The most significant social and economic benefit that wetlands provide is flood control. Peatlands and wet grasslands alongside river basins can act like sponges, absorbing rainfall and controlling its flow into streams and rivers.
When peat becomes completely saturated and unable to absorb any more water, surface pools and peatland vegetation – including sedge meadows and some types of forest – help to slow and reduce runoff. Similarly, floodplains alongside the lower reaches of major rivers, such as the Nile, Yangtze and Danube allow heavy rainfall or spring snowmelt to spread
out slowly. When the peat bogs are drained or the floodplains reduced, the risk of flash floods is increased.
Wetlands act as the Earth's filters, cleaning up water in a number of ways. For example, nitrogen in water is transformed to harmless nitrogen gas, nutrients are taken up by wetland plants in the water. Wetlands remove pollutants such as phosphorous, heavy metals and toxins which are trapped in the sediments of the wetlands. In addition, nitrogen and heavy metals are incorporated into peat during its formation.
New York City found that it could avoid spending USD$3-8 billion on new waste water treatment plants by investing USD$1.5 billion in the purchase of land around the reservoirs upstate. This land purifies the water supply for free.
Rice is the staple diet of nearly 3 billion people - half the world's population. It is grown in wetlands across Asia and west Africa, and in the United States. Almost as important is sago palm, which provides starch from which sago flour is made. And palms from the wetlands of Africa yield valuable oils for cooking and soap making.
Shoreline and storm protection
The devastating effects of natural phenomena such as hurricanes, cyclones and tsunamis cannot be denied. Worldwide, an estimated 200 million people who live in low-lying coastal regions are at potential risk from catastrophic flooding.
Coastal wetlands – such as reefs, mangroves and saltmarshes – act as frontline defences against potential devastation. The roots of wetland plants bind the shoreline together, resisting erosion by wind and waves and providing a physical barrier that slows down storm surges and tidal waves, thereby reducing their height and destructive power.
Throughout history humans have gathered around wetlands and these areas have played an important part in human development and are of significant religious, historical or archeological value to many cultures around the world. For example, on the Coburg Peninsula (the world’s first Ramsar site), traditional Aboriginal owners still conduct an active ceremonial life and undertake semi-traditional hunting and gathering in this coastal wetland.
Materials and Medicines
Wetlands yield fuelwood for cooking, thatch for roofing, fibres for textiles and paper making, and timber for building. Medicines are extracted from their bark, leaves, and fruits, and they also provide tannins and dyes, used extensively in the treatment of leather.
Wetlands everywhere provide important leisure facilities - canoeing and fishing, shell collecting and bird watching, swimming and snorkelling, hunting and sailing.