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'''INTRODUCTION:''' Section 111 of the 1968 Rivers and Harbors Act, Public Law 90-483 gives the Federal government the authority to study, plan, and prevent or mitigate damages to shores caused by navigation projects. Since the 1970s, there have been numerous Section 111 studies that have estimated the erosion caused by navigation channels, jetties, and dredging and placement activities over the lifetime of an individual navigation project. The goal of a Section 111 study is to evaluate data to assign a number to the percentage of damages caused by the Federal navigation project. Cost of the mitigation project, usually in the form of beach restoration, will then be shared with the local partner at the same percentage as the original navigation project. Section 111 studies have applied a range of methods, including an assessment of processes (waves, currents, sediment transport) with and without the project, analysis of historical shoreline position and beach profile data, and formulation of sediment budgets. The goal of this document is to provide an orientation to Section 111 studies and present guidance for assessment. | '''INTRODUCTION:''' Section 111 of the 1968 Rivers and Harbors Act, Public Law 90-483 gives the Federal government the authority to study, plan, and prevent or mitigate damages to shores caused by navigation projects. Since the 1970s, there have been numerous Section 111 studies that have estimated the erosion caused by navigation channels, jetties, and dredging and placement activities over the lifetime of an individual navigation project. The goal of a Section 111 study is to evaluate data to assign a number to the percentage of damages caused by the Federal navigation project. Cost of the mitigation project, usually in the form of beach restoration, will then be shared with the local partner at the same percentage as the original navigation project. Section 111 studies have applied a range of methods, including an assessment of processes (waves, currents, sediment transport) with and without the project, analysis of historical shoreline position and beach profile data, and formulation of sediment budgets. The goal of this document is to provide an orientation to Section 111 studies and present guidance for assessment. | ||
'''IMPROVED VERSUS NATURAL INLET SYSTEMS:''' Improved inlets may include dredged navigation channels and placement sites; and stabilizing structures such as jetties, spurs, groins, and revetments. The improved inlet system may differ from the pre-project system in terms of hydrodynamics such as the tidal range in the estuary/bay, circulation and water quality, flooding characteristics in the back bay, and wave breaking characteristics in the nearshore, which are of particular interest to the surfing community. | |||
'''TYPES OF DATA FOR ANALYSIS:''' Ideally, data to quantify the pre-project and post-project conditions would be available and compared to assess the differences prior to and after project construction. Many times the temporal availability and quality of such data are insufficient. An evaluation of background (non-project) processes, such as relative sea level change and long-term regional erosion or accretion, must be accounted for in the analysis. Uncertainty and error associated with each data set must be quantified so that the percentage of damage to the adjacent shores caused by the navigation project can be characterized relative to the reliability of the data and analysis methods. | '''TYPES OF DATA FOR ANALYSIS:''' Ideally, data to quantify the pre-project and post-project conditions would be available and compared to assess the differences prior to and after project construction. Many times the temporal availability and quality of such data are insufficient. An evaluation of background (non-project) processes, such as relative sea level change and long-term regional erosion or accretion, must be accounted for in the analysis. Uncertainty and error associated with each data set must be quantified so that the percentage of damage to the adjacent shores caused by the navigation project can be characterized relative to the reliability of the data and analysis methods. | ||
Revision as of 21:56, 10 March 2011
PURPOSE: This Wiki-Technical Note presents an overview of the Section 111 Authority, presents methods that can be applied in Section 111 studies, and provides a reference list to previous Section 111 studies. The Wiki-TN concludes with recommendations for a systematic, defensible Section 111 analysis.
CITATION:
Rosati, J.D., 2011, Assessing the Impact of Federal Navigation Projects on Adjacent Beaches:
Methods to Conduct Section 111 Studies, Wiki-TN, Vicksburg, MS: U.S. Army Engineer Research and Development Center.
INTRODUCTION: Section 111 of the 1968 Rivers and Harbors Act, Public Law 90-483 gives the Federal government the authority to study, plan, and prevent or mitigate damages to shores caused by navigation projects. Since the 1970s, there have been numerous Section 111 studies that have estimated the erosion caused by navigation channels, jetties, and dredging and placement activities over the lifetime of an individual navigation project. The goal of a Section 111 study is to evaluate data to assign a number to the percentage of damages caused by the Federal navigation project. Cost of the mitigation project, usually in the form of beach restoration, will then be shared with the local partner at the same percentage as the original navigation project. Section 111 studies have applied a range of methods, including an assessment of processes (waves, currents, sediment transport) with and without the project, analysis of historical shoreline position and beach profile data, and formulation of sediment budgets. The goal of this document is to provide an orientation to Section 111 studies and present guidance for assessment.
IMPROVED VERSUS NATURAL INLET SYSTEMS: Improved inlets may include dredged navigation channels and placement sites; and stabilizing structures such as jetties, spurs, groins, and revetments. The improved inlet system may differ from the pre-project system in terms of hydrodynamics such as the tidal range in the estuary/bay, circulation and water quality, flooding characteristics in the back bay, and wave breaking characteristics in the nearshore, which are of particular interest to the surfing community.
TYPES OF DATA FOR ANALYSIS: Ideally, data to quantify the pre-project and post-project conditions would be available and compared to assess the differences prior to and after project construction. Many times the temporal availability and quality of such data are insufficient. An evaluation of background (non-project) processes, such as relative sea level change and long-term regional erosion or accretion, must be accounted for in the analysis. Uncertainty and error associated with each data set must be quantified so that the percentage of damage to the adjacent shores caused by the navigation project can be characterized relative to the reliability of the data and analysis methods.
There are three types of data that can be applied, data characterizing the condition of the beaches adjacent to the inlet, process data, and anthropogenic activities such as dredging and placement:
Condition data in vicinity of inlet
- Shoreline position
- Beach profiles
- Topography and bathymetry
- Sediment type and distribution
Processes
- Long-term sea level change
- Offshore (and nearshore, if available) wave and wind climatology
- Tidal data
Anthropogenic Activities
- Dredging and placement history
- Construction of jetties, seawalls, groins, and other structures
- Mining activities