Different Types of Floods
Flash floods are short-fuse weather events, typically lasting on the order of 6 hours or less. Usually, flash floods occur within a few minutes or hours following an excessive rainfall event. They can also be caused by a man-made event, such as a dam or levee failure. Flash floods cause most of the fatalities associated with flooding events. Usually, less warning lead time is provided for flash flooding which requires quick action on the part of the public.
Flash flooding is most severe in urban areas like the Houston metropolitan area. Urbanization increases runoff by 2 to 6 times over what would occur in natural terrain. Flood waters can fill streets, freeway underpasses, and parking lots and can sweep away cars.
Heavy rainfall falling over a widespread area (such as a large portion of a watershed) over a prolonged period (like several days) can cause river flooding. Typically, river flooding begins as a high crest on the upper part of a watershed that takes several days to move downstream. Due to the slow nature of river flooding, ample advanced warning is provided to evacuate people or property in the path of the flooding.
Flooding Impacts on Southeast Texas
Flash flooding is a relatively common event over Southeast Texas. Tropical systems during the summer and early fall, and strong winter storm systems can cause widespread flooding and flash flooding across the area. Flash flooding can also be produced by strong slow-moving thunderstorms especially during the spring and summer months. Flooding and flash flooding can occur anywhere in southeast Texas, but is usually most severe near major watersheds like the Colorado, Brazos, San Jacinto, or Trinity Rivers, and near urban areas like the Houston metropolitan area.
Things You Can Do Ahead of Time to Prepare for Major Floods
- Know the flood risk at your place of home or business and its elevation above flood stage.
- Store drinking water in clean bathtubs or containers. This is very important as flood waters will contaminate the drinking water supply in your area.
- Stock non-perishable food items requiring little cooking and no refrigeration.
- Keep first aid supplies on hand.
- Keep NOAA Weather Radio, battery-powered portable radio, emergency cooking equipment, and flashlights in working order.
- Install check valves in sewer traps to prevent flood waters from backing into your home.