Surface Water Interaction Modelling Using Visual MODFLOW and GIS

PHYLARESResults and Discussion / ch.8_________________________________________________________________________________58Figure 8. 5 Equipotential head for layer 38.3 Groundwater - Surface Water InteractionsAquifers are often partially fed by seepage from streams and lakes. In other locations, thesesame aquifers may discharge through seeps and springs to feed the streams, rivers, andlakes. The exchange of flow between the aquifer and river at different locations has beenmodeled to find out the groundwater and surface water interactions. The interactions mainlydepend on the difference of the water level in the river and in the underground reservoir andaquifer materials in the river-banks and in the bed of the rivers. When the aquifer water level isnear land surface, seepage from the river is partially controlled by the height of the aquifer waterlevel. Activities or events that result in a lowering of the water table, such as ground waterpumping, induce more seepage from the river. Conversely, events that cause the aquifer waterlevel to rise (recharge events) will result in a decrease in river seepage. If aquifer water levelsrise above the level of the river, what was previously a losing river reach will become a reachthat is gaining water from the aquifer.______________________________________________________________________________________Groundwater – Surface water interaction modeling using visual MODFLOW and GIS