Some considerations on coastal processes relevant to sea level rise

The effects of potential sea level rise on the shoreline and shore environment have been briefly examined by considering the interactions between sea level rise and relevant coastal processes. These interactions have been reviewed beginning with a discussion of the need to reanalyze previous estimates of eustatic sea level rise and compaction effects in water level measurement. This is followed by considerations on sea level effects on coastal and estuarine tidal ranges, storm surge and water level response, and interaction with natural and constructed shoreline features. The desirability to reevaluate the well known Bruun Rule for estimating shoreline recession has been noted. The mechanics of ground and surface water intrusion with reference to sea level rise are then reviewed. This is followed by sedimentary processes in the estuaries including wetland response. Finally comments are included on some probable effects of sea level rise on coastal ecosystems. These interactions are complex and lead to shoreline evolution (under a sea level rise) which is highly site-specific. Models which determine shoreline change on the basis of inundation of terrestrial topography without considering relevant coastal processes are likely to lead to erroneous shoreline scenarios, particularly where the shoreline is composed of erodible sedimentary material. With some exceptions, present day knowledge of shoreline response to hydrodynamic forcing is inadequate for long-term quantitative predictions. A series of interrelated basic and applied research issues must be addressed in the coming decades to determine shoreline response to sea level change with an acceptable degree of confidence. (PDF contains 189 pages.

Evaluation of Border Leicester and Targhee crossbred ewes for the Pacific coastal Northwest

Published November 1978. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Management considerations for accelerated lambing in western Oregon

Published February 1979. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Comparison of a mid-shelf wave hindcast to ADCP-measured directional spectra and their transformation to shallow water

In conducting a cross-shelf wave transformation experiment off the Atlantic coast of north Florida, a unique opportunity was exploited in which an Acoustic Doppler Current Profiler (ADCP) instrument was installed 30 km offshore at the exact location of one of the archive-nodes of a WAM-like wave hindcast model (OWI3G). A second ADCP was installed 550 m from shore. Approximately 53 days of directional wave spectra collected with the two ADCPs are used to (a) locally test the reliability of a subsequent update of the hindcast, (b) document the loss in energy as the waves crossed the broad, relatively shallow continental shelf between the two instruments, (c) test the ability of the SWAN (Gen2) nearshore wave transformation model to replicate the measurements taken in shallow water when driven by the offshore ADCP spectra, and (d) reassess the spectral transformation results when the offshore hindcast is used as input. In addition to direct comparison of the time series of frequency spectra and the directional distribution of energy, typical spectral parameters are each subjected to standard error tests. Results indicate that the offshore hindcast performs well in replicating significant wave height, fairly well for mean period, but not as reliably for peak period. Directional spreading in deeper water is generally well-represented, although vector mean direction is not, and is believed due to the proximity of the coast to the hindcast node. The nearshore model requires an order-of-magnitude reduction in bed roughness from its default value before agreement in wave energy at the nearshore ADCP can be achieved. Outcomes of the error tests for the hindcast-driven versus the ADCP-driven nearshore results (after roughness calibration) are quite similar, but nevertheless indicate that transformed wave period, wave direction, and directional spreading require improvement

The longshore transport enigma and analysis of a 10-year record of wind-driven nearshore currents

Previous analysis of a 10-year record of nearshore directional wave spectra collected with an Acoustic Doppler Current Profiler (ADCP) installed outside the surf zone in Melbourne Beach, Florida, unexpectedly revealed that the long-term average wave-induced radiation stress (Sxy) was nearly balanced between northerly and southerly forcing. More than 4 years of wind data collected at the site with a directional anemometer also showed a nearly balanced net longshore wind stress. However, shoreline offsets at nearby jettied inlets clearly indicate a predominant north-to-south net sediment transport. This enigma was investigated by analyzing the nearshore currents measured by the ADCP, and examining their correlation with the wind and incident waves. Significant correlation was found between the depth-averaged wind-driven longshore current and the incident wave conditions; e.g., the average energy-based significant wave height mo is typically larger (0.95 m) when the current is directed to the south than when the current is directed to the north (0.73 m). Guided by the classic Coastal Engineering Research Center (CERC) formula for longshore sediment transport, it is found that is significantly more correlated with southerly directed longshore currents (r = 0.47) than northerly currents (r = 0.21). Also, if a storm is defined as whenever Hmo exceeds 1.75 m, 40% of this time, the mean wave direction is out of the northeast quadrant, 33% is from the southeast, and 27% approaches shore-normal. Additionally, during storms, a stronger correlation between Sxy is found with southerly directed wind-driven currents (r = 0.51) than with northerly directed currents (r = 0.32). These findings indicate that net longshore sediment transport may in fact be heavily influenced by the correlation of the local wind with the waves, a feature not included in traditional longshore sediment transport formulas

Evaluating the Impact of Beach Nourishment on Surfing: Surf City, Long Beach Island, New Jersey, U.S.A.

Utilizing the Cornell University Long and Intermediate WAVE (COULWAVE) Boussinesq wave model, the effect of the construction of a conventional beach nourishment project in Surf City, New Jersey, on the quality of the local surf break is examined in detail. A 20-year-long nearshore synthetic wave record is first developed for use in creating a monthly wave climate almanac so that typical seasonal effects on surf-break quality can be objectively portrayed. The wave model is then run with preconstruction bathymetric conditions, and with three postconstruction surveys performed in subsequent months. Construction of the nourishment project was found to affect the quality of the surf break adversely by (1) compression of the surf zone, (2) an increase in the occurrence of closeouts, (3) a shift in breaker type toward collapsing breakers, particularly during high tide, and (4) an increase in wave reflectioncfindings that are in agreement with anecdotal testimony offered by local surfers. On the basis of modeling results conducted using the sequential postconstruction surveys and the wave almanac, it appears to have required nominally 21-22 months for the surf-break quality to return to preproject conditions. A paradigm shift in the design and construction of beach nourishment projects in the United States is required if such effects are to be avoided, and several options are offered and discussed

Analysis of a 10-Year Record of Nearshore Directional Wave Spectra and Implications to Littoral Processes Research and Engineering Practice

Slightly more than 10 years (August 28, 2001, to October 28, 2011) of high-resolution directional wave spectra were measured by an Acoustic Doppler Current Profiler installed in the nearshore at Spessard Holland North Beach Park in Melbourne Beach, Florida. Analysis of the record yields an average wave power of 17.6 MW/m of shoreline but with a standard deviation of 22.5 MW/m. Cumulative annual wave power ranged from 43,455 to 93,722 MWh/m, and the annual storm count was between 3 and 14. The mean spectrum for the entire record shows an almost symmetric directional distribution of wave energy centered on the shore-normal direction, which is somewhat unexpected considering that the net longshore transport in the region is definitively N-S. Partitioning the data into shore-normal, NE, and SE windows shows that most wave energy approaches from the SE, again contrary to expectations. The rigorously integrated mean longshore forcing of wave radiation stress, Sxy, is slightly N-S (7.2 N/m) but has a standard deviation of 77.2 N/m. Computing a cumulative average through the record indicates that it takes between 4 and 5 years for the net magnitude and direction of Sxy to be conclusively revealed. Using significant wave height, peak wave period, and mean wave direction to estimate Sxy yields values nominally 42% greater than the integrated results, confirming that fully directional spectra should be used in both study of littoral processes and coastal engineering practice. Finally, the supposition that the wind plays an important role in driving longshore currents and consequently longshore transport is tested. However, analysis of more than 4 years of wind data collected at the site reveals a mean longshore wind stress that is essentially balanced (i.e. nil)