FLOOD06826

• County: Statewide
• Basin: Statewide
• Title: National Economic Development Procedures Manual-Urban Flood Damage
• Date: 3/1/1988
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

2) Basement or cellar damage may occur when flood stage rises above

the floor due to backing up through drains, seepage through foundation

walls, or when flow through doors and windows occur, The primary factors

will be the design of the sewer system, the soil types (soils with high

clay content will absorb and filter water much slower than soils with high
sand or loam content), and building material (concrete foundations will be

subject to less infiltration than cinder blocks). Water pressure can also

cause cracks or collapse of building walls and foundations, especially if'

water has not entered the building.

3) Damages at the same stage in different floods may vary with

seasonal flood characteristics. There may be seasonal differences in

velocities, duration, silt, debris, and ice content, Estimated damages

might be tied to these seasonal factors and the probabilities of floods

occurring at any particular time of the year,

4) Changing trends in property use, such as the more intense use of

properties (game rooms in the basement and the accumulation of residential

electronic equipment) will affect the stage-damage relation, and produce

significant differences in estimates of current and future conditions.

5) Generally, for low and moderate velocity flood occurrences, the

magnitude of damages on furnished levels will increase most rapidly to 3

or 4 feet above floor level, with an appreciably slower rate of increase

to the next floor level.
6) The mobility of some personal property should tend to reduce

losses, particularly when there is sufficient warning time, However, some

damages, even of mobile property, will probably be inevitable due to lack

of warning lead time and variations in judgement,

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