Ground water contribution to surface water can be in the form of base flow to rivers and streams, submerged springs or seepage of ground water into coastal zones.
http://dep.state.fl.us/geology/programs/hydrogeology/sur_wtr_grd_wtr.htm
The USGS has estimated the average of ground water contribution to surface water in the US to be over 40% (Ground Water and Surface Water-A Single Resource, USGS Circular 1139, 1998).
http://dep.state.fl.us/geology/programs/hydrogeology/sur_wtr_grd_wtr.htm
Investigate ground-water contribution to surface water via springs and seeps, including seepage of groundwater in coastal zones; support data collection and modeling efforts that address karst hydrogeologic settings; quantify interactions for regulatory purposes. 1  Applied Geosciences Services Home.
http://dep.state.fl.us/geology/programs/hydrogeology/sur_wtr_grd_wtr.htm
Water Interaction. Groundwater and surface water are essentially one resource, physically connected by the hydrologic cycle. Although water law and water policy often consider groundwater and surface water as separate resources, groundwater and surface water are functionally inter-dependent. Groundwater and surface water interactions are controlled by their hydraulic connection.
http://www.water.ca.gov/groundwater/groundwater_basics/gw_sw_interaction.cfm
Traditionally, management of water resources has focused on surface water or ground water as if they were separate entities.
https://water.usgs.gov/ogw/gwsw.html
In many situations, surface-water bodies gain water and solutes from ground-water systems and in others the surface-water body is a source of ground-water recharge and causes changes in ground-water quality.
https://water.usgs.gov/ogw/gwsw.html
Hydraulically Connected Systems. If the groundwater table is in physical contact with the stream bed, it is a hydraulically connected system. The exchange of water between the groundwater system and a stream is controlled by the difference in elevation between groundwater table and the water level in the stream.
http://www.water.ca.gov/groundwater/groundwater_basics/gw_sw_interaction.cfm
Ground-water interaction with surface water is a natural phenomenon dictated by the fact that the two water media are critical components of one system that some workers in this field have described as a three-dimensional watershed.
http://dep.state.fl.us/geology/programs/hydrogeology/sur_wtr_grd_wtr.htm
As a result, withdrawal of water from streams can deplete ground water or conversely, pumpage of ground water can deplete water in streams, lakes, or wetlands. Pollution of surface water can cause degradation of ground-water quality and conversely pollution of ground water can degrade surface water.
https://water.usgs.gov/ogw/gwsw.html
As development of land and water resources increases, it is apparent that development of either of these resources affects the quantity and quality of the other. Nearly all surface-water features (streams, lakes, reservoirs, wetlands, and estuaries) interact with ground water. These interactions take many forms.
https://water.usgs.gov/ogw/gwsw.html
what is the interaction between surface water and groundwater in a watershed?
Three dimensional interaction is between surface water and groundwater in a watershed.