EX 2 Luzern -

Flood defences in the conurbation and town of Lucerne The city of Lucerne and its conurbations have always been at risk of flooding due to their location by and the and Kleine rivers. A current example of how flood security is being increased in a central, inner-city area while also redesigning transport routes can be seen in Malters, and Em- men. Particularly interesting is the new Ettisbühl timber separation facility, which can retain up to 5,000 m3 of driftwood from the river. The next highlight is the historic needle dam in the city of Lucerne at the outflow of the lake, which dates back to 1852. The dam has recently been renovated and is still in operation. If conditions allow, experts will show us how the wooden needles are raised and lowered to manage the flow of water.

Technical aspects The flood event of 21/22 August 2005 in the conurbation municipalities of Malters, Littau (now Lucerne) and Emmen along the Kleine Emme river resulted in insured losses totalling CHF 310 million. Flood security is being implemented in the central part of Lucerne where the principal damage occurred – around Seetalplatz – along with a redesign of various traffic modes (individual transport, public transport, cycling, pedestrian). Core elements of the flood defence measures include establishing a second channel at the point at which the lake drains into the Reuss river, constructing two railway bridges over this channel, and constructing two new higher and wider road bridges. Participants will tour the construction sites, after which there will be a description of the flood event, the flood defence measures at Seetalplatz and the Ettisbühl timber separation facility. The Kleine Emme river always carries driftwood after storms in its highly forested catchment area. The flood event of 21/22 August 2005 caused an estimated 4000 m3 of driftwood to wash down the river, some 3500 m3 of which collected in residential areas (7 hectares of woodland along the river were flattened). In 2011 a timber separation facility was constructed in Ettisbühl downstream from the confluence of the main subcatchments of the Kleine Emme and upstream of the conurbation. This permits the retention of up to 5000 m3 of driftwood. Participants will tour the facility and discover how it works: the ancillary benefits it provides as a recreational area are clearly in evidence.

Lunch by the timber separation facility and Ettisbühl run-of-river power plant, Malters

Cultural tour Since 1861 the height of Lake Lucerne has been regulated by means of a needle dam, the Poirée weir, in the Reuss river. This underwent a refurbishment in 2009-2011, during which it was supplemented by a side weir and equipped with a needle management device. The perpendicular and lateral needle dam installa- tion is of historical importance in terms of its cultural and industrial significance. Its function had to be pre- served. Participants will have a chance to tour the dam and view the control systems, the manual extrac- tion and insertion of the timber "needles" and the needle management device. Access to the weir may have to be restricted in the event of flooding or if staff are working on it. Life jackets will be issued.

Requirements for participants There will be two hours of walking along footpaths and touring sites. Surefootedness is a requirement for anyone accessing the needle dam. Clothing suitable to the weather and sturdy footwear required.

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