Officials urge preparedness ahead of post-fire flooding, flows

Officials urge preparedness ahead of post-fire flooding, flows

A helicopter drops mulch on an area in Oak Creek Canyon burned by the Slide Fire. Photo credit: Coconino National Forest, USFS

PHOENIX -- On a sunny afternoon in Sedona, business and home owners in the Slide Fire burn area gathered at Sedona Red Rocks High School to discuss the less sunny topics of post-fire flooding, debris flows and rock falls in Oak Creek Canyon.

 

About 140 people attended the meeting on June 19 organized by Coconino and Yavapai counties, the City of Sedona, Sedona Fire District, the U.S. Forest Service (USFS) and other partner agencies to outline what the Whole Community is doing to prepare for the monsoon.

 

The Arizona Division of Emergency Management (ADEM) is one of many cooperating agencies supporting Coconino County in its emergency response and recovery planning. In the event of a post-fire emergency, Coconino County could request the assistance of ADEM. The State Emergency Operations Center (SEOC) was partially activated during the Slide Fire.

 

The Slide Fire burned over 21,200 acres in about two weeks. Concurrent to the crews fighting the fire, Coconino County, the City of Sedona, USFS and a multitude of other agencies were thinking ahead to the monsoon.

 

The monsoon, according to the National Weather Service (NWS), is characterized by “large-scale wind and rainfall shifts” which can produce intense thunderstorms, high winds and blowing dust in July, August and September. The monsoon season opened on June 15.

 

In the aftermath of the fire, retired USFS hydrologist Greg Kuyumjian led a Burned Area Emergency Response (BAER) team into the area to “analyze the effects of the fire and answer the question, so what?” In particular, the BAER team wanted to assess the risk of post-fire events and recommend treatments for the burn area.

 

According to Kuyumjian, 46 percent of the Slide Fire’s 21,227 total acreage (or 10,182 acres) burned at moderate to high severity. If rain falls in a moderate to high severity burn area there is the potential for a severe hydrological response; in other words, rapid water and debris runoff.

 

The USFS’ plans to reduce the risk of post-fire floods, debris flows and rock falls in Oak Creek Canyon with a regimen of 20 or so different treatments. Hydrologist Rory Steinke expects seeding and mulching in areas of moderate to high burn severity to have a meaningful mitigative effect. The USFS plans to treat the burn area in mid-July.

 

Steinke acknowledged that the USFS is in a race against the arrival of monsoon precipitation, which normally starts in early July. On average, the Sedona area gets 7 to 8 inches of rainfall annually; however, NWS is predicting a “wetter than normal” summer.

 

Brian Kilmowski of the NWS in Flagstaff said a quarter inch of rain in 15 minutes would be enough to trigger debris flows. To put that in perspective, a half inch or more of rain fell on parts of Oak Creek Canyon on nine separate occasions in 2013. “If we do get the average amount of precipitation,” said Kilmowski, “we’re going to have multiple events that are likely going to cause significant responses over the burned area.”

 

When the thunderstorms do arrive, Coconino County’s chief concern is the health and safety of everyone in Oak Creek Canyon. Coconino County, the City of Sedona and the USFS must work out how to alert upwards of several thousand Canyon residents, business owners and recreationists to imminent threats.

 

Chief Deputy Jim Driscoll of the Coconino County Sheriff’s Office described, for example, plans to establish “advisory checkpoints” at either end of the canyon, and install message boards and signs with the help of the Arizona Department of Transportation. The County is considering establishing a short-range AM radio station like those used in construction zones and national parks.

 

And, of course, there’s the County’s emergency notification system, CodeRED. There are two important limitations on the system. First, unless they’re County residents, visitors to the canyon won’t be registered in the system. Moreover, cell phone service in the canyon is spotty. The County is thinking of installing a mobile cell tower in the Canyon to boost reception. To register for CodeRED notifications, visit the Coconino County website.

 

Oak Creek Canyon is equipped with a siren system made up of nine individually-placed sirens. Coconino County Emergency Manager Robert Rowley said the sirens have been activated “intermittently” in the past but pledged to make greater use of the sirens, starting with a full system test on June 26.

 

“Be prepared” was the unofficial theme of the evening. More specifically, the presenters want residents, business owners and visitors to Oak Creek Canyon to pay attention to alerts and warnings, and be prepared to react at a moment’s notice.

 

For preparedness information, visit the Arizona Emergency Information Network (AzEIN) at www.EIN.Az.gov. The new website features recommendations and resources for how to Plan, Prepare, Inquire and Inspire for all hazards.

 

Coconino County has uploaded a recording of the community meeting to its YouTube channel at http://www.youtube.com/user/coconinocnty.