South Jetty Research Articles

Remote-Sensing Measurements of Wave Breaking at Two Pacific Northwest Jettied Inlets

Breaking waves constitute one of the main environmental stressors on coastal structures as well as a leading hazard to navigation in nearshore regions. In this paper, we use camera-based methods to measure wave breaking over two jetty systems in the Pacific Northwest; the North jetty of the Columbia River, Washington state, and the two jetties of Coos Bay, Oregon, as well as over three nearby nearshore dredge disposal areas. Data were collected using the “brightest” images and Argus camera technology over a span of 847 days for the Columbia River and 202 days for Coos Bay. Wave breaking over the Columbia north jetty reached 100% for wave heights greater than 3 m and for tides above mid-tide level and was concentrated on the seaward half of the jetty. For Coos Bay, the south jetty saw substantially more breaking than the north one with the worst overtopping occurring mid-jetty and seeming to be associated with sediment transport through the jetty and into the inlet, as well as possibly the navigation channel. Wave breaking at the Coos Bay inlet mouth was enhanced during ebb flow conditions. Argus imagery analysis showed no evidence of enhanced breaking over any of the three dredge material placement sites.

Emerging Downdrift Erosion by Twin Long-Range Jetties on an Open Mesotidal Muddy Coast, China

Downdrift shoreline recession associated with the construction of a shore-crossing hard structure represents one of coastal erosional hotspots that must be addressed for an integrated, sustainable coastal zone management. To prevent siltation within the navigation channel, two rubber-mounted jetties were installed at the Sheyang River mouth on the open mesotidal muddy coast in Jiangsu province, China, in October 2013. The north jetty is 7.9 km long, while the south jetty is 7.8 km long. The net longshore sediment transport is from the north to the south due to flood-tide dominance. As disclosed by high-resolution satellite images, a 36-km-long downdrift shoreline stretch had experienced remarkable retreats at alongshore varying rates by March 2019. The eroding shoreline planform does not resemble a classic “S” shape, a crescentic shape, or a parabolic shape but an irregularly indented curved shape. Transect topographic survey also reveals an almost immediate response of the downdrift coast from the original accretionary scenery to an erosional regime, with the erosion front translocating downcoast at a much faster speed than a normal speed of 1–1.5 km/yr. Using FVCOM and SWAN, 2DH process-based numerical simulations are performed to simulate the flow, the sediment transport, and the yearly-magnitude accretion/erosion distribution in the jetty-affected area by a representative tidal force and an annual-magnitude wave force. The results demonstrate that the reciprocal tidal flow is predominantly responsible for the muddy sediment accretions at downdrift intertidal and surf zones shallower than a 4.0-m isobath, whereas big wind waves play a decisive role in triggering and developing the downdrift erosional process. The predicted spatial extent of the downdrift erosional segment matches closely the actual eroding front. The loss of the net annual longshore sediment transport volume, i.e., 3.08 million m3 due to the blockage by the twin jetties is recovered from a much larger spatial extent than the 36-km-long retreating shoreline stretch. With regard to the Bruun model, the one-line model, the headland-bay model, and the 2DH numerical model, the potential maximum recession length and the planform shape of the downdrift erosional shoreline arc are further elaborated to gain new insights into the spatial and temporal impact of a hard structure on the adjacent shoreline and flat (beach).

Projecting Hydro-Morphodynamic Impacts of Planned Layout Changes for a Coastal Harbor

Abstract The macrotidally influenced harbor of Dagebull on the North Sea coast of Germany features a piled south jetty, for which provided constructive designs are investigated regarding their pote...

COASTAL WAVE MODELING FOR JETTY REHABILITATION AT COOS BAY, OREGON

Coos Bay Inlet, located on the Pacific coast of southwestern Oregon, is protected by dual jetties constructed in 1928. Because the inlet is exposing to high energy environment, both north and south jetties have deteriorated since the initial construction. Aging, erosion of foundation, lack of effective maintenance, and channel dredging in the past have accelerated the jetty deterioration. To ensure navigation safety, the U.S. Army Corps of Engineers is presently investigating the rehabilitation and redesign of jetties. This paper is focused on numerical storm wave modeling of the existing jetties to provide input forcing information to physical model and redesign of jetties.

