Tag Archive for: forests

How fast are we replacing forests and wetlands with concrete?

We all know that concrete is impervious and that it increases both the amount and speed of runoff, which contributes to flooding. But how fast are we losing wetlands, forest and prairie to development? Does anyone really know? The folks at the Houston Advanced Research Center (HARC) in The Woodlands have attempted to quantify the answer.

You can see their findings in a presentation called Houston-Galveston & Southeast Texas Land Cover Change. This interactive presentation/tool allows you to zoom into individual watersheds or examine data regionally.

“Green infrastructure such as forests, prairies, and wetlands,” they say, “can capture and slow the release of rainfall. When preserved and integrated with engineered retention systems, this can help alleviate runoff issues.”

Concrete Details from Montgomery and Northern Harris Counties

The presentation consists of a series of interactive maps that lets you explore the world immediately around you. It begins with measurements of the extent of “imperviousness.” Then it goes into a series of maps that show the rate of change in the amount of upland forests, wetlands and developed areas over the last 20 years throughout the region and state. Below, some examples from the Lake Houston/Montgomery County Area.

In 2001, the Lake Houston Area was 10-20% impervious. Most of Montgomery County was less than 10. Compare this to…

By 2011, imperviousness in the Lake Houston area had not changed much. But look at the large finger extending up into Montgomery County along the San Jacinto West Fork.

This map shows the loss of wetlands between 1996 and 2010. The deep orange color shows the greatest loss of wetlands. Note the dramatic changes upstream of Lake Houston along the West Fork, Spring Creek and Cypress Creek. The East Fork, Peach Creek and Caney Creek watersheds show loss also.

This map shows loss of forests upstream of Lake Houston between 1996 and 2010. Again, the deep orange color shows the greatest loss. Note the similar pattern to loss of wetlands. According to the US Forest Service, a single large tree can soak up 100 gallons of water a day.

HARC ends with a discussion of future development by showing the Montgomery County Thoroughfare Plan (circa 2016) and how it would impact important eco-systems.

The Montgomery County Thoroughfare Plan as of 2016. The orange areas show planned additions. Note the density of additions in the Spring, Porter, New Caney and Splendora areas.

Montgomery County is the second fastest growing county in the region (3% per year) after Fort Bend County (3.1%).

Unchecked Upstream Development can Cause Downstream Flooding

HARC’s data underscores the need for a regional approach to watershed development and the strict enforcement of flood plain regulations. We need look no farther than the west side of Houston, in areas like Meyerland and Bellaire, to see the impact of encroachment on flood plains.

Posted by Bob Rehak on November 11, 2018

439 Days since Hurricane Harvey