Stream Restoration In Pennsylvania

Author : Corey Anne Robinson
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (135 download)

DOWNLOAD NOW!

Download or read book Changing the Landscape : Floodplain Reconnection in the Breakneck Creek Watershed, Pennsylvania written by Corey Anne Robinson and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In 2008, the National Resource Council warned that the complexity of stormwater pollution was only expected to grow in the years that followed. As the principal contributor to water quality impairments in waterbodies across the United States, the magnitude of stormwater pollution presents a significant challenge to improving water quality. Unfortunately, awareness of the long-term impacts of stormwater pollution and stormwater runoff in the United States has only existed for the past few decades (National Research Council, 2008). Impacts of Stormwater Pollution and Runoff Traditional strategies to manage stormwater runoff - termed 'gray' infrastructure - were designed with a single purpose in mind; move stormwater runoff away from the built environment as quickly as possible. Gray infrastructure includes curbs, gutters, drains, pipes, or other solid structures like sewer systems that collect and convey stormwater runoff from impervious surfaces (e.g. roadways, parking lots, rooftops, etc.). During this process nutrients, organic contaminants, heavy metals, and pesticides attach to fine sediment particles which are carried from densely populated areas and discharged untreated into local streams, rivers, or lakes. Despite having consistently high maintenance and upgrade costs, gray infrastructure does little to capture these pollutants or accommodate aspects related to ecosystem services (Ahilan et al., 2018; US EPA, 2019). It is now understood that urban development and large-scale changes in land use combined with stormwater pollution and runoff has severely degraded the quality of streams. Streams are often lost to development through diversion, piping, and burial strategies resulting in a significant decrease in the total number of streams in a watershed. Over time, streams being replaced with piped networks capable of conveying stormwater results in water discharging to streams at a significantly faster rate (Julian et al., 2015). This has a broad impact on the connection between streams and their floodplains. When the rate of stormwater entering streams increases it can result in 'down-cutting' which means the stream channel deepens and becomes physically and ecologically discounted from its floodplain (Boyer et al., 2009). In addition, when floodplains are paved over and streams are destroyed it is common for remaining streams to widen and streambanks to become unstable. As a result, we often see farmland, roads, bridges, homes, and other infrastructure located in the floodplain being washed away or damaged (Ahilan et al., 2018; Boyer et al., 2009). Impervious surfaces common with urbanization in floodplains can alter the size of sediment delivered to a stream; hindering large sediment while allowing disproportionally high levels of finer silt and clay to enter the remaining streams. Fine sediments directly impact fish and wildlife by covering spawning gravels, impairing fish respiration, diminishing food sources, and reducing dissolved oxygen levels. These fine sediments also absorb heat from sunlight leading to higher water temperatures and the loss of fish and embryos (Ahilan et al., 2018). The vast quantity of stormwater entering a stream also contributes to increases in downstream flooding (Boyer et al., 2009). The Federal Emergency Management Agency (FEMA) considers flooding to be the number one natural hazard in the United States. Damages associated with flooding cost on average $7.96 billion in property damages annually (tracked from 1985 to 2014) (Ahilan et al., 2018). The vulnerability and potential flooding damages will continue to rise while humans continue to develop floodplains and could be exacerbated by climate change in some regions through a rise in flood frequency (Zhu et al., 2007). In contrast to gray infrastructure, green infrastructure is a multifunctional strategy offering a diverse range of benefits and commonly discussed as a sustainable approach to address the complex challenges of managing stormwater runoff in urban environments (Lovell & Taylor, 2013). Green infrastructure uses a range of techniques to keep stormwater runoff on-site or mitigate the impacts of stormwater runoff such as rainwater harvesting (e.g. rain barrels), rain gardens, bioswales, permeable pavements, green roofs, and land conservation and or restoration. Restoring natural processes requires a mix of vegetation and soils that soak up and store stormwater runoff at both small (rain gardens or rain barrels) and large (land restoration) scales (US EPA, 2020). Small scale green infrastructure focuses more on mimicking nature to soak up stormwater runoff on-site while large scale strategies focus on interventions capable of providing wildlife habitat, clean air and water, and flood protection. Large scale interventions can take many forms but generally explore opportunities with wetlands, riparian areas, or stream and river channels (Carter et al., 2018; Lovell & Taylor, 2013). Over the past few decades, river restoration projects across the United States have accelerated. Used to describe a broad range of modifications to river channels, riparian zones and floodplains, river restoration projects address degrading streams and rivers and are often designed to improve fish habitat, water quality or recreation opportunities (Wohl et al., 2015). However, channel stabilization and reductions in bank erosion - the primary focus in the United States - soaks up the billions of dollars invested in river restoration. This narrow focus is often undermined in urban environments by the elevated quantity of stormwater runoff discharging into streams washing away or damaging projects (McMillan & Noe, 2017). River restoration projects within urban environments typically focus on small sections of streams which is not as effective at mitigating the impacts of the physical, hydrological or chemical changes specifically at the watershed-scale (Wohl et al., 2015). ..." -- from Introduction