How Samedan taught the Flaz a lesson

First mountain river relocation – today an international showpiece

by Heini Hofmann

Samedan in the Engadin, known for its mountain air port and the highest acute services hospital in Europe, has yet another trump: As part of the flood protection, the first mountain river relocation across the Alps was realized here, a spectacular once-in-a-century building with a signalling effect, showing in retrospect, that where there’s a common will, there’s a way.
“Il fö e l’ova sun buns servituors, ma noschs patruns” (“Fire and water are good servants, but bad masters.”), says an old Romansh wisdom. In other words: Just as without water life is not possible (“Wassernot” = need of water), so unleashed water can bring death and destruction (“Wassersnot” = too much water, flood). This is known in Samedan, which appropriately shows Aquarius in his coat of arms, from bitter experience.
Therefore action had to be taken: Courageous decisions of both the responsible persons and the population caused to realize a once-in-a-century water engineering building in just four years (2002–2006), which, as the former mayor and promoter Thomas Nievergelt asserts today – not without a certain pride, “stands as a model for security, quality of life and nature.”

Two extremely dissimilar rivers

The founding fathers of Samedan had had something in mind, when they chose a terrace above the plain for their village, protected against avalanches and floods. Here one was safe. But that changed in the early 20th century, when beginning to underestimate the dangers. the settlement expanded into the plain. For here in the plain, two very different mountain rivers paved their way, the serene Inn and unruly Flaz.
Whereas the Inn, tempered by the Engadin lakes, presented only muted flood peaks and carries virtually no sediment, the Flaz, fed by the Bernina and Roseg streams, transports large amounts of sand and stones from the Bernina region. This is also the cause for the almost 70 meters thick alluvial plain of Samedan, formed by countless floods since the last ice age.
Samedan was threatened severely mainly when – usually in August or September – large-scale, cross-regional precipitation events occurred, which caused the Flaz to become a wild water. An outbreak of glacier water below the Roseg glacier could also, as in 1954, exacerbate the situation further.

Disasters rare but devastating

While the catchment areas of Inn and Flaz hardly diverge in terms of surface area, the glacier share of the Flaz is about eight times greater than that of Inn. Glaciers are able to store large amounts of water and thereby attenuate the risk of flooding. If, however, extreme rainfalls coincide with a period of intense ice melting, the flood risk increases dramatically. Also, climate-induced glacier shrinkage increases it. Conversely dwindling permafrost leads to increased debris flows and thereby more sediment in the river.
Extreme, damage causing floods are probably rare; but they usually occur unexpectedly and devastatingly. In the last 200 years the cadence was about 15 to 20 years. The worst floods occurred in 1888 and 1954, followed by those of 1834 and 1868, and most recently that of 18 July 1987, when the Inn almost spilled over the dam crowns.

Early ideas for conceptual change

Dam buildings stemming from the early 20th century already proved as insufficient as the devastating floods occurred in the twenties. Therefore, the communal council proposed as early as in 1932 a fundamental conceptual change with installation of an overflow for the Flaz and replacement of the railway embankment by bridges. However, that was met with deaf ears and rejected in Federal Berne, where the high lords “do not accept any lesson about cause and effect of circumstances, created as a result of facts of nature beyond control”…
But in 1995 a long and consistent political decision-making process finally led to the contract with the ETH Zurich granting comprehensive studies, the results of which clearly documented the flood threat to Samedan and had as consequence that the Canton in 1997 – ironically, in the most densely populated areas of Samedan – eliminated “highly threatened areas”, suspending their construction permit and thus made the community accountable. Now action was definitely called for.

Pilot project relocation mountain river

On 15 June 2000, a far-sighted decision was made – despite the higher construction costs – in favour of a future-oriented, holistic solution. Instead of merely constructional rehabilitation of the existing protective buildings it opted for the relocation of the mountain river Flaz, the more problematic one of the two rivers, a pilot project, the first of its kind.
The population and especially the affected farmers demonstrated foresight and sanctioned this request at the meeting of the communal council with 128 to 6 votes, and at the ballot in fall, the hefty gross borrowing of CHF 28.4 million (with a net credit of CHF 6.6 million at the expense of the commune) was comfortably approved of with 459 Yes to 145 Nays. The municipality decided in favour of a secure future also for the generations that were to follow and recognized the opportunities in environmental factors and tourism.
The Federal Office for Water and Geology, pleased by the sustainable pilot project of canton and municipality, then exceptionally increased the maximum granted subsidy rate for the canton of 39 % by a surcharge of 11 %, which means, the subsidy rate amounted to 50 % or CHF 14.2 million. And everyone was happy! This story recalls a bit the tactics of positive obstruction of a Danilo Dolci: first realize, then collect.

What was the outcome of the courageous manoeuvre?

With this project of the century, central requirements of modern flood protection were met: The settlement area, with its high damage potential is exempt from danger, and the flooding zone is now situated in a less sensitive area. But also nature has gained: Due to the new Flaz, the dismantling of the old Flaz raceway and the renaturated Inn, new networked habitats for flora and fauna had emerged.
In short: This courageous, flood control pilot project, realized in record time by taking the bull by the horns, brought an – even from the perspective of tourism – valuable ecological enhancement of the landscape, secured the livelihoods in the valley for generations to come: a win-win situation for man and nature. In other words: A prime example of what can be achieved when all parties show ability to consensus and the willingness to work together and when an active and open information policy creates confidence.
At a time where envy, fear and lack of optimism often prevent a great success, it was possible to realize this mammoth project only thanks to courageous action and will to cooperate. The result shows obviously that security can be combined with environmental concerns, which even earned international attention and imitation. Here the old pioneer spirit of the Upper Engadin revived. Sober assessment in retrospect: an undertaking that deserves the highest rating. •
(Translation Current Concerns)

Change in flood protection

HH. That precious substance water can change from a blessing to a curse when it is no longer containable in streams and rivers when it overflows the banks, causes devastation or even death. Therefore, always knowing that there is no absolute safety – the measures to avoid risks with regard to current knowledge, were constantly improved with the maintenance of the avalanche forests, rules for construction areas and falling-object protection structures.
Soon it was shown that in cleaned-out and installed pipes, flowing water could have exactly the opposite effect that, in accumulation with the danger of flood, dams and artificial water courses alone are not enough. Sustainable flood protection provides for running water and overflow areas, it is about deciding between economic disadvantages and ecological advantages.
This is the situation in Samedan with the shifting of the Flaz and the land restoration of the Inn; a successful example with a multi-purpose use for people and nature. The special aspect of this: That this man-made construction is ready, however, the concluding touches are taken care of by nature. Nature will put its stamp on the newly formed valleys to the joy of the residents and the tourists.

A construction project unlike others

HH. Such a construction work of the century was also something special for the experts; only in view of the surface of 100 ha. The Flaz project had to be divided into 12 construction sections – with 5 bridges and 4 water construction objects, a temporary re-routing of the street and a land restoration project.
The putting into effect of this large project together with an accompanying ecological group, the councils of the Canton, all the specialists, representatives of the interest groups and neighbours submitted high demands when trying to reach a consensus. In the end, everyone was proud of the results.
That is especially advantageous in the opinion of an excavator operator. “That was a singular event. One could drive the machine to its limits. Everyone was interested in working here. At the smaller construction sites there are often latencies. This was not the case here. The filling of the dam’s crest would have been a wasteful tinkering about. Now we have a tidy solution.” He said it and went for a walk with his family on the new hiking trail.