DELAWARE BAY MISPILLION INLET ENVIRONMENTAL RESTORATION PROJECT

The Delaware Department of Natural Resources and Environmental Control (DNREC) has received grants from Hurricane Sandy funding to rehabilitate and improve environmental functionality and sustainability for areas along the Delaware Bay shoreline. The Mispillion Inlet Complex near Milford, Delaware was one of the projects selected due to its importance as habitat for both American Horseshoe Crabs (Limulus polyphemus) and shorebirds, specifically the threatened species Rufa Red Knot (Calidris canutus rufa). The complex includes the Mispillion River and Cedar Creek that connect at Mispillion Inlet and provide access for tidal flow and navigation into the Delaware Bay via federally-authorized and maintained channels. Efforts to stabilize Mispillion Inlet first occurred in 1859 when a 560-foot long timber pile jetty was constructed along the north side of the inlet. In 1908 a south jetty was constructed, and in subsequent years, several additional jetty extensions were made to a total length of about 5,800 feet. In 1985, the barrier spit separating Mispillion River and the Delaware Bay north of the inlet breached and was subsequently closed with a stone dike and sand fill. Two years later, the repaired area was breached again, followed by placement of more rock and sand.

SOIL CONTAMINANT SAMPLING RESULTS FROM LOWER RIO GRANDE VALLEY NATIONAL WILDLIFE REFUGE'S BOCA CHICA TRACT, CAMERON COUNTY, TEXAS

SOIL CONTAMINANT SAMPLING RESULTS FROM LOWER RIO GRANDE VALLEY NATIONAL WILDLIFE REFUGE'S BOCA CHICA TRACT, CAMERON COUNTY, TEXAS

Recent evolution of Jiuduansha Shoal in Yangtze Estuary and its corresponding to engineering projects

Zheng, J.H., Peng, Y.X., Zhang, C. and Ju, Y., 2013. Recent evolution of Jiuduansha Shoal in Yangtze Estuary and its corresponding to engineering projects. In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.)The Jiuduansha Shoal is located in Yangtze Estuary of China and has attracted a lot of attentions with respect to its historical bathymetry evolution because it involves rich environmental resources. Based on the measured bathymetry data from 1997 to 2008, the digital elevation model of Jiuduansha Shoal was developed and used to analyze the recent shoal evolution. It is of particular interest to investigate its corresponding to engineering projects. Results show that from 1997 to 2008, the shoal area increased very slowly but the increasing rate gradually decreased, which is well correlated to the decreasing of sediment discharge due to dam construction at the upstream of Yangtze River. The deep- water navigation channel project in Yangtze Estuary has obvious effects on the nearby hydrodynamic condition and the morphology of the Jiuduansha Shoal. Remarkable deposition in north and erosion in south occurred at the middle and lower parts of the shoal. A 10.2 km long sand spit formed along the outer edge of the south jetty of the navigation channel project, which is due to both the jetty construction and the flow circulation in the North Passage.

Erosion and accretion in the Ria de Aveiro inlet (N Portugal) and exportation of fine–grained sediments to the shelf

Harbours are important man made economic structures that are usually constructed in hydrodynamic complex settings. Their life/ service cycle, integrity and maintenance are highly dependent on the knowledge of these settings and the capability to predict future changes and thus their economic impact. In this paper, data regarding bottom and suspended sediments of the Aveiro Harbour inlet were gathered and analysed. Measurements of suspended sediment concentrations (SSC) in the Aveiro inlet were taken during eight tidal cycles in 2007, including spring and neap tides throughout winter and summer oceanographic regimes. Results suggest significant temporal variability. Sediments were imported from the ocean sink, mostly near the south jetty and the western side of the Mira Channel, as textural, mineralogical, compositional, geochemical and microfaunal data of bottom sediments suggest. Higher stabilization of the Aveiro Harbour structures is achieved on these accretional areas. The high tidal-current velocities contribute to the erosive character which dominates the central area of the entrance channel, which is located between both breakwaters and close to the north jetty; thus some segments of the north jetty could become damaged through erosion. This is evidenced as much bottom sediments characteristics as patterns of SSC. SSC are in general higher during the winter, due to climatic conditions, current velocities, wind stress and greater availability of sediments provided by the local-river flooding. Our data also suggest that SSC are predominantly higher during ebb and low tide throughout the year, as compared to periods of flood, when a higher flux of sediments is transported seaward than landward. The lagoon exports to the continental shelf mostly muddy sediments, composed essentially of quartz and phyllosilicates.

