New Dimensions in Estuary Classification1

Hansen, Donald V.; Rattray, Maurice

doi:10.4319/lo.1966.11.3.0319

Cited by 582 publications

(297 citation statements)

References 3 publications

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“…This paper focuses on the changes induced by different seasonal discharge levels. Estuarine regime shifts driven by seasonal river discharge variability have long been observed [e.g., Hansen and Rattray, 1966] in estuaries and deltas of all sizes. For example, the Columbia [Hughes and Rattray, 1980], San Francisco Bay [Walters et al, 1985], Tamar [Bale et al, 1985], and Merrimack [Ralston et al, 2010] estuaries transition from highly stratified to moderately stratified conditions depending on seasonal river discharge.…”

Section: Introductionmentioning

confidence: 99%

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

et al. 2015

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A better understanding of flow and sediment dynamics in the lowermost portions of large‐tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and suspended‐sediment concentration were measured for 25 h at three cross sections in the tidal Song Hau distributary of the Mekong River, Vietnam. Two campaigns took place during comparatively high‐seasonal and low‐seasonal discharge, and estuarine conditions varied dramatically between them. The system transitioned from a tidal river with ephemeral presence of a salt wedge during high flow to a partially mixed estuary during low flow. The changing freshwater input, sediment sources, and estuarine characteristics resulted in seaward sediment export during high flow and landward import during low flow. The Dinh An channel of the Song Hau distributary exported sediment to the coast at a rate of about 1 t s−1 during high flow and imported sediment in a spatially varying manner at approximately 0.3 t s−1 during low flow. Scaling these values results in a yearly Mekong sediment discharge estimate about 65% smaller than a generally accepted estimate of 110 Mt yr−1, although the limited temporal and spatial nature of this study implies a relatively high degree of uncertainty for the new estimate. Fluvial advection of sediment was primarily responsible for the high‐flow sediment export. Exchange‐flow and tidal processes, including local resuspension, were principally responsible for the low‐flow import. The resulting bed‐sediment grain size was coarser and more variable during high flow and finer during low, and the residual flow patterns support the maintenance of mid‐channel islands.

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Section: Introductionmentioning

confidence: 99%

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

et al. 2015

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“…Un des indices les plus simples est celui de Schultz & Simmons (1957) in Hansen & Rattray (1966). Il s'agit du rapport R entre la somme des apports d'eau douce au cours d'une marée (ici 12,4 h) et le prisme de marée défini comme le volume d'eau salée entrant pendant le flot.…”

Section: Comportement De Pestuaire Au Cours De La Période Considéréeunclassified

Elaboration et validation d'un modèle simple de mélange des eaux en estuaire. Application au Bou Regreg (Côte atlantique marocaine)

Massio

1993

Ann. Limnol. - Int. J. Lim.

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A partir de données morphologiques et de mesures de salinité, un modèle numérique de mélange des eaux dans l'estuaire du Bou Regreg a été élaboré. L'estuaire a été divisé en 23 tronçons d'un kilomètre de long pour lesquels le modèle permet de calculer l'évolution dans le temps des salinités moyennes à mi-marée. Au cours de la période étudiée, les échanges entre les 23 tronçons paraissent largement dominés par la dispersion. Le modèle reproduit correctement l'évolution de la salinité après une crue artificielle due à un lâcher de barrage mais également dans d'autres situations. Elaboration and validation of a simple mixing water model for an estuary. Application to the Bou Regreg (Moroccan atlantic coast)Keywords : estuary, salinity, residual discharges, operating models, dispersion, Morocco.Using morphological data and salinity measurements, a numerical model describing the mixing of water along the Bou Regreg estuary was developed. The estuary has been divided into 23 sections, each 1 km in length.The model can be used to calculate the temporal changes of the average salinity for each section at midtide. During the study period the exchanges between the 23 sections were largely governed by dispersion. The model reproduces correctly the salinity variations after a major release of fresh water from an upstream reservoir and also in other situations.

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“…Within the regions where freshwater flows in, buoyancy input into the bay head is responsible for producing a physical regime that is radically different from lakes and open ocean (Simpson 1997). It is well known that less saline lighter water flows seaward in the upper layer, while more saline heavier water flows landward in the lower layer (Hansen and Rattray 1966). This flow pattern is called "estuarine circulation" and often observed in estuaries and bays, as the water exchange between coastal basins and adjacent ocean has long been a topic of great interest to oceanographers (e.g., Geyer and Cannon 1982;LeBlond et al 1991;Allen and Simpson 1998).…”

Section: Formation Mechanism Of Hypoxiamentioning

confidence: 99%

“…Inside the bay, the buoyancy input by freshwater and weak tidal currents (~10 -1 m s -1 ) cause the water to stratify. Based on the stratification-circulation diagram by Hansen and Rattray (1966), the water condition is classified as a strongly stratified regime in summer, and a weakly stratified regime in winter. Both large freshwater discharge and sea surface heating reinforce the stratification in summer.…”

Section: -1 Introductionmentioning

confidence: 99%

Hypoxia Controlled by Hydrodynamics

Kasai¹

2014

Aqua-BioSci. Monogr. (ABSM)

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In summer dissolved oxygen is often depleted in the lower and bottom layers in many coastal basins all over the world. This phenomena is called hypoxia. When the oxygen consumption exceeds oxygen supply, the water becomes hypoxic. The oxygen is consumed by decomposing organic matter by bacteria (biochemical processes), while the oxygen is supplied by physical processes such as convection, advection and diffusion. The primary cause of hypoxia is the consumption of oxygen in the water column, but physical processes mainly control its generation, distribution and configuration. In addition to the vertical supply of oxygen by mixing, horizontal transport by estuarine circulation plays the major role in the formation of hypoxia in regions of freshwater influence. As the hypoxic water contains a lot of nutrients, it plays an important role for primary production, producing middle layer chlorophyll maximum in summer and inducing bloom of phytoplankton in autumn.

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New Dimensions in Estuary Classification1

Cited by 582 publications

References 3 publications

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

Elaboration et validation d'un modèle simple de mélange des eaux en estuaire. Application au Bou Regreg (Côte atlantique marocaine)

Hypoxia Controlled by Hydrodynamics

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