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FAQ: Floodplains


aerial photograph of a blue river running through green grassland with mountains surrounding

Floodplains are essential features of the natural landscape that can be found all over the world. They are associated with rivers, lakes, and coastlines and have immense ecological and economic value. Similarly, they play a role in real estate development and they affect property values across the country. In this guide, we will discuss some frequently asked questions surrounding floodplains and their impacts on property values and development.




What is a floodplain?


A floodplain is a flat or nearly flat area of land adjacent to a river, stream, or other body of water. It is typically dry but can become inundated during periods of high water flow or flooding events. Floodplains are important natural features that provide various ecological functions and benefits.



What is a 100-year floodplain?


As per the Flood Insurance Rate Map released by the Federal Emergency Management Association (FEMA), a floodplain refers to an area with a minimum 1 percent probability of experiencing or surpassing base flood elevations in a given year, or encountering flooding exceeding 6 inches.



How are floodplains formed?


Floodplains are formed through a combination of natural processes such as erosion, sedimentation, and deposition. Over time, rivers and streams erode the land and carry sediments downstream. The sediments are then deposited on the floodplain during periods of low water flow, gradually building up the land.



Why are floodplains important?


Floodplains play a crucial role in regulating and managing the water cycle. They act as natural reservoirs, absorbing excess water during periods of high flow and releasing it slowly back into the river or groundwater system. This helps prevent downstream flooding and erosion. Floodplains also provide important habitat for various plant and animal species.



Can you build on floodplains?


While federal and state laws generally permit construction in floodplains as long as buildings are elevated above the base flood elevation, it's important to acknowledge the inherent risks involved. Despite these risks, building on a floodplain may be enticing for developers due to the desirability of waterfront homes and the relatively lower cost of land compared to higher ground. This allows property owners to capitalize on the opportunity to purchase at a lower price and potentially sell at a higher value.


However, the low-lying floodplains that surround a river play a crucial role: they have the ability to absorb excessive water. However, when these floodplains are filled or covered with pavement, they lose their capacity to absorb water. Consequently, the excess water has nowhere to go, leading to floods. Moreover, the process of "fill and build" creates elevated pockets of land, resulting in runoff that can flood properties located at lower elevations.



How do floodplains impact property values?


While the physical effects of rising seas and intensifying rainfall may seem like problems for the future, more frequent flooding is already happening, taking a toll on property values throughout the U.S. Flooding can impact property value regardless of community size or whether the community is inland or coastal. Generally, property values are lower for properties located in floodplains compared to those that are not located in floodplains. If you live in a floodplain or are considering purchasing property in a floodplain, keep in mind that flood insurance is required by law and is not typically covered by a homeowners insurance policy.



How do floodplains impact development?


As mentioned above, many developers actively search for investment properties located in floodplains due to their lowered property values, even though there are a handful of additional considerations that must be evaluated before beginning a project. Floodplains also impact the potential of a property to be leased for renewable energy. For example, solar and wind energy developers cannot place standard solar panels, wind turbines, or any other electrical infrastructure on properties where there is a flood risk.


Whether you are a current or a prospective property owner, it is important to be aware of floodplains located on or near your property because the presence of floodplains impacts property values and the potential for future development. LandGate's LandApp tool and free property reports contain floodplain data- get your free property report on our map today!



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