Norbert P. Psuty

The Coastal Foredune: A Morphological Basis for Regional Coastal Dune Development

Coastal dunes are ubiquitous elements of the dune-beach system that exist along the shores of many water bodies in the world where waves and currents interact with available sediment and local vegetation to create combinations of form and habitat at the water-land interface. They occur in a variety of dimensions from minor hummocks of 0.5 m to huge ridges measuring more than 100 m in elevation; from a single, shore-parallel, linear ridge with a width of a few tens of meters to a complex of dune forms that extend inland tens of kilometers. From a geomorphological perspective, the commonality associated with this myriad of forms and situations is the amassing of sand to create a depositional landform proximal to the shoreline. The fundamental concept in coastal geomorphology is that processes of wind, waves, and currents act upon the sediments to produce a set of landforms that are causally related. This relationship is described as a processresponse model and it is the conceptual foundation for all geomorphological inquiry. In coastal areas of adequate sediment supply, the coastal processresponse model is the beach profile: the accumulation of sand that extends from the offshore bar, through the dry beach, and into the adjacent coastal foredune where vegetation stabilization is a further active element of the morphological process (Fig. 2.1). This dune-beach profile is the basic sand-sharing system whose components respond to variations in energy level and to mobilization of sand from one portion to another. Each component episodically stores and releases sand in an exchange of sediment, a classic closed system. The coastal foredune is the uppermost and inlandmost component of the sand-sharing system. It has accumulated sand in association with a range of pioneer vegetation types to create a positive landform perched above the dry sand beach. It is the most conservative portion of the profile, undergoing

HOLOCENE SEA LEVEL IN NEW JERSEY

Recent cores and isotopic dating of the coastal and estuarine marsh accumulations in New Jersey are producing insights into the Holocene transgression of this portion of the Atlantic coast. Sea level curves support the concept of a steadily rising sea with the range of rise declining after 2000–2500 B.P. Sedimentation sequences and dates indicate that infilling of the bays and estuaries was post 2000–2500 B.P. Barrier island topography and marsh expansion was keyed to positive sediment budgets. The offshore zone contributed to the infilling. Recent changes may indicate that the offshore source is exhausted and the process is reversing.

Barrier Islands: Coupling Anthropogenic Stability with Ecological Sustainability

Abstract Barrier islands provide a host of critical ecosystem services to heavily populated coastal regions of the world, yet they are quite vulnerable to ongoing sea level rise and a potential increase in the frequency and intensity of oceanic storms. These islands are being degraded at an alarming rate, in part because of anthropogenic attempts at stabilization. In this article, we outline a possible sustainability strategy that incorporates the natural degree of substrate instability on these sedimentary landscapes. We recommend placing the focus for managing barrier islands on maintaining ecosystem function and process development rather than emphasizing barrier islands as structural impediments to wave and storm energy.

The Role of Pulsing Events in the Functioning of Coastal Barriers and Wetlands: Implications for Human Impact, Management and the Response to Sea Level Rise

Coastal wetland and barrier systems exist in a dynamic equilibrium, in both horizontal and vertical planes, between forces which lead to their establishment and maintenance and forces which lead to deterioration. Rising sea level will affect both of these systems. The functioning of coastal barriers and coastal wetlands is affected by energetic forcings which serve to enhance productivity, increase materials fluxes, and affect the morphology and evolution of these systems. These forcings occur over a hierarchy of different spatial and temporal scales and include waves and daily tides, frontal passages and other frequent storms, normal river floods, strong storms, great river floods, and switching of river channels. Human impact over the past century has diminished these forcings at all temporal and spatial scales. Sustainable management should include the re-integration of these forcings into coastal management.

An application of science to the management of coastal dunes along the Atlantic coast of the U.S.A.

Coastal foredune management begins with an understanding of and appreciation for the dynamics of dune creation, development and decay. Sediment exchange between the dune and beach components of the total dune–beach profile is a necessary element in foredune creation and development. Foredune development is enhanced by a slightly negative total dune–beach budget. Foredune crestlines display alongshore periodicities in displacement that are related to beach processes. Effective management is based on the dimensions of the alongshore foredune variations and the retention of sediment in the migrating foredune system.

