Best Management Practices along the Trinity River
Protecting Water Resources in Fort Worth, Texas
Where does your water come from?
Do you know where your water comes from? The simple answer is that it comes from rain events, and then is channeled through your watershed into streams, reservoirs and aquifers.
A watershed is an area that accumulates water due to a divide, or higher elevation within the landscape. The yellow line in the picture here represents this divide, creating two different watersheds. Wherever you live, you are within a watershed. Here in Fort Worth, Texas, the Trinity River is our watershed. It travels downstream and passes through reservoirs before it enters into the ocean.
Recently, the majority of the world population has migrated to cities and urban centers, which has caused an increase in impervious surfaces. Impervious surfaces are commonly made from asphalt, concrete, and metal, which limit infiltration of water into the ground. This effect of urbanization causes more surface water runoff and pollution to enter into our streams and reservoirs.
Population all over the world is increasing, especially within the North Texas region. For every 1% increase in population, there is an average 1.37% increase in impervious surfaces (Brophy-Price, 2010).
Best Management Practices (BMPs)
Due to the effects of population growth and associated urban growth patterns, actions need to be taken to protect our water resources. Best Management Practices (BMPs) and associated green stormwater infrastructure (GSI) offer ways for us to manage risks related to water quality and quantity.
BMPs are ecosystem management based practices that decrease potential harmful effects of urbanization, development, and natural processes of the landscape. These practices help build resilient ecosystems, and increase ecosystem services for both humans and wildlife. They are not only functional, but may also serve as an amenity to the landscape, providing visually appealing aesthetics to an area.
When considering the use of BMPs, it can be helpful to consider these key aspects:
- Is there an environmental risk associated with an area that a BMP may be able to address, and what is that specific risk?
- Which BMP can address the issue/issues?
- What are the components of the BMP that allow for it to be effective and function as intended? In order for the BMP to remain effective over time, each part of it should be monitored and inspected routinely to help maintain structural integrity and ensure that it continues to perform at its peak capacity.
To learn more about BMPs click here
To better understand how BMPs can be used, lets take a look at some real world applications in the area!
Stormwater Inlets
These are a common BMP, and are often used in combination with other BMPs. Inlets not only help capture water, but also direct it to other BMPs as part of a treatment train. In this case, the inlet is capturing sheet flow from the parking lot and directing it to an irrigation basin.
Retention / Irrigation Basins
These kinds of wetlands capture stormwater runoff and use the water captured water as an irrigation source. This helps to conserve water usage, among offering other numerous benefits. Wetland systems have special soil and aquatic plants that offer additional services to humans and wildlife.
Constructed Wetlands
Constructed wetlands are most similar to natural, or non-human made wetlands. These wetlands are often surrounded by riparian buffers and they have diverse aquatic vegetation species growing within them. When integrated in an urban context as part of a channelized stormwater runoff system, these types of wetlands are able to provide numerous services due to the rich diversity of plant species.
The outlet for the constructed wetland can be seen here.
The weir box design helps to channel water out of the system during floods.
Wet Basins
These are common in urban areas. Wet basins typically have turf grasses planted at the shoreline edge, and have steeply sloped shores leading to the waters edge. Sometimes decorated with fountains, these types of wetlands differ from constructed wetlands in the sense that they are more manicured, and require higher costs allocated towards management of vegetation and algal growth. Naturally occurring wetlands are sometimes re-constructed into wet basins once urban development begins in an area.
The outlet of the wet basin can be seen here.
Permeable Concrete
This type of concrete is porous, which allows for water to readily infiltrate through it, permeating down into the ground below. This helps reduce runoff, minimize erosion, and mitigate flood events. Permeable concrete is one of many different types of permeable surfaces.
Permeable Pavers
These are another type of permeable surface, designed to allow for water to infiltrate into the spaces found in between each paver. Instead of using conventional concrete for a whole parking lot or walkway, these areas can incorporate permeable pavers to help reduce runoff before it enters into a drain or gutter.
Trench Drains
This is another type of inlet which helps to convey water from paved surfaces, including sidewalks and parking lots. The grate over the top can withstand heavy traffic, and also helps to filter out large debris.
Bioretention Basins and Curb Cuts
These BMPs are defined as a stormwater system that treats rainfall and runoff through the integration of native and adapted plants and microorganisms which are rooted in the soil media. Plants and soil help enhance the removal of pollutants, and encourage infiltration. Plants also increase evapotranspiration rates, and add beauty to an area. Curb cuts allow for water to pass through into other areas. In this instance the curb cuts allow water from the parking lot to enter the bioswale.
Energy Dissipation BMPs
The next 3 images are different energy dissipation BMPs. These types of BMPs help slow down the flow of water, and filter out large debris.
Splash Pads
In this first image notice how the splash pads are made of rocks and are positioned in between the curb cuts and the bioretention area, helping to slow down the rate of flow. If it were not for the splash pad, the force of water would erode the inlet area.
In this image you can see energy dissipation paired with curb cuts and a drain inlet. The curb cuts allow for water to flow from the parking lot into the rocked channel, and then the drain. The rocked channel not only helps with energy dissipation, but also gives the water a chance to infiltrate into the ground before it enters into the drain inlet.
Grass Swales and Check Dams
This type of energy dissipation is called a check dam, and is placed within a sloped grass swale in sequence with other check dams. As water is slowed down and filtered by a check damn, it moves through it and again builds momentum as it travels down hill, calling for the need of another check damn to slow it down again. In this process, the grass is helping to reduce runoff by increasing infiltration into the ground. The grass also helps to filter water as well.
Vegetated Filter Strips
This BMP utilizes shallow slopes and vegetation to receive and maintain sheet flows over the area. Similar to bioretention basins, curb cuts are easily incorporated with vegetated filter strips, which can be composed of turf or landscape beds with native and adapted plants. Here, there are also rocks placed at the edge of the curb cuts to help dissipate the energy as it enters the filter strip.
Landscaping
Landscaping as a BMP deals with establishing vegetative communities in an area, which has numerous benefits other than treating stormwater. Using native and adapted plants is encouraged for landscaping projects because these plants have symbiotic relationships with native wildlife species, and are drought and disease tolerant. They also have appropriate root structures that help reduce erosion and encourage infiltration. Since these types of plants thrive in their native area, they require less maintenance and are cost efficient.
Landscaping for Dry/Wet Conditions
Appropriate vegetation for an area depends on specific site conditions, not just the region. For instance, how much sun and water does the area provide, and what is the soil type? In this image you can observe plants that thrive in dry to wet conditions.
Vegetated Channel
This site has worked closely with the TRWD where they have followed the Water Quality Guidance Manual, and operate under our MS4 permit to allow for discharge into the river. A vegetated filter strip treats the water before it enters into the Trinity River.
Interested in Learning More?
Learn more about landscaping and vegetation at these links:
Learn more about the effects of impervious surface here:
Follow this link to learn more about BMPs and GSI at the TRWD Rainscapes in Fort Worth
