Comparative Estimation of Groundwater Recharge Using the Thornthwaite-Mather Method in Vegetable Farming Areas: A Case Study of Sarangan and Pujon, Indonesia Aprizal Verdyansyah (a,b*), Tang-Huang Lin (a)
a) Center for Space and Remote Sensing Research (CSRSR), National Central University, Taiwan
b) The Indonesian Agency for Meteorology, Climatology, and Geophysics
*verdyansyahaprizal[at]gmail.com
Abstract
Highland vegetable farming areas in Sarangan and Pujon, Indonesia, face increasing water stress from intensive agricultural practices, threatening water resource sustainability. This study aims to estimate and compare monthly groundwater recharge patterns in both locations from 2021 to 2023 to support sustainable water management. By applying the Thornthwaite Mather water balance method and utilizing remote sensing data for precipitation (CHIRPS) and evapotranspiration (MODIS), this study analyzes the hydrological dynamics in both regions. The results indicate that groundwater recharge is highly seasonal, occurring exclusively during the rainy season (November to April) when precipitation exceeds the rate of evapotranspiration. During the study period, Sarangan showed a higher average annual recharge (2201 mm/yr) compared to Pujon (1883 mm/yr). Notably, the 2023 El Nino phenomenon caused a significant rainfall deficit, leading to a drastic decrease in recharge rates in both locations. This impact was more severe in Pujon, where soil moisture failed to reach field capacity, resulting in very low recharge. This study successfully demonstrates the effectiveness of the Thornthwaite Mather method for recharge estimation in highlands and underscores the vulnerability of groundwater resources to extreme climate variability. These findings emphasize the urgent need for adaptive, climate informed water resource planning to ensure the future sustainability of the agricultural sector.
Keywords: Sarangan, Pujon, groundwater, CHIRPS, MODIS, Thornthwaite-Mather, El Nino
