Degradation of Wetlands
Globally, about 50% of the wetlands have ceased to exist as a result of human actions. While the temperate region was mostly responsible for their disappearance till the 1950s since then tropical countries have accelerated the pace of wetland conversion into alternate land uses like dams construction, agriculture, and urbanization. India also lost over 30% of wetlands over the last three decades. While Chennai lost about 90%, Mumbai, Ahmedabad, Bengaluru, and many other large cities have lost more than 50% of wetlands.
As per Global Wetland Outlook, current wetland coverage is about 12 million square kilometers area. It is suspected that much of this is now degraded. The factors responsible for the degradation of wetlands are:
- over utilizing provisioning services like fishing, water withdrawal, etc, which in turn impact regulating, supporting and cultural services
- indiscriminate use of fertilizers in agriculture leading to eutrophication
- invasion by alien species
- land use change for urban sprawl and agricultural expansion
- high sediment load and hence sedimentation rates due to enhanced levels of soil erosion and increased particulate matter in the air
- climate change
Wetlands and Wise Use Principle of the Ramsar Convention
Wetlands are distinct ecosystems, that are flooded either permanently or temporarily resulting in an anoxic (oxygen-free) environment and hydric soils. These may be considered as ecotones, providing a transition between terrestrial and aquatic ecosystems. These are characterized by the hydric soils and hydrophytes (aquatic plants) adapted to wetland conditions.
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