Texas Flood Surveys

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Detailed Description

Hydrologists from Arizona aid the Texas Water Science Center in gathering measurements and other information after the catastrophic Blanco River flooding event that swept Austin, Texas.

Details

Image Dimensions: 480 x 360

Date Taken:

Length: 00:02:15

Location Taken: Tucson, AZ, US

Transcript

My name’s Brandon Forbes, I am a hydrologist
at the Arizona Water Science Center in Tucson,

Arizona.

On Memorial Day of 2015 a catastrophic and
historic flooding event occurred on the Blanco

River watershed near Austin, Texas.

Scientists from Arizona traveled to Texas
to help the USGS Texas Water Science Center

document these historic and widespread flooding
events.

We were lucky enough to have the permission
from local landowners to go on their property

to gather this information, and without that
we could not have done these surveys or conducted

these estimates.

We used methods called indirect discharge
estimation methods, or slope area measurements,

as we call them in the survey, which involves
surveying channel geometry, estimating “n”

values, and surveying the water surface profile
that’s left by the flood to estimate the

peak discharge.

The highest high water marks or the depth
of water, which we surveyed around where their

stream gage was located, was about 40ft of
water.

That turned out to be about 175,000 cubic
feet per/second which is more than two times

the discharge of Niagara Falls.

Other issues we have are there was still a
lot of water present, so a lot of sites could

not be waded, we couldn’t cross these rivers.

We had to use different methods to estimate
the geometry under the water surface.

To do that we used ADCP or Acoustic Doppler
current profilers to measure the geometry,

and we did this by dragging these ADCP boats
across the water that we couldn’t wade and

those instruments can measure the channel
geometry when we physically can’t.

For this particular flood in the Blanco River,
it was very high up into places where people

lived.

So a lot of the damage that we saw, it was
tragic in a sense that these people’s lives

were heavily impacted by this event.

Houses had 5, 6, 7ft of water, sometimes more,
and some houses were completely removed from

foundations, and many lives were lost.

So it was definitely an eye opening experience
to see that kind of damage caused by a flood.