Project

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Towards forecasting extreme flash floods in karst terrains

Applicant Luetscher Marc
Number 195321
Funding scheme Spark
Research institution
Institution of higher education Institut Suisse de Spéléologie et Karstologie - ISSKA
Main discipline Other disciplines of Earth Sciences
Start/End 01.12.2020 - 31.07.2022
Approved amount 88'140.00
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All Disciplines (4)

Discipline
Other disciplines of Earth Sciences
Hydrology, Limnology, Glaciology
Geochemistry
Climatology. Atmospherical Chemistry, Aeronomy

Keywords (14)

Karst; Hydrogeology; Paleoclimate; Climate change; Natural hazards; Floods; Spring; Cave; Sediments; Speleothems; Stalagmites; U/Th dating; Hydraulics; Time-series

Lay Summary (French)

Lead
Les inondations représentent un danger naturel des plus significatifs affectant la population à l’échelle globale. En région karstique les crues peuvent être aussi soudaines que brutales, avec une variation du débit de plusieurs ordre de grandeurs en l’espace de quelques heures. En conséquence, des sources temporairement inactives peuvent se remettre à couler, inondant d’importantes zones habituellement sèches. Ces crues soudaines sont d’autant plus inattendues que l’évènement est rare. Identifier ces évènements extrêmes relève, dès lors, d’une importance primordiale pour la planification et la gestion des risques hydrologiques.
Lay summary

Contenu et objectifs du travail de recherche

Ce projet vise à reconstruire les crues extrêmes (millénaires) au moyen de sédiments de grottes déposés ces derniers 10'000 ans. En particulier, nous allons étudier des stalagmites en vue d’identifier et de dater des dépôts argileux associés à une montée sporadique des eaux. Une approche originale combinant processus hydrologiques et analyse de concrétions permettra une interprétation quantitative pour mieux comprendre 1) la réponse d’un système karstique lors de précipitations extrêmes ; 2) si les enregistrements dans une grotte peuvent être reproduits à l’échelle régionale, et 3) dans quelle mesure la fréquence et l’amplitude des crues est variable dans le temps. Ces résultats permettront de mieux comprendre les évènements hydrologiques extrêmes à l’aune du changement climatique et serviront de base pour affiner les prédictions de crues en région karstique.

Contexte scientifique et social du projet de recherche

Les données instrumentales, voire historiques, étant peu nombreuses, cette recherche apportera des informations essentielles pour anticiper l’impact des crues dans un contexte climatique changeant. Nos simulations seront confrontées aux cartes des risque existantes et serviront de base pour discuter et conseiller les administrations communales et cantonales en vue de protéger la population locale face aux risques d’inondations. Notre étude contribuera également au développement de stratégies visant à minimiser la charge sédimentaire dans les captages d’eau potable en région karstique, améliorant ainsi l’accès à des ressources essentielles.

Direct link to Lay Summary Last update: 22.10.2020

Responsible applicant and co-applicants

Employees

Publications

Publication
The potential of Ojo de Valjunquera cave (NE of Iberia) sediments for paleoflood reconstructions
BartoloméMiguel, BenitoG., LuetscherMarc, Badules-IglesiasJ., Pérez-VillarG., EdwardsR.L., MorenoA. (2021), The potential of Ojo de Valjunquera cave (NE of Iberia) sediments for paleoflood reconstructions, in Cuaternario y Geomorfología, 35(3-4), 11-28.
Effects of glaciation on karst hydrology and sedimentology during the Last Glacial Cycle: The case of Granito cave, Central Pyrenees (Spain)
Bartolomé Miguel, Sancho Carlos, Benito Gerardo, Medialdea Alicia, Calle Mikel, Moreno Ana, Leunda Maria, Luetscher Marc, Muñoz Arsenio, Bastida Joaquín, Cheng Hai, Edwards R.L. (2021), Effects of glaciation on karst hydrology and sedimentology during the Last Glacial Cycle: The case of Granito cave, Central Pyrenees (Spain), in CATENA, 206, 105252-105252.
L'impact climatique sur les grottes et le karst - perspectives de spéléologues
Luetscher Marc (2021), L'impact climatique sur les grottes et le karst - perspectives de spéléologues, 71(1), 100-106, Stalactite, La Chaux-de-Fonds 71(1), 100-106.
A Last Interglacial speleothem record from the Sieben Hengste cave system (Switzerland): Implications for alpine paleovegetation
Luetscher Marc, Moseley Gina E., Festi Daniela, Hof Florian, Edwards R. Lawrence, Spötl Christoph (2021), A Last Interglacial speleothem record from the Sieben Hengste cave system (Switzerland): Implications for alpine paleovegetation, in Quaternary Science Reviews, 262, 106974-106974.

