height of mean high water of neap tide

Keyword(s):  
2009 ◽  
Vol 6 (2) ◽  
pp. 1879-1905 ◽  
Author(s):  
D. C. Shaha ◽  
Y.-K. Cho

Abstract. Intensive measurements of salt intrusion in the Sumjin River estuary were taken at high and low waters during both spring and neap tides in each season from August 2004 to April 2007. The estuary demonstrated partially- and well-mixed characteristics during the spring tide and stratified condition during the neap tide. The salt intrusion at high water varied from about 13.39 km in summer 2005 to 25.62 km in autumn 2006. The salt intrusion depended primarily on the freshwater discharges rather than those of spring-neap tidal oscillations. Analysis of three years of observed salinity data indicated that the salt intrusion length scale in the Sumjin River estuary was proportional to the river discharge to the −1/5 power. Five empirical models were applied to the Sumjin River estuary to explore the most suitable as an easy-to-use tool for prediction of the salt intrusion length as functions of the geometry, river discharge and tide. Comparative results showed that the Nguyen and Savenije (2006) model developed under both partially- and well-mixed estuaries yielded the most satisfactory results of all the models studied for computing the salt intrusion length in the Sumjin River estuary. Our study suggests that the model can generate reasonable results for stratified conditions also.


1980 ◽  
Vol 7 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Rick A. Linthurst ◽  
Ernest D. Seneca

Spartina alterniflora is the dominant endemic saltmarsh angiosperm along the East and Gulf coasts of the United States. Dieback of S. alterniflora became evident through aerial surveys of the Lower Cape Fear Estuary of North Carolina. The areas affected varied in size, the largest being greater than 40 ha in areal extent. As S. alterniflora productivity losses can subsequently affect the productivity of the estuarine detritus-based food-web, studies were initiated in 1975 to examine the dieback phenomenon, follow successional trends, and determine the recolonization potential of S. alterniflora in dieback-affected salt-marshes.Three S. alterniflora dieback sites in the Lower Cape Fear Estuary were selected for study. Two of the sites, both above mean high-water, were recolonized by Salicornia europaea, Distichlis spicata, Scirpus robustus, Spartina patens, and S. alterniflora. At a third site, found to be below mean high-water, all volunteer plants were of S. alterniflora. Final stabilization of all three sites was mainly by S. alterniflora, with the living standing-crop biomass ranging from 341 to 1,565 g/m2 in September of 1978.Experimental plots within each of the three dieback sites were sprigged with S. alterniflora plants from three sources: (i) sandy dredge-material, (ii) volunteer plants within affected sites, and (iii) unaffected sites near the dieback areas. The success of these sprigs was strongly site-dependent. It is suggested that the plants used for revegetation of dieback sites should be obtained from areas similar to the site that is being transplanted and/or plants which have large rhizome systems.


Author(s):  
Lily Batten

When shore-collecting for marine algæ at Plymouth in early April, an organism which has now been identified as a calcareous lichen was brought to my notice by Dr. Orton. It occurred in large patches on the rocks both above and below high-water mark in the neighbourhood of the Marine Biological Station, and was also very frequent on the limpets and barnacles in the vicinity. When examined with a lens, the thallus of the lichen was observed to be thickly dotted either with perithecia or with well-marked pits which had apparently been previously occupied with fruits. The lichen was found to be identical with the species collected in Robin Hood Bay, Yorkshire, by E. M. Holmes, in 1901, and described by A. Lorrain Smith as Arthopyrenia foveolata. Arthopyrenia differs from Verrucaria in the fact that the associated alga is Trentepohlia, and the above species is easily distinguished by the pits which occur on the thallus.The same species has been recorded by M. C. Knowles from various places round the coast of Ireland, including the western shore of Blacksod Bay. It occurred on limestone rocks at about high neap-tide level, and also on live and dead barnacles where it was almost always associated with colonies of Rivularia atra. At Plymouth, the frequent occurrence of the lichen on limpet shells is a conspicuous feature in the distribution.


Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2434
Author(s):  
Guanghai Gao ◽  
Junqiang Xia ◽  
Roger A. Falconer ◽  
Yingying Wang

This paper presents a study of two transport timescales (TTS), i.e., the residence time and exposure time, of a hyper-tidal estuary using a widely used numerical model. The numerical model was calibrated against field measured data for various tidal conditions. The model simulated current speeds and directions generally agreed well with the field data. The model was then further developed and applied to study the two transport timescales, namely the exposure time and residence time for the hyper-tidal Severn Estuary. The numerical model predictions showed that the inflow from the River Severn under high flow conditions reduced the residence and exposure times by 1.5 to 3.5% for different tidal ranges and tracer release times. For spring tide conditions, releasing a tracer at high water reduced the residence time and exposure time by 49.0% and 11.9%, respectively, compared to releasing the tracer at low water. For neap tide conditions, releasing at high water reduced the residence time and exposure time by 31.6% and 8.0%, respectively, compared to releasing the tracer at low water level. The return coefficient was found to be vary between 0.75 and 0.88 for the different tidal conditions, which indicates that the returning water effects for different tidal ranges and release times are all relatively high. For all flow and tide conditions, the exposure times were significantly greater than the residence times, which demonstrated that there was a high possibility for water and/or pollutants to re-enter the Severn Estuary after leaving it on an ebb tide. The fractions of water and/or pollutants re-entering the estuary for spring and neap tide conditions were found to be very high, giving 0.75–0.81 for neap tides, and 0.79–0.88 for spring tides. For both the spring and neap tides, the residence and exposure times were lower for high water level release. Spring tide conditions gave significantly lower residence and exposure times. The spatial distribution of exposure and residence times showed that the flow from the River Severn only had a local effect on the upstream part of the estuary, for both the residence and exposure time.


1979 ◽  
Vol 30 (5) ◽  
pp. 653 ◽  
Author(s):  
DS Kettle ◽  
EJ Reye ◽  
PB Edwards

In soil samples flooded for 18 h C. molestus larvae were scarce in the top 0.5 cm, most dense in 0.5-1.5 cm and most numerous in 1.5-8.5 cm depth. They were recovered from mean high water springs to mean tide level but were concentrated (87.6%) in a narrow zone above mean tide level and including mean high water neaps. There was no evidence that their distribution was influenced by remoteness from the main body of tidal water. Higher density fluids than normal, e.g. syrup, specific gravity > 1.3, were required to extract larvae of C. molestus.


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