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Geomorphology of Cheyenne Bottoms
Geomorphology
Source of water to the bottoms is completely limited to precipitation with in
the Upper Cow River Drainage Basin (Appel and Jacob, 1959). This supply of water
available to the basin occurs first in the form of stream discharge then as the
water pools it moves across the basin by sheet flow. Sheet flow is also known as
laminar flow, surface runoff, and overland flow but will be referred to as sheet
flow for this report. Intermittent streams such as Blood Creek and Deception
Creek discharge directly into the Bottoms and are the primary natural inlets of
the basin. The two creeks enter the flats and pools and start to flow over the
bottoms in a general sheet flow migration south and east. Sheet flow is defined
as a thin layer of water moving across a surface without the formation of
concentrated streams of water. It is only in modern times which management
practices have turned the sheet flow into channeled flow.
The initial process that occurs when this precipitation enters the bottoms is
for the velocity of intermittent streams to slow rapidly and enter pools and
small lakes. With a change in the rate of flow, the carrying capacity of
sediment is thus changed. Carrying capacity is conceptual term defined as the
amount of sediment a stream can transport under the given flow conditions. It is
opinion of the author that the process of carrying capacity is by far the most
important geomorphologic process at Cheyenne Bottoms. This process can be seen
by the ephemeral storm events. The precipitation in the river basin is generally
associated with quick short lived thunderstorms dumping larger amounts of
precipitation in a relatively small amount of time. Sediment is carried in with
the storm events and settles on the basins floor. There are three main natural
components that this study focuses on: the overbank natural levee forming
process along the stream channels, the deltaic nature of the stream/pond
interface, and the sheet flow across the flat topography of the basin.
Soil
A brief analysis of the soil was noted in September, 2004. An exposure of one
type of the basin's many complex soils was seen along a drainage canal that was
built to drain the marsh area below the Nature Conservancy. Upon clearing the
soil, a Mollic Epipedon was observed at the A horizon. This was approximately 48
inches thick from the surface. The root zone extended through out the profile,
although they tend to be with in the top 70 cm. The most notable feature, which
would be expected to be in a wetland area that experiences repetitive wet-dry
cycles, was remnant mud cracks fill. These are vertical filled in cracks deep
into the C horizon contains material the same color as the A horizon. However,
absence of pressure faces or slickensides on the pedo-structure surface is
evidence that this is no longer an active vertic soil. Although presence of the
deep mud cracks is evidence that this is (or was) a vertic-molisol.
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Soil profile taken along a drainage ditch. The flags marks the gradual
boundaries between the O horizon, A horizon, and C horizon. A prominent vertical
crack is seen just left of the trowel. The interpretaion of this feature is the
remains of past mud cracks. Photo date 9/04, © S. W. Salley |
| The 'mud cracks' were seen all along the exposed section. These cracks
contain material that fell into the expansion cracks during a dryer period.
Photo date 9/04, © S. W. Salley |
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Small Aerial Format Photography
Cheyenne Bottoms, with its flat topography, poses problems with viewing the
geomorphic patterns from the ground. To view the topography a selection of Kite
Aerial Photography and Blimp Aerial Photography was picked to show elements of
the drainage patterns near the Nature Conservancy.
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Low oblique view of the upper marsh in the Nature Conservancy land. This
picture, taken after a storm event, shows sedimentation pouring into the basin
from tributary Blood Creek. Photo taken by J. S. Aber, 3/03, used with permission.
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Low oblique view of the artificial dam with walk way created to divide the
upper marsh. The this damn and some cattails have created a barrier for the
sediment. Photo taken by J. S. Aber, 3/03 used with permission.
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Elevation Modeling
Digital Elevation Models (DEM) obtained from the USGS National Elevation Dataset
(NED) were used to see the drainage relationship and the surficial features. To
show the position of the Galatia Channel, the overlaid Pleistocene deposits were
draped onto the DEM to see relationship between the two drainage basins. The
extent of the deposits were taken from Fent (1950).
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DEM showing the general topography of the Cheyenne
Bottoms basin. View to the north-east. VE = 15x (DEM Data acquired
from NED and processed by S. W. Salley ©, 11/04) |
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DEM showing upstream of the paleo-drainage above the Bottoms across the
Galatia Channel and into the Smoky Hills River. VE = 15x (DEM Data acquired from
NED and processed by S. W. Salley ©, 11/04) |
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DEM showing the geomorphic position of Cheyenne Bottoms and the Smokey Hill
River. The Galatia Channel (outlined in blue) rests on the drainage divide
between the two very different geomorphic zones. (DEM Data acquired from NED and
processed by S. W. Salley ©, 11/04) |
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