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#12539237 - 12/15/17 09:15 AM Can Someone Cross Check Figures
Donald Harper Online   happy
TFF Guru

Registered: 01/25/08
Posts: 14427
Loc: Justin, TX.
Looking at Choke Canyon:
- Want to know what Contour line to look at that will now be the shoreline as the lake is low.
- Something is not right when looking at the water level tables.
- Says the lake is at 30%.
- Another chart says it is 24.5 ft. below pool.
- That can't be right.

Thanks for your help.
Donald
_________________________
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#12539261 - 12/15/17 09:34 AM Re: Can Someone Cross Check Figures [Re: Donald Harper]
grout-scout Offline
TFF Celebrity

Registered: 12/08/08
Posts: 6894
Loc: Boerne, Texas
It’s right, very shallow water lake and if it drops 4’ it will be nothing but a river channel.


If you look at a navionics card then it might be screwed up, they seem to have surveyed the lake when it was 20’ low and there’s a lot of the map missing.

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#12539266 - 12/15/17 09:41 AM Re: Can Someone Cross Check Figures [Re: Donald Harper]
SkeeterHawk Offline
TFF Celebrity

Registered: 06/08/01
Posts: 5855
Loc: Garland,TX USA
There is a phone app out there called Lake Level. It shows Choke to be down 24.37 feet.

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#12539270 - 12/15/17 09:47 AM Re: Can Someone Cross Check Figures [Re: Donald Harper]
Slide_R Offline
TFF Celebrity

Registered: 05/31/03
Posts: 5287
Loc: Richardson
Here is a 5 ft interval contour map:
http://www.twdb.texas.gov/hydro_survey/chokecanyon/2012-06/ChokeCanyon_ContourMap.pdf

Look at the 195 ft contour and you should have the "Current" lake.
_________________________
Robert Oleson
aka Slide_R


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#12539282 - 12/15/17 09:57 AM Re: Can Someone Cross Check Figures [Re: Donald Harper]
epicoutdoors Online   content
Extreme Angler

Registered: 02/18/08
Posts: 1974
Loc: On The Water NE Texas
When looking at surface area v capacity, they are very different and the changes as a lake falls or rises will be very different from one lake to another depending on each lakes contours and depth.

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#12539301 - 12/15/17 10:08 AM Re: Can Someone Cross Check Figures [Re: Donald Harper]
Donald Harper Online   happy
TFF Guru

Registered: 01/25/08
Posts: 14427
Loc: Justin, TX.
All I need to know; looking at Nav. Apps. is:
- At what contour is the shoreline right now.
_________________________
Each person you work with holds some promise to your future success.
www.eletewater.com - Staying Hydrated
www.lakeoviachic.com - Booking Mexico Trips
Shallow Water Mapping - Custom Spinner Baits - Jigs -Spooks
Pure Extracts - Minnow-Night Crawler-Crayfish-Craylic



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#12539327 - 12/15/17 10:32 AM Re: Can Someone Cross Check Figures [Re: Donald Harper]
grout-scout Offline
TFF Celebrity

Registered: 12/08/08
Posts: 6894
Loc: Boerne, Texas
It would be easier to get on your graph and take off 25’ from the max/min water highlights.

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#12539335 - 12/15/17 10:34 AM Re: Can Someone Cross Check Figures [Re: Donald Harper]
DALE W Offline
Outdoorsman

Registered: 08/04/15
Posts: 42
Loc: College Station
At the current lake level the shoreline would be around 196’

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#12539421 - 12/15/17 11:23 AM Re: Can Someone Cross Check Figures [Re: Donald Harper]
DedShort Offline
Extreme Angler

Registered: 04/18/06
Posts: 2077
Loc: Decatur, TX
I understand your dilemma Donald. I found that when Falcon showed to be down (I don't remember exactly how many foot) if I set the offset on my Navionics app to match that supposed level, it was not correct for what the actual level of the lake was. I want to say that the difference in where it was supposed to be and where it was was either 7 foot or 17 foot. I spent weeks looking at my app in my spare time, planning my trip accordingly. When I got there, all of my planning went out the window because the lake was so much higher than I had anticipated.
_________________________
"Liberty is always dangerous, but it is the safest thing we have." - Harry Emerson Fosdick


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#12539547 - 12/15/17 01:39 PM Re: Can Someone Cross Check Figures [Re: Donald Harper]
Brad R Offline
Extreme Angler

Registered: 03/09/15
Posts: 1839
Loc: Texas
Originally Posted By: Donald Harper
Looking at Choke Canyon:
- Want to know what Contour line to look at that will now be the shoreline as the lake is low.
- Something is not right when looking at the water level tables.
- Says the lake is at 30%.
- Another chart says it is 24.5 ft. below pool.
- That can't be right.

