scholarly journals Transformation of Water Wave Spectra into Time Series of Surface Elevation

Earth ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 997-1005
Author(s):  
Phelype Haron Oleinik ◽  
Gabriel Pereira Tavares ◽  
Bianca Neves Machado ◽  
Liércio André Isoldi
Keyword(s):  
Time Series ◽  
Time Domain ◽  
Water Surface ◽  
Large Scale ◽  
Wave Spectrum ◽  
Ocean Waves ◽  
Surface Elevation ◽  
Sea Waves ◽  
Water Surface Elevation ◽  
Input Spectrum

Spectral wave modelling is widely used to simulate large-scale wind–wave processes due to its low computation cost and relatively simpler formulation, in comparison to phase-resolving or hydrodynamic models. However, some applications require a time-domain representation of sea waves. This article proposes a methodology to transform the wave spectrum into a time series of water surface elevation for applications that require a time-domain representation of ocean waves. The proposed method uses a generated phase spectrum and the inverse Fourier transform to turn the wave spectrum into a time series of water surface elevation. The consistency of the methodology is then verified. The results show that it is capable of correctly transforming the wave spectrum, and the significant wave height of the resulting time series is within 5% of that of the input spectrum.

scholarly journals Nonintrusive Measurement of Ocean Waves: Lidar Wave Gauge

2006 ◽  
Vol 23 (11) ◽  
pp. 1559-1572 ◽  
Author(s):  
Jennifer L. Irish ◽  
Jennifer M. Wozencraft ◽  
A. Grant Cunningham ◽  
Claudine Giroud
Keyword(s):  
Water Surface ◽  
Field Research ◽  
Ground Truth ◽  
Ocean Waves ◽  
Surface Elevation ◽  
Ground Truth Data ◽  
Water Surface Elevation ◽  
Nonintrusive Measurement ◽  
Pressure Meter ◽  
Elevation Measurement

Abstract In December 1999, a nonintrusive directional lidar wave gauge (LWG) was field tested at the Field Research Facility (FRF) in North Carolina. The LWG uses proven lidar technology to directly measure water surface elevation from above the water’s surface. Therefore, unlike bottom-mounted gauges, the surface elevation measurement from the LWG is independent of other hydrodynamic processes. The LWG prototype consists of four rangefinders, where each collects water surface elevation time series at a rate of 10 Hz. During the field test, ground truth data were collected concurrently with the LWG data using a biaxial current and pressure meter mounted directly beneath the LWG. Additional ground truth data were available from the existing FRF wave-gauging infrastructure. This paper describes principles of LWG operation and field experiment setup, LWG environmental and technical constraints, and LWG performance in measuring spectral wave parameters.

scholarly journals Assimilation of wide-swath altimetry water elevation anomalies to correct large-scale river routing model parameters

2020 ◽  
Vol 24 (5) ◽  
pp. 2207-2233 ◽  
Author(s):  
Charlotte Marie Emery ◽  
Sylvain Biancamaria ◽  
Aaron Boone ◽  
Sophie Ricci ◽  
Mélanie C. Rochoux ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Water Surface ◽  
Large Scale ◽  
Global Scale ◽  
Surface Elevation ◽  
Water Surface Elevation ◽  
Input Parameters ◽  
Water Elevation ◽  
Water Depths ◽  
River Routing

Abstract. Land surface models combined with river routing models are widely used to study the continental part of the water cycle. They give global estimates of water flows and storages, but they are not without non-negligible uncertainties, among which inexact input parameters play a significant part. The incoming Surface Water and Ocean Topography (SWOT) satellite mission, with a launch scheduled for 2021 and with a required lifetime of at least 3 years, will be dedicated to the measuring of water surface elevations, widths and surface slopes of rivers wider than 100 m, at a global scale. SWOT will provide a significant number of new observations for river hydrology and maybe combined, through data assimilation, with global-scale models in order to correct their input parameters and reduce their associated uncertainty. Comparing simulated water depths with measured water surface elevations remains however a challenge and can introduce within the system large bias. A promising alternative for assimilating water surface elevations consists of assimilating water surface elevation anomalies which do not depend on a reference surface. The objective of this study is to present a data assimilation platform based on the asynchronous ensemble Kalman filter (AEnKF) that can assimilate synthetic SWOT observations of water depths and water elevation anomalies to correct the input parameters of a large-scale hydrologic model over a 21 d time window. The study is applied to the ISBA-CTRIP model over the Amazon basin and focuses on correcting the spatial distribution of the river Manning coefficients. The data assimilation algorithm, tested through a set of observing system simulation experiments (OSSEs), is able to retrieve the true value of the Manning coefficients within one assimilation cycle much of the time (basin-averaged Manning coefficient root mean square error, RMSEn, is reduced from 33 % to [1 %–10 %] after one assimilation cycle) and shows promising perspectives with assimilating water anomalies (basin-averaged Manning coefficient RMSEn is reduced from 33 % to [1 %–2 %] when assimilating water surface elevation anomalies over 1 year), which allows us to overcome the issue of unknown bathymetry.

scholarly journals Deep visual domain adaptation and semi-supervised segmentation for understanding wave elevation using wave flume video images

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jinah Kim ◽  
Taekyung Kim ◽  
Sang-Ho Oh ◽  
Kideok Do ◽  
Joon-Gyu Ryu ◽  
...  
Keyword(s):  
Time Series ◽  
Water Level ◽  
Wave Height ◽  
Water Surface ◽  
Domain Adaptation ◽  
Surface Elevation ◽  
Nearshore Processes ◽  
Water Surface Elevation ◽  
Wave Flume ◽  
Visual Domain

