Exfiltration and re-infiltration of groundwater

Exfiltration from groundwater is calculated only for those grid cells which are marked as river cells in the river width and river depth grids. When the groundwater in such a cell is hiugher than the elevation of the river bed (DEM minus river depth value compared to groundwwater table depth), base flow will be generated by exfiltrating water from the groundwater into the river

For calculating river water re-infiltration into the groundwater, the so-called "link-grid" is required as an additional grid. This grid contains for each routing channel the code of the tributary river, so that the model always can track the amount of water available for re-infiltration (water from the inbetween area is not available in the channel yet!).

The river widths and depths as well as the routing paths can be determined using the WaSiM-Help Tool TANALYS or similar programs. Of course, if there are profile data available, these may be used instead of the automatically created river depth and widths.

Details on calculating re-infiltration from rivers and exfiltration from groundwater into rivers can be found in the WaSiM model documentation.