Beach Nourishment and Protection (1995) / Chapter Skim
Currently Skimming:
6 Monitoring
6 Monitoring
Pages 127-139
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 127... ...
OVERVIEW Monitoring is the systematic collection of physical, environmental, or economic time-series data or a combination of these data on a beach nourishment project in order to make decisions regarding the need for or operation of the project or to evaluate the project's performance. Beach nourishment projects are continually responding to storms and seasonal changes in the physical and biological environments.
|
From page 128... ...
Often, many physical monitoring programs address only the beach's response to sand-moving forces and do not include important forces such as waves and currents. Environmental monitoring is undertaken to document a project's effects on the biota of the nourishment project.
|
From page 129... ...
Preconstruction monitoring involves collection of data on the physical and biological environments that describe regional and site-specific processes. It includes collecting data helpful for design as well as baseline biological data.
|
From page 130... ...
If beach fauna show only limited impacts during nourishment, monitoring of these impacts may not be necessary in subsequent renourishments or for similar nourishment projects. The analysis of data from an effective monitoring program would provide feedback to the design process.
|
From page 131... ...
Historical data may include anecdotal information in addition to well-documented information on the physical environment and on the performance of earlier coastal projects. Information may include: · historical erosion rates from aerial photographs or shoreline-change maps; relative changes/trends in sea level; astronomical tides; local anthropogenic impacts, such as past nourishments; documented information on historical storms and wave climate; and assessment of the geological setting (i.e., the type of underlying geology that may influence coastal processes and the sediment budget)
|
From page 132... ...
They include surface-piercing gauges, pressure gauges, accelerometer buoys, and inverted echo sounders. Measurements of wave direction, necessary to determine alongshore sediment transport rates, require directional buoys in deep water, multiple gauge arrays, or pressure-gauge slope arrays in shallow water.
|
From page 133... ...
coastlines (NOAA, 19931. These gauges record water levels that include the astronomical tides, and when the predicted astronomical tide is subtracted from the gauge record, they yield data on the meteorologically caused water levels (storm surges)
|
From page 134... ...
A complete monitoring program would provide adequate data to ensure that biological impacts are only short term relative to the interval between renourishment projects. If long-term impacts are experienced, other approaches to the project must be considered.
|
From page 135... ...
The size of the survey area and the spacing of transects in the area will depend on the equipment used, but all bottom habitats in the area potentially affected by the project need to be mapped fully. Data on fishery resources in the project area or on use of the area by threatened or endangered species are often available through monitoring programs conducted by state and federal natural resource agencies.
|
From page 136... ...
Based on the limited data available from previous monitoring efforts, several key questions need to be addressed in developing the biological study design: · What is the duration of disturbance to the biological resources of concern, and is it compatible with the anticipated frequency of redisturbance resulting from subsequent renourishment operations? · Are biological resources adjacent to the project area affected by construction activities or subsequent movement of sediments from the project area?
|
From page 137... ...
What was the actual distribution of the costs and benefits of the projectthat is, who benefited and who paid? Although the USACE is charged with conducting preconstruction costbenefit analyses, there have been few follow-up analyses of projects to determine whether projected benefits were actually realized, whether secondary benefits occurred, or whether unanticipated costs could be attributed to the project (Haveman, 1979; Stronge, 1992b, 1994~.
|
From page 138... ...
Nonetheless, it would be useful to design a hedonic study that attempts to reveal the marginal value associated with beach nourishment, although it may require incorporating a lagged response in the model. It would also be useful if the hedonic analysis could be designed to separate the storm damage reduction benefits from the aesthetic and recreational benefits of the nourishment; however, the high correlation between these two characteristics may pre clude doing so.
|
From page 139... ...
Alternatively, the need for a particular project may be due to interruption of the natural sand flow by a navigational project. Information on the distribution of costs and benefits from beach nourishment projects of different types would help inform the cost-shar~ng policy makers in the future.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.