Although wetlands are not the only solution for clean water, they are a key part of the answer.
Wetlands are complex, fascinating and dynamic. They are hardworking ecosystems that provide us with a range of benefits, including some that are not immediately apparent.
In providing these ecosystem services, healthy wetlands play an important role in keeping people healthy. They are valuable assets to farmers, downstream water users, communities living nearby and larger society. If we protect healthy wetlands and rehabilitate those that have been degraded, we can reduce suffering due to droughts, floods and compromised livelihoods, especially for the most vulnerable members of society.
As urbanisation increases, so does the pressure to provide adequate sanitation and water. South Africa’s water resources are already well utilised and in many areas show signs of stress because of high demand. The answer to our looming water crisis does not lie only in complex and expensive engineering solutions. Nature provides robust and free technology, including ecosystem services provided by wetlands, which we should recognise, respect and protect.
|Sunset over Verlorenvlei, the Ramsar-proclaimed wetlands in the Western Cape. Read the blog "West Coast media trip: part 2 (Moutonshoek and Verlorenvlei)"|
2. What is a wetland?
Wetlands are areas in the landscape where the water in rivers and streams slows down and spreads out. This results in the sediments and nutrients in the water being deposited. Over time, wetlands become fertile areas that provide good habitat for plants (bulrushes, reeds, waterlilies and sedges) and a range of creatures (e.g. microbes, specialised waterbirds, insects etc). Hectare for hectare, there is more life in a healthy wetland than in almost any other habitat.
The National Wetland Inventory has mapped over 114,000 wetlands, ranging greatly in size and value and accounting for about 3,6% of South Africa’s surface area. Different wetland types supply different ecosystem services including provision of clean water and carbon storage. Through natural processes in their soils and plants, wetlands aid in improving water quality. They also reduce the damaging impacts of floods, help to control erosion, and contribute to more stable stream flow throughout the year. They supply wild food, grazing, building and craft materials to people, and are important refuges for specialised plants and wildlife. In urban areas they are important green spaces.
Wetlands and water
Wetlands play an important role in ensuring a steady supply of clean water, which is essential for human health. Where people use water directly from natural sources such as rivers, wetlands play a strong role in keeping people healthy. For those who get their water from taps, healthy wetlands in river systems contribute significantly to reducing the cost of purifying water.
Wetlands are uniquely designed to purify water through natural processes, acting like the kidneys of the landscape. Firstly, they slow down water flow and this allows sediments in the water to be deposited. Then, wetland plants, such as bulrushes and reeds, and wetland soils and microbes stabilise and store or use many pollutants including excess nutrients and toxins from sewage and agricultural chemicals and fertilisers. This helps reduce the possibility of excess nutrient enrichment downstream. They can also trap many heavy metals including cadmium, zinc and mercury that result from mining and industrial processes. The roots of some wetland plants secrete toxic substances that kill some pathogenic bacteria.
Wetlands also act like sponges, slowing down flood waters, storing water when it rains, and then releasing it slowly during the dry season, helping to ensure steady river flow. Special wetland soils such as peat are highly effective water stores and filters. Peat is able to hold a thousand times its own weight in water, which makes it valuable in a semi-arid country like South Africa. Some wetlands also play a role in recharging groundwater.
Life in wetlands
Wetlands are warehouses of biodiversity. They support plants and animals that are specially adapted to waterlogged environments and can live nowhere else. They also provide feeding, roosting and breeding sites for a range of other species. Even in urban areas they are important refuges for small mammals, birds and amphibians.
Some animals are completely dependant on wetlands, whilst others use wetlands for only part of their lives. For example, the Wattled crane is dependant on wetlands for breeding, and hippo’s use wetlands as a daytime refuge.
|The rich diversity of waterbirds in southern Africa (totalling 130 species) is possible because of the many different types of wetlands across the sub-continent. The wetlands of southern Africa are of international importance as they are the southern destination for many migratory wading birds.|
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