River Neretva Coastal Aquifer System Perspectives under the Climate Changes Impact and Mitigation Measures Implementation: Modelling and Vulnerability Assessment

Sea water intrusion (SWI) has been evidenced as a mechanism influencing ground and surface water bodies in coastal aquifer systems along the Mediterranean. During the past, SWI has been monitored either modeled leading to the unique conclusion coastal systems are significantly affected by the decrease of the natural water quality thus resulting in the reduction of agricultural production in these areas.

Neretva coastal system is located in the southeastern Croatia, at the coast of the Adriatic sea. The area is mainly arable, offering in total 4300 ha of land found within three melioration sub systems. Along the hydrological year two main periods are recognized, rain and dry one, creating different local conditions and resulting in variable salinity regimes of ground and surface water.

Following climate changes influence, we demonstrate spatio temporal salinity features driven by the increase of the sea water elevation and reduction in precipitation as found along the area of interest. As a baseline, SEAWAT has been used to conduct a 3D variable density model to mimic local conditions observed by the local monitoring system. After the model calibration and verification performance, implementation of the climate induced changes has been performed. For the purpose of simultaneous effects of SWI and climate change mitigation to control the groundwater salinity, specific mitigation measures have been tested in the laboratory conditions and afterwards implemented into the model.

To demonstrate the potential of applied mitigation measures and climate changes in the same time a modification of the GALDIT method has been applied to assess the SWI vulnerability along the Neretva valley coastal aquifer system. Our study presents a data based and reliable baseline for future water management of the study area.