Syed M. Khalil

New Approaches to Sediment Management on the Inner Continental Shelf Offshore Coastal Louisiana

Abstract Coastal restoration in Louisiana requires clean sands for beach and dune restoration, whereas mixed sediments are required to rebuild marshes. The Louisiana coastal erosion problem is especially dire because it occurs on several fronts with the narrowing and overtopping of barrier islands and loss of back barrier bay and interior marshlands. Coastal restoration efforts in Louisiana depend on emplacement of sediment to build up barrier island and deltaic systems. Discovery of usable sediment is thus a vital factor in restoration efforts because up to 80% of some restoration project budgets can be allocated to exploration, exploitation, and emplacement of sediment. Because this cost is directly proportional to the distance of borrow sources from the project area, the cost-effectiveness of barrier island restoration and marsh creation depends on locating sufficient sediment volumes that are suitable for placement on beaches and dunes and for creating marshes. The restoration of Louisianas barrier islands and the creation of coastal marshes are critically dependent on the availability of suitable modern marine and riverine sediments and other buried fluvio-deltaic deposits. It is thus imperative that a comprehensive sediment management plan be developed to systematically and efficiently identify and allocate suitable sediment resources. At present, coastal and barrier island restoration projects are included in regional planning efforts, and the restoration project is decided before sediment sources are considered. The new approach proposed here is based on planning projects around locations of dredgeable sedimentary deposits in order to optimize sediment resources. Centralization of voluminous historical geoscientific and oil and gas infrastructure data is being accommodated in a new data management system called the Louisiana Sand Resource Database (LASARD). Managing sediment resources more strategically optimizes regional planning strategies and reduces construction costs. The Louisiana Sediment Management Plan (LASMP) conceptualizes systematic planning and better coordination of essential components of the huge restoration and protection effort currently undertaken in Louisiana.

Fluvial Sand Sources for Barrier Island Restoration in Louisiana: Geotechnical Investigations in the Mississippi River

Abstract Coastal land loss in the Mississippi River delta region, related to degradation of wetlands and erosion of barrier islands, contributes to loss of valuable habitat, endangerment of infrastructure and socioeconomic systems, and coastal flooding hazards. Restoration of these ecosystems is thus a primary activity that requires large volumes of sand to rebuild beach–dune systems and restore wetland habitats. Sand sources have traditionally been sought offshore in the marine environment, but there are problems associated with setbacks from oil and gas infrastructure, presence of muddy overburden, and limited reserves of beach-quality sediments. Fluvial sand sources in channel and point-bar deposits become an attractive alternative for barrier island restoration because of large volumes of relict deposits and because active sand waves are renewable. Results of preliminary geophysical and geotechnical investigations in the lower Mississippi River (south of New Orleans) along a 32-km stretch of the river indicate the presence of at least 23 million cubic meters of usable sediments in seven potential borrow sites. Caveats to assessment and exploitation of river sands include interpretation of vibracores and seismic reflection profiles that include evidence of lateral translation-type bank failures along bendways, lateral slumps, and postdepositional disturbance of strata above −30 m. Reliable extraction of good quality sediment should occur down current from bendways.

Offshore sand sources for beach replenishment : Potential borrows on the continental shelf of the Eastern Gulf of Mexico

Erosion of sandy beaches is a worldwide problem that elicits innovative geoengineer‐ing techniques to reduce adverse impacts of shoreline retreat. Beach replenishment has emerged as the “soft”; shore‐stabilization technique of choice for mitigating beach erosion. This method of shore protection involves the addition of sand to the littoral sediment budget for sacrificial purposes. Because inland sand sources are often uneconomical or impractical to use, and known nearshore sources are limited, finding adequate quantities of suitable sand on the inner continental shelf is often vital to beach replenishment projects. The technical studies of survey and materials analysis that identify and delineate usable sand sources are sometimes almost as expensive as small‐project dredging, pumping, and placing the sand on the beach as fill. Inadequate quantity or substandard quality of shelf sand, as well as often‐prohibitive overhead expenses, thus compel shoreline managers to seek suitable sand sources offshore. In t...

