Freshwater wetland management

A wetland is an area of land whose soil is saturated with moisture either permanently or seasonally. Such areas may also be covered partially or completely by shallow pools of water. Wetlands include swamps, marshes and bogs. The water found in wetlands can be saltwater, freshwater, or brackish (a mixture of fresh and salt water). The world's largest wetland is the Pantanal which straddles Brazil, Bolivia and Paraguay in South America.

Brackish water: Water that has a higher salinity content than freshwater, but not as high as saltwater.

Ramsar Convention: The Ramsar Convention is an international treaty for the conservation and sustainable utilisation of wetlands, i.e. to stem the progressive encroachment on and loss of wetlands now and in the future, recognising the fundamental ecological functions of wetlands and their economic, cultural, scientific, and recreational value. It is named after the town of Ramsar in Iran.

The convention was developed and adopted by participating nations at a meeting in Ramsar on February 2, 1971, and came into force on December 21, 1975.
The Ramsar List of Wetlands of International Importance now includes 1,888 sites (known as Ramsar Sites) covering around 1,853,000 km², up from 1,021 sites in 2000.

The Ramsar convention classifies wetlands as either; marine, coastal, inland or artificial. For a full list look at the list below:

Ramsar Wetland Classification

Wetlands now only cover 6% of the earth's surface. This is roughly half the amount of the planet that was covered in wetlands 100 years ago. The most important are:

Bogs (30%): A wetland area that accumulates acidic peat, a deposit of dead plant material. Bogs occur where the water at the ground surface is acidic, either from acidic groundwater, or where water is derived entirely from precipitation Water flowing out of bogs has a characteristic brown color.

Fens (26%): Low land that is covered wholly or partly with water unless artificially drained and that usually has peaty alkaline soil.

Swamps (20%): A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of dry-land areas, covered by aquatic vegetation or vegetation that tolerates periodical inundation (being covered by water).

Floodplains (15%): All rivers have floodplains. They are the valley floors that get covered in water when a river exceeds bankfull discharge. However, with an increasing amount of rivers being managed e.g. levees and dams, floodplains are spending less time underwater.

Lakes (2%): Lakes are surface stores that are fed by rivers. Some lakes e.g. Caspian Sea are being drained because of unsustainable use.

Importance of Wetlands

• Flood control: Many wetlands are covered in vegetation which can intercept precipitation, absorb rainwater and transpire water. Wetland vegetation can also reduce the velocity of rivers flowing into them or from them and act as natural stores of water. If you remove or drain areas of wetland more pressure is placed upon the main river channel. Coastal and marine wetland areas can also absorb the energy of tropical storms, tsunamis etc.
• Groundwater recharge: Wetlands can collect large areas of precipitation and river discharge. As this water is held in storage it will infiltrate and percolate into the ground to recharge groundwater.
• Transport Network: Wetland provide many natural waterways that people can move around on easily.
• Tourism and Leisure: Some wetlands, like the everglades in Florida or the fens in East England become tourist attractions. They also become popular locations to bird watch, fish and hunt.
• Flora and Fauna: Many wetlands are unique habitats that support indigenous aquatic plants and animals. Many wetlands support rare reptilian and amphibian species. Many migratory birds also rest in wetlands flying to and from nesting and breeding grounds.
• Fisheries: Wetlands can support large numbers of fish which can support local populations. Wetlands are not normally viable commercial fisheries.
• Water purification: The soils, geology and vegetation of wetlands can help clean and purify water.
• Storage of organic matter: Wetlands support large areas of organic matter that can hold large stores of methane (greenhouse gas).
• Coastal stabalisation: Wetlands that occur along the coastline and on river banks have prevent erosion from the sea or by rivers.