SPECIES COMPOSITION AND SEASONAL PERIODICITY OF MACROALGAL SPECIES IN CORPUS CHRISTI BAY, TEXAS

Benthic algal sampling from selected sites along Corpus Christi Bay and from one site at the Port Aransas, Texas south jetty was completed between April 1999 and February, 2000. Species composition, seasonal periodicity, and fluctuations in temperature and salinity were determined. This is the first comprehensive study of benthic macroalgae conducted in Corpus Christi Bay, which is shallow, turbid, and lacks natural hard substrate. Man‐made jetties are necessary for suitable floral attachment. Macroalgae are affected by changes in salinity as freshwater inflows are followed by periods of drought, which increase salinity. These effects are most notable where freshwater enters at the south end near Oso Bay and at the north end at Nueces Bay. Previous Texas algal collections described species of Enteromorpha, Ulva, Gelidium, and Gracilaria as the most dominant plants of the area. This supports the current study with the additions of Hypnea musciformis and Centroceras clavulatum. Dominant plants at the Port Aransas jetty include Ulva fasciata, Padina gymnospora, and Hypnea musciformis. The Rhodophyta including Gracilaria, Gelidium, and Centroceras clavulatum dominate the bay and do so throughout the year. Chlorophytes, although few in species richness, are important to benthic coverage and biomass. Phaeophyta are found predominantly at the Port Aransas jetty with Sargassum, Dictyota dichotoma, and Petalonia fascia being most abundant. A transition occurs in species composition as the water temperature changes seasonally. Hincksia, Ectocarpus, and Petalonia fascia are found only during the cooler months.

Six Years of Harbor Seal Censusing at Yaquina Estuary, Oregon

Six Years of Harbor Seal Censusing at Yaquina Estuary, Oregon

SURVEYS OF COASTAL STRUCTURES USING GEOPHYSICAL TECHNIQUES

Coastal engineers have long relied upon bathymetric surveys to determine the extent of underwater damage to jetties and breakwaters. Though such surveys supply important information about variations in water depth around structures, they alone do not show in sufficient detail the nature of the material on the structure, the extent of subbottom features, or the nature of the subbottom upon which the structure sits. However, by conducting bathymetric surveys in conjunction with other remote-sensing techniques and diving observations, it is possible to obtain more complete knowledge of the subaqueous condition of coastal structures. During the summer of 1983 and the spring and summer of 1984, we conducted side scan sonar and shallow subbottom surveys in conjunction with bathymetric and diving surveys along three northern California coastal structures to determine the condition of the structures before extensive damage occurred. Then, we evaluated the applicability of the data collection techniques for condition surveys in general. Two of the structures surveyed are the parallel jetties that protect the entrance to Humboldt Bay, California, and the third structure is the outer breakwater at Crescent City, California. Bathymetric records and sonographs from Humboldt Bay show deep holes along much of the inside of the south jetty and off the heads of both jetties. The subbottom record from inside Humboldt Bay shows a subsurface fault, the extension of which would run under the south jetty. Sonographs from Crescent City show significant bedrock outcrops throughout the area outside the breakwater, making it difficult in places to identify the toe of the structure. The subbottom record shows that pockets of sand exist amidst the bedrock, but they are generally less than 2 m (6 ft) in thickness. We found that the side scan sonar is an excellent tool for defining the toe of the structure; also, when waves are low, it can be useful in determining armor types and the slope of structures Our subbottom system provided information on fault and bedrock locations; however, other systems need to be tested to see if any of them can locate buried armor near the structures.

NEW JETTIES FOR TUNG-KANG FISHING HARBOR, TAIWAN

Tung-Kang Fishing Harbor, which is about 16 km to the south of Kaohsiung Harbor, is a river harbor on the south-west coast of Taiwan. This harbor is located at the estuary of the Niu-Pu River, which meets the Tung- Kang River and the Kao-Ping River on the north side, (see Fig. 1) The original north and south jetties were constructed in 1959. Because the entrance is located at the meeting of the three rivers and the water depth at the entrance is shallower than that in the breaking zone, the entrance is easily chocked with sand during the summer season when the south-west wind and waves are strong. Therefore, dredging is always necessary to maintain the required depth. On. the other hand, because of the increasing number of fishing boats and deeper draft, the port cannot function effectively. There-fore, how to keep the required water depth at the entrance and to obtain a wider and stable water basin is an urgent problem with this harbor. Based on the sounding of 1973, the littoral drift is mainly from the south. In the next year the construction of a 176 m long new south jetty was begun to protect the entrance and to facilitate the sedimentation study. In 1975, the Taiwan Fisheries Consultants was appointed to undertake the investigation and long-term planning work. This project includes littoral process study, planning, model test and design. Finally it is recommended that an adequate layout of south and north jetties can solve the problem of accretation of the harbor entrance. The purpose of this paper is to describe some aspects with emphasis on how to prevent the shoaling of the entrance channel located at the meeting of the rivers.

CASE STUDIES OF DELAWARE'S TIDAL INLETS: ROOSEVELT AND INDIAN RIVER INLETS

Studies were undertaken to document the past and present characteristics and trends of Delaware's two major tidal inlets, Roosevelt and Indian River Inlets. It was found that both inlet complexes are effective sediment traps causing considerable downdrift erosion. The major mechanism by which sand enters Indian River Inlet is by overtopping the impounded south jetty. At Roosevelt Inlet sediments are readily transported past the severed steel sheet pile jetties. The results of a one-dimensional hydraulic model, as well as field measurements, predict the presence of a mean southerly flow through the canal and bay system which connects these two inlets. This flow is shown to have a substantial effect on the behavior and stability of these entranceways, causing major asymmetries on the depositional patterns at each location. Roosevelt Inlet was found to have a strong tendency to trap sediment within its throat; whereas, Indian River Inlet, on the opposite end of the system, was found to retain large quantities of sand on its developing ebb tidal shoal.

