Flood of 2013 has Happened, Part 2.

As prolonged as the rain was, and as intense as the flooding was, this extreme weather event is all over…and the sun is shining.  Now people have the job of picking up the pieces, cleaning up the mud, and getting back to normal.   For some, the damage was extensive – you have our sympathy.

 The purposes of Part 2 are:

  • To give you access to other  rainfall data, besides the two gauges  located in the  watershed  that are maintained by the USGS,
  • To share the other on-line tools for tracking storms and floods, and
  • To call for your pictures of flooding and flood damage, your rain gauge data, descriptions of your damage, and your experience.

Here is the crazy thing. If visit these web sites now – there are no extreme data – no flood levels to get excited about.  So I will try to show the benefit of these storm tracking sites using “captured screens” from yesterday.

 More Rainfall Data

Let me introduce you to the Automated Flood Warning System (AFWS), maintained by the National Weather Service, part of NOAA.  After that I will show you a site that “uses the data”… the Advanced Hydrologic Prediction Service.   Here you can see how bad a flood we will probably get, but it is most useful when it is raining like mad and you want to know how high the creek will rise.

Go to either      AFWS Jackson Co                or            AFWS Swain Co.

to get recent rainfall data or the stage (height of water) of creeks.  Of course, there are only data for sites with gauges – you can’t see the height of the creek at the end of your road, unless you are fortunate enough to live on a gauged creek and you are near the gauge, itself.

For Jackson County, you get a map like this:


To help find the location of your home or creek, zoom in with the icon in the upper left of the map.  (NO you can’t on this map – it is only a screen capture.  You must go to the site via the link.)  Or you may zoom in on one of these symbols:

For the stream stage, rainfall amounts, or both — at a combined station.

Click on the symbol and data for the site will pop up.  Alternatively, scroll down from the map, and see the rainfall data for all the AFWS rain gauges in Jackson County.


Some of the gages may be out of commission, like the Thorpe Dam rain gage, as shown above.

Question: Which rain gauge recorded the most rainfall in the past 24 hours?  Answer: Cullowhee Creek rain gauge.  You can scroll up and find this rain gauge on the map.  It helps if first identify the gauge label, which is CUNC7.  (Get the label by clicking on Tabular Data beneath “Cullowhee Creek.”)

Stage Data

Continue to scroll down the same page ( AFWS Jackson Co)  until you see the thumbnail icons for stream gauges.

In addition to the gages for the 4 sites shown here, you can get data for four more sites:

Scotts Creek nr Beta                         Soco Creek
Tanasee Creek                                    Wolf Creek

But it gets better.   Click on one of the hydrographs (a graph of the discharge or stage across time) and you get more information.   We clicked on Cullowhee Creek and got this:

See the added information?  It is about conditions for different flood stages. Look for this: with a 5-ft flood, Cullowhee Mtn Road and Tilley Creek Roads will be flooded. That is cool information, but the graph only gives you historical data.  The creek level one hour ago is now history, it may not help you know the flood conditions one hour into the future.

Hint:  For Scotts Creek, the gage reads the level at the confluence with the Tuckasegee River.  For this reason, the water level reflects conditions in the river and not in the creek.  This is because the river is a bigger body of water.

AWFS in Swain County

Go back to the top of this blog and click on the AWFS Swain County link.  You will find a map that includes Swain and data symbols.  The rainfall gages and stream stage data for these sites are:

Rain Gage Sites                                    Stage Gage Site
Alarka fd- Wesser                                                Deep Creek SG
Deep Creek RG                                                      EBCI Trout Farm
EBCI Trout Farm                                                 Tribal Hatchery
Pin Oak Gap
Potato Knob
Tribal Hatchery

There are fewer sites and much less data available for Swain County, as compared to Jackson County.

Lake levels

Going upstream, the watershed explorer finds the reservoir lakes maintained by Duke Energy.  The link for water levels is Nantahala Region Lake Levels.  As you look at the information, remember the convention of using 100 ft as the “full lake level.”  This is the level of the top of gates or the spillway.  If the level is 101 ft, then the lake is spilling over the control points and rushing down the valley below.  Duke doesn’t like this condition because that water is lost, that is to say, it does not go through the turbines and generate electricity.  TVA had to report any releases like this back to the federal government.

 Prediction

 Now let’s move to flood prediction.  Get out the Ouija Board, roll the dice, and ask Carnac the Magnificent.  “Oh, Great Swamee, how high will the river get?”

For selected sites with long historical records of stage and discharge, the Advanced Hydrologic Prediction Service will show you future conditions, or rather the Duke computer system will make a calculated guess.  For the Tuckasegee River there are two sites:

Tuck. River at Bryson City                         Ocon River at Birdtown

To get to these links directly from any USGS gauge web page (with sufficient historical data)  find the sentence near the top of the web page:  “Forecasts for gage height (stage) are available for this station through the National Weather Service’s River Forecast Center”  

Click on the this station link and find the prediction.   I did this for the Oconaluftee River on the 4th day of rainfall.  It was about 7 AM on Thursday, 1/17…the last day of rainfall.

1

On the left, the heavy blue line on the graph shows the measured stage (height of water).  On the right is the prediction.  A second peak is predicted at about 1 PM — early afternoon on 1/18 (half way between 7 AM 1/17 and  7 PM 1/18).  Now that is cool.

Was there a third peak on the Oconoluftee?  Was the peak at about 7.9 ft?  And did it happen at about 7 PM on 1/18?  Well, in is now Friday 1/18 and we can look at the actual data.

If we go back to the Oconaluftee River Site on the USGS system, we get this plot:

Yes, there was a third peak, but the water level was about 6.9 ft (less than the predicted 7.9 ft) and it occurred at about 7 PM, which is 6 hours later than the predicted “time of peak” — 1 PM.

Why the difference?  I will leave that up to your probing mind and your imagination.

 Well, what is going to get flooded?

Most of the AFWS and AHP web sites are best used during big storms when flooding will happen.  While the rainfall amounts may be interesting throughout the year, the predictions are most useful during floods and droughts.

You can go to the AHP sites and click on the Inundation tab.  There the web page  will show you what areas of Bryson City will be flooded at different levels of stage for the Tuckasegee River.  You explore this capability rain or shine.

On the left side of the screen, I clicked on a water level of 13.6 ft, the maximum water level during the Ivan storm in 2004.  The map shows the areas that will be flooded with white shading.  Notice that the entire Island Park island is covered with the white shade.  It will be totally underwater when the river level reaches 13.6 ft.  (Actually, it is covered up with even less flooding in the Tuckasegee.)  (Oh! You will still be able to see the trees!)

  Wrap up

Now you know how to get more rain data prior to your next picnic…using the AFWS.  And you are poised to track floods along the Tuckasegee River and several creeks throughout the watershed using the AHP.

Enjoy, but stay safe.  And after the flood – send WATR your pictures and your stories to our Facebook page.

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