Silver Creek Watershed EarthCache
Hidden : 12/9/2008
Difficulty:
1 out of 5
Terrain:
1.5 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:


Silver Creek near Ruthton


WHAT IS A WATERSHED?

A watershed is a drainage basin.*  It’s an extent of land where water from rain or snow melt drains downhill into a body of water, such as a river, lake, reservoir, estuary, wetland, sea or ocean.  The drainage basin includes both the streams and rivers that convey the water as well as the land surfaces from which water drains into those channels, and is separated from adjacent basins by a drainage divide.  The drainage basin acts like a funnel, collecting all the water within the area covered by the basin and channeling it into a waterway.  Each drainage basin is separated topographically from adjacent basins by a geographical barrier such as a ridge, hill or mountain, which is known as a water divide.

In the technical sense, a watershed refers to a divide that separates one drainage area from another drainage area.  However, in the United States and Canada, the term is often used to mean a drainage basin or catchment area itself.  Watersheds drain into other watersheds in a hierarchical form, larger ones breaking into smaller ones or sub-watersheds with the topography determining where the water flows.

*  Other terms that are used to describe a drainage basin are catchment, catchment area, catchment basin, drainage area, river basin, water basin and watershed.


GEOMORPHOLOGY


Understanding geomorphology is essential in understanding how watersheds interconnect.  In hydrology, the drainage basin is a logical unit of focus for studying the movement of water within the hydrological cycle, because the majority of water that discharges from the basin outlet originated as precipitation falling on the basin.  A portion of the water that enters the groundwater system beneath the drainage basin may flow towards the outlet of another drainage basin because groundwater flow directions do not always match those of their overlying drainage network.  Measurement of the discharge of water from a basin may be made by a stream gauge located at the basin's outlet.  Rain gauge data is used to measure total precipitation over a drainage basin, and there are different ways to interpret that data.  If the gauges are many and evenly distributed over an area of uniform precipitation, using the arithmetic mean method will give good results.  In the Thiessen polygon method, the watershed is divided into polygons with the rain gauge in the middle of each polygon assumed to be representative for the rainfall on the area of land included in its polygon.  These polygons are made by drawing lines between gauges, then making perpendicular bisectors of those lines form the polygons.  The isohyetal method involves contours of equal precipitation are drawn over the gauges on a map.  Calculating the area between these curves and adding up the volume of water is time consuming.

Drainage basins are important elements to consider also in ecology.  As water flows over the ground and along rivers it can pick up nutrients, sediment, and pollutants.  Like the water, they get transported towards the outlet of the basin, and can affect the ecological processes along the way as well as in the receiving water source.  Modern usage of artificial fertilizers, containing nitrogen, phosphorus, and potassium, has affected the mouths of watersheds.  The minerals will be carried by the watershed to the mouth and accumulate there, disturbing the natural mineral balance.

The catchment is the most significant factor determining the amount or likelihood of flooding.  Catchment factors are:
  • topography,
  • shape,
  • size,
  • soil type, and
  • land use (paved or roofed areas).

Catchment topography and shape determine the time taken for rain to reach the river.
Catchment size, soil type and development determine the amount of water to reach the river.


Watershed Topography



Topography
Topography determines the speed with which the runoff will reach a river.  Clearly, rain that falls in steep mountainous areas will reach the river faster than flat or gently sloping areas.

Shape
Shape will contribute to the speed with which the runoff reaches a river.  A long thin catchment will take longer to drain than a circular catchment.

Size
Size will help determine the amount of water reaching the river, as the larger the catchment the greater the potential for flooding.

Soil Type
Soil type will help determine how much water reaches the river.  Certain soil types such as sandy soils are very free draining and rainfall on sandy soil is likely to be absorbed by the ground.  However, soils containing clay can be almost impermeable and therefore rainfall on clay soils will run off and contribute to flood volumes.  After prolonged rainfall even free draining soils can become saturated, meaning that any further rainfall will reach the river rather than being absorbed by the ground.

Land Use
Land use will contribute to the volume of water reaching the river, in a similar way to clay soils, only faster.  Rainfall on roofs, pavements and roads will be collected by rivers with almost no absorption into the groundwater.