CHANGES DUE TO JETTIES AT TILLAMOOK BAY, OREGON

Bayocean Spit, separating Tillamook Bay from the Pacific Ocean on the north Oregon coast, underwent severe erosion following construction of a north jetty at the bay entrance in 1914-17. This erosion ultimately led to the complete breaching of the spit in 1952. Simultaneous to the spit erosion south of the entrance, the shoreline north of the north jetty advanced seaward by some 600 m (2000 ft). This pattern of erosion and deposition following jetty construction has generally been interpreted as the jetty blocking a large north to south net littoral drift in the area, estimated by a previous study at 620,000 m3/yr (800,000 yd3/yr). Our reexamination of the shoreline changes and patterns of erosion and deposition following jetty construction disagrees with this interpretation, and instead we conclude that all of the changes resulted from local rearrangements of the beach due to the disrupted equilibrium following jetty construction, but at the same time maintaining an overall condition of zero net littoral drift. This interpretation is supported by other evidence that indicates a near-zero net drift on this portion of the Oregon coast. Thus severe coastal erosion can result from jetty construction even in areas of zero net littoral drift. A new south jetty has been recently completed (1974). The result has been further realignments of the shoreline with accretion and shore-: line advance immediately south of the south jetty. This provides further confirmation that a zero net littoral drift exists in the area. This study also demonstrates the effects of building only a single jetty rather than a pair of jetties. Following construction of the north jetty, the outer bar or ebb-tide delta at the Tillamook Bay inlet grew appreciably in size.

DESIGN AND CONSTRUCTION OF HUMBOLDT JETTIES, 1880 to 1975

In the Chief of Engineers annual report of 1877, it was concluded that "The only way...in which a safe entrance could be obtained into this harbor would be by the construction of two parallel jetties, of very heavy stone, about 500 yards apart, from the north and south spits at the entrance." In 1882, a special Board of Engineers concluded that the "occupation of the south breaker spit by a structure...carried to low water and running from the south head (spit) in a north-westerly direction..." be built. Construction of the south jetty began in 1889 and of the north jetty, subsequently authorized, in 1891. Due to the severe wave action, a number of rubble-mound construction techniques including stone, concrete cubes, tetrahedrons, and finally dolos armor units have been used. A description will be given of the construction and associated results. Experience with the reinforced and unreinforced concrete dolosse units will also be discussed.

COASTLINE CHANGES NEAR A TIDAL INLET

Extensive coastline changes around the Ponce de Leon Tidal Inlet, Florida, are described, discussed and explained. These changes started developing immediately after the beginning of the construction of two jetties on both sides of the inlet forming part of a plan to stabilize the inlet, improve navigation conditions and bypass sand effectively. The mean annual littoral transport of sand was considered to be from north to south. Rapid sand accretion south of the south jetty started immediately after the beginning of its construction in 1969, reaching by November, 1971, a volume of approximately 1,400,000 cu. yds. Aerial photographs suggest that the sand was transported there from the south during the summer periods of northerly drift and from the offshore bar by refracted waves from the north. The accumulated sand is well protected by the south jetty during the winter storms from the northeast. Coastline and duneline recession occurred north of the inlet due, at least partially, to the described sand retention. It is concluded that for inlets where the littoral drift reverses its direction, the net annual rate of littoral transport is not a unique design criterion. Instead the total sand volumes transported annually in either direction should be considered.

Movement of Seabed Drifters Near the Columbia River

Seabed drifters were released on the continental shelf within 50 km of the mouth of the Columbia River to study near-bottom water and sediment movements. From June, 1966 to October, 1966, the net movement in water deeper than 55 m was northward; at lesser depths, the movement was southward and toward the coast. Drifters grounded in considerable numbers on the ocean beach within 5 km north of the north jetty of the Columbia River and also on Clatsop Spit 5 km upriver on its south bank. Relatively few were found on the ocean beach near the south jetty. The movement near shore is in agreement with that deduced for bottom water, considering the prevailing seasonal winds and waves and the intrusion of seawater into the estuary.

The South Pass Jetties.–Ten Years Practical Teachings in River and Harbor Hydraulics

The South Pass Jetties.–Ten Years Practical Teachings in River and Harbor Hydraulics

The South Pass Jetties—Ten Years' Practical Teachings in River and Harbor Hydraulics

The South Pass Jetties—Ten Years' Practical Teachings in River and Harbor Hydraulics

Discussion on “Notes on the South Pass Jetties”

Discussion on “Notes on the South Pass Jetties”