Arid wetlands are vital sources of water in otherwise uninhabitable landscapes. They are critically important life-support systems for the survival of people as sources of water, food and fibre. They help provide regular water supplies and fertile soils, improve water quality, recharge underground aquifers and lessen the impact of seasonal floods. They also support large numbers of plants and animals.
Dry regions of the world exist where climatic factors, ocean conditions and land features, such as mountains, prevent rainfall. They are found in parts of Asia and Australia, southwestern and northern Africa, the Middle East and the western parts of North and South America.
Instead of a complete lack of water, arid and semi-arid areas are often characterised by seasonal rainfall and wetlands that retain water long after the rest of the landscape has dried out. These wetlands include rivers, swamps, and lakes and springs that may dry up for portions of the year. Inland marshes, vernal pools and playa lakes store water in areas where there are no permanent rivers or streams.
The importance of wetlands in arid regions
A prime example of critical arid wetlands is the Inner Niger Delta and its seasonal floodplains in Mali. This inland delta is extremely rich in natural resources; arid areas with little water turn into vast wetlands for a portion of the year. These wetlands are essential for farmers who use irrigated agriculture, pastoralists who graze animals, and the livelihoods of people who fish and collect plants.
The region is also hugely important to millions of waterbirds that breed in Europe and Asia, such as waders and herons. Another example are the dambo seasonal wetlands in Zambia and Malawi, which if well-managed are the greatest source of food production in areas that are dry much of the year.
Threats to arid wetlands
In such water-scarce regions, diversions of water can negatively impact healthy wetlands and the services they provide. Population growth, irrigation, industrial activities, dams and other large-scale water management systems increasingly cause the diversion of water from rivers, floodplains and lakes. Reduced rainfall due to climate change – the predicted occurrence of dry areas getting drier – is creating additional water scarcity.
The result is growing water stress, increased levels of wetland drainage and pollution, deforestation, lowering of water tables and vegetated lands drying out and becoming desert. Many rivers no longer reach the sea due to upstream water diversions and once-permanent lakes have dried up completely.