Tsunami: Mangroves saved lives - BBC article

Wetlands key for birds survival - BBC article

Functions and values of wetlands - US Department of Ecology

Importance of African Wetlands - BBC article

Factors Causing Loss and Degradation of Wetlands

• Increased demand for agricultural land: As the world population grows there is an increasing demand for food. With the amount of viable agricultural land decreasing, increasingly areas of wetland are being artificially drained to make ways for agricultural land e.g. the draining of the fens in East England.
• Population growth: As the world's population grows, it demands more water, more food and more land. The increasing demand for water can mean wetlands are drained of their water or their source of water. This problems is made worse as the world's population develops and uses more water e.g. showers and toilets.
• Urbanisation: With the world population growing, there is a greater demand for housing. Increasingly this demand for housing is in urban areas. With urban areas growing more and more wetland areas are being drained or inhabited. Urbanisation on or near wetlands can cause pollution, changes in river flow and river channels and disturbance of wildlife. Land reclamation is the process of reclaiming land from the water.
• Sea level rises: Global warming is causing glaciers and ice sheets to melt causing sea levels to rise. These rising sea levels can flood coastal and marine wetland areas. Even if the whole wetland is not flooded, water conditions can be changed from fresh to brackish.
• River flow changes: Many rivers have been channelised and straightened, reducing the amount of wetlands. Others have been drained or dams have altered flow. Some have been polluted or redirected. All these natural changes are removing or changing the ecosystems of many wetland areas.
• Pollution: Any form of pollution, but particular chemicals and metals can change the delicate ecosystems of wetlands. Process like eutrophication, caused by fertiliser run-off can completely kill whole wetland areas by preventing the wetland oxygenating properly and receiving sunlight.
• Infrastructure projects: As populations grow and we become more mobile, there is an increasing demand for new roads, airports, railways. etc. Unfortunately wetlands are often drained or disrupted (bridges, dykes and causeways) to make way for these projects.
• Alien species invasion: Many alien species like the cane toad in Australia or the American mink in the UK have been introduced to wetlands and devastated indigenous species. The introduction of any alien, however small can disrupt food webs and ecosystems.
• Tropical storms: Although wetlands can be a natural defence against tsunamis and tropical storms, they can also been damaged by them. Freshwater wetlands in particular can be flooded by storms surges associated with tropical storms, changing the salinity of water and damaging vegetation.

Freshwater wetlands vulnerable in hurricanes - BBC article

Oxfordshire's water voles under threat of extinction - BBC article

Mercury turns wetland birds such as ibises homosexual - BBC article

Local turtles disappear as urbanisation destroys Illinois wetlands - Medill Reports Chicago

Birds starve at South Korean wetland - BBC article

Kissimmee River

Location and Background The Kissimmee River is found in south central Florida. The source of the Kissimmee river is in East Lake Tohopekaliga and its mouth is in Lake Okeechebee. It has a drainage basin of about 7,800km2 and is approximately 200km long (figures vary depend on when it was measured, before channelisation, after channelisation or after restoration). The Kissimmee river was home to wetland plants, fish and wading birds. However, the 5km wide floodplain that population living nearby, were regularly effected by its flooding. Because of the flooding the river was widened and channelised from 1962 to 1971. The once meandering river was turned into a 90km long and 10 metre wide drainage canal. Although the scheme was effective at reducing flooding, it had a devastating effect on the wetland ecosystem of the Kissimmee River. The channelisation was undertaken because of regular flooding. The flooding had been worsened by regular floods hitting the Florida peninsula. River channelisation: This means artificially widening and lining a river channel. By increasing cross-sectional area and smoothing the bed and the banks, the rivers discharge will flow quicker away from population areas. River straightening: When meanders are removed from a river and the course is straightened. By removing meanders the river is able to flow faster. The idea is to remove the rivers discharge more quickly from areas with high population densities or land with high value.

PROBLEMS CAUSED BY RIVER MANAGEMENT

THE RESTORATION AND ITS BENEFITS

The Kissimmee River floodplain dried up after channelisation. The river no longer exceeded bankfull discharge. The reduction of the floodplain reduced waterfowl habitat by 90% Egret, heron and wood stork populations declined by two-thirds. Catches of largemouth bass (types of fish) reduced after channelisation Pollution levels from the Kissimmee flowing into Lake Okeechobee after channelisation. The Kissimmee after channelisation accounted for 25% of nitrogen pollution and 20% of phosphorous pollution. Fishing, bird watching and hunting tourism declined after channelisation

The aim is to restore over 100km2 of river and wetland floodplain by 2015 The restoration project started in 1999 The river is being dechannelised, by refilling the flood canal and reestablishing the old natural course of the river. Restored sections now flood naturally The nutrient loads in Lake Okeechobee should be reduced as more is absorbed in the wetland. Wading birds have returned to the restored sections Dissolved oxygen levels have doubled in restored sections Increased revenue from tourism potential of restored river Reestablishment of natural ecosystem

There are a few possible negative impacts from restoration:

• Greater evaporation because more surface stores
• Increased risk of flooding
• The river will be less navigable in dry periods
• The restoration will cost $414 million

Call for regeneration of wetlands - BBC article