Constraining a 2D/3D density dependent saltwater ...

Object Details

View

XVI International Conference on Computational Methods in Water Resources (CMWR-XVI) Ingeniørhuset

Constraining a 2D/3D density dependent saltwater intrusion model using time-lapse electrical imaging data
Paper
Author:Arni Antonsson <arni@geol.ku.dk> (Geological Institut of University of Copenhagen)
Peter Engesgaard <pe@geol.ku.dk> (Geological Institut of University of Copenhagen)
P.I. Meldrum <pim@bgs.ac.uk> (British Geological Survey, Electrical Tomography Programme, Keyworth, Nottingham NG12 5GG, UK)
Andreas Kemna <a.kemna@fz-juelich.de> (Institue of Chemistry and Dynamics of the Geosphere, Forschungszentrum Juelich)
Frederic Nguyen <f.nguyen@fz-juelich.de> (Institue of Chemistry and Dynamics of the Geosphere, Forschungszentrum Juelich)
Oliver Kuras <oku@bgs.ac.uk> (British Geological Survey, Electrical Tomography Programme, Keyworth, Nottingham NG12 5GG, UK)
R.D. Ogilvy <rdo@bgs.ac.uk> (British Geological Survey, Electrical Tomography Programme, Keyworth, Nottingham NG12 5GG, UK)
Jose Gisbert <jgisbert@ual.es> (Department of Hydrogeology, University of Almeria, Spain)
Sara Jorreto <sjorreto@ual.es> (Department of Hydrogeology, University of Almeria, Spain)
Fransisco Sanchez Martos <fsanchesmartos@ual.es> (Department of Hydrogeology, University of Almeria, Spain)
Antonio Pulido-Bosch <apulido@ual.es> (Department of Hydrogeology, University of Almeria, Spain)
Presenter:Arni Antonsson <arni@geol.ku.dk> (Geological Institut of University of Copenhagen)
Date: 2006-06-18     Track: Special Sessions     Session: Modeling and managing coastal aquifers
DOI:10.4122/1.1000000485
DOI:10.4122/1.1000000486

In groundwater model development, calibration is one of the critical aspects that determine its reliability and applicability in terms of e.g. system (hydrogeological) understanding, groundwater quality predictions, and general use in water resources context. The result of a groundwater model calibration is determined by different factors, where both data quantity and quality is of crucial importance. A density dependent saltwater intrusion model has been established for a coastal aquifer in Almeria, SE Spain, where hydraulic and solute transport parameters had to be calibrated in order to simulate the intrusion dynamics realistically. Furthermore, the sources of saltwater in the coastal aquifer are not unambiguously defined yet but current state of knowledge seems to suggest the possibility of multiple sources e.g. present seawater intrusion, solution of evaporites, fossil waters and anthropogenic influences. Typically the availability of conventional monitoring installations (e.g. depth specific monitoring wells for Chloride measurements) and the cost of constructing new ones limit the amount of obtainable data. These factors can seriously hinder a successful monitoring strategy and consequently limit the reliability of the calibrated model. An effective alternative to conventional measurements is the use of geophysical methods to monitor the saltwater intrusion front. If applied in a time-lapse manner, electrical images give both spatial and temporal information on the salinity distribution compared to conventional methods, which only give (few) point information. As a result a more comprehensive understanding of the hydrogeological system is obtained and a greater confidence in the calibrated model is achieved. In this (case) study from Almeria, we demonstrate how the use of time-lapse electrical imaging data improve the calibration of a density dependent intrusion model compared to using data from conventional (existing) measurements installations. This was achieved by calibrating the model with the different data sets and subsequently evaluate the performance of the model. The results illustrate the benefit of using electrical images for calibration purposes but also its contribution to system understanding and how it, together with modeling, can assist in the identification of saltwater sources in the area.