Lidar Terrain Data

How LIDAR is Used to Develop New Flood Maps

The Texas Water Development Board published a new video today in their Texas Water Newsroom. The title: “Data from the sky informs flood planning on the ground.” The video explains how Lidar (light detection and ranging) data helps develop accurate, up-to-date flood maps.

900X Higher Resolution

Surveyors can acquire high resolution data quickly from the air using pulses of light.

Lasers mounted under planes pulse hundreds of thousands of times per second producing incredibly detailed images of the terrain.

Texas Water Development Board

The data has one square-meter resolution compared to the old standard of 30 square-meters used in older USGS surveys. That’s a 900x improvement (1m x 1m vs. 30m x 30m) in resolution.

That increased resolution lets mapmakers see much more detail in the landscape, including low areas where water tends to pool during floods.

Play the Video

Filtering Out Buildings and Foliage Reveals Terrain

By filtering out portions of the spectrum, say those that have to do with buildings and foliage…

Screen Capture from TWDB Video

…scientists can reveal the terrain under them.

Lidar Now FEMA Requirement for Mapping

FEMA now requires the use of Lidar in floodplain mapping. As the state continues to grow rapidly, Lidar helps floodplain modelers better understand what is happening on the ground during a flood.

Inspiring the Next Generation

This is a fascinating little video. It has enough meat for curious adults. It also has a wow factor for students that might someday inspire interest in science, technology or engineering careers.

Updated Harris County Floodplain Maps

Harris County Flood Control District uses Lidar data to help develop the next generation of flood maps for the region. FEMA last updated the maps in 2007 as a result of massive flooding from Tropical Storm Allison. The District could release preliminary maps as early as 2022. But it could then take several more years for FEMA to review and approve them. The FEMA process involves a lengthy public comment period.

Source: Harris County Flood Control District.

Posted by Bob Rehak on 9/16/2020

1114 Days since Hurricane Harvey