Univrsity of Tehran Press Geopersia 2228-7817 16 1 2026 06 03 Application of Hydrological Balance Approach to Estimate Karstic Groundwater Discharge to the Sea: Nekarood Karst Basin, Iran - 19 31 102238 10.22059/geope.2025.390468.648808 EN Narges Nabizadeh Chamazcoti Department of Geology, Shahrood University of Technology, Shahrood, Iran Gholam Hossein Karami Department of Geology, University of Kharazmi, Tehran, Iran Azizollah Taheri Department of Geology, Shahrood University of Technology, Shahrood, Iran Ramazan Ramazani Omali Department of Geology, Shahrood University of Technology, Shahrood, Iran Journal Article 2025 02 13 Nekarood karst basin (NRKB) is located near the southern coast of the Caspian Sea, in Mazandaran province, Iran. The recharge potential map of this karst basin was prepared by considering lithology, slope, aspect, density of streams, precipitation, density of fractures, epikarst and karst features using GIS. These factors have been weighted using information obtained from geological maps, satellite images and field investigations. The results show that the values of recharge in NRKB varies from 12 to 45%. Based on this, the total amount of annual recharge in this basin is estimated to be about 243 million cubic meters. Based on the obtained results, the annual discharge of groundwater in the area is estimated about 71 million cubic meters. Due to the fact that there is no important consumer in the NRKB, the discharges of the springs in this basin form the base flow of the river. The evaluation of the annual volume of the base flow of Nekarood River shows that it is in good agreement with the annual discharge of the springs in the area. The water budget studies in NRKB indicate that the recharge volume is significantly higher compared to its discharge. In addition, the investigations show that there are no discharge zones in adjacent areas. Due to the existence of an important fault zone in this karst basin which extends towards the sea, most likely a significant part of the recharge water in this karst basin is discharged into the sea. . https://geopersia.ut.ac.ir/article_102238_d4d0e6b263b4d89b1b8c779bb9597a5e.pdf