Automatic calibration of a 3D groundwater model ...

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

Automatic calibration of a 3D groundwater model applied to the Muravera-Flumendosa coastal aquifer (SE Sardinia, Italy)
Paper
Author:Giuditta Lecca <giuditta@crs4.it> (Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy, Area of Hydrology & Water Resources Management)
Pierluigi Cau <plcau@crs4.it> (Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy, Area of Geographical Information System)
Federica Ardau <ardauf@unica.it> (University of Cagliari, Italy, Department of Territorial Engineering)
Presenter:Giuditta Lecca <giuditta@crs4.it> (Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy, Area of Hydrology & Water Resources Management)
Date: 2006-06-18     Track: Special Sessions     Session: Modeling and managing coastal aquifers
DOI:10.4122/1.1000000329
DOI:10.4122/1.1000000330

The performance evaluation of a groundwater model is a complex task due to the wide heterogeneity of hydrogeological properties, the scarcity of appropriate field data and the variability of boundary conditions. In this study an automatic calibration procedure has been developed and applied to the 3D groundwater model of the Muravera- Flumendosa coastal basin. The aquifer is threatened by seawater intrusion due to groundwater overexploitation and reduced replenishment. Aim of the study is to improve the understanding of the groundwater degradation mechanism in a complex hydrodynamic environment (diverted upstream surface waters, lagoons and channels) and to support the decision between alternative remediation scenarios. Field data are mainly represented by piezometric heads and salt concentrations and only for a very limited extent by hydraulic conductivity measurements. The finite element CODESA-3D model has been applied to simulate 3D density-dependent groundwater flow and contaminant transport in the subsurface. Inflow boundary conditions and aquifer recharge have been estimated on the basis of the distributed hydrological SWAT model calibrated against monthly streamflow data. Finally, the PEST model-independent tool has been instructed to calibrate hydraulic parameters of the groundwater system against head data in an iterative fashion. Software system integration issues, on the one hand, and data uncertainty, sensitivity analysis, and calibration rules, on the other hand, are carefully reviewed and described. Model calibration procedure has shown to be a highly demanding, although computationally feasible, task.