Thanks for your help.
Donald


Donald, based on the data, it is correct. You just divide "current" stats on acre-feet of water by surface area, then compare this to full lake stats. I did it and it checks out.

Hmm? I know you are a stickler for mapping accuracy to optimize angling opportunities and I thought I'd share some math that relates to your low Choke Canyon Lake. Some stuff below. It shows that as a foot of additional water level is added to Choke Canyon, it raises the average depth of the lake by a fraction of the full foot, usually falling in the 30 to 50% range. The reason, and this relates to your contour lines, is as a lake adds each foot of water, it increases its area. Again, the attached chart shows that, generally, for each foot of water column added, about 500 acres of additional lake coverage occur. This additional acreage will be concentric . . . increasing its, what, "belt size" around its shoreline. This is what causes the average depth of a lake to drag behind a full foot of column water increase (or decrease). Our lakes have slope. To be 1:1, it'd take vertical walls as shorelines, then your contour lines' depths would change 1:1 with increasing or decreasing water levels.

Anyway, sum up the acres in the far column from 220' to 196' and that is how much acreage has shrunk . . . taking some of your contour lines along for the ride.

Brad


Ft Surface Acres Acre-ft Avg. Depth Gain % Added acreage
195 12,076.00 189,763.22 15.71407917
196 12,567.00 202,085.89 16.08067876 36.66% 491.00
197 13,035.00 214,889.92 16.48560951 40.49% 468.00
198 13,512.00 228,163.52 16.88599171 40.04% 477.00
199 14,005.00 241,915.50 17.27350946 38.75% 493.00
200 14,676.00 256,258.58 17.46106432 18.76% 671.00
201 15,232.00 271,221.97 17.80606421 34.50% 556.00
202 15,737.00 286,712.91 18.21903222 41.30% 505.00
203 16,144.00 302,657.15 18.74734576 52.83% 407.00
204 16,539.00 318,997.48 19.28759175 54.02% 395.00
205 16,954.00 335,741.41 19.80307951 51.55% 415.00
206 17,409.00 352,919.50 20.27224424 46.92% 455.00
207 17,919.00 370,577.35 20.68069368 40.84% 510.00
208 18,453.00 388,763.39 21.0677608 38.71% 534.00
209 18,988.00 407,484.21 21.46009111 39.23% 535.00
210 19,523.00 426,739.82 21.85831173 39.82% 535.00
211 20,058.00 446,530.22 22.26195134 40.36% 535.00
212 20,593.00 466,855.41 22.67058758 40.86% 535.00
213 21,242.00 487,750.03 22.96158695 29.10% 649.00
214 21,722.00 509,245.31 23.44375794 48.22% 480.00
215 22,244.00 531,219.37 23.88146781 43.77% 522.00
216 22,853.00 553,757.42 24.23127904 34.98% 609.00
217 23,558.00 576,956.01 24.49087401 25.96% 705.00
218 24,145.00 600,818.10 24.88374819 39.29% 587.00
219 24,689.00 625,233.93 25.32439264 44.06% 544.00
220 25,173.00 650,178.52 25.82840822 50.40% 484.00

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#12540059 - 12/15/17 09:55 PM Re: Can Someone Cross Check Figures [Re: Donald Harper]
Jake Shannon(Skeet4Life) Offline
TFF Celebrity

Registered: 10/31/10
Posts: 8069
Loc: Tyler, Tx/Arlington, Tx
There are way to many numbers in this thread

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#12540076 - 12/15/17 10:08 PM Re: Can Someone Cross Check Figures [Re: Donald Harper]
Scoundrel Offline
Pro Angler

Registered: 01/05/13
Posts: 946
Loc: Bedrock.
All typed in entered manually and calculated data using paper and pencil. eeks
_________________________

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#12540086 - 12/15/17 10:21 PM Re: Can Someone Cross Check Figures [Re: Donald Harper]
grout-scout Offline
TFF Celebrity

Registered: 12/08/08
Posts: 6894
Loc: Boerne, Texas
And all Donald wanted to know was, “what are the right contour lines on the navionics page”. I know they aren’t right, but I don’t know how wrong they are exactly. I know they are missing a lot of things that I have found by accident over the years and they make up bridges & culverts where none exist.

