By Julia Bachman, Photojournalism Intern
The Outer Banks experiences constant challenges from shoreline erosion every year. With the continuation of coastal development, change in sea level rise, climate change, and intense storms, the configuration of our coast will change. Estuarine erosion is an obstacle that will proceed to impact coastal environments. We, humans, establish infrastructure in anticipation that it will remain, but inevitably the land encompassing us wants to shift.
Coastal Studies Institute (CSI) researchers have partnered with the Nature Conservancy to test possible concepts involving shoreline stabilization techniques, like sills (which is one of many stabilization techniques), which enrich shallow water habitats. This could be a potential solution to preventing erosion and sediment loss.
In this study, Installation of Experimental Shoreline Stabilization Sills at CSI Complete and Research Underway, 4 sills made from limestone have been installed in the sound to help researchers understand the shoreline processes and the erosion mitigation technique. So far, erosion rates have been measured before the sills were installed, during the installation, and after. The sills will be monitored frequently to evaluate the change in shoreline over a period of time. This ongoing study is designed to give substantial insight and quantify the effectiveness of these types of living shorelines. This project will provide homeowners/business owners with data on alternative methods opposed to conventional shoreline stabilization.
Our community contains valuable property that needs protection from damaging forces. Therefore, scientists have considered various stabilization options that will preserve our coastal community. “Hard” shoreline stabilization techniques like bulkheads and seawalls are more traditional ways to reduce erosion and sediment loss. With this method comes advantages and concerns. For example, “hard” techniques can be suitable for high wave energy, remain effective causing minor damage, and may create an aquatic habitat at the expense of the shallow water transitional zone. They can also pose navigation hazards, can be damaged by weather conditions, may disturb existing habitat, eliminate shallow water habitats and are susceptible to settling. Although, stabilization does not require the production of a barrier that will separate land and water.
CSI researchers have been showing more interest in an alternative technique involving a living shoreline because they can improve coastal resiliency by providing protection from storms. A living shoreline is composed of mostly native material and natural “soft” elements like vegetation. In some cases, for additional stability, “hard” elements like oyster reefs or rock sills are combined. These living shoreline techniques do not disturb existing habitats, they provide more habitat for coastal species, are biodegradable, and provide protection from wind and rain-driven erosion. Although they may take time to establish and require periodic renourishment, they protect the coast in a more natural way.
I had the opportunity to assist Coastal Studies Institute (CSI) researcher, Dave Sybert, on his Master’s research project along with lab technician Liz Mason and fellow interns Parker Sylvia (First Flight High School) and Bryson Casey (Manteo High School) in the lab. We analyzed sediment samples from the sills that were placed in The Croatan Sound. These tiles are used to understand where accretion is occurring in the marsh and to measure the rates. The sediment samples are collected along the transects to analyze sediment type and grain size. The matter located on top of the tiles extracted from the sound is put into sample bags and transported to the lab for further analysis. The amount of material that accumulates on individual tiles indicates how much has grown over a larger area after appropriate calculations are performed.
In the lab, we removed the matter from the sample bags and strategically placed it into Petri dishes. The Petri dishes were pre-weighed so the matter could be subtracted from the final weight only leaving the sample weight. We cut off the upper perimeter of the sample bags and rinsed with water to gather and flush all the material into the dish. Transferring as much of the material as possible would give the most efficient and accurate result.
We transported all of the Petri dishes containing matter to a furnace, burning anything that was living and organic. The water evaporated leaving only sediment and non-living material. After this process is complete the weight of the sediment and organic material deposited on the tiles was recorded. The data analyzed will help in future research when scientists are checking the actual marsh to see growth or recession.
Working in the lab gave me a chance to participate in hands-on learning and learn more about the current issues that CSI as a group is trying to find a solution to. The amount of erosion that occurs each year varies, but the idea is to understand our shoreline, so we can do all that we can to stabilize the Outer Banks in an environmentally friendly manner.
For project details and an update on current progress click here.