10th Anniversary of the Halloween Flood (10/30/2008)

By: Janet Spurgeon

The Halloween Flood of '98

by Janet Spurgeon
Service Hydrologist, WFO Wichita

Storm Total
 Precipitation from Halloween Flood 1998

Highest
 Precipitation Area The above image is the storm total radar derived precipitation ending the morning of November 2nd over the Wichita radar coverage area. Notice the high precipitation values of 6 plus inches (yellow color) covering the counties of western Sedgwick, eastern Kingman, northeastern Harper, northwestern Butler, and northern Greenwood. Near the center of the image is where the radar is located at the Wichita Mid-Continent Airport. The zoomed in second image – centered on Sedgwick County is a view of the high rainfall totals of 6 to 9 inches that fell just west of the radar. The highest rainfall totals were concentrated over the Cowskin Creek Basin.

Friday evening on the 30th of Oct 1998 was the start of a long weekend of widespread flooding rains impacting central and southeast KS. Common in the minds of most people was the question, “When was it going to stop raining?” By Sunday, up to 11 inches of rain drenched the area. More specifically, rainfall amounts of 4-8 inches were common in Central Kansas, with 6-10 plus inches being recorded across South Central and Southeast parts of the state.

Rivers in Flood

As a result, record flooding took place on the Whitewater, Cottonwood, Walnut, and Arkansas Rivers. However, record flooding also took place on the Cowskin Creek in Wichita but at the time there was no river gauging to record the water levels. However, at a later date an estimated peak discharge and stage was determined for the new gauging site at 119th Street West on the Cowskin Creek. The following list the record river levels at our forecast points:

1 Whitewater River    
  At Towanda 30.53 ft on 11/1/98  
  At Augusta 34.95 ft on 11/1/98  
2 Arkansas River    
  At Derby 16.60 ft on 11/1/98  
  At Arkansas City 28.89 ft on 11/3/98  
3 Walnut River    
  At Arkansas City 32.45 ft on 11/3/98  
4 Cottonwood River    
  At Florence 28.67 ft on 11/1/98 (highest obtained from actual gauge measurement; highest watermark level 32.53 ft on 7/11/1951)
  At Plymouth 36.77 ft on 11/1/98 (highest obtained from actual gauge measurement; highest watermark level 37.78 ft on 7/11/1951)
5 Cowskin Creek    
  At 119th St. Wichita 22.00 ft on 10/31/1998  

Many other rivers rose above flood stage across Central and Southeast KS. These included flooding on the Chikaskia, Ninnescah, Walnut, Little Arkansas, Neosho, Verdigris, and Fall Rivers, and along a section of the Smoky Hill River from Lindsborg to New Cambria. Then the expanse on the Arkansas River from Derby down to Arkansas City also incurred flooding. The tributary creeks affected by flooding were Gypsum, Emma, and Sand Creek.

Precipitation Totals

The above images show radar derived precipitation estimates. During this event the radar slightly underestimated the actual rainfall amounts as compared to “ground truth” measurements from rain gauge type catchments. The highest storm total rainfall amounts over 10 inches recorded from National Weather Service Cooperative Observers across the area were:

1. Thrall 10.55 inches (southeast KS)
2. Anthony 10.47 inches (south central KS
3. Runnymede 10.17 inches (south central KS)
4. Madison 10.15 inches (southeast KS)
5. Sedgwick 10.06 inches (south central KS)
6. Elbing 10.01 inches (south central KS)

However, to be included in this storm total rainfall was data obtained from KSN Weatherlab sites. Even higher rainfall amounts were reported from the following Weatherlab sites: at Wichita Brooks Middle School 12.66 inches, Valley Center West Elementary 12.30 inches, and Cheney Middle School 10.96 inches.

Impacts

The record flooding resulted in 1 fatality and 2 injuries. The one death occurred when a 50 year old female drove into a flooded roadway in Harvey County and then attempted to wade through the flood waters. The two injuries in Sumner County were due to hypothermia.

Then over 5,300 evacuations took place in the counties of Cowley, Butler, Chase, Sedgwick, Greenwood, Sumner, and Wilson. Of the evacuations, 3,000 occurred in and around Arkansas City when parts of the levy that protects the east side of Arkansas City from the Walnut River failed on Tuesday, November 3rd. In and around Augusta, 1,800 residents had to be evacuated, however there were many in the Meadowview Acres neighborhood that did not take heed of the warnings and later had to be rescued by boat. The swollen Whitewater River over topped the levee system in two areas, the first occurred south of Augusta by mid-afternoon Sunday, November 1st, and by that evening the water topped the levee just north of U.S. 54 on the west side of town. Then in west Wichita, 100 people were evacuated when Cowskin Creek flooded.

The approximate dollar damage to crops, roadways, property and soil erosion totaled a whopping $32 million accounting for over 12 counties in South Central and Southeast KS. The most significant damage occurred in and around Augusta where 565 homes, 230 mobile homes, and 100 businesses sustained damage. Approximately $10 million dollar damage was assessed in Butler County due to structure, crop and road damage. Cowley County was the 2nd hardest hit area with $8 million damage assessed including 479 structures, both residential and business. Most of this damage was centered around Arkansas City. In Sedgwick County, flooding from Cowskin Creek caused $4 million in damage to homes, businesses, roads, and crops.

Looking Forward

What changes have been made since 10 years ago? Within the Cowskin Creek Basin, a series of 3 satellite gages, installed by the USGS in cooperation with the city, called Data Collection Platforms or DCPs transmit real-time data of river stage and rainfall amounts located along Cowskin Creek. Also a network of ALERT gauge sites scattered across the Cowskin Creek Basin monitor stream levels on the upper end of the Cowskin Creek, Dry Creek and Calfskin Creek. The creek gauges along with 3 other raingauge sites in the basin also transmit rainfall amounts to the Wichita Storm Water Management for any potential problems. This data is also transmitted to the NWS. There were also two other automated streamflow-gauging stations that were installed by the USGS on the Whitewater River at Augusta and on the Walnut River at Arkansas City in 2002. With this new set of data, this information is input into hydrologic models to come up with better and more accurate forecasts of river crests. As result from the enormous flooding on the west side of Wichita, a new river forecast point has been established on the Cowskin Creek at 119th St. What this means is the National Weather Service in Wichita will closely monitor this site when the river levels begin to reach flood stage or above and issue flood warnings and statements for this site to warn the public of the impending hazard. The established flood stage along this site is 18 ft. The USGS has dedicated a website to monitor river levels on the Cowskin Creek. This is called the Cowskin Creek Flood Watch page. Here is the link to access the page: http://ks.water.usgs.gov/waterwatch/cowskin.floodwatch/index..html

Information regarding the river status on Cowskin Creek such as the current stage, impacts, historical crests, pictures of the site, and any current forecasts or warnings can be found on the Weather Service’s new AHPS – Advanced Hydrologic Prediction Service homepage. You can reach this site by the following link: http://www.crh.noaa.gov/ahps2/index.php?wfo=ict This will take you to a gauge map showing locations of river forecasts points in and around our County Warning Area. By clicking on any of those points will take you to that site’s page.

Since floods kill more people each year than any other severe weather phenomenon, we at the National Weather Service have made an emphasis to educate the public on the dangers of flood waters throughout the years. Did you know that a little as six inches of fast moving water can sweep you off your feet and 18 to 24 inches of water can float a car? Yes it’s true. So we want you to remember that if you encounter a water covered roadway, “Turn Around Don’t Drown.”

Turn Around Dont
 Drown

This story was brought to you by the National Weather Service - Wichita, Kansas.



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