As many of us have recently experienced, storms and flood issues definitely have to be taken seriously. It is a fact that global warming is affecting water levels, hence increasing the chances of low or coastal areas to become prone to flooding.
Could flooding be prevented? Well, I don’t think so, but certainly there are several ways in which we can minimize its effects on our properties.
To begin, everyone who lives or wishes to live close to a body of water, suc
h as the ocean, river, lake, pond, etc., should investigate, by checking into the FEMA (Federal Emergency Management Agency), FIRM (Flood Insurance Rate Maps) or NFIP (National Flood Insurance Program) to determine whether the property is located within a flood zone. If indeed it is, there are different flood hazards zones that the property may fall under, such us A, V, X, etc. (SEE PICTURE).
These flood hazard maps are based on present studies of riverine areas and shore locations, although “Future Condition Hydrology” studies can also be obtained.
Each of these zones indicates the chances that your area has of becoming flooded, taking into consideration the risk of the wind activity & wave action, or the records for 50, 100, or 500 year old floods.
A 100-yr old flood, for example, does not mean that the flood will occur once every 100 years. It means that there’s a 1% chance for it to occur in any given year.
Once the flood hazard zone is determined, some guidelines need to be followed in order to achieve a flood resistant construction.
Flood can impact a structure by any of the following:
1- source of flooding
2- depth of flood
3- effect of waves
4- debris brought in by the flood
5- speed and duration of the flood
6- receding water
7- erosion caused by the flood.
Keep in mind that the idea is to have buildings with as little damage as possible after the flood, where the main structure will remain stable, mechanical equipment & utilities remain usable or easily repaired, and that the building could be safely accessible & usable.
Here are some of the items to be considered:
A- Design the lowest floor of the building above the “designed floor elevation”. Check your local building codes, but that’s usually 1′ over the flood plane elevation.
B- Avoid locating mechanical systems (boilers, water heaters, etc.) at lowest level, or if that’s not possible, make sure they’re watertight or enclosed in a waterproofed walls to prevent them from floating away, or incurring into costly repairs.
C- Design for building foundations capable of resisting the force of the water, should a flood occur.
Always, health & safety for all building occupants are most important.
Entities like FEMA, National Flood Insurance Program, & Local Codes will give all the information necessary to build, or to rebuild, and to have as little impact as possible after the effects of a flood.
Check with your architect/engineer of additional ways in which building in flood-prone areas can be erected or retrofitted.