Foredune morphology and sediment budget, Perdido Key, Florida, USA

Abstract Along-shore foredune morphology on the eastern portion of Perdido Key is fitted to a model of foredune development related to sediment budget. The Perdido Key barrier island has a long history of shoreline erosion, up to 2 m a−1 for over a century. Sediment availability was altered in 1985 because of beach nourishment. Subsequent re-working of the beach fill has transferred sediment in the along-shore direction as well as cross-shore. Over three years of survey data, including passage of three hurricanes, and aerial photo coverage portray the morphological changes in the foredune system and the displacement of the shoreline. Measurements of the changes in a spatial context record sediment redistribution from the nourishment area. Measurements of cross-sectional area changes support the model of foredune enhancement associated with negative sediment budget in the beach. Net along-shore changes of the foredune compare well with the barrier-island foredune development model.

Management considerations for beach nourishment at Sandy Hook, New Jersey, U.S.A.

Abstract A major problem facing the National Park Service in their management of Sandy Hook is the maintenance of its rapidly eroding principal recreation beach. Among the structural and non-structural alternatives, beach fill is regarded as the most suitable method of protection because it is in harmony with the Park Service objectives of providing the opportunity to use the recreation beaches, of protecting areas for wildlife, and of retaining the natural character of the Hook. The concept of recycling sand from the accreting northern portion of the spit to the eroding southern beaches is viewed as a viable long-term management strategy. The details of two recent beach-fill operations conducted at Sandy Hook are presented as case studies to determine the probable success of future sand replenishment programs. If recycling is to be successful, it should be combined with the ongoing maintenance dredging project at the northern tip of Sandy Hook. Short-term, small-scale beach fill solutions are considered to be impractical due to the high unit costs involved and the rapid rate of removal of the fill materials.

Dune district management: A framework for shorefront protection and land use control

Abstract The establishment of a dune preservation district is a means to employ land use controls to favor creation of natural dunes designed to provide protection to shorefront structures and to serve as wildlife habitat. The application of dune district zoning is derived from a conceptual framework that analyzes the numerous factors contributing to dune formation and modification and that incorporates appropriate uses of this dynamic environment. The establishment of a preservation district requires an analysis of the physical processes and the cultural modifications that affect dune formation and shoreline migration. This information can be used to determine the appropriate dune characteristics necessary for adequate protection and the maintenance required to continue to provide this protection.

Sediment budget as a driver for sediment management at plumb beach, New York, USA: vectors of change and impacts

Persistent erosion at Plumb Beach, New York, USA, has been countered by a series of isolated actions to stabilize the shoreline. Sediment placed at the erosion site has quickly been removed and re-deposited in downdrift locations to the detriment of the existing habitats. In a renewed effort to better understand the dimensions of change at Plumb Beach, detailed spatial analysis of shoreline displacement, dune-beach profile evolution, and sediment budget has been undertaken through intensive surveying and comparisons of Digital Elevation Models. Products derived from these surveys establish that the sector of maximum erosion has shifted downdrift and that the scale of the changes is twice the volume exchange as previously estimated. Improved knowledge of the dimensions and spatial distributions of the changes is used to create a focused approach that is functioning within the scale of the local sediment budget and reducing its impacts.

Suitability of Decision-Theoretic Models to Public Policy Issues Concerning the Provision of Shoreline Stabilization and Hazard Management

This article examines the suitability and potential advances of decision-theoretic models from finance regarding investment decisions in shoreline stabilization projects. A set of scenarios represents the dynamics of the decision-state facing the planner and identifies factors that should be incorporated into the decision-making process. It is shown that decision models from finance can account for the risk and uncertainty inherent in shoreline stabilization projects, potentially suggest improvements and refinements to presently used cost-benefit analysis procedures, and offer new tools that can aid in decisions concerning provision of shoreline stabilization. The outcomes of these scenarios justify better planning and control of existing and future building, and that of poststorm policies. Lastly, these models allow us to explore the range of our understanding of coastal processes and interactions with shoreline stabilization projects and can identify new and useful data needed in coastal management and hazard management decisions.