Without rivers, human development would probably have been different. But at some point people not only used the rivers and their water, but tried to control them. That takes revenge today, but it’s not irreversible.
When it comes to rivers, the majestic currents of this world come to mind, such as the Nile, the Amazon, the Yangtze. Or the little river that flowed near home. Maybe even the stream that is so good for fishing. It is similar to Josef H. Reichholf. The aquatic ecologist “was lucky enough to grow up in the Lower Bavarian Inn Valley, very close to the Inn, this alpine river with the greatest abundance of water”. This is how he describes it in his recently published book “Flussnatur”.
All his life he researched and marveled at rivers. “People are enthusiastic about water, about the diversity of nature and, as an evolutionary biologist, I have a strong suspicion that it slumbers in us as an ancient legacy,” Reichholf told ntv.de. Clean water, as rivers normally carry, was vital for human development and in a certain way is still today. “Everything that is not good for us gathers in stagnant water like ponds.” An example of this are mosquito larvae that develop in stagnant water and turn into mosquitoes, which in turn transmit life-threatening diseases.
But that’s not what Reichholf means by river nature. Rather, it is about understanding rivers in their flow again. It was a mistake to restrict rivers more and more their scope of action, to take away the floodplains on the sides or in the valley expansions, to dike them, to push them back and to straighten them. The second big mistake is the assumption “that the river should always come along with the same amount of water as consistently as possible and thus fulfill all the functions that we want to combine with it”. Reichholf calls this “simply unreal”.
Average is the exception
“The rivers naturally fluctuate in their water flow, they have high and low water phases. The calculable mean value is just as significant or insignificant as the average temperature value for a year.” Even if you know this mean value, there are still the heat of summer and the cold of winter. “There are also all possible transition phases. We are more familiar with the temperatures than with the rivers, although it is the same there,” says the scientist.
In the meantime, human fantasies of omnipotence are bitterly taking revenge on the rivers. Floods like that in the Ahr valley tear away houses and even cost human lives. Low water levels make sections of the river almost dry and, for example, make inland navigation impossible for weeks or even months. But not every mistake made in the past can be corrected. “If a city is built right up to the river bank, then the water just has to go through without flooding the city,” says Reichholf. But that does not mean that you have to watch unconscious.
Modern water ecology no longer relies on letting all the water drain off as quickly as possible. Because this clearly leads to more violent floods, because all of the meltwater or rainwater arrives in the rivers far too quickly. This also harms the land next to the rivers, which then loses water far too quickly. The expert suggests sufficient reservoirs upstream with which floods can be intercepted. And floodplains and thus flood retention areas, such as wide meadows on the banks of the rivers.
Free space for the rivers
In his opinion, conflicts with farmers, who are still often doing business there, can hardly be avoided. For the rivers, from Reichholf’s point of view, it would be best if “agriculture went back out of the areas that were drained for them with public money”. At that time it was about making the fields machine-friendly, now it has to be about making the rivers natural again. Many of the arguments that may have spoken in favor of the agricultural use of these areas are now out of date anyway. As an example, Reichholf cites the sufficient production of food, which has long since become overproduction. New land consolidation procedures, with which the rural property can be rearranged, should pursue the goal of creating free space along the rivers. “Then everyone contributes equally to a small extent to this socio-politically important and ecologically indispensable functional enhancement of the streams and rivers, without individual or a few being specifically affected.”
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The aquatic ecologist sees no alternative to renaturation efforts, even if hardly a river will regain its original face. “When reservoirs are built, they are built. You can’t blow them up and say, so the river flows and carry on like it did 10,000 years ago. But there are stretches of river that can be restored to their original state. And there are areas the vast majority of rivers that could be changed to such an extent that at least parts of the normal flow behavior, including flood retention, can function again, “says Reichholf. This is shown, for example, by the renaturation of the Isar right into the Munich urban area.
For the scientist, rivers have never lost their beauty and fascination. “We experienced that in the Corona crisis, when people were drawn to the lakes and rivers and not to the agricultural landscape.” A kingfisher by the stream or other water birds such as the great egret or little egret, huchen in the Isar or salmon in the Rhine are not only exciting to observe, but also valuable. Likewise, the many insects by the water that do not sting, but are even useful because they catch the little vermin that you don’t want. “It’s all amazingly beautiful.” After reading Reichholf’s book, one sees the rivers with different eyes.