Basin Management Map



Kentucky River Basin



Kentucky River Subbasins



SILVER CREEK WATERSHED:  A Member of the Lower Subbasin of the Kentucky River Basin


Silver Creek Watershed is part of the Lower Subbasin of the Kentucky River Basin.  The Lower subbasin of the Kentucky River stretches from Madison County north to Carroll and Gallatin Counties.  The Silver Creek watershed covers much of southern Madison County.  Most of the upper reaches of the watershed lie in the outer subregion of the Bluegrass physiographic region, characterized by undulating terrain, moderate to rapid surface runoff, and moderate rates of groundwater drainage.  The southernmost section (around Berea) is part of the Knobs region, characterized by hilly terrain, very rapid surface runoff, and very slow groundwater drainage.  In level parts of the Knobs, runoff and groundwater drainage are slow.  The lower part of the watershed is in the hills of the bluegrass subregion of the Bluegrass physiographic region, characterized by hilly terrain, very rapid surface runoff, and slow groundwater drainage.  Parts of the watershed lie over interbedded shales and limestones (these are 20% limestone; water conduction is poor because of the clay content of the shale).  Other areas are underlain by interbedded limestones and shales (>20% limestone, allowing groundwater flow where the clay content is low enough).


Silver Creek Watershed



Waterways
Silver Creek empties into the Kentucky River near the western corner of Madison County.  Among the creeks that feed it are Terrill Branch, Brushy Fork, Hays Fork, Harts Fork, Elk Garden Branch, Taylor Fork, Bogie Branch, and Jackson Branch.


Land and water use
Land in the watershed is more than 75% agricultural, about 15% rural and wooded, and about 7% residential or commercial.  The surface waters of the watershed supply drinking water for the Berea College system.  Thirteen businesses and organizations hold permits for discharges into the creeks.


Silver Creek Watershed Detail


Silver Creek Watershed topography ranges from the Outer Bluegrass region in the north to the Knobs region in the area of Berea in the south.  The Outer Bluegrass proper, an area of hummocky, irregularly rolling hills and low ridges, is developed on Upper Ordovician limestones, siltstones, and interbedded shales of the Garrard Siltstone, Calloway Creek, Ashlock, and Drakes formations.  Because carbonates are more abundant in this part of the section, the topography is not steep and the soils are fertile.  Hence, farms are large, and both cattle grazing and burley tobacco are major sources of income.  The gently rolling hills and low ridges of the Outer Bluegrass proper continue up to the city of Berea, where the low-lying topography in and near the city abruptly gives way to a hilly and "mountainous" topography of conical hills and detached ridges known as the Knobs region of the Outer Bluegrass.  The Knobs form a horseshoe-shaped belt that surrounds the Bluegrass.  Near Berea, the Knobs are generally 300- to 600-feet high and are erosional remnants formed as streams cut into the Highland Rim, which defines the outer margin of the Bluegrass in east-central Kentucky.

Watershed Highlights
  • The Silver Creek watershed covers 126 square miles.
  • Provides some water for the Berea College water system.
  • Berea discharges treated sewage into the watershed.
  • Pathogens partially impair contact recreation in Silver Creek below Taylor Fork.
  • Aquatic life and secondary contact recreation (boating) are partially impaired in Wilgreen Lake by overenrichment.
  • Aquatic life partially impaired by sedimentation in Silver Creek between Taylor Fork and Harts and Hays Forks and by industrial point sources in Harts Fork at Ajax Magnathermic.
  • Aquatic life threatened in Hays Fork.
  • Water supply is an issue.
  • Groundwater substantially more sensitive than basin average.
  • Livestock density, potential for agricultural erosion, and unsewered population substantially above basin average.



DIRECTIONS
From exit 87 on Interstate 75, proceed west on Barnes Mill Road.  Turn right onto Bogie Mill Road and proceed to the earthcache.




DO NOT LOG AS A FIND UNTIL YOU HAVE A PICTURE READY TO POST.  To get credit for this EC, post a photo of you (I do not accept pictures of just a hand) at the posted coordinates with Silver Creek in the background (like my photo above) and please answer the following questions.
  1. What is the elevation at this location?
  2. How wide is Silver Creek at this location?
  3. What geographic region of Kentucky does the Silver Creek Watershed begin in?
  4. Where is flooding more likely, in the Knobs region near Berea or the rolling hills nearer the Kentucky River?

Do not wait for my reply to log your find.  I will contact you if there is a problem.  Logs with no photo of the actual EarthCacher/Geocacher (face must be included) logging the find or failure to answer questions will result in a log deletion.  Exceptions will be considered if you contact me first (I realize sometimes we forget our cameras or the batteries die).  Logs with no photos will be deleted without notice.  I have used sources available to me by using google search to get information for this earth cache.  I am by no means a geologist.  I use books, the Internet, and ask questions about geology just like 99.9 percent of the geocachers who create these great Earth Caches.

Reference:  Kentucky Geological Survey, and Conservation Ontario.


Congratulations to   WH1266FD   for the FTF!

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