By Elizabeth Dabundo, LRWP Green Infrastructure & Planning Intern
In the first of the LRWP’s Natural Asset Mapping speaker series we hosted two wonderful speakers, JeanMarie Hartman and Jessica Jahre, on the topics of the importance of riparian areas and floodplains.
Wetlands of the Lower Raritan Watershed, Map by Jeanine Kopec-Zanghi
Rutgers Professor JeanMarie Hartman, Director of the Hartman Lab of Watershed Systems Studies, spoke on the importance of preserving riparian areas around streams as “buffer zones” for stream and habitat protection. She explained that the best type of “green infrastructure” for flood protection is the kind that doesn’t have to be engineered or installed – it is the natural “infrastructure” already found in forests and wetlands. It is best to keep a 300-foot buffer zone around streams in order to keep the stream itself, its inhabitants, and the surrounding watershed healthy. Professor Hartman explained these conclusions as almost common sense, but provided findings from an ongoing study of watershed management in Lower Raritan Watershed streams (Bound Brook and Lawrence Brook) that demonstrate a positive relationship between forest and wetland cover and biological water quality.
The study measured the presence of three groups of macroinvertebrates (aquatic animals) in the streams to determine stream health. Certain macroinvertebrates are more or less sensitive to environmental pollutants, and they can be grouped thusly:
-Pollution Intolerant (mayflies, stoneflies, caddisflies)
-Pollution Sensitive (dragonflies, damselflies)
-Pollution Tolerant (aquatic worms, midge larvae)
The presence of more pollution intolerant or pollution sensitive macros in a stream signifies that the stream and its waters are unimpaired, since they cannot live within polluted waters. These are often found in shaded streams with low levels of fine sediments, which not surprisingly are often streams with significant riparian buffers.
Next, Jessica Jahre of Princeton Hydro spoke on the importance of healthy floodplains. Floodplains are the areas surrounding streams and rivers that flood periodically, relating to risk. We often hear of 100-year or 500-year floods, but recently, we have seen more frequent and more intense flooding in the Lower Raritan Watershed. Floodplains are expanding, and more people are being put at risk for residing in or near the floodplain. Ms. Jahre explained that a healthy floodplain is integral for mitigating flood risk and damage in our communities, and she explained how she works with flood claims data to identify the areas most at risk.
It is important for a floodplain to be healthy in order to not only reduce instances of flooding, but also to improve water quality, recharge aquifers, and create wildlife habitat. It is often the case that floodplains have to be enhanced from current degraded conditions. This process includes reforesting or naturalizing (removal of development) floodplains, reconnecting the stream to the floodplain, lowering the floodplain through re-grading, or hydrologic restoration (eliminating abandoned agricultural ditches, removing dams). The problem we face in New Jersey and in many other densely populated areas is that development often comes right up to or is centered around rivers or streams, which only become more prone to flooding as the floodplain becomes more impaired through development and deforestation. In order to minimize future risks from flooding, we must enhance and improve our floodplains statewide.
Susan Edmunds identifying riparian areas of interest
Thank you to our wonderful speakers and attendees. Next up in the speaker series are presentations on Lower Raritan Watershed recreational assets and neighborhood, cultural, and historic assets. Please join us on March 15 from 9:30am-12:00pm at the Middlesex County Administration Building, 75 Bayard Street, New Brunswick.
Speaker themes for 2016 include natural resource assets, cultural and historic assets, transportation and mobility assets, seeing brownfields as community assets for restoration, and economic assets, innovation, & regional planning. We are very excited for the opportunity to have state and regional experts on these topics join us for these presentations, and we hope you will join us as well! Please see our events page for more information.