Spatial and temporal controls on overwash occurrence on a Great Lakes barrier spit

1992 ◽  
Vol 29 (1) ◽  
pp. 102-117 ◽  
Author(s):  
Robin G. D. Davidson-Arnott ◽  
John D. Fisher
Keyword(s):  
Lake Level ◽  
Field Measurements ◽  
High Water ◽  
Water Phase ◽  
Storm Events ◽  
North Shore ◽  
The North ◽  
High Lake Level ◽  
Washover Fan

Field measurements from 1985 to 1990 and sequential aerial photography since 1945 show that overwash plays an extremely important role in the dynamics of Long Point, a large barrier spit on the north shore of Lake Erie. Overwash occurs primarily in the transgressive proximal and central zones of the spit, which together account for some 65% of the total shoreline length of 41 km. During periods of high lake level, over 50% of the shoreline in these zones may be overwashed. Washover morphology ranges from continuous washover terraces in areas of low foredunes to isolated washovers with narrow throats and distinct fans where breaching has occurred through high dunes. Individual overwash events commonly produce deposits on the fan surface 0.25–0.75 m or more in thickness. Washover-fan sediments are dominated by nearly horizontal planar bedding, with deposits near the fan margins often having foreset bedding, reflecting deposition in standing water of the bay or of interdune ponds.The frequency of overwash occurrence is strongly influenced by long-term lake-level fluctuations, which produce a distinct cycle of overwash activity. During the high-water phase more than 40% of the shoreline may consist of active washover fans or inlet breaches. Even storms with a return frequency of 1–2 per year can lead to significant overwash activity, and the washovers are generally reactivated several times in a 2 or 3 year period around the peak water level. During the low-water phase wider beaches offer protection against even extreme storm events, resulting in washover healing and restoration of a continuous foredune.

scholarly journals Observations of Tidal Flat Sedimentation within a Native and an Exotic Spartina Species

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1566
Author(s):  
Barbara Proença ◽  
Florian Ganthy ◽  
Richard Michalet ◽  
Aldo Sottolichio
Keyword(s):  
Single Point ◽  
Field Measurements ◽  
Species Variation ◽  
Storm Events ◽  
Level Variation ◽  
Wave Forcing ◽  
Bed Elevation ◽  
Sediment Stabilization ◽  
Consistent Response

Field measurements of bed elevation and related wave events were performed within a tidal marsh, on two cordgrass species, Spartina anglica (exotic) and Spartina maritima (native), in the Bay of Arcachon (SW France). Bed- and water-level time series were used to infer on the sediment behavior patterns from short to long term. A consistent response was found between the bed-level variation and the wave forcing, with erosion occurring during storms and accretion during low energy periods. Such behavior was observed within the two species, but the magnitude of bed-level variation was higher within the native than the exotic Spartina. These differences, in the order of millimeters, were explained by the opposite allocation of biomass of the two species. On the long term, the sedimentation/erosion patterns were dominated by episodic storm events. A general sediment deficit was observed on the site, suggested by an overall bed-level decrease registered within both species. However, further verification of within species variation needs to be considered when drawing conclusions. Despite possible qualitative limitations of the experimental design, due to single point survey, this work provides original and considerable field data to the understanding the different species ability to influence bed sediment stabilization and their potential to build marsh from the mudflat pioneer stage. Such information is valuable for coastal management in the context of global change.

scholarly journals Mass mortality of Northern Map Turtles (Graptemys geographica)

2015 ◽  
Vol 129 (1) ◽  
pp. 80 ◽  
Author(s):  
Jordan Catrysse ◽  
Emily Slavik ◽  
Jonathan Choquette ◽  
Ashley E. Leifso ◽  
Christina M. Davy
Keyword(s):  
Lake Erie ◽  
Mass Mortality ◽  
Species At Risk ◽  
Long Term Effects ◽  
North Shore ◽  
The North ◽  
The Poor ◽  
Map Turtles ◽  
Graptemys Geographica

We report a mass mortality of Northern Map Turtles (Graptemys geographica [LeSueur, 1817]) on the north shore of Lake Erie, Ontario, Canada. Thirty-five dead adult females were recovered from a nesting area over a period of four weeks. Predation and boat strikes were both excluded as potential cause of death, but the actual cause could not be determined because of the poor condition of the carcasses. Other possible explanations for the mortality include poisoning, drowning, and infection with an unidentified pathogen. Mass mortality in long-lived species, such as turtles, can have long-term effects on population growth and is a cause for concern in a species at risk.

scholarly journals XI. Researches on the tides.—tenth series. on the laws of low water at the port of plymouth, and on the permanency of mean water

1839 ◽  
Vol 129 ◽  
pp. 151-161 ◽  
Keyword(s):  
High Water ◽  
Level Line ◽  
English Channel ◽  
Know How ◽  
North Shore ◽  
The North ◽  
South Shore ◽  
The Subject ◽  
The Mean ◽  
The Difference

