi Bureau Standard for drinking water. Results reported in this study provide scientific data significant for designing monitoring programs of groundwater in the southern region of Malawi and beyond, it also render service to others exploring similar groundwater studies. Regardless, future research could continue to explore geochemical assessment of the soils to determine pollution sources of groundwater salinity in the hand-dug wells.

At each well point, two sets of water samples were taken in 250ml sterilized glass bottles and analyzed for Physio-chemical parameters including temperature, pH, total dissolved solids, electrical conductivity, carbonate, sodium, potassium, magnesium, chloride, sulfate, carbonate, and bicarbonate. The results further demonstrate three things; first 33.3% of the samples are characterized by relatively low salinity, second 50% are characterized by medium salinity, and thirdly 16.6% of all samples, are characterized by relatively high values of salinity and the water is brackish saline. The implications of these findings indicate that well (W6) is not good to draw water for household or irrigation while most of the Wells their Physio-chemical parameters fell within the acceptable range of World Health Organization and Malawi Bureau Standard for drinking water. Results reported in this study provide scientific data significant for designing monitoring programs of groundwater in the southern region of Malawi and beyond, it also render service to others exploring similar groundwater studies.

The study was conducted in Thyolo district T/A Chimaliro in the following villages Nantheleza, Mina, Mitabali, and Mangaazi. Thyolo district is located in the southern region of Malawi. The greater part of thyolo district is underlined by what is referred to as the Malawi Basement Complex,(Habgood et.al., 1973). The Basement complex of thyolo is composed of the high-grade magmatic gneisses and granulite’s which lie in the Precambrian to Lower Paleozoic Mozambique Belt. The Biotitic hornblende gneisses and Charnokitic granulite’s are the dominant rock types in this area. Thyolo is also filled with a swarm of dolerite dykes which cuts the basement complex rocks on a NE – SW (north-east to south-west) trend. These alkaline dykes of the late Jurassic to early cretaceous are assigned to the Chirwa alkaline province and these dolerite dykes act as the groundwater traps and can be essential for conducting groundwater surveys, (Habgood et.al., 1973). The Thyolo area is entitled to a generous amount of rainfall that supplies water to this area. Thyolo is composed of zones of weathered gneiss and unconsolidated deposits with faults which are used for the construction of boreholes, (Habgood et.al., 1973).

Traditional authority: TA Chimaliro

District: Thyolo

Coordinates: -15.9729, 35.19975