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Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution March 1984, The offshore tide becomes distorted as it propagates into shallow inlet/estuarine systems. Time asymmetries develop in the rise and fall of sea surface with consequent time and magnitude asymmetries in tidal currents. Flood-dominant estuaries are characterized by longer falling tides and stronger flood currents while ebb-dominant estuaries have longer rising tides and stronger ebb currents. The asymmetries are reflected in the non-linear growth of harmonics and compound tides of the principal equilibrium tidal constituents. This dissertation consists of three papers which examine the development of tidal asymmetries in shallow estuarine systems: a study of the recent migration history of Nauset Inlet (MA), a shallow estuarine system located on Cape Cod; an analysis of the results of a series of field experiments conducted at Nauset; a numerical model study of the types of estuarine characteristics controlling tidal asymmetry. The analysis of field results focuses on sea surface measurements. Non-linear distortion of the tide at Nauset is characterized by the strong growth of harmonics and compound constituents particularly in the quarter-diurnal band. Phase relationships between the forced constituents and their parent produce a flood-dominant estuary. Numerical modeling of M2 tidal propagation in shallow estuarine channels utilizes the one-dimensional equations of motion. Shallow, frictionally dominated channels with moderate tidal flat area develop a flood-dominant asymmetry while deeper channels with extensive tidal flats develop an ebb-dominant asymmetry. Model results are supported by observations of tidal asymmetry in natural estuaries. Implications of non-linear tidal distortion on bedload and suspended material transport are profound. Flood-dominant estuaries tend to import sediment if the supply is adequate whereas ebb-dominant estuaries can flush entering sediment effectively. Over long time periods, flood-dominant estuaries may eventually fill. Ebb-domina, This study was supported by the Department of Commerce, NOAA Office of Sea Grant under Grant numbers NA79AA-D-00102 and NASOAA-D-00077, the U.S. Army Research Office under Grant DAAG 29-81-K-0004, the Woods Hole Oceanographic Institution's Coastal Research Center and the W.H.O.I. education program.

Various aspects of sediment transport in and around natural, unstructured tidal inlets were investigated over the two year period of study. Concentrating on two tidal inlets (Nauset Inlet and Popponesset Inlet, Cape Cod, MA), and combining detailed field observations with numerical model studies of tidal flows in inlet/estuarine environments, several aspects of tidal inlet behavior have been clarified. In addition, field work has resulted in a number of technical publications of general utility to a wide spectrum of coastal research interest. Primary scientific items addressed in this study include: 1) diagnostic numerical model of generation and propagation of tidal non-liniarities in shallow estuarine channels; 2) effects of flow curvature on tidal inlet sediment transport; 3) definition of mechanisms by which tidal inlets migrate in a direction opposite to the net littoral drift direction; 4) hypothesis of a mechanism for rapid barrier spit growth in locations with low rates of littoral transport; 5) clarification of long-term patterns of sea-level rise in the United States to assess its role in tidal inlet/esturarine evolution; 6) historical descriptions of massive inlet migration at two study inlets as supporting evidence for the inlet modeling studies. Technical information generated by the study includes a description of a low-cost, reliable method to join nearshore electrical cables; description and intercomparison of instrumentation and analysis routines for estimating directional spectral parameters from wave gage data; and development of a field system and laboratory analysis package for preparing accurate bathymetric charts in shallow, nearshore regions, using microwave navigation and precision echo-sounding., Funding was provided by the U.S. Army Research Office under Grant DAAG 29-81-K-0004 and the Department of Commerce, NOAA Office of Sea Grant under Grants NA79AA-D-00102 and NA80AA-D-00077.