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#12540131 - 12/15/17 11:42 PM Re: Can Someone Cross Check Figures [Re: Donald Harper]
Bobby Milam Offline
TFF Team Angler

Registered: 07/13/14
Posts: 3376
Loc: Arlington
I thought that I accidentally logged into the math forum.

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#12540225 - 12/16/17 07:16 AM Re: Can Someone Cross Check Figures [Re: Brad R]
361V Online   content
TFF Team Angler

Registered: 11/21/08
Posts: 4933
Loc: somervell county
Originally Posted By: Brad R
Originally Posted By: Donald Harper
Looking at Choke Canyon:
- Want to know what Contour line to look at that will now be the shoreline as the lake is low.
- Something is not right when looking at the water level tables.
- Says the lake is at 30%.
- Another chart says it is 24.5 ft. below pool.
- That can't be right.

Thanks for your help.
Donald


Donald, based on the data, it is correct. You just divide "current" stats on acre-feet of water by surface area, then compare this to full lake stats. I did it and it checks out.

Hmm? I know you are a stickler for mapping accuracy to optimize angling opportunities and I thought I'd share some math that relates to your low Choke Canyon Lake. Some stuff below. It shows that as a foot of additional water level is added to Choke Canyon, it raises the average depth of the lake by a fraction of the full foot, usually falling in the 30 to 50% range. The reason, and this relates to your contour lines, is as a lake adds each foot of water, it increases its area. Again, the attached chart shows that, generally, for each foot of water column added, about 500 acres of additional lake coverage occur. This additional acreage will be concentric . . . increasing its, what, "belt size" around its shoreline. This is what causes the average depth of a lake to drag behind a full foot of column water increase (or decrease). Our lakes have slope. To be 1:1, it'd take vertical walls as shorelines, then your contour lines' depths would change 1:1 with increasing or decreasing water levels.

Anyway, sum up the acres in the far column from 220' to 196' and that is how much acreage has shrunk . . . taking some of your contour lines along for the ride.

Brad


Ft Surface Acres Acre-ft Avg. Depth Gain % Added acreage
195 12,076.00 189,763.22 15.71407917
196 12,567.00 202,085.89 16.08067876 36.66% 491.00
197 13,035.00 214,889.92 16.48560951 40.49% 468.00
198 13,512.00 228,163.52 16.88599171 40.04% 477.00
199 14,005.00 241,915.50 17.27350946 38.75% 493.00
200 14,676.00 256,258.58 17.46106432 18.76% 671.00
201 15,232.00 271,221.97 17.80606421 34.50% 556.00
202 15,737.00 286,712.91 18.21903222 41.30% 505.00
203 16,144.00 302,657.15 18.74734576 52.83% 407.00
204 16,539.00 318,997.48 19.28759175 54.02% 395.00
205 16,954.00 335,741.41 19.80307951 51.55% 415.00
206 17,409.00 352,919.50 20.27224424 46.92% 455.00
207 17,919.00 370,577.35 20.68069368 40.84% 510.00
208 18,453.00 388,763.39 21.0677608 38.71% 534.00
209 18,988.00 407,484.21 21.46009111 39.23% 535.00
210 19,523.00 426,739.82 21.85831173 39.82% 535.00
211 20,058.00 446,530.22 22.26195134 40.36% 535.00
212 20,593.00 466,855.41 22.67058758 40.86% 535.00
213 21,242.00 487,750.03 22.96158695 29.10% 649.00
214 21,722.00 509,245.31 23.44375794 48.22% 480.00
215 22,244.00 531,219.37 23.88146781 43.77% 522.00
216 22,853.00 553,757.42 24.23127904 34.98% 609.00
217 23,558.00 576,956.01 24.49087401 25.96% 705.00
218 24,145.00 600,818.10 24.88374819 39.29% 587.00
219 24,689.00 625,233.93 25.32439264 44.06% 544.00
220 25,173.00 650,178.52 25.82840822 50.40% 484.00
I am feeling like complete dumb-azz right now. hmmm
_________________________

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