Dataset Information

Shortwave Sand Transport in the Shallow Surf Zone.

ABSTRACT: Empirical parameterizations of the shortwave sand transport that are used in practical engineering models lack the representation of certain processes to accurately predict morphodynamics in shallow water. Therefore, measurements of near-bed velocity and suspended sand concentration, collected during two field campaigns (at the Sand Engine and Ameland, the Netherlands) and one field-scale laboratory experiment (BARDEXII), were here analyzed to study the magnitude and direction of the shortwave sand flux in the shallow surf zone. Shortwave sand fluxes dominated the total sand flux during low-energetic accretive conditions, while the mean cross-shore current (undertow) dominated the total flux during high-energetic erosive conditions. Under low-energetic conditions, the onshore-directed shortwave sand flux scales with the root-mean-square orbital velocity urms and velocity asymmetry Au but not with the velocity skewness. Under more energetic conditions the shortwave flux reduces with an increase in the cross-shore mean current u¯ and can even become offshore directed. For all data combined, the contribution of the shortwave flux to the total flux scales with (-Auurms)/|u¯| , with a high contribution of the shortwave flux (?70%) when this ratio is high (? 10) and low contributions (?0%) when this ratio is low (?1). We argue that the velocity asymmetry is a good proxy for the net effect of several transport mechanisms in the shallow surf zone, including breaking-induced turbulence. These field and laboratory measurements under irregular waves thus support the hypothesis that the inclusion of velocity asymmetry in transport formulations would improve the performance of morphodynamic models in shallow water.

SUBMITTER: Brinkkemper JA

PROVIDER: S-EPMC6049877 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Shortwave Sand Transport in the Shallow Surf Zone.

Brinkkemper J A JA Aagaard T T de Bakker A T M ATM Ruessink B G BG

Journal of geophysical research. Earth surface 20180528 5

Empirical parameterizations of the shortwave sand transport that are used in practical engineering models lack the representation of certain processes to accurately predict morphodynamics in shallow water. Therefore, measurements of near-bed velocity and suspended sand concentration, collected during two field campaigns (at the Sand Engine and Ameland, the Netherlands) and one field-scale laboratory experiment (BARDEXII), were here analyzed to study the magnitude and direction of the shortwave s ...[more]

PMID: 30034978

Similar Datasets

Project description:Soil salinization limits crop growth and yield in agro-ecosystems worldwide by reducing soil health and altering the structure of microbial communities. Salt-tolerant plant growth-promoting rhizobacteria (PGPR) alleviate plant salinity stress. Wild soybean (Glycine soja Sieb. and Zucc.) is unique in agricultural ecosystems owing to its ability to grow in saline-alkali soils and fix atmospheric nitrogen via symbiotic interactions with diverse soil microbes. However, this rhizosphere microbiome and the nodule endosymbionts have not been investigated to identify PGPR. In this study, we investigated the structural and functional rhizosphere microbial communities in saline-alkali soil from the Yellow River Delta and coastal soil in China, as well as wild soybean root nodule endosymbionts. To reveal the composition of the microbial ecosystem, we performed 16S rRNA and nifH gene amplicon sequencing on root nodules and root zones under different environmental conditions. In addition, we used culture-independent methods to examine the root bacterial microbiome of wild soybean. For functional characterization of individual members of the microbiome and their impact on plant growth, we inoculated isolates from the root microbiome with wild soybean and observed nodulation. Sinorhizobium/Ensifer accounted for 97% of the root nodule microbiome, with other enriched members belonging to the phyla Actinobacteria, Bacteroidetes, Chloroflexi, Acidobacteria, and Gemmatimonadetes; the genera Sphingomonas, Microbacterium, Arthrobacter, Nocardioides, Streptomyces, Flavobacterium, Flavisolibacter, and Pseudomonas; and the family Enterobacteriaceae. Compared to saline-alkali soil from the Yellow River Delta, coastal soil was highly enriched for soybean nodules and displayed significant differences in the abundance and diversity of ?-proteobacteria, ?-proteobacteria, Actinobacteria, and Bacteroidetes. Overall, the wild soybean root nodule microbiome was dominated by nutrient-providing Sinorhizobium/Ensifer and was enriched for bacterial genera that may provide salt resistance. Thus, this reductionist experimental approach provides an avenue for future systematic and functional studies of the plant root microbiome.

Dataset Information

Shortwave Sand Transport in the Shallow Surf Zone.

Publications

Shortwave Sand Transport in the Shallow Surf Zone.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure