Estimating extreme water levels with long-term data by GEV distribution at Wusong station near Shanghai city in Yangtze Estuary

The ability to predict coastal flooding events and associated impacts has emerged as a primary societal need within the context of projected sea level rise (SLR) and climate change. The duration and extent of flooding is the result of nonlinear interactions between multiple environmental forcings (oceanographic, meteorological, hydrological) acting at varying spatial (local to global) and temporal scales (hours to centuries). Individual components contributing to total water levels (TWLs) include astronomical tides, monthly sea level anomalies, storm surges, and wave setup. Common practices often use the observational record of extreme water levels to estimate return levels of future extremes. However, such projections often do not account for the individual contribution of processes resulting in compound TWL events, nor do they account for time-dependent probabilities due to seasonal, interannual, and long-term oscillations within the climate system. More robust estimates of coastal flooding risk require the computation of joint probabilities and the simulation of hypothetical TWLs to better constrain the projection of extremes (Serafin [2014]).

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Fluctuating water levels influence access to critical habitats for threatened Cowichan Lake lamprey

FACETS ◽

10.1139/facets-2019-0054 ◽

2020 ◽

Vol 5 (1) ◽

pp. 488-502

Author(s):

Chiranjib Chaudhuri ◽

Joy Wade ◽

Colin Robertson

Keyword(s):

Water Level ◽

Water Levels ◽

Spawning Period ◽

Habitat Area ◽

Management Actions ◽

Bear Lake ◽

Aerial Vehicle ◽

Key Drivers ◽

Term Data

Cowichan Lake lamprey ( Entosphenus macrostomus) is a threatened species resident to Mesachie Lake, Cowichan Lake, and adjoining Bear Lake and their major tributaries in British Columbia. Decreases in trapping success have created concerns that the population is declining. Some potential threats include water use, climate change, and management actions. Owing to the absence of long-term data on population trends, little information is available to estimate habitat quality and factors that influence it. We sought to fill this gap by examining associations between habitat area and variables representing suspected key drivers of habitat availability. Critical habitat areas were imaged using an unmanned aerial vehicle over a period of three years at three sites at Cowichan Lake and a subsequent habitat area was classified. Meteorological and anthropogenic controls on habitat area were investigated through automatic relevance detection regression models. The major driver of habitat area during the critical spawning period was water level during the storage season, which also depends on the meteorological variables and anthropogenic control. It is recommended that regulation of the weir should aim to ensure that the water level remains above the 1 m mark, which roughly equates to the 67% coverage of water on the habitat area used for spawning.

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EXTREME LEVELS ARISING FROM METEOROLOGICAL SURGES

Coastal Engineering Proceedings ◽

10.9753/icce.v14.1 ◽

1974 ◽

Vol 1 (14) ◽

pp. 1 ◽

Cited By ~ 1

Author(s):

P. Ackers ◽

T.D. Ruxton

Keyword(s):

Sea Level ◽

North Sea ◽

High Tide ◽

Water Levels ◽

Return Periods ◽

The North ◽

Extreme Water Levels ◽

Independent Events ◽

The North Sea

The design of coastal works depends on estimating the probabilities of extreme water levels, as well as of waves Previous studies of surge-affected levels have extrapolated observed annual maxima or the n highest levels in n years to predict rarer events In addition to using these well-established methods, m this study of tide levels on the Essex coast of Britain a long term record of extreme levels was synthesised by adding surge residuals at the time of predicted HW to predicted HW levels, treating them as statistically independent events Many more large surge residuals have been measured than extreme water levels as many surges are associated with small tides Events with return periods up to 1000 years may be estimated without extrapolating beyond the range of observed surge residuals and predicted tides This method is assessed in relation to previous methods and information relevant to the design of coastal works in the south western part of the North Sea was obtained In addition to forecasting the probabilities of high tide levels, the study included wave forecasts and the encounter probabilities of combinations of sea level and wave height for various aspects of coastal developments.

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Multizone monitoring well completion design in the GAB

The APPEA Journal ◽

10.1071/aj14037 ◽

2015 ◽

Vol 55 (2) ◽

pp. 402

Author(s):

Garth Naldrett

Keyword(s):

Local Community ◽

Cost Effective ◽

Water Levels ◽

Borehole Data ◽

Well Completion ◽

Online Portal ◽

Zonal Isolation ◽

Term Data ◽

Responsible Manner

To provide the community with assurance that Santos GLNG operations are performed in a safe and responsible manner, the company has undertaken a major project to equip a large number of boreholes with multizone aquifer monitoring systems. These systems ensure aquifer water levels are monitored accurately. To provide a cost-effective design that reduces the need for multiple wells and provides long-term data reliability, a packer and gauge system with full redundancy was designed and co-developed with Santos. The focus of this design was zonal isolation between aquifers, full redundancy, and retrievability. This extended abstract describes a project where a fully retrievable seven-zone system was designed, deployed and monitored. Although the swell packers used to isolate zones are a mature technology, this is the first application where they have been designed to be recovered from the borehole with a pull-to-release system. The design and deployment was especially complex as both the retrievable packers and 14 pressure temperature gauges were deployed in a slim 4 inch bore. The system was successfully deployed in the first quarter of 2014. A compact solar power surface acquisition system has also been integrated. It gathers and transmits the borehole data to an online portal. Santos is fully transparent with the data gathered and the local community is able to get this data from the online portal.

