mammoth caves national park, kentucky a collection of webcams of the green river showing changes...

Mammoth Caves National Park, Kentucky

A collection of webcams of the Green River showing changes that occur on the landscape scale

throughout a year (from July 2007 to June 2008)

Teacher’s version:Includes narrative indicating what changes are visible

between webcam images.

• Vegetation growing on the sandbars in the river• Little distinction can be made between the different tree species during the summer.

• Trees that frame the webcam are deciduous but other species are presently indistinguishable.

• Sandbar outlined to show the change in size over next several slides, indicating a change in the discharge

• Vegetation continues to grow on the sandbars• Outlined sandbar is less exposed, indicating a rise in the water level (increase in discharge)

• River color is still the same as the last image – river sediment has not changed

• The sandbars in the river are at their greatest extent – river water level (discharge) is low

• Trees growing on the right slope are in the beginning stages of changing color

• Some haze in sky (notice clearness on next slide)

•Black line drawn on river marks the extent of the sandbar on the previous slide

Leaves are starting to change

Distinct leave color change

Noticeable differences in color Water level as indicated by the bank

•Vegetation on sandbar has changed to a brownish green color, another indication of the changing seasons

• 4 days after the last image• Heavy amounts of sediment in river - evidenced by

rich brown color

Water level

•Water level dropped – bank edge is visible (arrow)•Less sediment in river – color returning to a greenish hue

• Change of seasons makes it easier to see the complex series of slopes (drawn with black lines) within the valley

• Water level continues to drop – bank edge• Re-emergence of sand bar in river, indicating

drop in water level • Bare trees evident

Note different species of trees, based on leaf color

• Continued water level drop and emergence of secondary sand bar

• Increase in water level, gravel bars immersed • Deep red and orange leaves are most prominent now

Near absence of deciduous leaves remaining on trees

Evergreen trees are only trees left with leaves

• The river is noticeably greener indicating less sediment• Gravel bars are also re-emerging

• River flooding with a high sediment load caused the river to turn a sandy brown color

• The river is out of its bank with tree trunks in the water

The extent of the flooding increased from the last slide as more trees are now inundated with flood waters

A light covering of snow on the ground illustrates the extent of the flood

•15 days after the last image: •Flood waters have decreased•River is returning to a green hue

A heavier snowfall this time: again indicating the extent of flooding

The greatest flood event witnessed over a 12 month period with the flood waters at its greatest extent out of its banks

• Receding flood waters and a return of the natural color of the river

• A slight trace of spring green up can be found (arrow)

• River is flooding again• Spring green-up has begun• Note the budding of the tree in the foreground

over the next several images (arrow)

Pink buds are fading, to be replaced with leaves over the next several images

•Gravel bars just beneath surface, general outline visible

•Re-emergence of gravel bars

• Submergence of gravel bars due to flooding• Note high sediment load of river, evident from water color

The camera angle was adjusted slightly between May 3rd and May 6th (this webcam image).The flood waters have receded slightly (bank is visible (right arrow)Tree in foreground continues to leaf-out (left arrow).

Evidence of a recent flood is no longer visible in this image: the river is, once again, a greenish hue, the bank is visible, and sand bars in the middle of the river are slowly being exposed

The extent of sandbar exposure is similar to last year’s webcam image, indicating it is probably normal in the summer months