How To Prevent Floods? Dig Up Forest Roads, Says an Expert

Excavator digging up an old forest road. © Stefan Valo / Povodne.sk.

If we want to save our homes from ever-increasing floods we should go up to the mountains and dig up unused forest roads. At first sight it may look peculiar, but the findings of Štefan Vaľo, a lively Slovak builder, have already been approved by the Slovak Academy of Sciences. Disturbance of compact forest soils is a highly efficient way to retain water in areas where it causes no damage.

Avid walkers in the mid-European mountain forests have probably experienced it: whether you walk down or uphill, during rain you can clearly see how the forest road drains the water away. It can be just a small spring, now and then a small stream and sometimes even a pretty strong torrent.

Štefan Vaľo has been building forest roads for 40 years. About six years ago he asked himself why the floods had become so frequent in recent years. “I saw water running down the logging roads for the forest machinery. The flow was sometimes so heavy it would carry branches, rocks, even the whole trees!” said Štefan Vaľo to the Thinkbrigade reporter.

He has been visiting every area in Slovakia hit by floods or landslides for the last two years. He has experience even from the Ukraine and Poland, in 2010 he travelled also to the Izera Mountains in the Czech Republic. “It was the same everywhere – the compact soil channeled water straight to the villages,” recalls Štefan Vaľo. At the same time the power of streams on the logging roads contrasted with the calm situation on the soil covered with vegetation or trees. In this terrain you could easily walk even during heavy rains because water was slowly soaking into the soil, rising groundwater levels.

Mr. Vaľo concluded it’s in the hills and mountains where the floods actually begin. And the problem is not only with big forest roads but also with logging paths and forest machinery tracks, which people left behind after they had abandoned them. So for retaining more water up in the forests it’s necessary to dig them up. “My precise definition is: dig up compact forest surface transversely from the top downwards,” explains Štefan Vaľo. “Thus we will achieve that every raindrop will stay in the place where it fell and will slowly soak to the roots of plants and feed springs and wells.”

Former logging path eroded and draining water. © Jan Stejskal

Štefan Vaľo tested his approach in the forests above the village Ťahanovce, east Slovakia, part of which had been regularly flooded by a nearby stream. Unused roads were dug up at full length and a few ponds were built below the forest to catch the water that possibly wouldn’t be retained. What was the result? Rainwater remained in the small pits dug out by the excavator. It partly evaporated and the rest was absorbed by the soil. In some pits the water remained longer and turned into a water resource for wild animals.

Last summer a team of scientists from the Hydrological Institute of Slovak Academy of Sciences came to Ťahanovce to evaluate how the alternative flood control option works. They poured artificial rain on the compacted forest road, then on the road with small wooden barriers and also on the road recultivated according to Mr. Vaľo. The experiment clearly showed that the dug up road retained by far the largest amount of water – practically all of it. On the contrary, water on the compacted surface had no chance to soak and got accelerated even on a gentle gradient – and with an increasing amount it could get even pretty destructive power.

International Law?

In November 2011, Mr. Vaľo attended a seminar in the Brussels building of the European Parliament. He was invited by Pavel Poc, the Czech Member of the European Parliament (MEP). “It is not really such a new approach, there were similar studies and practical procedures already existing in the former Czechoslovakia before 1989. Unfortunately, these studies and procedures did not survive the days that followed,” said Pavel Poc to the Thinkbrigade reporter.

Mr. Vaľo was accompanied by Tomáš Orfánus who conducted the experiment in Ťahanovce on behalf of the Slovak Academy of Sciences. “After floods (in another Slovak village) we carried out another study in which we figured out that unused forest roads with compact surface had contributed by some 52 % to the total flood flow. We can just hope that in reality it was less than that,” Mr. Orfánus said at the seminar.

Mr. Vaľo was trying to convince even the participants at the 6th World Water Forum that took place in Marseille in the middle of March. “At these political meetings and conferences no one speaks about the compact forest surfaces,” complains Štefan Vaľo. “But I have observed in detail what happens in the forests during rain for the last six years. And water flows away only on the compact surfaces.”

Dug up old forest road retaining water. © Stefan Valo / Povodne.sk

Therefore he persuades politicians to make legislation determining a duty to reclaim every degraded square meter of the forest surface as soon as possible after logging. And if such legislation already exists, then enforce all subjects to abide by it. “These are not issues that could be solved by only one country. Only by a common approach we can achieve positive solutions,” said Štefan Vaľo. “Only binding regulations at the top level establishing obligatory reclamation of compact unused land can reverse the present state.”

At the European level Mr. Vaľo may be successful. “If my information from the European Commission is correct, the Commission is now searching for legislative and practical solutions similar to those of Mr. Vaľo´s and to those that existed in our country already more than 20 years ago,” said Pavel Poc, Czech MEP. “I connected our former and current Slovak experts with the responsible Directorate General of the European Commission and I will be carefully monitoring further development. If my help is needed I am ready to help.”

On his webpages Štefan Vaľo even published a few particular recommendations on how to retain water in forests. For example he urges eliminating road drainage ditches and keeping them only in places where the road stability would otherwise be compromised. He also suggests to rethink the methodology of designing, construction and inspecting of new forest paths and roads.

But apart from these rather technical measures there is one quite different point in the list: the one that encourages people to go up to the mountains during rain and observe for themselves what’s happening. “The thing is that I found it made no sense to discuss the matter with people who had no clue what I was talking about,” explains Mr. Vaľo. “For this reason people have to see right in the mountains what rainwater can cause. Go to any forest in your surroundings and you will see that I’m right. You will see eroded land everywhere. And then ask yourself: Why is the land eroded? Why is it eroded right now? The answer is clear: Because we use much more mechanization. And it does damage not only to our villages and towns, but it harms our forests too.”

Disruption of compacted soil. © Stefan Valo / Povodne.sk

Rainwater Retention. © Stefan Valo / Povodne.sk