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Analysis of Hydro-Chemical Characteristics of Groundwater to Assess Seawater Invasion into Gowa-Takalar Coastal Aquifer
Ramli M.
Aip Conference Proceedings
Abstract
Development of groundwater irrigation to support agricultural activity in the Gowa-Takalar Coastal Area has been done since the 1990s by the Groundwater Irrigation Project of the Public Work Ministry. Furthermore, farmers developed several wells to support their activities leading to heavy exploitation during the dry season. To maintain sustainable groundwater exploitation in this coastal area, seawater invasion into the aquifer need to be assessed. The invasion of seawater is affected by the dynamic process within the aquifer due to annual seasonal variation, human activities, or global climate changes. This dynamic process can be observed by examining groundwater chemistry a series of times. A total of 22 groundwater samples were collected and analyzed in 2020 and then to be compared with published data in 2018 to learn the dynamic processes within the aquifer. The chloride concentration of groundwater in 2018 vary from 3.55 - 81.65 mg/L changed to a range of 24.85 - 3,976.00 mg/L. Identification of freshwater-seawater mixing by using chloride-bicarbonate ratio shows value 0.008 - 0.035 in.2018, and increase to be 0.18 - 35.53 in.2020. Finally, plotting chemical data into hydro-chemical facies evolution diagram figure out that all groundwater samples in freshening of F1 − F2 sub-stages in 2018, and change to freshening of F2 - F3 sub-stages and intrusion of I4 sub-stages in 2020. These analysis results indicated that seawater begins to invade the Gowa-Takalar Coastal Aquifer.