APPLICATION OF THE METHOD GALDIT FOR THE CARTOGRAPHY OF GROUNDWATERS VULNERABILITY: AQUIFER OF CHAOUIA COAST (MOROCCO)

This study focuses on the application of the new method, GALDIT, for the cartography of aquifer vulnerability due to seawater intrusion in the area of Chaouia coast (Morocco) which is characterized by intense agricultural activity and low depth of the groundwater. The method was developed by Chachadi and Lobo-Ferreira in 2001 after that modified in 2005 and is specific for coastal aquifers. The computing of the GALDIT index (GI) is based on six parameters: Groundwater occurrence (aquifer type); Aquifer hydraulic conductivity; Depth to groundwater level above the sea; Distance from the shore (distance inland perpendicular from shoreline); Impact of existing status of seawater intrusion in the area; and Thickness of the aquifer. This GALDIT is the indicator scores and summing them and dividing by the total weight for determining the relative role of each one. The results of this study show a vulnerability of the aquifer to the seawater intrusion with a high risk in the fringe littoral areas and areas in proximity to the estuary of Oum Er-Rbia River and can reach 3 km towards land.