Reference no: EM133416476

Read the following Editorials on the Figure 8 Community Groin Request

TOM JARRET PRO GROIN EDITORIAL: Research indicates terminal groins can be effective

Tom Jarrett is a respected coastal engineer who spent 25 years with the U.S. Army Corps of Engineers. He is currently works as a consultant to coastal communities in North Carolina and nationwide. There has been much debate lately regarding a proposal to help reduce beach erosion along the North Carolina coast. Much of the criticism is based on a faulty assumption that is simply not supported by a close examination of the facts. The issue revolves around terminal groins and whether these low-lying shoreline protection structures can protect the beach from erosion without causing adverse consequences for neighbors. A group of scientists and academicians says it can't be done. In fact, groins already have been proven successful in North Carolina and elsewhere without any major disruption to the natural flow of sand. North Carolina has two successful examples of terminal groins - one of the north end of Pea Island in Dare County and the other on the east end of Bogue Banks in Carteret County - that have not created the type of adverse impacts being predicted by those who oppose Senate Bill 599. The performance of the Pea Island terminal groin has been well documented. NC State University has conducted continuous shoreline monitoring for more than 16 years and the data clearly demonstrates shoreline erosion on the northern 6 miles of Pea Island is considerably less than the erosion rates the island was previously experiencing. The negative impacts feared by some have simply not materialized at Pea Island. Here's why: a terminal groin quickly traps sand to form an accretion fillet that protects the shoreline - but once the fillet is formed, sand continues to move into the inlet by passing over, through or around the seaward end of the groin. In other words, the terminal groin has a temporarily impact and then allows sand to continue its normal flow. The Bogue Banks groin has experienced similar results. While a formal monitoring program was not established, beach surveys and aerial photos of the area clearly demonstrate the groin has not had any significant negative impacts on the shoreline west of the structure. What makes these structures successful? They are located adjacent to unstabilized tidal inlets. Robert G. Dean, a world renowned coastal engineering expert at the University of Florida, has specifically studied the use of terminal structures at inlets. He examines six successful examples - Boca Grande Pass, FL; Johns Pass, FL; Bakers Haulover, FL; Clearwater Pass, FL; St. Lucie Inlet, FL; Ocean City Inlet, MD - in a 1993 paper, "Terminal structures at Ends of Littoral Systems," that was published in the Journal of Coastal Research. The legislation being considered in North Carolina would only allow terminal groins to be considered if they are located adjacent to unstabilized tidal inlets. Those opposed to terminal groins have attempted to raise concerns about the negative impacts of groins by referring to a Coastal Engineering Manual issued by the U.S. Army Corps of Engineers. The reference used by opponents was intended as a precautionary warning that the casual application of groins without proper engineering design and impact considerations could lead to undesirable results. A closer look at the manual provides a more relevant statement on the potential impact of terminal groins: "Groins on the updrift side of inlets can benefit nearby beach nourishment projects by controlling (or gating) the amount entering (lost) to the inlet....Terminal groins fill quickly and do not have major impacts on ebb tidal shoals, and normal inlet, sand-passing processes." That statement is the exact opposite of what critics would have you believe. It demonstrates that terminal groins can have a positive impact when constructed under the right circumstances. North Carolina has successfully used terminal groins in the past and should consider the use of groins adjacent to unstabilized tidal inlets. This is where our state faces the most significant beach erosion challenges and the area where science has proven that groins can work.

OPPOSITION GROIN EDITORIAL: Western Carolina University Program for the Study of Developed Shorelines

North Carolina law (G.S 113A-115.1) prohibits the use of groins - steel, rock or wood walls built perpendicular to the beach in order to trap shifting sand - and other permanent erosion control structures along ocean shorelines. This ban is based on: 1) extensive studies and technical data documenting the detrimental impacts of erosion control structures and 2) 150 years of documentation of the negative impacts of shoreline stabilization on the barrier islands in New Jersey. The negative impact of groins and jetties on downdrift shorelines is well understood. When they work as intended, sand moving along the beach in the so-called downdrift direction is trapped on the updrift side, causing a sand deficit and increasing erosion rates on the downdrift side. This well-documented and unquestioned impact is widely cited in the engineering and geologic literature. The United States Army Corps of Engineers' Coastal Engineering Manual describes groins as: "...probably the most misused and improperly designed of all coastal structures...Over the course of some time interval, accretion causes a positive increase in beach width updrift of the groin. Conservation of sand mass therefore produces erosion and a decrease in beach width on the downdrift side of the groin" (USACE, 2002). In his textbook (used by most coastal engineering programs to introduce beach processes) Paul Komar, professor emeritus in the College of Oceanographic and Atmospheric Sciences at Oregon State University, states, "Groins and jetties have the same effect in damming the longshore sediment transport, the shoreline builds out on the updrift side and erodes in the downdrift direction" (Komar, 1998). There is no debate: A structure placed at the terminus of a barrier island, near an inlet, will interrupt the natural sand bypass system, deprive the ebb and flood tide deltas of sand and cause negative impacts to adjacent Islands. In a complex coastal system, the precise location, onset and scale of these impacts are very difficult to pinpoint. As with all erosion control structures, it may take years for groin impacts to become apparent. This is why promises to monitor such projects ring hollow, and why disputes over groin impacts often end up in court where judges, rather than scientific experts, end up making critical coastal management decisions. Using groins in conjunction with beach nourishment projects is of dubious value as well. When big storms occur, groins direct strong currents that carry large amounts of sand seaward, in an offshore direction parallel to the groins. After Hurricane Hugo, for example, sidescan sonar studies showed gullies excavated on the continental shelf adjacent to each of the groins on Pawleys Island in South Carolina. Because much sand loss is offshore during storms, groins will have little impact on holding sand in place (and may even accelerate loss). There is nothing experimental about groins, terminal or otherwise, and the insinuation that a terminal groin will be removed or altered if it doesn't work is nothing more than lip service. Experience on many other American shorelines indicates that removal of a structure, once put in place, is a rare event - no matter what promises were made beforehand. The localized and temporary updrift benefits afforded by groins and jetties rarely, if ever, justify the downdrift damage caused by increased erosion - regardless of whether it is to developed or undeveloped shorelines, inlets and islands. We urge you to maintain the State of North Carolina's high standards for coastal management by preventing any change to the current ban on coastal hard structures. Doing so is the surest way to protect the state's beaches for future generations. Thank you for your time and consideration

QUESTIONS

Choose a Position (anti or pro groin) You should decide whether you would support the building of the structures to protect Figure 8 Island or not. Come up with an argument that supports your stance. Spend a little time poking around the internet for additional information on groins and their effects. You may even want to consider if other states allow groins or not.

1. What type of structure do the residents of the Figure 8 Community wish to build? (You may have to do some internet research to determine what this is)

2. How have the residents been dealing with erosion up until now? Describe this technique.

3. Knowing what scientists know now, if Figure 8 Island did not have any homes or other structures built on it, should development be allowed in the future? Why or why not?

4. Should the Figure 8 community be allowed to build a hard stabilization structure to protect their homes? Support your answer with information that you learned from your research?

5. If the structure is built and there are negative consequences to other communities what should be done? (maybe look up examples of legal battles over groins or other hard stabilization structures).