Development of New Restoration Strategies for Louisiana Barrier Island Systems, Northern Gulf of Mexico, USA

ABSTRACT Khalil, S. M.; Finkl, C. W., and Raynie, R. C., 2013. Development of new rRestoration strategies for Louisiana barrier island systems, northern Gulf of Mexico, USA The rapid degradation of Louisianas barrier island (BI) systems adversely impacts the vitality of strategic economic and biological resources (including aquatic habitat). Louisianas BI systems have undergone landward migration through BI rollover, area loss and island narrowing as a result of complex interactions among land subsidence, sea-level rise, wave processes, inadequate sediment supply, and intense human disturbance. Consequently, the structural continuity of the BI shorelines has weakened as the islands narrowed, fragmented and, in some cases, submerged. Several multipronged restoration strategies are currently underway to develop effective interdisciplinary restoration projects that mitigate degradation of the Mississippi River delta plain and compensate for coastal land loss. Restoration of the BI systems requires strategies that protect interior wetlands and bolster the first lines of storm defense in a post- Hurricane Katrina-Rita-Gustav-Ike-Isaac and post-Deep Water Horizon era. Coastline degradation would have continued were it not for a series of massive barrier island restoration projects. Such efforts commonly consist of beach nourishment on the Gulfside and marsh creation on the bayside of barrier islands. Regionalizing monitoring, maintenance, and data management efforts support the still evolving scientific and engineering aspects of rebuilding BIs.

An Introduction to the Technical Framework for the Gulf Regional Sediment Management Master Plan

Abstract A partnership has been instituted through the Gulf of Mexico Alliance (GOMA) among the Gulf States to enhance the ecological and economic health of the Gulf of Mexico. Established under the GOMA, the Habitat Conservation and Restoration Team (HCRT) recognized that sediments are integral to and a critical resource in accomplishing the GOMA conservation and restoration objectives. As a result, the Gulf Regional Sediment Management Master Plan (GRSMMP) was initiated for managing sediment resources and corroborates the need for an understanding of regional sediment processes. The plan provides guidelines using the understanding of sediment dynamics to manage resources toward accomplishing environmental restoration, conservation, and preservation while enhancing abilities to make informed, management decisions. A key step in this process is the recognition of a technical framework that provides a foundation associated with regional sediment management processes essential for establishing management guidelines that balance sediment dynamics and available sediment resources with needs and that enhance abilities to make informed management decisions and develop regional strategies. Issues surrounding sediment management, both natural and dredged sediments, have a considerable impact on the ability to sustain coastal habitats. Sediment management must occur on a regional scale unencumbered by agency, state, or political boundaries. Guidelines and recommendations from this effort will aid the Gulf States in more effective management of sediment resources, recognizing they are a part of a regional system involving natural and man-made processes. The effort involves a range of state and federal agencies, as well as nongovernmental representatives. Thus, a technical framework for the GRSMMP was compiled/completed and submitted to the HCRT/GOMA. The decision was made to publish this document as peer-reviewed papers in a special issue of the Journal of Coastal Research for benefit of the global scientific community. In return, feedback in terms of review and comments will be beneficial for the team.

A Geomorphological Approach to Carbonate Sand Searches

Geophysical data obtained during an offshore geotechnical sand-search defined the surficial extent and sub-bottom configuration of geomorphological features such as reef tracts, infills of carbonate sediments within back reef troughs, and karstified rock outcrops along the upper shorefaee. Coastal process zones (CPZ) were derived from interpretation of spatial distribution patterns of morphostructural units. Recognition of discrete morphostructures and CPZs additionally provided a basis for conceptualizing a new model for exploration of offshore sand deposits that are suitable for beach renourishment. Morphostructural mapping showed that the present carbonate setting can be explained in terms of representative CPZs. The relationships between form and function, including paleoforms and processes as relics in the present environment, distinguish sediment distribution patterns and CPZs that typify this carbonate arena. Uniformly graded clastic sediments are deposited in inter-reefal fiats that act as a depocenters for accumulating calcareous sands. The intersection of paraand diabathic process zones at reef gaps produces mixed sand bodies that are also useful for beach replenishment. Study of morphostructural units and coastal process zones, provides a useful exploration paradigm for seabed sand sources within the dimensional framework of the southeast Florida Sand Search Model. Iprofessor, Department of Geography & Geology, Florida Atlantic University, 2 Boca Raton, FL 33431; Senior Geologist, Geological Survey of India, Calcutta, India; 3Senior Vice President, Coastal Planning and Engineering, 2481 NW Boca Raton Boulevard. Boca Raton. FL 33431.