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Surface Water and Ground Water Interaction
DIVISION OF WATER
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ENT OF NATURAL RESOURCES
Ohio Department of Natural Resources
Division of Water Fact Sheet
Fact Sheet 9743
Surface Water and Ground Water Interaction
Continued on back!
aquifer.
This water is free to move laterally (again under the
influence of gravity) following the slope of the me-
dium containing the aquifer. Travel rates will vary
depending on the material and are generally much
slower than surface water velocities. Typically, coarser
grained material will transmit water more readily than
finer grained material.
Over time ground water will travel to the surface.
Groundwater is discharged to the surface through
several ways. Such examples would be the formation
of natural springs, discharge to river and stream banks,
discharge under river and stream beds, or direct dis-
charge into the ocean. Where and how groundwater is
discharged to the surface depends on the water table.
Surface water will appear where the water table inter-
sects the surface topography.
Losing and Gaining Streams
Many streams (including rivers) throughout Ohio are
strongly influenced by ground water. As streams flow,
their primary source of recharge is precipitation. Dur-
ing times of drought or low precipitation streams may
rely totally on ground water input.
Ground water contribution may range from zero to
100% of normal flowing streams. Depending on the
height of the water table and discharge of ground
water, the contribution to the stream will vary. Along
certain stretches of a stream path, ground water may
discharge into the stream and the volume of the stream
increases. This is called a gaining stream. Conversely,
certain streams may overlie a deeply buried water
table. During dry or arid conditions, water may seep
from the stream down to the water table causing a
reduction in the flow volume of the surface water. This
is called a losing stream. Annually, Ohio has humid
conditions, so water tables are generally high and
losing streams are not common.
T
here is only a finite quantity of water on the
Earth. Of that quantity, only a limited amount is
available for human consumption. Roughly
98% is saline and is found in the oceans. The last 2%
is fresh water found mostly in the atmosphere and
locked up in glaciers. Drinkable water in lakes, rivers,
and ground water only accounts for less than 2% of the
planets fresh water reserves. Because we have a small
amount of consumable water, it is key that we know the
mechanisms of how and where water flows.
Hydrologic Cycle
Ground water and surface water are intimately linked
through the hydrologic cycle. The hydrologic cycle is
a global phenomenon in which water continuously
moves through an intricate system. We will begin our
simplified explanation of the cycle at the oceans be-
cause they are the largest reservoirs of water on the
planet.
Water from the oceans evaporates as a result of
energy received from the sun. The water vapor even-
tually condenses to form clouds, some of which get
blown landward. Once over land, if the condensation
of the water vapor exceeds what the cloud can hold,
precipitation will occur. Some precipitation will re-
evaporate, some is absorbed by plants, and some
infiltrates into the soil. When precipitation exceeds the
rates of evaporation and infiltration, runoff into lakes,
streams, and oceans starts. Eventually ground water
and surface water find their way back to the oceans,
thus completing the cycle.
Ground Water Basics
Recalling the hydrologic cycle, lets examine in
greater detail the time following infiltration of the soil.
Relatively small amounts of water can infiltrate below
the surface. Water that does infiltrate will fill any
subsurface pore spaces, cracks, or crevices. The water
will continuously travel downward under the influ-
ence of gravity until an impermeable layer is reached.
Water will continue to stockpile above the imperme-
able layer to create a large underground storage, or I 10/14/97
Bob Taft
Governor
Samuel W. Speck
Director

James R. Morris, P.E.
Chief
Sensitivity of Ground Water Recharge Areas
As the hydrologic cycle reveals, groundwater is re-
charged primarily from precipitation. Precipitation
that is actually converted into ground water depends on
numerous factors. Such factors include the topogra-
phy of the land, the nature (permeability) of the soils,
the intensity and frequency of precipitation, and the
density of vegetative cover.
Areas that have much precipitation, easily permeable
soil, a low density of vegetative cover, and little relief
are conducive for ground water recharge. These areas
must be watched closely because any pollutant dis-
carded in these areas can be rapidly transferred to the
ground water aquifer. Once the contaminant is in the
aquifer, it travels with the ground water and is eventu-
ally discharged to surface water. Soils and rock may
act as a limited filter for contaminants. Once these
natural filters are overcome with excessive concentra-
tions of pollutants, discharge to surface water is un-
avoidable.
Summary
We have seen that water resides in the ground and on
the surface, and examined some interactions between
the two. Through knowledge of these interactions we
know that ground water and surface water are interwo-
ven through the hydrologic cycle. As humans we must
be aware of our influences on the natural environment.
We must be aware that whatever we place on the land
can affect our water supply either directly to surface
water or indirectly via ground water.
For more information on surface and ground water
interaction in buried valleys and other geologic set-
tings contact:
Ohio Department of Natural Resources
Division of Water
Water Resources Section
1939 Fountain Square
Columbus, OH 43224-1336
Voice: (614) 265-6739 Fax: (614) 265-6767
E-mail: water@dnr.state.oh.us
Web site: http://www.dnr.state.oh.us/water
This publication was financed in part through a grant
from Ohio Environmental Protection Agency under provi-
sions of Section 319 of the Clean Water Act as amended in
1987.