- Where do I report flooding?
- Do I need flood insurance?
- How do I get flood insurance for my home or business?
- I'm a renter. Do I need flood insurance?
- What is the difference in responsibilities between the Harris County Flood Control District and the City of Houston?
- Can flooding be eliminated in our community?
- What causes flooding?
- Why does my street flood?
- Why can't we just drain the water out of my subdivision to the nearby bayous or creeks?
- What is a floodplain?
- What is a 100-year storm?
- Am I still at risk for flooding even though I do not live in a floodplain?
- What kinds of storms are roadside ditches and storm sewers currently designed and constructed for?
Click here to go to report flooding.
If you own or rent residential or commercial structures within the city of Houston, you are likely at risk of incurring property damage from flooding. If your structure is not within the floodplain, your mortgage lender may not require that you purchase flood insurance as a condition of your mortgage loan, but this does not alter your exposure to flood damage. Many properties not located within the 100-year floodplain are routinely damaged from various storm events in our area. Your basic homeowner's insurance policy does not cover damage caused by flooding.
How do I get flood insurance for my home or business?
Contact your insurance agency. They should be able to provide you with information on obtaining flood insurance coverage.
I'm a renter. Do I need flood insurance?
Yes. The contents of your home or apartment (i.e., your personal property) should be insured against flood damage.
What is the difference in responsibilities between the Harris County Flood Control District and the City of Houston?
Generally speaking, the Harris County Flood Control District (HCFCD) is responsible for the bayous, creeks, and major open channels within the City limits; whereas, the City is responsible for the design, construction, and maintenance of the storm sewers, roadside ditches, and some open channels within the City rights-of-way.
While the HCFCD and the City work together in managing the storm water systems and floodplains within our community, the improvement, modification, and maintenance responsibilities for these natural and man-made storm drainage systems is unique to each agency.
Flooding in the Houston area is a function of the bayou, stream, or creek systems in conjunction with the City's storm water infrastructure systems. The reduction of floodwaters in a bayou, stream, or creek may not necessarily result in the reduction of floodwaters in the adjoining City communities, especially if the City storm sewer infrastructure is inadequate to facilitate the particular storm event.
Can flooding be eliminated in our community?
No. Flooding is a natural event common to our area. By implementing storm water improvement projects and by utilizing proper floodplain management practices, the flooding levels, duration, and frequency can be reduced without negatively affecting our surrounding environments.
Flooding frequently refers to when flood waters inundate the floodplain of a river as the result of a storm or dam break. Flooding occurs when the carrying or holding capacity of a system (comprised of storm sewer inlets, curb and gutter streets, storm sewers, roadside ditches, culverts, creeks, bayous, rivers, lakes, etc.) used to convey runoff, storm water, or other surface water is exceeded, resulting in the inundation of the area adjacent to that system. Flooding may also occur when the costal water level rises significantly above the mean high tide elevation as the result of a surge generated by a storm in the Gulf of Mexico. In summary, flooding is caused by the inadequate capacity of a defined system to convey or hold the excess runoff generated by a storm of a given duration and intensity.
There are several reasons why streets may flood. The primary reasons for flooding are insufficient street grades to convey water to inlets and the inadequate capacity of inlets and storm sewers. A second contributor to flooding is clogged, damaged, or obstructed storm sewer inlets and/or storm sewers. In this case, the runoff is hindered from entering the storm water system and has nowhere to go; consequently, water ponds and begins to fill the street. Another reason for street flooding is when a nearby bayou or stream has the same water surface elevation as the street itself, or perhaps even higher in some cases, resulting in the storm water system "backing up" and flooding - a very common occurrence in areas immediately adjacent to our bayou and stream systems. In many cases, roads are meant to serve as a secondary conveyor of storm water during extreme events so that the road floods instead of the houses and buildings located along the street. In virtually all curb and gutter streets, the streets are intended to flood for a given rainfall intensity and duration in order to provide protection to the adjacent properties.
Why can't we just drain the water out of my subdivision to the nearby bayous or creeks?
In some cases, if the water level in the nearby bayou or creek were low enough relative to the drainage system in the subdivision, then the drainage system would be able to convey the runoff to it; however, this might cause someone else to flood. This is referred as "moving the flood from one location to another." During storm events that result in flooding, the floodplain provides storage for the excess runoff. If this storage is eliminated in one place, it will end up forcing itself somewhere else. In storm water capital projects addressing flooding, the intent is to protect structures and property from flood waters without adversely affecting or causing flooding to areas downstream. Even after a storm water capital project is completed by the City, the streets will still experience flooding, by design, in order to maximize the flood protection of the adjacent properties and structures.
A floodplain is the normally dry area, usually low land, adjacent to a stream, river, lake, watercourse, or bayou that is inundated on a periodic basis with flood waters. The extent or size of the floodplain depends on the magnitude of the flow, as defined for a given frequency of occurrence, and the physical attributes of the bayou, river, etc., and the watershed which it drains. Floodplains are usually referred to by a given recurrence interval with respect to the flows generated by a storm event, for example: "These homes are located in the 100-year floodplain" or "This subdivision is situated within the 500-year floodplain." click here for more information
The term "100-year storm" or "100-year frequency" does not refer to a rainfall event that occurs once every 100 years. Rather, in any given year, a 1 percent chance exists of a 100-year flood event occurring. Storm frequencies are used to refer to the average rainfall intensity for a given duration of time, the volume of rain that falls over a given period of time, or the peak flow that occurs from an event. For example, a 100-year storm (or worse) may occur three years in a row, or maybe twice in the same year, or perhaps not at all in 100 years. The chance that a storm will occur with some given frequency is known as the "return period" or "recurrence interval." A 500-year storm event occurs, on average, once in 500 years, or has a 0.2 percent probability of occurring or being exceeded in any given year; a 25-year storm event occurs on average once in 25 years, or has a 4 percent probability of occurring or being exceeded in any given year; a 2-year storm has a 50 percent chance of occurring or being exceeded in any given year. A storm event for some specified return period such as a 2-year or 100-year storm is frequently used in order to design storm water drainage systems, and is known as the design storm for that system.
Am I still at risk for flooding even though I do not live in a floodplain?
Yes. Even though you may not live in a defined floodplain, such as the 100-year or even 500-year floodplain, an adjacent or nearby storm sewer system or roadside ditch that has an inadequate capacity may cause localized flooding during a storm event. In essence, you do not have to live in a defined floodplain to experience flooding. If the runoff from a storm event exceeds the capacity of the storm sewer system for whatever reason, localized flooding will occur.
What kinds of storms are roadside ditches and storm sewers currently designed and constructed for?
Under the City of Houston design guidelines, storm sewers and roadside ditches are designed for the 2-year frequency. The complete storm water system, including curb and gutter streets and/or roadside ditches acting as secondary storm water conveyors, is then checked with the 100-year storm event to verify that the water surface elevation is maintained within the public right-of-way. It is crucial to understand that Mother Nature will never produce rainfall events that replicate the parameters used in storm water engineering, since those events are the abstracted rainfalls based on the frequency distribution of historic rainfall records.