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Indus River Delta-Arabian Sea mangroves
The Indus River Delta-Arabian Sea mangroves are a large mangrove ecoregion on the Arabian Sea coast of Sindh Province, Pakistan. The Indus River Delta forms a vast alluvial fan composed of mud flats interspersed with channels and fringed with mangrove forests. Much of the forested area has been destroyed and the remaining parts are threatened.
==Location and description==
With a length of , the Indus River is one of the longest rivers in the world, starting in the glaciers of the Himalayan range in Tibet and flowing through India and Pakistan. Where the river enters the Arabian Sea in Sindh Province, Pakistan, there is an alluvial fan that extends along of coastline. It is formed from the vast quantities of silt that have been washed down the river for over fifty million years and covers an area of about . There are seventeen major channels, many smaller ones, extensive mudflats and fringing mangrove swamps which form a barrier against storm surges.
These mangroves are found in the Indus River Delta on the Arabian sea, an even saltier estuary than usual due to the salts brought to the coast by the Indus from the Thar Desert, a process that is ongoing as the river is increasingly used for irrigation and water supply. Mangroves are an important habitat where salt and fresh water mix and support a range of plants specialised to survive in this salty environment, and large numbers of fishes and crustaceans that find food, shelter and oxygen in the waters beneath the tree roots. The temperature is hot in summer, reaching , and may fall to near freezing point in winter. The rain falls in the southwest monsoon between July and September and averages of precipitation. The Indus River is used extensively for irrigation and by the time it reaches the delta, the flow of freshwater is down by more than 90% compared to historic levels. Active flow only lasts for about two months, and the sediment load is similarly diminished. Saline water intrudes upstream for about and this affects both the mangroves growing in the area and the agricultural land. Loss of sediment causes increased coastal erosion, and this is exacerbated by land subsidence and rising sea levels. Other factors affecting the mangrove areas are pollution from sewage and industrial effluent, and parts of the mangrove area have been lost to agriculture and urban development.
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