In former communications to the Society, the laws of high water at Plymouth and other places have been the subject of my researches. These being obtained, the laws of low water are a subject of importance and interest on many accounts. The first ground of my pursuing this subject was the desire to ascertain how far the mean water , that is, the height midway between high and low water, is permanent during the changes which high and low water undergo. That it is approximately so at Ply­mouth, had been ascertained both by Mr. Walker and myself, by means of a com­parison of a short series of observations. But it was desirable to know with more exactness what was the real amount of this permanency, when, by using a long series of observations of high and low water, the irregularities arising from accident, and from taking imperfect cycles of inequalities, were eliminated. There was another reason which made this inquiry important at the present time. An operation has been recently carried on by the direction and at the expense of the British Association, with a view of ascertaining what surface ought to be taken as the permanent level of the sea. A Level Line has been carried with great care and accuracy from the north shore of Somerset to the south shore of Devon ; and the po­sition of this line has been fixed, so as to be recognised at any future time, by means of marks at Axmouth, at East Quantockshead, at Stolford, and at Portishead. This line has also been referred to the sea at its extremities ; and the observations show that the height of mean water coincides, at least very nearly, at different places, as well as at the same place at different times. While the difference of levels of low water at Axmouth on the English Channel, and Wick Rocks on the Bristol Channel, is not less than twelve feet; the mean water at those two places coincides in level within a few inches. In order to determine further what accuracy may be attained in this result, we are led to inquire what is the degree of permanency at one place. I may further add, that it cannot but be instructive to know how far the corrections of the height and time of low water, for lunar parallax and declination, agree in form and amount with the same corrections already obtained for high water.

scholarly journals Agroecología del sistema de aboneras en el litoral atlántico de Honduras.

2016 ◽  
Vol 7 (1) ◽  
pp. 117
Author(s):  
Bernard Triomphe
Keyword(s):  
Nutrient Cycling ◽  
Biomass Accumulation ◽  
Field Measurements ◽  
North Coast ◽  
The North ◽  
Baseline Information ◽  
Long Term Trends ◽  
Continuous Use ◽  
Time Substitution

The present study constitutes an initial effort to provide baseline information about the internal workings of the mucuna system. It includes a discussion of biological mechanisms which shape this system, especially with regard to nutrient cycling. Long-term trends in soil chemical and physical fertility are also analyzed. Chronosequences (also known as space-for-time substitution schemes) form the backbone of this long-term analysis: they were constructed by taking advantage of the diversity of adoption dates of the mucuna system among farmers. All field measurements were made at the level of small observation plots selected on uniform backslopes within farmers’ fields and subjected to a periodic agronomic monitoring throughout the maize growing season. After describing general characteristics of the mucuna system, an analysis of the various pools participating in nutrient cycling is conducted. Mucuna biomass accumulation and descomposition are then discussed, as well as the dynamics of mineral nitrogen in the soil profile, an analysis which in turn helps understand maize response to limited applications of nitrogen fertilizer. Although it appears that the mucuna system is too specific to the conditions prevailing in the North coast of Honduras to be extrapolated directly. After 12 years or more of continuous use of the mucuna rotation, a result which can undoubtedly be attributed to the high yearly organic additions and efficient nutrient cycling in this system.

scholarly journals Numerical simulation of a tsunami event during the 1996 volcanic eruption in Karymskoye lake, Kamchatka, Russia

2010 ◽  
Vol 10 (11) ◽  
pp. 2359-2369 ◽  
Author(s):  
T. Torsvik ◽  
R. Paris ◽  
I. Didenkulova ◽  
E. Pelinovsky ◽  
A. Belousov ◽  
...  
Keyword(s):  
Wave Speed ◽  
Field Measurements ◽  
Wave Model ◽  
Tsunami Source ◽  
Wave Runup ◽  
Underwater Explosions ◽  
North Shore ◽  
The North ◽  
Order Of Magnitude ◽  
South Shore

Abstract. Karymskoye caldera lake is a nearly circular body of water with a diameter of approximately 4 km and a depth of up to 60 m. The sublacustrine, Surtseyan-type eruption in the lake on 2–3 January 1996 included a series of underwater explosions. A field survey conducted the following summer showed signs of tsunami wave runup around the entire coastline of the lake, with a maximum of 29 m runup at the north shore near the source of the eruption, and 2–5 m runup at locations on the east and south shore far away from the source. The tsunami has been simulated using the numerical long wave model COULWAVE, with input from reconstructed realistic pre-eruption bathymetry. The tsunami source was chosen as suggested by Le Mehaute (1971) and Mirchina and Pelinovsky (1988). The initial wave was prescribed by a parabolic shape depression with a radius of R=200 m, and a height of 23 m at the rim of the parabola. Simulations were conducted to show principle directions for wave propagation, wave speed and arrival time for the leading wave group at the shore, and the distribution of wave height throughout the lake. Estimated result for wave runup are of the same order of magnitude as field measurements, except near the source of the eruption and at a few locations where analysis show significant wave breaking.