Collaboration

Group / person Country
Types of collaboration
Pyrenean Institute of Ecology Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
H. Stoll / ETH Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
F. Anselmetti / UniBe Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
M. Mudelsee Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
R.L. Edwards, Univ. Minnesota United States of America (North America)
- Publication
- Research Infrastructure

Scientific events

Communication with the public

Communication Title Media Place Year
Media relations: print media, online media «Ewiges» Eis im Oberland Berner Zeitung German-speaking Switzerland 2021
Media relations: radio, television Eishöhlen: Die unterirdischen Gletscher drohen zu verschwinden SRF1 German-speaking Switzerland 2021
Media relations: radio, television Les glacières de l'arc jurassien menacées de disparition: interview de Marc Lütscher RTS Western Switzerland 2021

Associated projects

Number Title Start Funding scheme
201364 SPELAION Forum21 01.11.2021 Agora

Abstract

Floods represent one of the most significant natural hazards affecting communities worldwide. Although there is a general understanding that, in the Alpine region, flood frequency may increase under climate change scenarii, the natural variability of hydrological systems combined with the lack of sufficiently long records makes the analysis of hydrological extremes, and therefore rare events, difficult. This is particularly true for flash-floods in karst terrains, where a sudden rise in the hydraulic head may temporarily reactivate inactive emergences, sometimes located tens of kilometres away from the main recharge area. This project aims at reconstructing extreme floods from well preserved cave records. Because, they are preserved from surface erosion processes speleothems have emerged as a promising archive for the reconstruction of paleofloods on short and long time-scales. Applying an original approach combining modern hydrological process studies with speleothem paleoclimate science we want to investigate 1) how the hydraulics of selected karst systems responds to extreme precipitation events; 2) whether extreme flood records from singular caves are reproducible on a regional scale, and 3) to which extent changes in paleoflood frequencies and magnitudes can be associated with climate changes.Based on detailed cave surveys, we will model the hydraulics for 5-10 selected cave sites using pipe-flow solutions and calibrate our results against empirical head data acquired over the last 25 years. This calibration will be extended to include extreme floods identified microscopically and geochemically from detrital layers incorporated in speleothems. U-series dating of pristine calcite layers will provide the age control to determine the return period of singular events. By establishing a direct link between the hydrological response of a karst system and the transport and incorporation of sediments into speleothems we will provide, for the first time, a quantitative approach for the interpretation of speleothem paleoflood layers. The estimates of aquifer recharge triggering flash-floods will contribute to a better understanding of the synoptic climatology. Our results will serve as a basis for predictive modelling of the karst hydrology under contrasted climate scenarios with the ultimate objective to provide a methodology to predict flush floods from meteorological forecasts. The results anticipated from this research will provide original information about the hydrological transmissivity and maximal discharges anticipated under contrasting climate scenarios. By supporting the identification of sporadic karst emergences, our data will provide a basis for discussing local and regional maps of natural hazards with policy makers and stakeholders. Elaborating on these results, we will be in position to propose a detailed methodology for predictive modelling of karst discharges based on meteorological data. Besides contributing to the management of flood risks, this research is also relevant for groundwater abstraction strategies which aim at minimizing sedimentary loads. The main outcomes of this project will thus be implemented in teaching activities and dedicated public outreach towards local communities relying on karst water resources.
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