Seasonal dynamic of a shallow freshwater lens due to irrigation in the coastal plain of Ravenna, Italy

Vandenbohede, Alexander; Mollema, Pauline N.; Greggio, Nicolas; Antonellini, Marco

Seasonal dynamic of a shallow freshwater lens due to irrigation in the coastal plain of Ravenna, Italy | Dynamique saisonnière d’une lentille d’eau douce sous l’effet de l’irrigationdans la plaine côtière de Ravenne, Italie Dinámica estacional de una lente somera de agua dulce debido a la irrigación enla planicie costera de Ravenna, Italia 意大利Ravenna (拉文那) 沿海平原灌溉造成的浅层淡水透镜体季节性动态变化 Dinâmica sazonal de uma lente pouco profunda de água doce devido a rega naplanície costeira de Ravenna, Itália

2014

Vandenbohede, Alexander | Mollema, Pauline N. | Greggio, Nicolas | Antonellini, Marco

Irrigation in low-lying coastal plains may enhance the formation of fresh groundwater lenses, which counteract salinization of groundwater and soil. This study presents seasonal dynamics of such a freshwater lens and discusses its influence on the salinity distribution of the unconfined aquifer in the coastal plain of Ravenna, Italy, combining field observations with numerical modeling (SEAWAT). The lens originates from an irrigation ditch used as a water reservoir for spray irrigation. The geometry of the freshwater lens shows seasonal differences because of freshwater infiltration during the irrigation season and upconing of deeper saltwater for the remainder of the year. The extent of the freshwater lens is controlled by the presence of nearby drainage ditches. Irrigation also results in a temperature anomaly in the aquifer because of the infiltration of warm water during the irrigation season. The surficial zone in the vicinity of the irrigation ditch is increased considerably in thickness. Finally, different irrigation alternatives and the influence of sea-level rise are simulated. This shows that it is necessary to integrate irrigation planning into the water management strategy of the coastal zone to have maximum benefits for freshening of the aquifer and to make optimal use of the existing infrastructure.

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