Wetlands are highly productive ecosystems where land and water meet. They found in different forms in climatic zones and regions all over the world. Wetlands have fundamental ecological functions as regulators of water regimes and as habitats supporting a characteristic flora and fauna, especially waterfowl. They also constitute a resource of great economic, cultural, scientific, and recreational value, the loss of which would be irreparable. Wetlands have been exploited by human cultures for centuries, sometimes by working with natural processes, e.g. by sustainably harvesting wetland biota (fish, mangroves, reeds etc.), but more often by altering their fundamental properties and damaging wetland functioning, e.g. draining or filling them to produce dry land for agriculture or other forms of development.
Wetlands are of two basic types: coastal (also known as tidal or estuarine wetlands) and inland (also known as non-tidal, freshwater, or palustrine wetlands). Inland wetlands include floodplains along rivers and streams (e.g., bottomlands and other riparian wetlands); isolated depressions surrounded by dry land (e.g., prairie potholes); areas where the groundwater intercepts the soil surface (e.g., fens) or where precipitation saturates the soil for a season or longer (e.g., vernal pools and bogs). Marshes and wet meadows are dominated by grasses and other herbaceous plants or shrubs; and swamps are dominated by trees.
The Convention on Wetlands of International Importance especially as Waterfowl Habitat, signed in Ramsar, Iran in 1971, is an intergovernmental treaty which provides the framework for international cooperation for the conservation and wise use of wetlands and their resources. There are presently 110 Contracting Parties to the Convention, with 924 wetland sites, totalling 68.15 million hectares, designated for inclusion in the Ramsar List of Wetlands of International Importance.
Article 1 of the Ramsar Convention defines wetlands as areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres.
Article 2 of the Ramsar Convention requires that each Contracting Party shall designate suitable wetlands within its territory for inclusion in a List of Wetlands of International Importance. Such wetlands should be selected for on account of their international significance in terms of ecology, botany, zoology, limnology or hydrology. In the first instance wetlands of international importance to waterfowl at any season should be included.
This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. Owing to their ecological and habitat importance for many species, Agenda 21 recommends the conservation and protection of wetlands taking social and economic factors into account.
The Ramsar Convention on Wetlands is named after the city where it formed. Ramsar sits aside a stunning freshwater wetland in Iran. The treaty has 171 signatories (at 2021).
The UK Habitat Scheme, announced in 1994, reverses the drive to reclaim land in the UK. UK farmers are retreating from wetlands by being offered money to let agricultural land revert to riverine wetlands, swamp and salt-marsh. The scheme results from changes in the EEC/EU Common Agricultural Policy. At a cost of £3 million annually, the first step is to allow "water fringe habitats" of 20 metres wide along rivers, where farmers will not apply fertiliser or pesticides. These fringes will act as a buffer zone from normal agriculture and be havens and corridors for wildlife. The most radical scheme is to reverse the programme the Romans began in the Wash 2,000 years ago when they erected banks to enclose salt-marshes and create agricultural land. Thousands of acres were won from the sea to form some of the richest farmland in the UK at the expense of breeding grounds for fish, and feeding and resting places for birds. But sea defences are increasingly expensive and where one part of the coast is reclaimed another part may be eroded or inundated. Hence the economics of land reclamation have changed, favourably assisting the economics of wetland conservation for biological conservation.
In 1994, the Secretary of the Interior of the USA recommended changes in federal programmes that promoted the conversion, destruction and degradation of important wetland areas. He noted that "many of these programmes are designed and financed in ways that violated the most basic principles of economics, wasting resources and adding to the federal deficit". Limiting federal financial support is coupled with recommendations for the financing of new projects in a manner which ensures that those who benefit pay their fair share of cost, strengthening compensation for unavoidable adverse project impacts on wetlands, and the use performance bonds and wetland mitigation banking for more effective mitigation of wetland losses.
MedWet is an initiative of the Mediterranean countries, endorsed by the Kushiro Conference of the Contracting Parties to the Ramsar Convention in June 1993 and with the support of the European Commission and the co-operation of governments, NGOs and institutions, to coordinate actions for the conservation and wise use of Mediterranean wetlands. To facilitate the long-term management of this work and the implementation of the Mediterranean Wetlands Strategy (Venice, June 1996), the Standing Committee of the Ramsar Convention approved the setting up of a Mediterranean Wetlands Committee (MedWet/Com). At present 25 Mediterranean countries are members of the Committee, as are the European Commission, the Barcelona Convention, the Bern Convention and six international non-governmental organizations. The MedWet Committee is an autonomous consultative body within the Ramsar Convention involving all key players in the conservation and sustainable development of Mediterranean wetlands.
Since MedWet's initiation, two major projects involving more than ten Mediterranean countries have been completed. The projects have helped to develop methodological tools for wetland conservation and management, to stimulate concrete actions at of pilot sites and to develop policy guidelines in cooperation with national NGOs and experts. The Ramsar Bureau played a key role in the projects. Two further projects started at 1998: MedWet3 and MedWet4 ("the Evian Project") that involve actions at about twenty wetland sites in ten countries.