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Development of an Atlantic Canadian Coastal Water Level Neural Network Model

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2008jtecho569.1 ◽

2008 ◽

Vol 25 (11) ◽

pp. 2117-2132 ◽

Cited By ~ 3

Author(s):

Guoqi Han ◽

Yu Shi

Keyword(s):

Neural Network ◽

Water Level ◽

Sea Level ◽

Coastal Water ◽

Water Levels ◽

Atlantic Canada ◽

Level Data ◽

Coastal Water Level ◽

Term Data

Abstract Coastal water-level information is essential for coastal zone management, navigation, and oceanographic research. However, long-term water-level observations are usually only available at a limited number of locations. This study discusses a complementary and simple neural network (NN) approach, to predict water levels at a specified coastal site from the data gathered at other nearby or remote permanent stations. A simple three-layer, feed-forward, back-propagation network and a neural network ensemble, named Atlantic Canadian Coastal Water Level Neural Network (ACCSLENNT) models, was developed to correlate the nonlinear relationship of sea level data among stations by learning from their historical characteristics. Instantaneous hourly observations of water level from five stations along the coast of Atlantic Canada—Argentia, Belledune, Halifax, North Sydney, and St. John’s—are used to formulate and validate the ACCSLENNT models. Qualitative and quantitative comparisons of the network output with target observations showed that despite significant changes in sea level amplitudes and phases in the study area, appropriately trained NN models could provide accurate and robust long-term predictions of both tidal and nontidal (tide subtracted) water levels when only short-term data are available. The robust results indicate that the NN models in conjunction with limited permanent stations are able to supplement long-term historical water-level data along the Atlantic Canadian coast. Because field data collection is usually expensive, the ACCSLENNT models provide a cost-effective alternative to obtain long-term data along Atlantic Canada.

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Hydrogeological responses in tropical mountainous springs

Memorias del I Congreso Internacional de Ciencias Exactas y Naturales ◽

10.15359/cicen.1.37 ◽

2019 ◽

Author(s):

Ricardo Sánchez-Murillo

Keyword(s):

Costa Rica ◽

Isotope Composition ◽

Central Valley ◽

Distribution Functions ◽

Geochemical Composition ◽

Transit Times ◽

Management Plans ◽

Best Fit ◽

Term Data

This study presents a hydrogeochemical analysis of spring responses (2013-2017) in the tropical mountainous region of the Central Valley of Costa Rica. The isotopic distribution of δ18O and δ2H in rainfall resulted in a highly significant meteoric water line: δ2H = 7.93×δ18O + 10.37 (r2=0.97). Rainfall isotope composition exhibited a strong dependent seasonality. The isotopic variation (δ18O) of two springs within the Barva aquifer was simulated using the FlowPC program to determine mean transit times (MTTs). Exponential-piston and dispersion distribution functions provided the best-fit to the observed isotopic composition at Flores and Sacramento springs, respectively. MTTs corresponded to 1.23±0.03 (Sacramento) and 1.42±0.04 (Flores) years. The greater MTT was represented by a homogeneous geochemical composition at Flores, whereas the smaller MTT at Sacramento is reflected in a more variable geochemical response. The results may be used to enhance modelling efforts in central Costa Rica, whereby scarcity of long-term data limits water resources management plans.

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Morphometric studies of artemia males from different populations of the Altai region

Rybovodstvo i rybnoe hozjajstvo (Fish Breeding and Fisheries) ◽

10.33920/sel-09-2007-03 ◽

2020 ◽

pp. 28-38

Author(s):

L. Vesnina ◽

G. Lukerina ◽

T. Ronzhina ◽

A. Savos’kin ◽

D. Surkov

Keyword(s):

Sexual Dimorphism ◽

Hydrogen Index ◽

Morphometric Parameters ◽

Altai Region ◽

Sexual Structure ◽

Different Populations ◽

Artemia Population ◽

Term Data ◽

Brine Salinity

The long-term data from morphometric studies of Artemia males from bisexual and parthenogenetic populations from hyperhaline reservoirs of the Altai region (Bolshoe Yarovoe Lake, Maloe Shklo Lake, and the Tanatar Lakes system) is analyzed in this paper. The description of signs of sexual dimorphism and sexual structure in different populations is given. The influence of brine salinity and hydrogen index on morphometric parameters of males was analyzed. There are differences in the sexual structure of the Artemia population: in the lakes Maloe Shklo and the thanatar system, the populations are bisexual (the share of males is 28.5 — 75.0 %), in the lake Bolshoe yarovoe — parthenogenetic (the share of males on average does not exceed 3 %). At the same time, sexual dimorphism is typical for both types of populations: females are larger than males, males have a larger head (the distance between the eyes is greater by 15.5 %, the diameter of the eye is 26.1 %, the length of the antenna is 22.3 %) and a larger number of bristles (36.1 %). The greatest variability is observed in the parameters of the Furka structure associated with the salinity of water by feedback and the pH — line indicator. Significant differences between the samples of males were revealed. The largest number of significant differences in morphometric indicators was found between samples of males from bisexual populations (lake thanatar and lake Maloe Shklo), the smallest — between males from the parthenogenetic population of lake Bolshoe yarovoe and males from lake Maloe Shklo.

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