Assessment of Natural Hazards Exposure - Castle of Ambras ()

Veronika Lechner, Fabian Nagl, Bernhard Kohl and Gerhard Markart Department of Natural Hazards (BFW)

CHEERS – Workshop

BFW - Innsbruck 13-11-2019 Damage events – Ambras castle 1985 - The wall surrounding the castle was overturned by the high water discharge of the Lanser brook (which was additionally endowed with water from the Sistrans brook).

Sistranser Bach

Foto:Lanser Lageder Bach Damage events - Ambras castle Wall has been rebuilt – with culverts

Retention Basin at Amras

Foto: Lageder Road to Ambras Castle flooded - July 2016 Traffic chaos in Ambras

Monsoon-like storms over

Street near Ambras Castle

This event was triggered by an outbreak of the Sistrans brook above Aldrans  surface runoff caused landslides above Ambras Castle  flooded the road at Ambras Castle – access road acted as a dam Damage events - Ambras castle

Foto: Lageder Planned 1st attempt Further development of an approach developed for the region Pichl-Schladming- Haus in the Ennstal valley - derivation of flood potential not covered by WLV hazard zone maps Runoff coefficient map

Runoff Deduction of catchments areas without connection to torrents Routing the runoff from pixel to pixel – runoff potential in the catchments Calculation of surface runoff velocity Flooding potential map Runoff coefficient map for “catchment” Schintertalbach – to Ambras castle Flooding of access road and parking lots extremely unlikely in future  after the 2016 event extensive measures were taken to protect the access road to Ambras Castle from water accumulation

 Installation of culverts in the wall to ensure rapid drainage In torrential rain runoff from the inner courtyard of Ambras Castle repeatedly flooded adjacent rooms.  Securing of valuable goods by the personnel during rain events is necessary.  Access by staff during thunderstorms possible - due to the construction measures taken

Source photo: https://www.schlossambras-innsbruck.at/entdecken/das-schloss/innenhof/ Hence concentration of future work on an acute problem:

Rock (Innsbruck Quartz Phyllite) in the east of Ambras Castle is strongly loosened / weathered - Erosion by the Lanser brook, this undercuts the rock - sooner or later technical security Lanser Bach measures necessary to ensure stability of the castle in this area Ambras Castle Bank protection only partially functioning - “hanging in the air”

Loose sediment easy to mobilize

Forest ranger will be informed Side erosion rock partly heavily weathered rock break-offs

bank protection unstable Next steps BFW:

• Comparison of older and actual aerial photos - attempt to document changes in the last decades • Comparison with terrestrial photographs - Carrying out a flight with UAV not allowed (approach zone airport Innsbruck - no-fly zone for UAVs) • Short report for Stakeholders (e.g. administration)  Development of the channel section and the slopes should be observed at least

Taking Measures not within the competence of the WLV But: Hofburg administration / City of Innsbruck Thanks to DI Leopold Stepanek (Austrian Service for Torrent and Avalanche Control - WLV) for providing information and assistance in the field