Integrated Surface Water-Groundwater Modelling

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.