Movements Resulting from Mixing of Stratified Waters

1934 ◽  
Vol 1 (2) ◽  
pp. 133-143 ◽  
Author(s):  
H. B. Hachey
Keyword(s):  
Fresh Water ◽  
Salt Water ◽  
Water Layer ◽  
Surface Movement ◽  
Laboratory Tank ◽  
Mixed Water ◽  
Made In

Experiments in mixing steadily at one end of a laboratory tank an upper fresh water with a lower salt water layer demonstrate surface and bottom movements to the mixing area and an intermediate movement of mixed water away from it, which correspond with observations made in an inlet of the sea into which fresh water discharges. If fresh water is merely added at the mixing area to the tank containing salt water, the outward movement is at the surface, and there is no inward surface movement.

The evolution of under-ice melt ponds, or double diffusion at the freezing point

1974 ◽  
Vol 64 (3) ◽  
pp. 507-528 ◽  
Author(s):  
Seelye Martin ◽  
Peter Kauffman
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Freezing Point ◽  
Salt Water ◽  
Ice Sheet ◽  
Water Layer ◽  
Double Diffusion ◽  
Theoretical Models ◽  
Interfacial Region ◽  
Ice Melt

In an experimental and theoretical study, we model a phenomenon observed in the summer Arctic, where a fresh-water layer at a temperature of 0°C floats both over a sea-water layer at its freezing point and under an ice layer. Our results show that the ice growth in this system takes place in three phases. First, because the fresh-water density decreases upon supercooling, the rapid diffusion of heat relative to salt from the fresh to the salt water causes a density inversion and thereby generates a high Rayleigh number convection in the fresh water. In this convection, supercooled water rises to the ice layer, where it nucleates into thin vertical interlocking ice crystals. When these sheets grow down to the interface, supercooling ceases. Second, the presence of the vertical ice sheets both constrains the temperatureTand salinitysto lie on the freezing curve and allows them to diffuse in the vertical. In the interfacial region, the combination of these processes generates a lateral crystal growth, which continues until a horizontal ice sheet forms. Third, because of theTandsgradients in the sea water below this ice sheet, the horizontal sheet both migrates upwards and increases in thickness. From one-dimensional theoretical models of the first two phases, we find that the heat-transfer rates are 5–10 times those calculated for classic thermal diffusion.

scholarly journals ESTUARINE CURRENTS AND TIDAL STREAMS

2011 ◽  
Vol 1 (7) ◽  
pp. 28
Author(s):  
Roderick Agnew
Keyword(s):  
Fresh Water ◽  
River Flow ◽  
Salt Water ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Water Layer ◽  
Wave Theory ◽  
Constant Density ◽  
Salt Wedge ◽  
Tidal Streams

Fresh water spreading out from the mouth of a river as it enters a salt sea may preserve its identity for a considerable distance on the surface if wind-generated waves, longshore currents and tidal streams are capable of producing only weak mixing. Fig. 1 shows the three dimensional shape of a fresh-water tongue overlying more dense salt water, derived by Takano (1954) on the assumption of constant eddy viscosity and constant density in the fresh water layer, below which the density increases according to an assumed law, making an asymptotic approach to the density of salt water. Takano's model is thus a water jet entraining salt from around and below it. Salt or brackish water may penetrate along the deep channels of an estuary in the shape of a wedge complementary to the fresh water tongue, the salt wedge retreating seawards as heavy rainfall increases the river discharge, and advancing in dry weather intervals. Tidal streams cause a regular oscillation of both fresh and braok water in flood and ebb directions but the seasonal movements of the sloping boundary between fresh and salt water may still be important in low-lying delta regions. Strong tidal streams lead to intense mixing, when neither a fresh water tongue nor a salt wedge can be distinguished, but the isohalines (salinity contours) preserve the general wedge pattern - see Figs. 3 to 6. In the upper reaches of an estuary it is possible to study the effect of the tidal motion by treating it as a simple harmonic perturbation of the uni-directional river flow. Even in the middle portion of the estuary where there is reversal of the horizontal motion, one may seek a "quasi steady" solution for the net effect (seaward movement of fresh water) while allowing for the increased turbulence due to the tidal action. At the seaward end of the estuary there is little deviation from the astronomical tidal rhythm, so the problem reduces to simple harmonic oscillations of salt water. Higher harmonics may be introduced as an extension of the simple solution. For a first approximation it is sufficient to consider flow in the longitudinal vertical plane, to assume that the pressure distribution is hydrostatic as in long wave theory, and even to neglect inertia terms when investigating net effects.

46.—Oceanography in Scottish Sea Lochs and Estuaries in the Nineteenth and early Twentieth Centuries

1972 ◽  
Vol 72 (1) ◽  
pp. 459-462
Author(s):  
P. H. Milne
Keyword(s):  
Nineteenth Century ◽  
Fresh Water ◽  
Coastal Waters ◽  
Salt Water ◽  
Water Density ◽  
Estuarine Waters ◽  
Made In

The tradition of oceanographical research was established in Scotland, more especially in Edinburgh, in the mid-nineteenth century.The earliest observations to be made in coastal waters in Scotland are attributed to Robert Stevenson when in 1812 he carried out a survey of the Dee at Aberdeen (Stevenson 1872). He found that while there was an outward upper current of fresh water there was also an inward undercurrent of salt water, which gave rise to the tidal rise and fall in the river. This may be the first recorded example of salt-water density wedge penetration into estuarine waters.

