Half of the world's wetlands have disappeared since 1900!

GSTDTAP > 资源环境科学

	Half of the world's wetlands have disappeared since 1900!
	admin
	2018-02-02
发布年	2018
语种	英语
国家	国际
领域	资源环境
正文(英文)	*Do You Know what a wetland is?* A wetland is a place where the land is covered by water, either salt, fresh or somewhere in between. Marshes and ponds, the edge of a lake or ocean, the delta at the mouth of a river, low-lying areas that frequently flood—all of these are wetlands Wetlands are a critical part of our natural environment. They protect our shores from wave action, reduce the impacts of floods, absorb pollutants and improve water quality. They provide habitat for animals and plants and many contain a wide diversity of life, supporting plants and animals that are found nowhere else. By doing so, wetlands help keep river levels normal and filter and purify the surface water. Wetlands accept water during storms and whenever water levels are high. When water levels are low, wetlands slowly release water. Wetlands also release vegetative matter into rivers, which helps feed fish in the rivers. Wetland ecologists have already documented the following environmental benefits of wetlands: water purification, flood protection, shoreline stabilization, groundwater recharge, and stream flow maintenance. Wetlands also provide habitat for fish and wildlife, including endangered species In a report by BLM Bakobi (NEMC, 2017), It is estimated that wetlands cover over 7% of Tanzania’s surface area (NEMC/WWF/IUCN, 1990). The extensive open water areas and fringing swamps of the Great Lakes cover 5.2 million ha. Tanzania owns 47% of Lake Victoria, 45% of Lake Tanganyika and 20% of Lake Nyasa (Bwathondi, 1990). The remaining permanent freshwater lakes, account for only 45,000 ha (NEMC/WWF/IUCN, 1990). On the other hand, Tanzania possesses enormous areas of permanent and seasonal freshwater swamps, marshes and seasonal floodplains, distributed over most of the country's major river systems and covering 2.7 million ha. The largest in this category is the Rufiji- Ruaha River system which has wetlands covering 695,500 ha. Other river systems are: the Malagarasi-Moyowosi system (partly in the Moyowosi Game Reserve), and the Pangani, Wami, Ugalla, Siuwe, Ruvu, Kagera and Mara Rivers. The Little and Great Ruaha Rivers in the highlands have many small, seasonal and permanent marshes and swamps on acidic soils. At maximum flooding, Lake Rukwa and its associated fresh to brackish swamps and floodplains cover some 700,000 ha, making it one of Tanzania's largest wetland areas. The system includes Katavi plain, Kafufu Swamp, and the floodplain of the Msaginya River. Equally important wetland systems are the alkaline waters and lakes, endorheic swamps and freshwater swamps. Lake Eyasi is a seasonal alkaline lake of 116,000 ha. However, elsewhere in the Eyasi Basin there are large floodplains at Wembere, along the Nyahura River and the permanent freshwater Lake Kitangiri (36,000 ha). In the Manyara Basin are Lake Manyara, an alkaline lake of 42,300 ha, Shuriro Swamp and floodplain system, Tarangire Swamp, and the swamps at the headwaters of the Kisaki River. Important endorheic wetlands include the Bahi Swamp (125,000 ha), Yaida Swamp, the sodic Lake Natron (85,500 ha), Lake Burigi (a brackish lake of 7,000 ha), Lake Ikimba (12,500 ha), the alkaline lakes Balangida (6,000 ha) and Balangida Lelu (3,000 ha), Endeshi Swamp, and a number of smaller saline lakes and crater lakes, mostly in the northeast of the country. There are over 85,000 ha of man-made wetlands in Tanzania. The most important impoundments include the Mtera Dam (61,000 ha), Lake Nyumba ya Mungu (18,000 ha) and Mindu Dam. The coastal wetlal}ds (200,000 ha) are covered predominantly by mangroves which are concentrated in the sheltered creeks on the mainland and offshore islands. In some of the deltas and estuaries, the mangroves form a transition between the marine environment and the freshwater swamps further inland. The Rufiji Delta has the largest stand of mangroves on the entire East African coast (Semesi, 1989), accounting for 50% of all mangroves in Tanzania (Table 2). Other important mangrove areas include Mwanza, Tanga, the mouths of the Wami, Ruvu, Matandu and Ruvuma Rivers. Islands such as Mbegani, Kunduchi, Latham, Kisiju, Kivinje, Kilwa and Mafia have appreciable mangrove forests (Semesi, 1988; Semesi, 1989). Read about the threats facing wetlands today and what you can do to protect them http://wwf.panda.org/about_our_earth/about_freshwater/intro/threats/
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来源平台	World Wide Fund for Nature
文献类型	新闻
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/126043
专题	资源环境科学
推荐引用方式 GB/T 7714	admin. Half of the world's wetlands have disappeared since 1900!. 2018.