scholarly journals The Evaporation Estimation on Lake Most

2021 ◽  
Vol 4 (1) ◽  
pp. 221-231
Author(s):  
Dagmar Dlouhá ◽  
Viktor Dubovský ◽  
Lukáš Pospíšil
Keyword(s):  
Lake Level ◽  
Historical Data ◽  
Western Region ◽  
Artificial Lake ◽  
The Czech Republic ◽  
The Public ◽  
The North ◽  
Monteith Equation ◽  
North Western

Abstract After finishing the mining process, the best way to deal with the residual of open-cut coal mines in the north-western region of the Czech Republic has been proposed to be hydric recultivation. The area of our study is the first artificial Lake Most (formerly known as Ležáky-Most coal quarry) finished in 2014 and opened to the public in 2020 for recreational purposes. Since the lake is a closed system without natural inflow and outflow, the prediction of evaporation plays a crucial role in the securitization of long-term sustainability based on the capability of keeping the stable level of a dimension of the final water level. In this paper, we use the historical data consisting of the altitude of the lake level, its area, the perimeter of the shoreline, and especially the volume of refilled water. These data are compared against the computational methods; namely, the Penman-Monteith Equation and Hargreaves-Samani model calibrated by the method proposed in our previous work.

scholarly journals Lena Delta hydrology and geochemistry: long-term hydrological data and recent field observations

2015 ◽  
Vol 12 (2) ◽  
pp. 345-363 ◽  
Author(s):  
I. Fedorova ◽  
A. Chetverova ◽  
D. Bolshiyanov ◽  
A. Makarov ◽  
J. Boike ◽  
...  
Keyword(s):  
Field Measurements ◽  
High Water ◽  
The Arctic ◽  
Geochemical Processes ◽  
Lena River ◽  
Sediment Fluxes ◽  
Water And Sediment ◽  
Delta Branches ◽  
Ice Complex

Abstract. The Lena River forms one of the largest deltas in the Arctic. We compare two sets of data to reveal new insights into the hydrological, hydrochemical, and geochemical processes within the delta: (i) long-term hydrometric observations at the Khabarova station at the head of the delta from 1951 to 2005; (ii) field hydrological and geochemical observations carried out within the delta since 2002. Periods with differing relative discharge and intensity of fluvial processes were identified from the long-term record of water and sediment discharge. Ice events during spring melt (high water) reconfigured branch channels and probably influenced sediment transport within the delta. Based on summer field measurements during 2005–2012 of discharge and sediment fluxes along main delta channels, both are increased between the apex and the front of the delta. This increase is to a great extent connected with an additional influx of water from tributaries, as well as an increase of suspended and dissolved material released from the ice complex. Summer concentrations of major ion and biogenic substances along the delta branches are partly explained by water sources within the delta, such as thawing ice complex waters, small Lena River branches and estuarine areas.

scholarly journals Sources of Escherichia coli in a Coastal Subtropical Environment

2000 ◽  
Vol 66 (1) ◽  
pp. 230-237 ◽  
Author(s):  
Helena M. Solo-Gabriele ◽  
Melinda A. Wolfert ◽  
Timothy R. Desmarais ◽  
Carol J. Palmer
Keyword(s):  
Escherichia Coli ◽  
Soil Moisture ◽  
High Tide ◽  
Field Measurements ◽  
Temporal Variations ◽  
Storm Events ◽  
E Coli ◽  
The North ◽  
Cyclical Pattern ◽  
Large Pulse

ABSTRACT Sources of Escherichia coli in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in E. coli concentrations as well as experiments conducted under laboratory-controlled conditions.E. coli from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling tasks included sampling the length of the North Fork to identify the river reach contributing high E. coli levels, autosampler experiments at two locations, and spatially intense sampling efforts at hot spots. Laboratory experiments were designed to simulate tidal conditions within the riverbank soils. The results showed that E. coli entered the river in a large pulse during storm conditions. After the storm, E. coli levels returned to baseline levels and varied in a cyclical pattern which correlated with tidal cycles. The highest concentrations were observed during high tide, whereas the lowest were observed at low tide. This peculiar pattern of E. coli concentrations between storm events was caused by the growth of E. coli within riverbank soils which were subsequently washed in during high tide. Laboratory analysis of soil collected from the riverbanks showed increases of several orders of magnitude in soilE. coli concentrations. The ability of E. colito multiply in the soil was found to be a function of soil moisture content, presumably due to the ability of E. coli to outcompete predators in relatively dry soil. The importance of soil moisture in regulating the multiplication of E. coli was found to be critical in tidally influenced areas due to periodic wetting and drying of soils in contact with water bodies. Given the potential for growth in such systems, E. coliconcentrations can be artificially elevated above that expected from fecal impacts alone. Such results challenge the use of E. coli as a suitable indicator of water quality in tidally influenced areas located within tropical and subtropical environments.

Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

2000 ◽  
Vol 179 ◽  
pp. 201-204
Author(s):  
Vojtech Rušin ◽  
Milan Minarovjech ◽  
Milan Rybanský
Keyword(s):  
Emission Lines ◽  
High Latitudes ◽  
Green Line ◽  
Solar Cycles ◽  
The South ◽  
Coronal Emission ◽  
Local Maxima ◽  
The North ◽  
Cyclic Variations

AbstractLong-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18–23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

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