AbstractAccurate water surface elevation estimation is essential for understanding nearshore processes, but it is still challenging due to limitations in measuring water level using in-situ acoustic sensors. This paper presents a vision-based water surface elevation estimation approach using multi-view datasets. Specifically, we propose a visual domain adaptation method to build a water level estimator in spite of a situation in which ocean wave height cannot be measured directly. We also implemented a semi-supervised approach to extract wave height information from long-term sequences of wave height observations with minimal supervision. We performed wave flume experiments in a hydraulic laboratory with two cameras with side and top viewpoints to validate the effectiveness of our approach. The performance of the proposed models were evaluated by comparing the estimated time series of water elevation with the ground-truth wave gauge data at three locations along the wave flume. The estimated time series were in good agreement within the averaged correlation coefficient of 0.98 and 0.90 on the measurement and 0.95 and 0.85 on the estimation for regular and irregular waves, respectively.

scholarly journals The FLOod Probability Interpolation Tool (FLOPIT): A Simple Tool to Improve Spatial Flood Probability Quantification and Communication

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 666
Author(s):  
Mahkameh Zarekarizi ◽  
K. Joel Roop-Eckart ◽  
Sanjib Sharma ◽  
Klaus Keller
Keyword(s):  
Flood Risk ◽  
Water Surface ◽  
The United States ◽  
Surface Elevation ◽  
Exceedance Probability ◽  
Water Surface Elevation ◽  
Inundation Maps ◽  
Probability Maps ◽  
Flood Probability ◽  
Floodplain Development

Understanding flood probabilities is essential to making sound decisions about flood-risk management. Many people rely on flood probability maps to inform decisions about purchasing flood insurance, buying or selling real-estate, flood-proofing a house, or managing floodplain development. Current flood probability maps typically use flood zones (for example the 1 in 100 or 1 in 500-year flood zones) to communicate flooding probabilities. However, this choice of communication format can miss important details and lead to biased risk assessments. Here we develop, test, and demonstrate the FLOod Probability Interpolation Tool (FLOPIT). FLOPIT interpolates flood probabilities between water surface elevation to produce continuous flood-probability maps. FLOPIT uses water surface elevation inundation maps for at least two return periods and creates Annual Exceedance Probability (AEP) as well as inundation maps for new return levels. Potential advantages of FLOPIT include being open-source, relatively easy to implement, capable of creating inundation maps from agencies other than FEMA, and applicable to locations where FEMA published flood inundation maps but not flood probability. Using publicly available data from the Federal Emergency Management Agency (FEMA) flood risk databases as well as state and national datasets, we produce continuous flood-probability maps at three example locations in the United States: Houston (TX), Muncy (PA), and Selinsgrove (PA). We find that the discrete flood zones generally communicate substantially lower flood probabilities than the continuous estimates.

Morphodynamic stability and characteristic length scales of bifurcations and confluences loops

2021 ◽  
Author(s):  
Niccolò Ragno ◽  
Marco Redolfi ◽  
Marco Tubino
Keyword(s):  
Froude Number ◽  
Water Surface ◽  
Characteristic Length ◽  
Coupled Model ◽  
Surface Elevation ◽  
Momentum Balance ◽  
Water Surface Elevation ◽  
Control Volumes ◽  
Almost All ◽  
Fluvial Environments

<p>The morphodynamics of multi-thread fluvial environments like braided and anastomosing rivers is fundamentally driven by the continuous concatenation of channel bifurcations and confluences, which govern the distribution of flow and sediment among the different branches that are reconnecting further downstream. Almost all studies performed to date consider the two processes separately, although they frequently appear as closely interconnected. In this work, we tackle the problem of analyzing the coupled morphodynamics of such bifurcation-confluence systems by studying the equilibrium and stability conditions of a channel loop, where flow splits into two secondary anabranches that rejoin after a prescribed distance. Through the formulation of a novel theoretical model for erodible bed confluences based on the momentum balance on two distinct control volumes, we show that the dominating anabranch (i.e. that carrying more water and sediment) is subject to an increase of the water surface elevation that is proportional to the square of the Froude number. This increase in water surface elevation tends to reduce the slope of the dominating branch, which produces a negative feedback that tends to stabilize the bifurcation-confluence system. A linear analysis of the coupled model reveals that the stabilizing effect of the confluence depends on the ratio between the length of the connecting channels and the average water depth, independently of the channel slope and Froude number. Furthermore, the effect of the confluence is potentially able to stabilize the channel loop in conditions where the classic stabilizing mechanism at the bifurcation (i.e. the topographical effect related to the gravitational pull on the sediment transport) is very weak, as expected when most of the sediment is transported in suspension. The identification of a characteristic length scale that produces a coupling between the confluences and bifurcations opens intriguing possibilities for interpreting the self-adjustment of the planform scale of natural multi-thread rivers.</p>

Tsunamis

2017 ◽  
Author(s):  
John A. Adam
Keyword(s):  
Mathematical Model ◽  
Large Scale ◽  
Volcanic Eruptions ◽  
Ocean Waves ◽  
The Other ◽  
Tsunami Generation ◽  
Sea Waves ◽  
Tsunami Propagation ◽  
Tidal Waves ◽  
Special Cases

This chapter describes a mathematical model of tsunami propagation (transient waves). A tsunami is a series of ocean waves triggered by large-scale disturbances of the ocean, including earthquakes, as well as landslides, volcanic eruptions, and meteorites. Tsunamis have very long wavelengths (typically hundreds of kilometers). They have also been called “tidal waves” or “seismic sea waves,” but both terms are misleading. The chapter first considers the boundary-value problem before modeling two special cases of tsunami generation, one due to an initial displacement on the free surface and the other due to tilting of the seafloor. It also discusses surface waves on deep water and how fast the wave energy propagates and concludes with an analysis of leading waves due to a transient disturbance.

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