Publications

Hydraulic dredging uses centrifugal pumps to transport dredged material and often requires a long distance pipeline and additional booster pumps. It is important to locate each pump at an optimum location along the pipeline and to estimate the dredge production. This paper describes a dredging production-estimation program for a cutter suction dredge developed at the Center for Dredging Studies. The program objective is to determine the best location for each pump, including a main pump, a ladder pump, and booster pumps, and to estimate production. The ladder pump and the booster pumps are located with the consideration of pump cavitation and the power limitation of
the pumps, respectively. The corresponding pump head curve, the system head curve, the available net positive suction head (NPSH) curve, the required NPSH curve, and the critical flow rate are used for determining the operating flow rate and production. The input for the program includes the water depth, the location of the main pump, pump rpm, pump horsepower, specific gravity of the slurry, and the length of a discharge pipeline. Correspondingly, the program estimates production as well as the locations of the main pump, the ladder pump and booster pumps for given operating conditions.

In response to numerous recent high-profile cases of tropical storm and hurricane damage to coastal communities, there has been increasing attention on the storm protection services provided by coastal ecosystems. However, substantial knowledge gaps exist regarding the quantitative economic benefits of such services, particularly for coastal vegetated dune ecosystems. [Read more…] about The effects of coastal dune volume and vegetation on storm-induced property damage: Analysis from Hurricane Ike

A field experiment was conducted on the northern Yucatan coast from April 1 to April 12, 2014 to investigate the role of intense wind events on coastal circulation from the inner shelf to the swash zone. The study area is characterized by a micro-tidal environment, low-energy wave conditions, and a wide and shallow continental shelf. Furthermore, easterly trade winds, local breezes, and synoptic-scale events, associated with the passage of cold-fronts known as Nortes, are ubiquitous in this region. [Read more…] about Nearshore circulation on a sea breeze dominated beach during intense wind events

Vegetated coastal dunes were subjected to wave-induced erosion in a physical model wave flume experiment. Four different plant morphotypes including tall and short dune grasses, spreading vines, and shrubs were tested at different maturity levels to assess the effects of above- and below-ground vegetation characteristics on beach/dune erosion. [Read more…] about Physical model experiment investigating interactions between different dune vegetation and morphology changes under wave impact

A field study was conducted in man-made ditches in a tidal saltmarsh in Lewes, Delaware, USA. Ditches are prevalent throughout tidal marshes along the Atlantic US coast, and influence hydrodynamics and sediment transport. The field study focused on measuring near-bed velocity, shear stress, sediment concentration, and bed level variability at 5 stations over a 3-week period. Velocities in the ditch (2–5 m wide, 1 m deep) peaked between 0.4 and 0.6 m/s and were slightly ebb dominated. [Read more…] about In situ measurements of shear stress, erosion and deposition in man-made tidal channels within a tidal saltmarsh

Follet’s Island (FI) is a sediment-starved barrier island located on the Upper Texas Coast; a stretch of coastline along the Gulf of Mexico that experiences on average four hurricanes and four tropical storms per decade. During Hurricane Ike, water levels and wave heights at FI exceeded the 100-year and 40-year return values, respectively, leading to significant overtopping and morphology changes of this low-lying barrier island. [Read more…] about Numerical modeling of the morphodynamic response of a low-lying barrier island beach and foredune system inundated during Hurricane Ike using XBeach and CSHORE

Core-enhanced sand dunes are hybrid coastal defence structures that combine the storm surge protection offered by traditional hard coastal structures with the aesthetically pleasing appearance and wave energy dissipation potential of coastal sand dunes. Essentially, these are hard coastal structures covered under a sacrificial sand dune. [Read more…] about Conceptual Design and Physical Model Study of Core-Enhanced Dunes as Hybrid Coastal Defence Structures

One of the most efficient and versatile types of modern dredges is the cutter suction dredge. Specific regulations mandate the placement of screens over the suction mouth during dredging operations to prevent ordnance, wildlife, and other debris from entering the system; however, these screens change the operational capability of the dredge in the form of an additional minor loss. [Read more…] about Prediction of Minor Loss Coefficient at Suction Inlet of Cutter Suction Dredge

Coastlines have traditionally been engineered to maintain structural stability and to protect property from storm-related damage, but their ability to endure will be challenged over the next century. The use of vegetation to reduce erosion on ocean-facing mainland and barrier island shorelines – including the sand dunes and beaches on these islands – could be part of a more flexible strategy.
[Read more…] about Going with the flow or against the grain? The promise of vegetation for protecting beaches, dunes, and barrier islands from erosion

Barrier islands represent about 10% of the world’s coastline, sustain rich ecosystems, host valuable infrastructure and protect mainland coasts from storms. Future climate-change-induced increases in the intensity and frequency of major hurricanes and accelerations in sea-level rise will have a significant impact on barrier islands—leading to increased coastal hazards and flooding—yet our understanding of island response to external drivers remains limited. [Read more…] about Barrier Island Bistability Induced by Biophysical Interactions