Présentations Colloques

Oral Presentation
Session 8.05: Karst aquifers
Farid Achour
Conjunctive Water Supply Management through the Calibration of a Discrete Continuum Flow Model in a Fractured Karstic Aquifer. Example of the Castel De Vide Aquifer (Portugal)
The Algarve region, south of Portugal, is one of most tourist destination in Europe. Its population triples during the peak holiday season, and it receives an average of 7 million tourists each year. As its popularity grows, so does the demand for water. Due to the overexploitation of existing aquifers and climate change, the availability of water in the region keeps decreasing. ** **The Castelo De Vide Aquifer is a karstic aquifer located in Algarve. This aquifer has always been critical for Algarve’s water supply program. This is particularly evident by looking at the water shortages that happened due to the severe drought that affected Portugal in 2004 and 2005. During this drought, the water levels of the large dams used by Algarve’s Water Agency were severely depleted causing the water supply program to be entirely dependent on groundwater resources. The future water use in this region should be supported by integrated schemes of water management, including the conjunctive use of surface water and groundwater. Numerical models, such as the one presented in this paper, are fundamental tools for regional water use planning.****A 3-D discrete continuum finite element groundwater & surface water flow model was built, in which fractures zones were discretely incorporated into the continuum model of groundwater flow by injecting high hydraulic features to the finite model element grid. Three sectors were defined in the Castelo de Vide karst aquifer, with different degrees of hydraulic connectivity with the aquifer discharge areas in an initially defined “artificial conduit network”, controlling flow at aquifer scale. These sectors were identified by the detection of regional trends in the spatial distribution of hydraulic heads. This procedure yielded remarkably positive results in the simulation of the aquifer hydraulic behavior in both steady state and transient simulations. This proved that modeling systematic regional anomalies in the spatial distribution of hydraulic head gradients is a useful tool in the management and protection of water resources in karstic areas.**
United States