MAY MONTHLY HAZARD: FLOODING

During a flood, excess water overflows a body of water or watercourse (such as a river or creek) and spills into the floodplain nearby. Flooding is the most common and widespread weather hazard. Most flood dangers and deaths are caused by flash floods – when intense storms drop a lot of rain in a brief period. Based on the 38 flood events that occurred from 1995 through 2011, the City of Tulsa is considered to have a HIGH probability of future flood events. The City should expect an average of two or three flood events each year.

  Oklahoma Flooding Events by County 1990 to 2010 (Tulsa County outlined in bold) Source: National Climate Data Center U.S. Storm Events Database

Oklahoma Flooding Events by County 1990 to 2010 (Tulsa County outlined in bold) Source: National Climate Data Center U.S. Storm Events Database

Tulsa has 3 main types of flooding:

Riverine floods along major waterways with very large drainage basins, such as the Arkansas River and Bird Creek – This happens when excessive rain upstream collects into rivers and streams which then overflow their banks. This kind of flooding builds slowly, giving downstream areas more warning. However, due to debris, water velocity, and the depth of flooding, riverine flooding can cause more damage than other types.

Flash floods along tributary creeks and water ways that ultimately drain into the Arkansas River or Bird Creek – This kind of flooding happens when storms dump up to 5 inches of rain an hour. When the soil is already soaked, long, hard rains can accumulate into deadly walls of water that build in minutes and are strong enough to cause extensive damage to people, property, and the landscape. Rainfall in the City of Tulsa averages 39 inches per year, but thunderstorms can, and have, dumped more than half that amount on the city in a few hours, causing widespread flooding and devastating flash floods.

Urban floods that impact streets and transportation systems, as well as localized drainage and nuisance flooding problems – Streets flood and sewers back up when rain runoff from buildings and paved surfaces collects in an urban setting. Culverts and drains clogged with debris add to the problem. Storm drains are for rain, not pollutants or debris. The overland flow of rainwater on and between properties can be a nuisance due to poor landscape drainage design.

Flood risk still exists! You have options if you live in a repetitive loss or flood-prone areas.

Along tributary creeks and waterways, the number and size of floods have been greatly reduced, but not eliminated, by significant advances in Tulsa’s floodplain management. The city is still prone to frequent nuisance, street, and localized flooding; it is vulnerable to larger floods along rivers and creeks, and continues to be at risk of catastrophic flooding along the Arkansas River. For more information on your flood risk, call the City of Tulsa Customer Care Center at 311 or 918-596-7777 outside Tulsa, or visit https://www.cityoftulsa.org/government/departments/engineering-services/flood-control/ . You can also visit the Disaster Resilience Network at http://disasterresiliencenetwork.org/monthlymessages/ to review information on flood-related messages like these:

– You Need Flood Insurance
– Everyone should have an Emergency Plan in Case of Flooding or other Disasters
– You can protect your property from flooding
– Get A Building Permit When Constructing in Flood-Prone Areas
– Avoid flood-prone areas when taking shelter during tornado events
– Have a plan to protect your business from flooding or other disasters
– Turn Around Don’t Drown
– LID* Improves Water Quality and Quantity (*Low Impact Development)
– Get A Building Permit when Installing Safe Rooms in Flood-Prone Areas

Brittany Stokes