(only 2–6% area) of the Earth's land surface. They are distributed in every continent and country except Antarctica (Tiner 2009). The total estimated area of wetlands over the globe was recorded in a range of 747–885 million hectares (Finlayson et al. 2001). Approximately, half of the global wetland area occurs between 50°N and 70°N latitude, one‐third between 20°N and 30°S latitude, and the remaining in the temperate zones (Tiner 2009). A total of 2386 wetlands are identified as Ramsar sites in 171 countries, which cover 253 771 669 ha area.
2.1.1.2 Distribution of Wetlands in India
The total estimated area of wetland over the Asian continent was recorded in a range of 211–224 million hectares (Watkins and Parish 1999). In India, it is estimated as 15 260 572 ha (NWIA 2011; Panigrahy et al. 2012), which is about 4.63% of the total geographical area of the country (NWIA 2011). Most of the natural wetlands in India are found at high altitudes in the Himalayas, followed by wetlands of major rivers in their flood plains and coastal wetlands (Prasad et al. 2002). These are distributed from the cold arid trans‐Himalayan zone to wet Terai regions of the Himalayan foothills, including the floodplains of the rivers Ganga and Brahmaputra. In the Deccan peninsula, the river floodplains of Cauvery, Krishna, Godavari, and Tapti contribute to different wetlands. The vast Indian coastline of 7500 km, contributes different types of wetlands in the state of West Bengal, Orissa, Andhra Pradesh, Tamil Nadu, Kerala, Karnataka, Gujrat, Lakshadweep, and Andaman and Nicobar states (Figure 2.1). In addition, a large number of artificial wetlands also contribute to the total estimated wetland area (Panigrahy et al. 2012).
A total of 115 wetlands were identified in different states of India, as “wetlands of national importance” for conservation under the National Wetland Conservation Program in 2009. Wetlands in India have been classified under different categories as shown in Table 2.1 (NWIA 2011).
Currently, there are 37 wetlands of international importance in India that are designated as Ramsar sites, covering 1 067 939 ha.
2.1.1.3 Distribution of Wetlands in Bihar
In Bihar, the total estimated area of wetlands is 403 209 ha (NWIA 2011), which is approximately 2.64% of the total wetland area of India. Wetlands in Bihar are locally called Chaur, Maun, Taal, Jheel, and Pats. The natural inland wetlands dominate in Bihar, which comprises about 92% of the total estimated area of the wetlands of Bihar, while the artificial area accounts for 3.5% and the small wetlands area of 1–2.5 ha accounts for 4.5% (NWIA 2011).
As Bihar is a land‐locked state from all sides in the Gangetic flood plain, limited categories of wetlands exist here (Figure 2.2). The district‐wise wetland area in Bihar is shown in Figure 2.3 (NWIA 2011).
The major rivers which contribute to different wetlands in Bihar are Ganga, Kosi, Gandak, Bagmati, Mahananda, and Kamla‐Balan (Ghosh et al. 2004). The three important wetlands of Bihar, i.e. Kanwar, Barilla, and Kusheshwar Asthan were included in the list of NWCP (2009).
Figure 2.1 A map showing different types of wetlands in India.
(Source: National Wetland Atlas 2011, Space Application Centre, Indian Space Research Organization.)
Table 2.1 Category wise distribution of wetlands in India.
Source: National Wetland Atlas (2011), Space Application Centre (ISRO), Ahmedabad.
| S. no | Wetland category | Total wetland area (ha) | Wetland area (%) |
|---|---|---|---|
| 1 | Lake/pond | 729 532 | 4.78 |
| 2 | Oxbow lake | 104 124 | 0.68 |
| 3 | High altitude wetland | 124 253 | 0.81 |
| 4 | Riverine wetland | 91 682 | 0.6 |
| 5 | Waterlogged (natural) | 315 091 | 2.06 |
| 6 | River/stream | 5 258 385 | 34.46 |
| 7 | Reservoir/barrage | 2 481 987 | 16.26 |
| 8 | Tank/pond | 1 310 443 | 8.59 |
| 9 | Waterlogged (artificial) | 135 704 | 0.89 |
| 10 | Salt pan (inland) | 13 698 | 0.09 |
| 11 | Lagoon | 246 044 | 1.61 |
| 12 | Creek | 206 698 | 1.35 |
| 13 | Sand/beach | 63 033 | 0.41 |
| 14 | Intertidal mudflat | 2 413 642 | 15.82 |
| 15 | Salt Marsh | 161 144 | 1.06 |
| 16 | Mangrove | 471 407 | 3.09 |
| 17 | Coral reef | 142 003 | 0.93 |
| 18 | Salt pan (coastal) | 148 913 | 0.98 |
| 19 | Aquaculture pond | 287 232 | 1.88 |
| 20 | Wetlands (<2.25 ha) |
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