A Methodological approach for the effective infiltration assessment in a coastal groundwater

Abstract

Accurate estimates of spatial and temporal distribution of groundwater recharge are of utmost importance to protect groundwater systems. In coastal areas, the fragility of the systems makes such estimates critical for the correct management and protection of water resources from saltwater intrusion. The Muravera coastal plain, in the south-eastern Sardinia, has been studied since 1960, due to important saltwater intrusion phenomena. Since the early fifties, the natural hydrodynamic equilibrium between groundwater, surface-water and seawater has been deeply modified by the construction of four dams across the Flumendosa river and the development of agriculture, tourism and aquaculture activities along the coast. To implement an integrated and sustainable management system addressed to slow down the process of saltwater intrusion and, on the other, satisfy human requirements, it is important to develop a flexible scenario analysis system that considers changes of land-use and inputs to the hydrogeological system, also in relation to climate change. In this study, the innovative Soil Water Balance code (SWB) has been applied to the Muravera plain groundwater body to calculate spatial and temporal variations of groundwater recharge. The code calculates the recharge (R) by using geographic system (GIS) data layers in combination with tabular climatological data. It is based on a modified Thornthwaite - Mather soil water balance approach, with components of the soil water balance calculated at a daily time-step. A combined experimental approach of hydrogeological, satellite remote sensing and pedological methodologies has been applied to derive data layers describing local features of: (1) land-use classification, (2) hydrologic soil group, (3) flow direction, and (4) soil-water capacity. The code has proved to be promising for the effective infiltration assessment and it can be easily updated with high resolution data acquired in the field and from satellite images.