Remote sensing techniques to monitoring coastal plain areas suffering from salt water intrusion and detection of fresh water discharge in coastal, karstic areas: Case studies from Greece

This study aims to present remote sensing applications in monitoring coastal areas. It briefly describes the use of up-to-day remote sensing technology, applied to geosciences for multitemporal and multispectral monitoring of the environment, from geological point of view. It also gives emphasis: i) to detection and delineation of areas in coastal depositional landforms (plains) suffering from salt water encroanchment (intrusion), usually resulted from water overpumping, by the use of multitemporal satellite images where the geobotanical anomalies are shown (salt-tolerant plants, or halophytes, as plant indicators), and b) to delineation of water discharge zones along the coastal erosional rocky, mainly karstic, areas by the use of satellite thermal infrared images. The study also focuses on salt water intrusion in coastal areas where it becomes a hydrogeological issue which causes problems to cultivation. One other hydrogeological issue, is the discharge of significant unused quantities of ground water, in coastal areas. In our Laboratory, efforts have taken place to detect and delineate these coastal areas, with the help of LANDSAT-5/TM satellite images (30 in. resolution). With certain digital processing techniques of the above images, areas which are "suffering" from salinity are located in the coastal areas of Pieria prefecture (Macedonia Province, Greece). Furthermore, with the help of the TM6 band (thermal infrared), of LANDSAT-5 satellite, fresh water springs were also detected in the coastal areas, of the Gulf of Itea (Central Greece). The above findings can help hydrogeologists to locate areas suffering from salt water intrusion and coastal areas where ground water discharge takes place.