Social Sciences, asked by arunakumari7198, 4 months ago

where is the place wher we can go and see 4 colour water mixing in a river ? ​

Answers

Answered by ayanzubair
1

The sea lions stop bellowing and slip, one by one, off the jetty into the mocha-brown water of the Fraser River, near Vancouver, British Columbia. The surface of the water is smooth, except for a line of ripples moving slowly upriver. The sea lions seem to know that the calm surface belies turmoil beneath.

The tide has just turned, and a tongue of salt water is first creeping, then galloping, back into the Fraser just a few hours after being expelled by a strong outflow during the previous ebb. Although the surface appears calm, the underwater intersection of fresh and salt water roils with turbulent eddies as strong as any in the ocean. The confusion of swirling water and suspended sediments disorients homeward-bound salmon, providing an easy feast for the sea lions.

Not all rivers end as dramatically as the Fraser. But the mixing of freshwater streams and rivers with salty ocean tides in a partly enclosed body of water—natural scientists call it an estuary—fuels some of the most productive ecosystems on Earth, and also some of the most vulnerable.

Long before the advent of civilization, early humans recognized the bounty of the estuary and made these regions a focal point for human habitation. Unfortunately, overdevelopment, poor land use, and centuries of industrial contamination have taken a toll on most estuaries. Boston Harbor, San Francisco Bay, and the Hudson River are poster children for environmental degradation.

Yet there is hope. Estuaries are the borderlands between salt- and freshwater environments, and they are incredibly diverse both biologically and physically. The diversity and the high energy of the ecosystem make estuaries remarkably resilient. With a better understanding of these systems, we can reverse their decline and restore the ecological richness of these valuable, albeit muddy, environments.

How does an estuary work?

From a physicist’s point of view, the density difference between fresh and salt water makes estuaries interesting. When river water meets sea water, the lighter fresh water rises up and over the denser salt water. Sea water noses into the estuary beneath the outflowing river water, pushing its way upstream along the bottom.

Often, as in the Fraser River, this occurs at an abrupt salt front. Across such a front, the salt content (salinity) and density may change from oceanic to fresh in just a few tens of meters horizontally and as little as a meter vertically.

Accompanying these strong salinity and density gradients are large vertical changes in current direction and strength. You can’t see these swirling waters from the surface, but a fisherman may find that his net takes on a life of its own when he lowers it into seemingly placid water.

Pliny the Elder, the noted Roman naturalist, senator, and commander of the Imperial Fleet in the 1st century A.D., observed this peculiar behavior of fishermens’ nets in the Strait of Bosphorus, near Istanbul. Pliny deduced that surface and bottom currents were flowing in opposite directions, and he provided the first written documentation of what we now call the “estuarine circulation.”

Answered by lovinglavisha
8

The sea lions stop bellowing and slip, one by one, off the jetty into the mocha-brown water of the Fraser River, near Vancouver, British Columbia. The surface of the water is smooth, except for a line of ripples moving slowly upriver. The sea lions seem to know that the calm surface belies turmoil beneath.

The tide has just turned, and a tongue of salt water is first creeping, then galloping, back into the Fraser just a few hours after being expelled by a strong outflow during the previous ebb. Although the surface appears calm, the underwater intersection of fresh and salt water roils with turbulent eddies as strong as any in the ocean.

Similar questions