A historical study of barrier beach and inlet changes for the Nauset Inlet region, Cape Cod, Massachusetts, was performed to document patterns of beach and inlet change as a preliminary to designing and carrying out ffeld studies of inlet sediment transport. 120 historical charts from 1670 and 125 sets of aerial photographs from 1938 formed the basis for this study. Specific aspects of barrier beach and inlet change addressed include onshore barrier beach movement, longshore tidal inlet migration, and longshore sand bypassing past the inlet. In an effort to correlate forcing events with barrier changes, an exhaustive study of the local storm climate was performed. Detailed treatment of the specific mechanisms responsible for Nauset Inlet migration episodes in a direction opposite the dominant littoral drift are treated in a companion paper by Aubrey, Speer, and Ruder (1982). Documentation of the data base available for the Nauset Area is presented herein as appendices., Prepared for NOAA, 0ffice of Sea Gnant under Grant NA 80-AA-D- 00077 (R/B-21) and for the U.S. Army Research 0ffice under Grant DAAG29-81-K-0004.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1984., Microfiche copy available in Archives and Science., Includes bibliographies., by Paul Edward Speer., Ph.D.

Ecological Risk Assessments ERAs) are performed at hazardous waste cleanup sites under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA) program to determine the risk that contaminants pose to the environment. A number of concerns have been expressed with respect to ERAs and other studies conducted at CERCLA sites including the following: Too much effort is being spent on 'studies' instead of remedies; and remedies are largely determined on the basis of human health risk. As a result of these concerns, the Assistant Secretary of the Navy (Installations and Environment) asked the Center for Naval Analyses to conduct a study of the utility of ecological risk assessments. This study was to review the ERA process in general and address specific issues. This report documents the results of the study.

The offshore tide becomes distorted as it propagates into shallow inlet/estuarine systems. Time asymmetries develop in the rise and fall of sea surface with consequent time and magnitude asymmetries in tidal currents. Flood- dominant estuaries are characterized by longer falling tides and stronger flood currents while ebb-dominant estuaries have longer rising tides and stronger ebb currents. The asymmetries are reflected in the nonlinear growth of harmonics and compound tides of the principal equilibrium tidal constituents. This dissertation consists of three papers which examine the development of tidal asymmetries in shallow estuarine systems; a study of the recent migration history of Nauset Inlet (MA), a shallow estuarine system located on Cape Cod; an analysis of the results of a series of field experiments conducted at Nauset; a numerical model study of the types of estuarine characteristics controlling tidal asymmetry. The analysis of field results focuses on sea surface measurements. Non-linear distortion of the tide at Nauset is characterized by the strong growth of harmonics and compound constituents particularly in the quarter-diurnal band. Phase relationships between the forced constituents and their parents produce a flood-dominant estuary. Numerical modeling of M2 tidal propagation in shallow estuarine channels utilizes the one-dimensional equations of motion. (sdw), Sponsored in part by grants NA79AA-D-00102 and NA80AA-D- 00077.

Various aspects of sediment transport in and around natural, unstructured tidal inlets were investigated over the two year period of study. Concentrating on two tidal inlets (Nauset Inlet and Popponesset Inlet, Cape Cod, MA), and combining detailed field observations with numerical model studies of tidal flows in inlet/estuarine environments, several aspects of tidal inlet behavior have been clarified. In addition, field work has resulted in a number of technical publications of general utility to a wide spectrum of coastal research interest. Primary scientific items addressed in this study include: 1) diagnostic numerical model of generation and propagation of tidal non-linearities in shallow estuarine channels; 2) effects of flow curvature on tidal inlet sediment transport; 3) definition of mechanisms by which tidal inlets migrate in a direction opposite to the net littoral drift direction; 4) hypothesis of a mechanism for rapid barrier spit growth in locations with low rates of littoral transport; 5) clarification of long-term patterns of sea-level rise in the United States to assess its role in tidal inlet/estuarine evolution; 6) historical descriptions of massive inlet migration at two study includes a description of a low-cost, reliable method to join nearshore electrical cables; description and intercomparison of instrumentation and analysis routines for estimating directional spectral parameters from wave gage data; and a development of a field system and laboratory analysis package for preparing accurate bathymetric charts in shallow, nearshore regions, using microwave navigation and precision echo-sounding. (Author), Sponsored in part by Grant NA80AA-D-00077.

