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Posts tagged Tides

Bristol Bay and the Cook Inlet, Alaska

58.7N 156.7W

June 15th, 2009 Category: Lakes, Rivers

Alaska, USA - June 7th, 2009

Alaska, USA - June 7th, 2009

The Cook Inlet, far right, stretches 290 km (180 mi) from the Gulf of Alaska to Anchorage in south-central Alaska. Its watershed covers about 100,000 kmĀ² of southern Alaska.

The inlet is bordered on the east by the Aleutian Range, whose peaks are still snow-capped, and to the north by the Alaska River.

Several lakes are located in and near these mountains; the most visible are Becharof Lake (below) and Lake Iliamna (above). The former is located in the Aleutian Range; the latter at the northern end of the Alaskan Peninsula.

Lake Iliamna is the largest lake in Alaska. Through the Kvichak River, its waters drain into Bristol Bay, bottom center.

Bristol Bay is the eastern-most arm of the Bering Sea, about 400 km (250 mi) long and 290 km (180 mi) wide at its mouth.

The upper reaches of Bristol Bay experience some of the highest tides in the world. One such reach, the Nushagak Bay near Dillingham and another near Naknek in Kvichak Bay have tidal extremes in excess of 30 feet (9.9 m), ranking them as eighth highest in the world.

This, coupled with the extreme number of shoals, sandbars and shallows, makes navigation troublesome, especially during the area’s frequently strong winds.

Sediments pouring into Bristol Bay give its coastal waters a yellowish tinge, while those draining into the Cook Inlet are darker brown. The two lakes mentioned, on the other hand, appear dark blue and free of silt.

Sediments Brightly Color Thames Estuary, United Kingdom – June 8th, 2009

51.5N 0.1W

June 8th, 2009 Category: Image of the day, Rivers

London and Thames Estuary, UK - May 30th, 2009

London and Thames Estuary, UK - May 30th, 2009

The Thames Estuary is the estuary in which the River Thames meets the waters of the North Sea. Here, its waters show an intense mix of colors – brown, golden yellow and bright green – due to sediments flowing forth from the River Thames.

The estuary has the world’s second largest tidal movement, where the water can rise by 4 metres moving at a speed of 8 miles per hour. It is one of the largest of 170 such inlets on the coast of Great Britain.

The estuary constitutes a major shipping route, with thousands of movements each year including large oil tankers, container ships, bulk carriers and ferries entering the estuary for ports such as the Port of London.

The city of London itself can be seen as a greyish brown area in the lower left corner.

The Bay of Fundy, Canada – March 20th, 2009

March 20th, 2009 Category: Image of the day

Bay of Fundy, Canada - March 16th, 2009

Bay of Fundy, Canada - March 16th, 2009

The Bay of Fundy (bottom left to center) is a bay on the Atlantic coast of North America, on the northeast end of the Gulf of Maine between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the U.S. state of Maine.

The Bay of Fundy is known for its high tidal range and the bay is contested as having the highest vertical tidal range in the world with Ungava Bay in northern Quebec and The Severn Estuary in the UK.

Oceanographers attribute it to tidal resonance resulting from a coincidence of timing: the time it takes a large wave to go from the mouth of the bay to the inner shore and back is practically the same as the time from one high tide to the next. During the 12.4 hour tidal period, 115 billion tonnes of water flow in and out of the bay.

Brown sediments can be seen along the northern shores of the bay. North of the bay, ice floats on the water of the Northumberland Strait between mainland Canada and Prince Edward Island.