Assessment of Groundwater Recharge and Groundwater Quality in The Upstream of Tondano Watershed, North Sulawesi, Indonesia

Abstract

Raw water need increases along with the development of a region. In terms of quantity and quality, surface water tends to decrease, which causes an increase in groundwater exploitation. For groundwater in the Tondano watershed to be sustainable and meet the required quality standards, it is necessary to know about groundwater recharge and groundwater quality. This study’s objectives are to calculate groundwater recharge using a simplified groundwater balance and to evaluate groundwater quality using physico-chemical parameters. The method used in this study is to estimate groundwater recharge by calculating groundwater balance using data on annual rainfall, annual evapotranspiration, and annual runoff. Meanwhile, for groundwater quality, Physico-chemical properties were measured, including pH, TDS, EC, and temperature, at 21 measurement points, including springs, dug wells, and drilled wells. The results indicate that groundwater recharge calculation shows a positive value of 318.34 mm/year. The measurement of Physico-chemical parameters in the field suggests that the pH value is in the range of 6.1-7.9, the TDS range is 50-200 mg/L, the EC range is 110-400 μs/cm, and the temperature range is 23.4-35.6 °C. The analysis using World Health Organization standards and Ministry of Health standards show that the groundwater quality is suitable for use.