The offshore tide becomes distorted as it propagates into shallow inlet/estuarine systems. Time asymmetries develop in the rise and fall of sea surface with consequent time and magnitude asymmetries in tidal currents. Flood-dominant estuaries are characterized by longer falling tides and stronger flood currents while ebb-dominant estuaries have longer rising tides and stronger ebb currents. The asymmetries are reflected in the non-linear growth of harmonics and compound tides of the principal equilibrium tidal constituents. This dissertation consists of three papers which examine the development of tidal asymmetries in shallow estuarine systems: a study of the recent migration history of Nauset Inlet (MA), a shallow estuarine system located on Cape Cod; an analysis of the results of a series of field experiments conducted at Nauset; a numerical model study of the types of estuarine characteristics controlling tidal asymmetry. The analysis of field results focuses on sea surface measurements. Non-linear distortion of the tide at Nauset is characterized by the strong growth of harmonics and compound constituents particularly in the quarter-diurnal band. Phase relationships between the forced constituents and their parent produce a flood-dominant estuary. Numerical modeling of M2 tidal propagation in shallow estuarine channels utilizes the one-dimensional equations of motion. Shallow, frictionally dominated channels with moderate tidal flat area develop a flood-dominant asymmetry while deeper channels with extensive tidal flats develop an ebb-dominant asymmetry. Model results are supported by observations of tidal asymmetry in natural estuaries. Implications of non-linear tidal distortion on bedload and suspended material transport are profound. Flood-dominant estuaries tend to import sediment if the supply is adequate whereas ebb-dominant estuaries can flush entering sediment effectively. Over long time periods, flood-dominant estuaries may eventually fill. Ebb-domina

A historical study of barrier beach and inlet changes for the Nauset Inlet region, Cape Cod, Massachusetts, was performed to document patterns of beach and inlet change as a preliminary to designing and carrying out ffeld studies of inlet sediment transport. 120 historical charts from 1670 and 125 sets of aerial photographs from 1938 formed the basis for this study. Specific aspects of barrier beach and inlet change addressed include onshore barrier beach movement, longshore tidal inlet migration, and longshore sand bypassing past the inlet. In an effort to correlate forcing events with barrier changes, an exhaustive study of the local storm climate was performed. Detailed treatment of the specific mechanisms responsible for Nauset Inlet migration episodes in a direction opposite the dominant littoral drift are treated in a companion paper by Aubrey, Speer, and Ruder (1982). Documentation of the data base available for the Nauset Area is presented herein as appendices.

Various aspects of sediment transport in and around natural, unstructured tidal inlets were investigated over the two year period of study. Concentrating on two tidal inlets (Nauset Inlet and Popponesset Inlet, Cape Cod, MA), and combining detailed field observations with numerical model studies of tidal flows in inlet/estuarine environments, several aspects of tidal inlet behavior have been clarified. In addition, field work has resulted in a number of technical publications of general utility to a wide spectrum of coastal research interest. Primary scientific items addressed in this study include: 1) diagnostic numerical model of generation and propagation of tidal non-liniarities in shallow estuarine channels; 2) effects of flow curvature on tidal inlet sediment transport; 3) definition of mechanisms by which tidal inlets migrate in a direction opposite to the net littoral drift direction; 4) hypothesis of a mechanism for rapid barrier spit growth in locations with low rates of littoral transport; 5) clarification of long-term patterns of sea-level rise in the United States to assess its role in tidal inlet/esturarine evolution; 6) historical descriptions of massive inlet migration at two study inlets as supporting evidence for the inlet modeling studies. Technical information generated by the study includes a description of a low-cost, reliable method to join nearshore electrical cables; description and intercomparison of instrumentation and analysis routines for estimating directional spectral parameters from wave gage data; and development of a field system and laboratory analysis package for preparing accurate bathymetric charts in shallow, nearshore regions, using microwave navigation and precision echo-sounding.