Impact of climate change adaptation strategies on groundwater resources: a case study of Sari-Neka coastal aquifer, Northern Iran

Climate change complications have substantial impacts on groundwater systems. These changes should be monitored to facilitate the management of groundwater resources. This research evaluates the adaptation strategies to climate change in the Sari-Neka aquifer in Northern Iran, on the coasts of the Caspian Sea. To that end, first, the climatic parameters such as precipitation and minimum and maximum temperature were calibrated for a base period (2000-2019) using the LARS-WG model. Then, the mentioned climate parameters were simulated for the future period (2021-2040) using the CMIP5 models, namely, HadGEM2-ES, MIROC5, MPI-ESM-MR, and EC-EARTH under RCP4.5 and RCP8.5 scenarios. The results indicated a relative increase in minimum and maximum temperature (on average, 0.7 degrees C and 0.6 degrees C, respectively) and varied changes (from - 21.8% in August to + 63.8% in October) in precipitation in the future period. The quantitative status of groundwater was calibrated and validated using the MODFLOW model. The results indicate that the groundwater level for the future period may change by - 6% to + 3.7% on average as compared to the base period. Considering the possibility of a reduction in groundwater level in the future and the downward trend of groundwater level during the base period, some strategies were suggested to reduce groundwater extraction and artificial recharge and increase irrigation efficiency in addition to combined strategies to adapt to climate change. In 6 of the 8 used models and scenarios, increasing irrigation efficiency could significantly improve the groundwater level compared to the base period. This study's results can be expanded and applied to research on other coastal aquifers with insufficient data sets or models.