Continuous Slope Area Method: Sycamore Creek, AZ

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Detailed Description

A video depicting the installation & operation of Continuous Slope Area gage and radar sensor, installed after the Sunflower Wild Fire on Sycamore Creek to measure streamflow from the Sunflower burned area. The streamflow data is used to provide flood warning to communities affected by runoff from the burned areas and for collecting streamflow data from areas that have been recently burned.

Details

Image Dimensions: 1920 x 1080

Date Taken:

Length: 03:29:00

Location Taken: Sycamore Creek, AZ, US

Transcript

Dylan Cobean:
The Sunflower Fire of 2012 was sparked from a stray shotgun blast and went on to burn 17,446 acres of the Tonto National Forest in Maricopa County Arizona. In the aftermath of the fire, USGS scientists installed CSA's or Continued Slope Area sensors, at various cross sections on Sycamore Creek. Due to damage from debris in the flow, a non-contact radar sensor was also installed. These CSA's can withstand and measure the more extreme runoff events commonly seen after a watershed has been burned. 'These data can also be used to measure the rate of recovery for a burned area that has been affected by wildfire.
Chris Smith:
 Its 9/13/2012. Today we're at Sycamore Creek with Jeff Cordova, Brandon Forbes and Chris Smith, and we're going to dump the data from the CSA gage. The whole idea of these sensors is to measure the stage in this cross sections; during a flow event we have 3 of these sensors in this slope area reach. And they measure stage in each cross section; they're all synchronized to collect data every 5 minutes. So Brandon's going to go ahead and download the data from the sensor. The sensor measures pressure then records that on a data logger that's inside the sensor itself. 
Brandon Forbes: 
Here we are setting up surveying equipment to survey each cross section at each sensor in the reach. It is important to survey after large flow events because often the channel geometry will change.  This is what the channel looks like after the large flow event in August of 2012. Runoff from burned areas can be very intense containing heavy debris and can be flowing at a very fast rate. This can cause the channel to change shape, and to effectively estimate discharge using the CSA method the geometry at each cross section needs to be known. High water marks are also surveyed to estimate the slope of the water surface throughout the reach. When using the CSA method, it is common to conduct surveys after each flow event especially in ephemeral streams with sand and gravel bed material. 
Runoff from burned watersheds often contains large debris that can be moving at an exceptional rate. To adequately measure streamflow in Sycamore Creek after the Sunflower Fire, a rapid deployment non-contact sensor was installed. The radar sensor, mounted here above the channel, can measure flood stage without contacting the water surface which will improve the sensors survivability and will allow watershed managers to get the important data needed to issue flood warning when large runoff events occur. 
The Continuous Slope Area sensors that are deployed in Sycamore Creek are an experimental operation to test how well the sensors can survive and measure flood stage during intense runoff events from burned watersheds.