Sediment Transport and Morphological Response to Nearshore Nourishment Projects on Wave-Dominated Coasts

Nearshore nourishments are constructed for shoreline protection from waves, to provide sediment nourishment to the beach profile, and to beneficially use dredged sediment from navigation channel maintenance. However, it is poorly understood how placement morphology and depth influence nearshore processes operated on wave-dominated coasts. This study investigates the wave fields, sediment transport, and morphological response to three common nearshore nourishment shapes, nearshore berm (elongated bar), undulated nearshore berm, and small discrete mounds, with numerical experiments utilizing the Coastal Modeling System. The nourishments are placed in depths between 3 m and 7 m with a volume of approximately 100,000 m3 and between 400 m and 1000 m in alongshore length. Numerical experiments are carried out in three distinct coastal settings with representative wave climates and geomorphology. Simulation results indicate that shallower, more continuous berms attenuate the most wave energy, while deeper, more diffuse placements retain more sediment. Results from this study improve the understanding of nearshore nourishment shapes and can support decision makers identifying the most appropriate construction technique for future nearshore nourishment projects.

Biofilm accumulation in new flexible gastroscope channels in clinical use

Objective: Assess the accumulation of protein and biofilm on the inner surfaces of new flexible gastroscope (FG) channels after 30 and 60 days of patient use and full reprocessing. Design: Clinical use study of biofilm accumulation in FG channels. Setting: Endoscopy service of a public hospital. Methods: First, we tested an FG in clinical use before the implementation of a revised reprocessing protocol (phase 1 baseline; n = 1). After replacement of the channels by new ones and the implementation of the protocol, 3 FGs were tested after 30 days of clinical use (phase 2; n = 3) and 3 FGs were tested after 60 days of clinical use (phase 3; n = 3), and the same FGs were tested in phase 2 and 3. Their biopsy, air, water, and air/water junction channels were removed and subjected to protein testing (n = 21), bacteriological culture (n = 21), and scanning electron microscopy (SEM) (n = 28). Air–water junction channels fragments were subjected to SEM only. Results: For the FGs, the average number of uses and reprocessing cycles was 60 times. Extensive biofilm was detected in air, water, and air–water junction channels (n = 18 of 28). All channels (28 of 28) showed residual matter, and structural damage was identified in most of them (20 of 28). Residual protein was detected in the air and water channels of all FG evaluated (phases 1–3), except for 1 air channel from phase 2. Bacteria were recovered from 8 of 21 channels, most air or water channels. Conclusions: The short time before damage and biofilm accumulation in the channels was evident and suggests that improving the endoscope design is necessary. Better reprocessing methods and channel maintenance are needed.

Intermediary resources and export venture performance under different export channel structures

PurposeThe literature on export channels suggests that intermediary resources, namely intermediary competence and availability, are critical for export success. However, little is known about how the beneficial effects of intermediary resources differ amongst integrated, independent and dual channel structures. One difference between these channel structures is the degree of reliance on independent intermediaries. This study aims to investigate (1) the impact of intermediary resources on export venture success, that is, export sales performance and channel maintenance costs and (2) the moderating role of the degree of reliance on independent intermediaries.Design/methodology/approachEmpirical testing was conducted using survey data collected from 204 Japanese industrial exporting ventures. To test the proposed hypotheses, this study estimated a structural equation model with the maximum likelihood estimation procedure.FindingsEvidence shows that two aspects of intermediary resources have different beneficial effects on export venture success. Specifically, intermediary availability leads to export venture success by decreasing channel maintenance costs, whereas intermediary competence is not always beneficial for it. Furthermore, this study finds that reliance on independent intermediaries positively moderates the impacts of intermediary competence and availability.Originality/valuePrevious studies emphasise the importance of intermediary resources and export channel structures. However, the question of whether export channel structures determine the performance benefits of intermediary resources is unanswered. By addressing this question, this study provides helpful insight into how exporting managers can implement channel strategy and access intermediary resources to achieve export success.

The Regional Waterway Management System: A Tool for Balancing Coastal Resource Use and Protection

This document describes the Regional Waterway Managment System (RWMS), a tool for regional planning. The RWMS helps planners and policymakers identify, evaluate, and prioritize channel maintenance and improvement needs. Published February 2005.

Estimating River Bathymetry from Surface Velocity Observations Using Variational Inverse Modeling

Accurate river bathymetry characterization is important to understanding all aspects of the riparian environment and provides crucial information for ensuring the safe passage of vessels and guiding channel maintenance operations. Verified models based on readily collected physical data facilitate accurate predictions of changes to a riverbed caused by traffic, weather, and other influences. This paper presents a methodology for estimating river bathymetry from surface velocity data by applying variational inverse modeling to the shallow-water equations. The paper describes the mathematical framework for the methodology and the algorithm, and the numerical tools developed to test the methodology. The hydrodynamic modeling uses 2D depth-averaged solvers (under the hydrostatic assumption) and applies a standard empirical correlation that relates depth-averaged velocity to surface velocity. The application of the bathymetry estimation algorithm to water-surface velocity data was tested on a 95-km reach of the Columbia River in Washington State. The root-mean-square error (RMSE) of the estimated bathymetry field relative to the ground truth data is approximately 2 m over the entire reach. The results of the test case indicate that this approach can be used to estimate river bathymetry to a close approximation based on the bank-to-bank surface velocity data on the reach of interest.