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Analyzing estuarine shoreline change in coastal North Carolina .

机译：北卡罗莱纳州沿海河口海岸线变化分析。

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摘要

With continued climate change, sea-level rise, and coastal development, concern about shoreline dynamics has expanded beyond oceanfront areas to encompass more protected coastal water bodies, such as estuaries. Because estuaries are critically important ecosystems, understanding coastline changes in these areas is necessary for evaluating resource risks. Throughout the recent decades various methods have been developed to calculate shoreline change and multiple parameters have been hypothesized to correlate with estuarine erosion, including fetch, wave energy, elevation, and vegetation. A transect-based approach is commonly used to quantify shoreline change on linear (i.e., ocean) shorelines; however, due to the complex morphology of the estuarine environments, a point-based approach was developed and applied in this study. Shoreline-change rates and additional parameters (i.e., wave energy and shoreline composition) were determined using 1958 and 1998 aerial photography and available datasets. From these data the average shoreline change of Cedar Island, NC is determined to be -0.24 m yr-1, with 88% of the shoreline eroding. Of the parameters analyzed, shoreline composition appears to have an important control on shoreline erosion along Cedar Island, whereas wave energy is not significantly correlated with shoreline-change rates.;The point-based approach was applied to the trunk of the Neuse River Estuary to analyze parameters associated with estuarine erosion at two contrasting scales, regional (whole estuary) and local (estuary partitioned into 8 sections, based on orientation and exposure). With a mean shoreline-change rate of --0.58 m yr-1, the majority (93%) of the Neuse River Estuary study area is eroding. Although linear regression analysis at the regional scale did not find significant correlations between shoreline change and the parameters analyzed, trends were determined at the local scale. Local-scale analysis determined higher erosion rates, higher elevation, and lower exposure and fetch up-estuary. Erosion rates, fetch, and wave exposure increase, while elevation decreases moving eastward, down-estuary. The general trends found at the local scale highlight the importance of the spatial distribution on shoreline-change rates and parameters analyzed within a complex estuarine system, like the Neuse River Estuary.;Linear regression analysis between mean fetch and mean shoreline-change rates at the Local Scale determined an equation to predict shoreline-change rates. Predicted shoreline-change rates overestimate erosion on extremely high fetch shorelines and underestimate erosion on shorelines classified as sediment bank. Overall, the model is conservative in predicting shoreline-change rates by underestimating erosion and accretion within the Neuse River Estuary. Further analysis of mean fetch by specific vegetation type may offer additional insight into the influencing forces on estuarine shoreline change.
机译：随着气候变化，海平面上升和沿海开发的持续发展，人们对海岸线动态的关注范围已从沿海地区扩展到了更多受保护的沿海水域，例如河口。由于河口是至关重要的生态系统，因此了解这些地区的海岸线变化对于评估资源风险非常必要。在过去的几十年中，已经开发出各种方法来计算海岸线变化，并假设了多个参数与河口侵蚀有关，包括取水，波浪能，海拔和植被。通常采用基于断面的方法来量化线性（即海洋）海岸线上的海岸线变化；但是，由于河口环境的形态复杂，因此开发了一种基于点的方法并将其应用于本研究。使用1958年和1998年的航拍照片和可用数据集确定海岸线变化率和其他参数（即波浪能和海岸线组成）。根据这些数据，确定北卡罗来纳州锡达岛的平均海岸线变化为-0.24 m yr-1，其中88％的海岸线受到侵蚀。在分析的参数中，海岸线组成似乎对锡达岛沿岸的侵蚀具有重要的控制作用，而波能与海岸线变化率却没有显着相关。在两个相对不同的尺度上分析与河口侵蚀有关的参数，区域尺度（整个河口）和局部尺度（根据方向和暴露程度将河口分为8个部分）。 Neuse河口研究区的大部分地区（93％）的平均海岸线变化率为--0.58 m yr-1。尽管在区域尺度上的线性回归分析未发现海岸线变化与所分析的参数之间存在显着相关性，但在局部尺度上确定了趋势。局部尺度分析确定较高的侵蚀速率，较高的海拔高度，较低的暴露量和河口上游。侵蚀率，获取量和波浪暴露增加，而海拔降低则向东，河口向下移动。在地方尺度上发现的总体趋势突显了空间分布对岸线变化率和在诸如Neuse河河口这样的复杂河口系统中分析的参数的重要性；在平均取水量和平均岸线变化率之间进行线性回归分析当地尺度确定了一个预测海岸线变化率的方程。预测的海岸线变化率高估了极高进水岸线的侵蚀，而低估了归类为沉积物库岸线的侵蚀。总体而言，该模型在通过低估Neuse河口内的侵蚀和增生来预测海岸线变化率方面是保守的。通过特定植被类型对平均取水量的进一步分析可能会提供对河口海岸线变化影响力的更多见解。

著录项

  • 作者

    Cowart, Lisa.;

  • 作者单位

    East Carolina University.;

  • 授予单位 East Carolina University.;
  • 学科 Geology.
  • 学位 M.S.
  • 年度 2009
  • 页码 95 p.
  • 总页数 95
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

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