Wetlands Work Wonders!

In today's world of increasingly frequent, dramatic flooding often followed by severe drought, we should finally realise how the wetlands work.

Peat and marsh vegetation are crucial here. And all because of their unusual and highly beneficial feature - the ability of storage excess of water. Of course, in nature all the substances are in constant motion. So the water that was stored by wetlands at a time when there was too much of it and flood threatened, will be "released" when water is in short supply in the environment and a drought threatens. In any way, this is how it worked in the past until we drained our wetlands.

This reliable system operates today only in places where there are healthy wetlands. We can also observe the same system at work in microscale even in a small pond in the field or in the park. In any case, the ability our our few remaining wetlands to retain water are so great that if we freed all the water stored in them, Poland would all be covered with water to the depth of 11 cm.

Such large amounts of water in wetlands are derived mainly from rainfall. It is assumed that a peat bog is able to store about 1/3 of annual rainfall. And only 5% of the stored water is involved in its further circulation, which flows towards rivers and steams. The remaining 95% remains strongly bound in the peat. Such statistics begin to speak especially strongly to our imagination when we multiply the figures by the total capacity wetlands. For example, in the Biebrza Valley there are about 82 000 hectares of peatlands. Assuming that in the wet years the average rainfall is 650 mm, then wandering through the Biebrza Marshes we tread on 177.5 million cubic meters of water. And this is more than the capacity of Lake Goczałkowickie, the fifth largest retention reservoir in Poland.

However it is not the amount of accumulated water, but the time that it takes to release it and manner in which it is released which are the biggest assets of wetlands. The most intensive outflow of water from wetlands is not during the spring high water but only during the summer and autumn. This gradual release of water provides a sustainable and long-term irrigation to the local area. This process protects us both droughts on the one hand, and flood on the other. It is important to know that it is not the intensity of rainfall but the lack of natural retention which leads directly to a flood. Without retention, the rapid flow of rainwater into rivers and streams results in rapid accumulation of water in their lower sections leading to destructive floods.

Slowly we begin to see the qualities of wetlands. Still, every year, as a result of human damage to wetlands, about 159 million cubic meters of water are lost, which istwice as much water as is held in the Siemianówka reservoir. This is an enormous waste in the country where, despite numerous floods, there is serious water scarcity. It is worth considering what is more worthwhile: the protection of existing natural retention reservoirs, or construction of new, artificial equivalents. Most frequently regrettably, the artificial reservoirs are constructed in areas where the natural ones existed in the past - in the form of wetlands, of course.

If only the Vistula, the Oder and other rivers had areas where they could store the excess of water, we would avoid many disasters that involved flooding. In this way we would also improve microclimate and soil moisture in our fields, not to mention the securing of other wetland eco-services.

All the more surprising is the fact that we are continuing to drain our wetlands and ‘tame’ our rivers putting them in straight concrete troughs. Meanwhile, the threat of flooding keeps on growing, and the consequences of floods, both in terms of economic losses and the size of social tragedies, continue to be terrible.