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Posts tagged Delta

Santa Cruz Province, Argentine Patagonia – November 14th, 2009

47.7S 65.8W

November 14th, 2009 Category: Image of the day, Lakes, Rivers

Argentina - September 30th, 2009

Argentina - September 30th, 2009

Santa Cruz is a province of Argentina, located in the southern part of the country, in Patagonia. It borders Chubut province to the north, and Chile to the west and south. To the east is the Atlantic Ocean. It is the second largest province of the country, but the least densely populated of the Argentine mainland.

The average temperatures are 13°C in summer, and 3° in winter, when temperatures can fall to -25°. Strong winds blow all year round.

To the west, the Andes at these latitudes are lower than in the centre and north of Argentina, but still have year-round snow. An immense ice sheet feeds numerous glaciers. Even though precipitation in this western ice-sheet area is common, rain is scarce in other areas, with an average of 200 mm per year.

The lakes in western Santa Cruz province are mostly fed by glacieal melt-water; however, due to the cold climate their shores are not used for agriculture. The largest include Buenos Aires Lake (2,240 km², of which 881 km² is in Argentina), Cardiel Lake (460 km²), Viedma Lake (1082 km²), Argentino Lake (1560 km²), Pueyrredón Lake, Belgrano Lake and San Martín Lake (1.013 km²) are all in the west of the province.

The Atlantic coastline is a mixture of beaches and cliffs. From the centre to the Atlantic coast in the east, plateaux of descending height dominate the landscape. The cold, arid steppe is crossed by rivers that produce fertile valleys; Deseado River, Santa Cruz River, Gallegos River, Coyle River, Chico River and Pinturas River.

Here, the Deseado River can be seen crossing the upper half of the image horizontally and spilling greenish sediments into the Atlantic Ocean. Its source is the glacier-thaw of Buenos Aires Lake, visible as a large, dark blue body of water due west of the river along the mountainous border with Chile.

Further down the shoreline, the Santa Cruz and Chico Rivers create a large delta from which more sediments flow into the ocean. The source of the Santa Cruz Rivers begins at the shore of the Viedma and Argentino Lakes (both visible although partially covered by clouds west of the delta.

Atchafalaya Swamp, Louisiana, USA – March 10th, 2009

March 10th, 2009 Category: Image of the day, Lakes, Rivers

Louisiana, USA - March 1st, 2009

Louisiana, USA - March 1st, 2009

A series of bays and wetlands along the southern Lousiana coast. The Mississippi River flows down into the Gulf of Mexico, carrying dense tan and brown sediments.

The bays visible at the bottom center, including Vermilion Bay (left), West Cote Blanche Bay (center) and East Cote Blanche Bay (right).

West of these bays are two lakes: White Lake (right) and Grand Lake (left), which appear dark brown with sediments and practically joined together from high water levels.

East of the bays is the Atchafalaya Basin, or Atchafalaya Swamp, the largest swamp in the United States. It is a combination of wetlands and river delta area where the Atchafalaya River and the Gulf of Mexico converge.

The Atchafalaya is unique among basins because it has a growing delta system (notice the two branchlike protrusions in the full image) with nearly stable wetlands.

The Atchafalaya Basin, the surrounding plain of the river, is filled with bayous, bald cypress swamps, and marshes that give way to more brackish conditions and end in the Spartina grass marshes, near and at where it meets the Gulf of Mexico. It is susceptible to heavy flooding, is sparsely inhabited.

The basin is about 20 miles (32 km) in width from east to west and 150 miles (240 km) in length. With 595,000 acres (2,410 km2), it is the USA’s largest swamp wilderness, containing nationally significant expanses of bottomland hardwoods, swamplands, bayous and back-water lakes.

The Niger River during flood season – October 23rd, 2008

October 23rd, 2008 Category: Image of the day, Rivers

The Niger and Benue Rivers - October 19th, 2008

The Niger and Benue Rivers - October 19th, 2008

The Niger River is the principal river of western Africa, extending about 4180 km (2600 mi). It is visible in the image from the left to the center bottom. Its drainage basin is 2,117,700 square kilometres (817,600 sq mi) in area.

The source of the Niger River is in the Guinea Highlands in southeastern Guinea. It runs in a crescent through Mali, Niger, on the border with Benin and then through Nigeria, discharging through a massive delta, known as the Niger Delta of the Oil Rivers, into the Gulf of Guinea.

Close-up of the convergence of the Niger and Benvue Rivers

Close-up of the convergence of the Niger and Benvue Rivers

The Niger is the third-longest river in Africa, exceeded only by the Nile and the Congo River. Its main tributary is the Benue River, visible on the right side of the image. The Benue River is approximately 1,400 km long and is almost entirely navigable during the summer months. As a result, it is an important transportation route in the regions through which it flows.

The Niger River is a relatively “clear” river, carrying only a tenth as much sediment as the Nile because the Niger’s headlands are located in ancient rocks that provide little silt. Like the Nile, the Niger floods yearly; this begins in September, peaks in November, and finishes by May. In the image, taken on October 19th, 2008, we can clearly see the brownish waters of the flood season, left uncovered by the clouds veiling other parts of the region.

Close-up of the Niger Bend

Close-up of the Niger Bend

The northern part of the river, known as the Niger bend, is an important area because it is the closest major river and source of water to that part of the Sahara desert. This made it the focal point of trade across the western Sahara, and the centre of the Sahelian kingdoms of Mali and Gao. The Niger Bend, mostly golden-brown

An unusual feature of the river is the Niger Inland Delta, which forms where its gradient suddenly decreases. The result is a region of braided streams, marshes, and lakes the size of Belgium; the seasonal floods make the Delta extremely productive for both fishing and agriculture.

source Wikipedia

The Nile Delta, Egypt – September 29th, 2008

September 29th, 2008 Category: Image of the day, Rivers

September 29th, 2008 - The Nile DeltaNile

September 29th, 2008 - The Nile Delta

Nile River

Nile River

The Nile Delta (Arabic: دلتا النيل ) is the delta formed in Northern Egypt (Lower Egypt) where the Nile River spreads out and drains into the Mediterranean Sea. It is one of the world’s largest river deltas – from Alexandria in the west to Port Said in the east, it covers some 240 km of Mediterranean coastline – and is a rich agricultural region. From north to south the delta is approximately 160 km in length. The Delta begins slightly down-river from Cairo.

The Nile is considered to be an “arcuate” delta (arc-shaped), and resembles a triangle or lotus flower when seen from above. The outer edges of the delta are eroding, and some coastal lagoons have seen increasing salinity levels as their connection to the Mediterranean Sea increases. Since the delta no longer receives an annual supply of nutrients and sediments from upstream due to the construction of the Aswan High Dam, the soils of the floodplains have become poorer, and large amounts of fertilizers are now used.

Topsoil in the delta can be as much as 70 feet in depth. Also the topsoil falls off in the land and causes the water to rise.

source Wikipedia