Current Measurements in Knight Inlet, British Columbia

1959 ◽  
Vol 16 (5) ◽  
pp. 635-678 ◽  
Author(s):  
G. L. Pickard ◽  
Keith Rodgers
Keyword(s):  
British Columbia ◽  
Fresh Water ◽  
Salt Water ◽  
Current Profile ◽  
Tidal Period ◽  
Shallow Estuary ◽  
Layer Flow ◽  
Bottom Depth ◽  
Future Work ◽  
Made In

One of the features of the circulation in an estuary is the net outflow in the surface layer of the fresh water discharged into the estuary together with an appreciable volume of salt water entrained. Continuity considerations require that there be an inflow of salt water to compensate for that taken out in the surface. In a shallow estuary, such as Chesapeake Bay, this results in a two-layer flow, out at the surface and in below it.In a deep estuary, the questions arise whether or not it also possesses this simple two-layer flow and what is the depth and extent of the inflow. Measurements have been made in several inlets in the British Columbia coast to obtain information about the circulation in a deep estuary. Preliminary experiments were made in Toba, Bute and Knight Inlets, the series made in Knight Inlet in July 1956 being the most complete. The techniques employed and the results obtained are described and discussed.In a shallow section (75 m), in-and-out (flood-and-ebb) flow occurred in phase from surface to bottom, with a net outflow in the upper half and inflow below this. In the presence of an up-inlet wind, the flow in the surface few metres reversed and became up-inlet, with an increased outflow below it.In a deep section, both oscillatory (tidal period) as well as net currents occurred at all depths from the surface to 300 m (relevant bottom depth was 350 m). In this deeper section, the oscillatory components were not in phase from surface to bottom, and the net flow showed a three- or four-layer pattern, rather than the simple two-layer pattern which has previously been assumed to exist. The wind had a marked direct effect on the upper layers to a depth of about 10 m and possibly deeper.The movement of the ship while at anchor was monitored and found to be considerable. Most of the current observations were corrected for ship motion before analysis.Calculations of the net fresh water transport (in the upper layer) give reasonable values but similar calculations for the deep water show a net transport which is not to be expected. This apparent net transport may be a consequence of assuming that the current profile across the entire inlet is the same as that in the centre where measurements were made. Other possible sources of error are suggested. In addition, several recommendations are made for future work.

scholarly journals XII. An easy method to distill fresh water from salt water at sea; by Capt. Newland

1772 ◽  
Vol 62 ◽  
pp. 90-92 ◽  
Keyword(s):  
Fresh Water ◽  
Salt Water ◽  
Easy Method

The materials necessary for this process are the following; a copper or iron pot of 15 or 20 gallons, an empty cask, some sheet lead, a small jar, a few wood-ashes or soap, and billet-wood for fewel.

scholarly journals MEASUREMENT OF INTERFACE BETWEEN FRESH WATER AND SALT WATER USING ENERGY ABSORPTION CHARACTERISTICS IN MICROWAVE

2010 ◽  
Vol 66 (2) ◽  
pp. 189-195
Author(s):  
Yuji ITO ◽  
Hideki MIYAMOTO ◽  
Masumi KORIYAMA ◽  
Jiro CHIKUSHI ◽  
Masahiro SEGUCHI
Keyword(s):  
Fresh Water ◽  
Energy Absorption ◽  
Salt Water ◽  
Absorption Characteristics

Salt-Water Interface Near a Fresh-Water Canal

1964 ◽  
Vol 90 (6) ◽  
pp. 97-116
Author(s):  
Norbert L. Ackermann ◽  
Pachern Sridurongkatum
Keyword(s):  
Fresh Water ◽  
Salt Water ◽  
Water Interface ◽  
Water Canal

The use of saline water for irrigating rice in northern Australia

1968 ◽  
Vol 8 (33) ◽  
pp. 491 ◽  
Author(s):  
RW Strickland
Keyword(s):  
Fresh Water ◽  
Saline Water ◽  
Salt Water ◽  
Growth And Yield ◽  
Soluble Salts ◽  
Reproductive Phase ◽  
Panicle Number ◽  
Soil Conductivity ◽  
Restricted Use ◽  
Reproductive Phases

A pot trial to assess the effect of salt water on growth and yield of rice in the Northern Territory of Australia was conducted in 1962-63. Two varieties were irrigated with three levels of salinity for varied durations in either the establishment or reproductive phases. Plant emergence was significantly depressed by soil conductivities in excess of 4 m-mhos/cm at 25�C. The restricted use of up to 3000 p.p.m. total soluble salts from 10 days after emergence and of up to 6000 p.p.m. from 20 days after emergence, followed by fresh water, had no effect on flowering time, vegetative or grain yields. The application of 3000 and 6000 p.p.m. total soluble salts in the reproductive phase reduced mean panicle number and grain yield of both varieties and straw yield of one variety. Use of saline water in the establishment phase followed by fresh water and drainage, reduced soil conductivity. In the reproductive phase it nullified the effect of previous fresh water flushing and tended to increase soil conductivity above original levels.

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