Southern Mediterranean has been considered one of the most vulnerable coastal areas in the world due to flooding episodes, especially in low-lying coastal plains and deltaic areas (Nicholls et al., 1999). During de recent decades, coastal areas are experiencing rapid socio-economic development and hence a population increase. Infrastructures and social activities can be particularly affected. Groundwater inundation is poorly recognized and frequently confused with surface water floodings (Hughes et al., 2011). Rotzoll & Fletcher (2013) highlighted the importance of having a detailed understanding of groundwater level spatial distribution and the processes that control changes in water-table height throughout the coastal zone. This research evaluates the response of Motril-Salobreña aquifer to flooding on the deltaic plain of the Guadalfeo river. Periodic floods occur on this area and it causes ecological damage to a wetland nature reserve “La Charca de Suárez” and economic damages to: buildings, crops, and industry and tourism sector.
From February 2018 to April 2019, continuous water table data had been compared with precipitation, sea level, wind direction and sea wave height records. During the measurements period, several flood episodes took place and they could be related with water level rises registered in the piezometers.
Our results showed that water table lift plays an important role in the permanence of these floodings. A higher water table reduces the unsaturated zone and hinder surface infiltration, increasing overland runoff. The high water table events can be generated by: i) the lowering of atmospheric pressure that rises sea level. ii) Precipitation. The thin unsaturated zone favours the fast rising of the water table after rain events. iii) Wind speed and direction. East and southwest winds produce large waves which drive seawater inland and producing a local rise of sea level. Therefore, different types of inundation can be detected on the basis of the dominant factor with variable effect depending on the area.