Integrated Surface Water-Groundwater Modelling

Abstract

Two Integrated Surface water - Groundwater flow Models (ISGMs) have been developed at the National Technical University of Athens (NTUA), Greece and Cardiff University (CU), UK to investigate surface water-groundwater interactions. The models are based on physical processes and are capable of describing more accurately the recharge and discharge flow paths between surface and ground waters. The NTUA ISGM consists of a 3-D surface water flow sub-model (FLOW-3DL) and a 3-D saturated groundwater flow sub-model. The CU ISGM is based on the 2-D surface water model DIVAST, which has been extended to include 2-D saturated groundwater flow. Both models use the finite difference method and orthogonal grids. The momentum and mass conservation equations are the governing equations for both surface and groundwater flows. The ISGMs have been applied to two simple cases and their results have been compared to computations using only surface water models (FLOW-3DL and DIVAST) to demonstrate the need to use ISGMs for accurate and satisfactory calculations. Furthermore, the results of the two ISGMs are compared for a channel, which fully penetrates an aquifer. The two ISGMs show a similar behaviour; the NTUA ISGM exhibits a slightly slower response of the aquifer water levels to the water level changes in the channel than the CU ISGM.