ECOMANAGE Integrated Ecological Coastal Zone Management System Deliverable 2.8 Groundwater modeling of the sedimentary aquifer on Santos Estuary basin using GIS mapping of hydrogeologic parameters

Abstract

This report aims the presentation of the conceptual model, the mathematical model, and the computed results that allowed the quantification and mapping of the groundwater flow discharge, per kilometre of coastal line, towards Santos Estuary, in Brazil. The physical data of the Santos Estuary watershed is presented in terms of geology, hydrogeology, altimetry and precipitation. From the results it can be concluded that groundwater discharge to Santos Estuary depends on the watershed location, area and land use. Flow discharge is lower on a well drained basin, because groundwater contributions are mainly to the drains. There is a high fresh water discharge to the Atlantic Ocean, from Praia Grande and Santos area. Lower values are related with crystalline rock outcrop and small islands. Total groundwater discharge to the land-Estuary boundary from precipitation is about 8%, besides, other 17% flows as base flow to the drains. From the simulation it can be concluded that Boturoca watershed, São Vicente and Santo Amaro Island are the main contributors of fresh water from the sedimentary aquifer to the estuary. The results showed important groundwater discharges, higher from January to May. Lower discharges to the estuary were observed in Cubatão watershed. In this basin groundwater from the sedimentary aquifer flows to the drains and, afterwards as surface water, to the estuary.