One of the most effective tools the District uses involves no construction whatsoever. It involves buyout and demolishing of structures that were built deep in flood prone areas where structural projects to reduce flood levels are impractical. Structures in this situation were typically built years ago before detailed floodplain maps and studies were available and before floodplain management regulations were adopted by the county and the cities in the county.
Once a flood prone house is bought and demolished, it will never incur flood damages again. The District actively pursues voluntary buyout opportunities.
Structure Demolition as part of the Home Buyout Program.
LiDAR: A Vital Use of Laser Technology
LiDAR stands for Light Detection and Ranging. As part of the Tropical Storm Allison Recovery Project, highly detailed ground elevation data for all of Harris County was acquired through this cutting-edge technology that utilizes the projection of millions of laser signals to the ground from a specially equipped aircraft. Using powerful software, the data from these LiDAR reflections is collected by measuring the time it takes for the aircraft to receive each of the millions of laser reflections. The resulting data is then combined and converted into an image that looks exactly like the terrain below, including buildings, trees, roadways, creeks and bayous.
So, what do we do with this data?
In order to identify areas of higher flood risk, engineers need a detailed and accurate representation of the shape of the ground. It is just not economical to obtain such detailed information for an area as large as Harris County using conventional survey methods. But LiDAR makes it possible.
The LiDAR data is combined with surveyed creek and bayou cross sections in order to develop detailed computer simulations to determine an estimate of areas that have a higher risk of flooding.
LIDAR helps to provide a better understanding of flooding and is a benefit to every citizen in Harris County
Other Tools of the Trade
There are also other so-called "tools" that are utilized in the planning process, implementation phases and maintenance of the drainage infrastructure. Those can be generally thought of as "tools of the trade," or methods and materials that may help the District's flood damage reduction projects work more efficiently with regard for community and natural values.
An example of this would be the use of Cellular Concrete Mats (CCM) in constructing a new channel. Rather than building a solid lining with concrete, CCM is used to provide an armoring to guard against erosion while providing an opportunity to establish vegetation over its surface. Over time, holes in the interlocking blocks of concrete will naturally fill in with sediment, allowing vegetation to grow, which encourages other wildlife activity and enhances the overall aesthetics of the new channel.
Construction near FM521 and W. Orem, 2012.
Other examples of smaller tools of the trade are the use of native plants and wildflowers that beautify a project area, protect the integrity of a channel's slopes by strengthening against erosion, and also reduce mowing cycles, saving taxpayer dollars in the long run.