Hydrogeochemical Modelling and Isotopic Composition as Tracers of Ground Water Recharge in Chitipa District, Malawi
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The purpose of this study was to evaluate groundwater's hydrogeochemical and isotopic composition as indicators of recharge in the Chitipa district. This was accomplished by analyzing the hydrogeochemical processes that control groundwater quality, identifying groundwater recharge sources like precipitation and infiltration, characterizing hydrogeochemical-stable isotopic composition of groundwater, and evaluating changes in the hydrogeochemical and isotopic composition of groundwater with seasons. This research design was quantitative in nature. In the dry and rainy seasons, groundwater samples were taken from 25 randomly chosen boreholes in the two TAs of Mwaulambya and Misuku in the Chitipa district. With SPSS version 20, data analysis was carried out. The study's findings indicated a significant difference (p. < 0.05) in levels of: electrical conductivity (EC), nitrate (NO 3− ), chloride (Cl − ), bicarbonate (HCO 3− ), potassium (K + ) and calcium (Ca 2+ ) and no significant difference (p > 0.05) in the following parameters between the dry and wet seasons: pH, sodium (Na + ), sulfate (SO 4 2− ) and magnesium (Mg 2+ ). Combining Piper plots with ionic dominance sequence analysis revealed that the majority of the groundwater in the study area is of mixed types, specifically Ca-Na-HCO 3 and Ca-Mg-SO 4 . Overall, during both the dry and wet seasons, the ionic dominance sequence was as follows: Na + > Mg 2+ > Ca 2+ > K + for cations, and HCO 3 − > Cl − > SO 4 2− > NO 3 − for anions, all of which were within the Malawi Standards. The study suggests that pit latrines be built in accordance with established sanitary practices to prevent the infiltration of sodium and chlorides into the aquifers, that good agricultural practices be followed to minimize nitrate pollution, and that afforestation of the study area be intensified and sustained to ensure reliable rainfall, which is the main process of recharging the aquifers.
