Integrating GIS and RDBMS technologies during construction of a regional groundwater model

Abstract

Finite difference groundwater flow models like MODFLOW require cell-by-cell averages for a myriad of parameters. In reality, the data a modeller uses comes from many sources in a variety of formats. Point measurements from boreholes are a critical dataset and can be combined with lines (eg water level and structural contours), polygons (eg surface geology and land use maps) and rasters (eg Landsat imagery). Firstly, the modeller needs a working environment to store, integrate and analyse these datasets and to derive the cell-by-cell model input. Secondly, the model output needs to be compared with the original source data that describes the real world. Borehole information is typically stored in a relational database management system (RDBMS) and geographic information systems (GIS) are designed for managing spatial information. These technologies have been used as the working environment for the Lower Darling model, which is a large regional groundwater flow model within the Murray Geological Basin, southeast Australia. Different strategies were developed to manipulate the available data into MODFLOW input files and also for the modelled heads and flows to be compared with field observations. Some of these strategies are specific to the Lower Darling model, but others are generic and can be easily applied in the data manipulation and calibration of groundwater models for regional aquifer systems.