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Posts tagged Bombetoka Bay

Soil Erosion in Madagascar

15.8S 46.2E

January 4th, 2013 Category: Deforestation, Rivers, Sediments

Madagascar – December 30th, 2012

The red color of the Betsiboka River and Bombetoka Bay into which it flows (top edge) demonstrate one of Madagascar’s greatest environmental problems — soil erosion. Deforestation of Madagascar’s central highlands has resulted in widespread soil erosion, which in some areas may top 400 tons/ha per year.

For Madagascar, a country that relies on agricultural production for the foundation of its economy, the loss of this soil is especially costly.  The removal of the native forest for cultivation and pastureland during the past 50 years has led to massive annual soil losses approaching 112 tons per acre (250 metric tons per hectare) in some regions of the island, the largest amount recorded anywhere in the world.

Bombetoka Bay on Madagascar Coast – July 6th, 2011

15.8S 46.2E

July 6th, 2011 Category: Rivers

Madagascar - June 20th, 2011

This wide-swath ASAR image shows the northeastern coastline of Madagascar. Visible at the center of the coastline is Bombetoka Bay, a bay on the northwestern coast of Madagascar near the city of Mahajanga, where the Betsiboka River flows into the Mozambique Channel.

Numerous islands and sandbars have formed in the estuary from the large amount of sediment carried in by the Betsiboka River and have been shaped by the flow of the river and the push and pull of tides.

Central West Coast of Madagascar Flanked by Intense Red Sediments – July 16th, 2009

16.6S 45.0E

July 16th, 2009 Category: Image of the day, Rivers

Madagascar - June 30th, 2009

Madagascar - June 30th, 2009

Coast of upper Melaky Region

Coast of upper Melaky Region

Sofia and Betsiboka Rivers

Sofia and Betsiboka Rivers

The central western coast of Madagascar is flanked by an intense, rusty red outflow of sediments. Most are present along the coast of the Melaky region.

Although such red sediments along the coast are typical for Madagascar, due to its red soils and high erosion rates from deforestation further inland, they are usually also seen further north near the mouths of the Sofia River and the Betsiboka River.

Unusually, in this image (see close-up for better detail), those rivers and their respective bays show a lesser presence of sediments. The Sofia River and bay into which it flows (above) are completely lacking in the characteristic red shade. The Betsiboka River is orange, but is not carrying enough red sediments to completely color the Bombetoka Bay (below).

Erosion from Deforestation Turns Madagascar’s Rivers Red

15.4S 48.0E

June 28th, 2009 Category: Rivers

Madagascar - June 8th, 2009

Madagascar - June 8th, 2009

The Sofia River (above) and the Betsiboka River (below) are red in color due to sediments originating in the central highlands, where red lateritic soils predominate. The Betsiboka River discharges its sediments into the Bombetoka Bay, which then connects to the Mozambique Channel.

The red waters of the river demonstrate soil erosion, one of Madagascar’s greatest environmental problems, caused by deforestation in the central highlands. Such soil erosion is widespread exceding 400 tons/ha per year in some areas.

Soil erosion has also made the Betsiboka Estuary into one of the world’s fast-changing coastlines. The land has been cleared and incredible rates of erosion have occurred due to about 100 years of extensive logging in rainforests and coastal mangroves.

After every heavy rain, exacerbated by tropical cyclones, the bright red soils are washed from the hillsides into the streams and rivers, clogging the coastal waterways with sediment.

Sofia and Betsiboka Rivers, Madagascar

April 30th, 2009 Category: Snapshots

Madagascar - April 8th, 2009

Madagascar - April 8th, 2009

Reddish sediments spill into the Mozambique Channel from the Sofia River (top right) and Betsiboka River (center) along Madagascar’s west coast.

The Betsiboka River discharges its sediments into the Bombetoka Bay, which then connects to the Mozambique Channel.

This discharge of reddish sediments is due to erosion caused by heavy deforestation in Madagascar. Here, the presence of Tropical Cyclone 26S (Jade) near the country’s east coast, also contributed to the high flow of sediments by provoking heavy rainfall.