Surface water bodies are hydrologically connected to groundwater in most types of landscapes; as a result, surface-water bodies are basic parts of groundwater flow systems. Therefore, the main goal of this research is to develop a prototype model to investigate stream-aquifer interactions based on two-way mass balance simulation driven by level difference.
Feedback Models for Hydrological systems
Supervisors: George Bier, Paul Torfs
Open water bodies are hydrologically connected to groundwater in most types of landscapes; as a result, surface-water bodies are basic parts of groundwater flow systems. Therefore, it is of importance to understand the interaction mechanisms between groundwater and surface water. Mostly, the interaction between open water and groundwater can be performed using groundwater models (i.e MODFLOW) in the form of computer codes.
However, these computer codes are inefficient use of rectangular grids to represent complex geometries. Beside, investigation of the interaction between opens water and groundwater in such codes taken as cascade-equilibrium-reservoir, which completely neglects backwater effects. In flat catchments this effect is substantial for interaction between groundwater and open water.
The purpose of this research is to develop a prototype model to test the interaction processes on recently developed packages of FVflow1D and FVflow2D (Torfs, 2011). Such function based model that is technically easily executable codes allows degree of flexibility for the modeller to represent complex geometries and take into account backwater effect in the process of interaction.
Preliminary results showed that both stationary and transient application of FVflow1D and FVflow2D capable of calculate 99.99% exchange fluxes (including backwater) based on level difference and two-way mass balance. The coupling model also tested with ten percent increment and decrement for 23 parameters. The exchange flux and net boundary discharge varies non-linearly to interaction resistance and manning coefficient.
The coupled model proves that the exchange flux and net boundary discharge are most sensitive to exchange resistance and open water bottom width. While, less sensitive to change in river bed slope, upstream height, weir threshold and manning coefficient.