ORIGINAL ARTICLE A hydrochemical approach to estimate mountain front recharge in an aquifer system in Tamilnadu, India Banaja Rani Panda 1 • S. Chidambaram 1 • N. Ganesh 1 • V. S. Adithya 1 • M. V. Prasanna 2 • K. Pradeep 1 • U. Vasudevan 1 Received: 3 April 2017 / Revised: 7 June 2017 / Accepted: 16 August 2017 / Published online: 9 September 2017 Ó Science Press, Institute of Geochemistry, CAS and Springer-Verlag GmbH Germany 2017 Abstract Mountain-front recharge (MFR) is a process of recharging an aquifer by infiltration of surface flow from streams and adjacent basins in a mountain block and along a mountain front (MF). This is the first attempt in India to estimate MFR along the foothills of Courtallam using hydrogeochemistry and geostatistical tools. The estimation of MFR has been carried out by collecting groundwater samples along the foothills of Courtallam. Collected water samples were analyzed for major cations and anions using standard procedures. Hydrogeochemical facies show the existence of four water types in this region. Calcium-rich water derived from gneissic rock terrain indicates signifi- cant recharge from higher elevation. Log pCO 2 and ionic strength of the samples were also calculated to identify the geochemical process. Majority of the collected samples have sodium-rich water and weak ionic strength, which indicate foothill recharge and low residence time. Silicate and carbonate weathering have an equal interplay along the foothills with a relatively large fraction of Mg from the MF. The spatial diagrams of three factors show that the southern part of the study area is dominated by both weathering and anthropogenic processes, whereas the northern part is dominated by both leaching and weathering processes. Thus, the dominant weathering process repre- sented by the second factor indicates the large recharge process along the foothills. Keywords Mountain-front recharge  Geostatistical tools  Hydrogeochemical facies  Ionic ratio  Anthropogenic processes 1 Introduction The MFR is the contribution of mountains to recharging aquifers in adjacent basins along a MF. There are several techniques for the successful determination of MFR in different regions. Mohrbacher (1983) used stable isotopes and groundwater chemistry as indicators of MFR. Andrew et al. (2003) used noble gases to investigate MFR. Ping et al. (2014) have quantified groundwater recharge using the chloride mass balance method in a semi-arid mountain terrain, in South Interior British Columbia, Canada. Kambhammettu et al. (2011) evaluated three MFR esti- mation techniques using a numerical modeling in the Southern Jornada Del Muerto Basin, New Mexico. Table 1 lists the various studies that trialed a hydrogeochemical approach to understanding MFR. Several previous investigations that have been under- taken in the Courtallam region but only on groundwater potentiality and fluctuation (Balasubramanian and Sastri 1994; Public Works Department (PWD) 2002), quality and suitability of groundwater for domestic and irrigation purpose (Subramani et al. 2005a), and mineral composition and occurrence of various rock formation (Subramani et al. 2005b). But there has been no attempt to understand the MFR either by using hydrogeochemistry or by other techniques in this region. This is the first attempt on groundwater recharge estimation using hydrogeochemistry and geostatistical tools along the foothills of Courtallam. The main objective of our study is to estimate MFR by interpreting relevant hydrogeochemical data. This & M. V. Prasanna geoprasanna@gmail.com 1 Department of Earth Sciences, Annamalai University, Annamalai Nagar, Tamilnadu 608002, India 2 Department of Applied Geology, Faculty of Engineering and Science, Curtin University Malaysia, CDT 250, 98009 Miri, Sarawak, Malaysia 123 Acta Geochim (2018) 37(3):465–488 https://doi.org/10.1007/s11631-017-0229-4