GEOG 4350 GEOMORPHOLOGY LAB 6. NORTH TEXAS FLOODPLAINS.

May 2015 was an unusually wet month in North Texas:

May
"normal" = 5.11"		 Date Rain
5/05
5/06
5/07
5/08
5/09
5/10
5/13
5/17
5/20
5/21
5/22
5/23
5/24
5/25
5/26
5/27
5/28
5/29
5/30

Total 		0.12"
0.21"
2.14"
0.21"
0.43"
2.76"
0.94"
0.53"
0.50"
0.37"
0.03"
0.17"
0.95"
0.71"
0.50"
0.03"
1.08"
1.66"
2.10"

15.44"

The rainfall total for the month was over 3 times the average for May and was the all-time wettest month on record for Texas. Not surprisingly, widespread flooding occurred throughout North Texas.

flooded trinity
The Trinity River in Dallas, May 29, 2015.

In the Denton area, many creeks and rivers overtopped their banks and flooded their floodplains. The following images show a local example - Clear Creek, a few miles northeast of Denton. Find Clear Creek and the locations shown below on your map (note: A and B are the end points of the topographic profile across Clear Creek).
CLEAR CREEK MAP:

clear creek map

These photographs were taken on May 20th, 2015.

cc1
Intersection of Green Valley Rd and Sherman Drive (FM428) looking southwest across floodplain. The road is elevated 2-3 m above the floodplain (which is clearly flooded).

cc2
View west across floodplain from near location 1 above.

cc3
Elm Bottom Rd runs across the floodplain - here it is flooded and closed.


cc4
View east across the floodplain from half way across the floodplain.

cc5
View of Clear Creek from the bridge.

cc6
Another view of the bridge showing flood water spilling from the channel over the floodplain.

dry clear creek
Clear Creek on a "normal" day (use the power lines to compare to the photos above).

ELM FORK OF THE TRINITY RIVER MAP:
Elm Fork map
Map of the Elm Fork showing end points (A and B) of topographic profile.

topo1

However, unlike the map, the profile also has a vertical scale determined by the Y-axis. For example if the Y-axis is 1 inch = 200 feet, this is a vertical scale of 1:2,400 (1 inch = 2400 inches).

Because of this, profiles usually have vertical exaggeration (vertical scale is larger than horizontal scale). In the example above, the vertical exaggeration is 24,000/2,400 = 10x.


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