Research highlights

Lütschine fan delta response to climate variability and land use during the last 2400 years.

The Late Holocene depositional and vegetation history of the Lütschine fan delta records important environmental changes. The sedimentological findings showed a general agreement between geochemical and pollen cycles and δ14C anomalies from 2400 to 850 yr cal. BP and could be interpreted as natural response to climate forcing (Figure 7). Furthermore, the coarse-grained layers, deposited during paleofloods about 100, 700, 1100, 1528, and 1831 yr AD, correlate with positive radiocarbon anomalies, suggesting that aggradation in the Lütschine fan delta during the focused period was triggered by solar forcing. According to our pollen data and the traced correlations, the Lütschine river floods occurred during cold and wet periods. The return interval of recorded flooding events during the last 2400 years varies between 300 and 600 years. With regard to the last millennium, anthropogenic impacts, such as woodland clearance for grazing and agriculture and river diversion, have changed the sedimentary and geomorphic pattern on the Lütschine fan delta, reducing wetland environments (Figure 7).

Correlation between geochemistry, pollen proxies, lithology and geomorphology of the Lütschine fan delta according to Schulte et al. (2006)

Figure 7: Correlation between geochemistry, pollen proxies, lithology and geomorphology of the Lütschine fan delta according to Schulte et al. (2006). The inverse relationship between SiO2, Al2O3 and CaO contents, determined by X-ray fluorescence, stresses a lithological control of the geochemistry of the profile IN-2 samples. Variations result predominately from the deposition of siliciclastic sediments (upper reach) and carbonate rich fine sediments (lower reach) and pedogenic processes in the peat horizons. The deposition of coarse-grained flood layer and shifts (arrows) of Lütschine channel results from exceptional flood event during the last 2400 years.

Relevant publications

L. Schulte1, J. C. Peña, F. Carvalho, T. Schmidt, R. Julià, J. Llorca, and H. Veit, 2015.

A 2600-year history of floods in the Bernese Alps, Switzerland: frequencies, mechanisms and climate forcing

Hydrol. Earth Syst. Sci., 19, 3047-3072, 2015


J. C. Peña1, L. Schulte, A. Badoux, M. Barriendos, and A. Barrera-Escoda, 2015.

Influence of solar forcing, climate variability and modes of low-frequency atmospheric variability on summer floods in Switzerland

Hydrol. Earth Syst. Sci., 19, 3807-3827, 2015


L. Schulte, J.C. Peña, R. Julià, F. Carvalho, J. Llorca, J. Losada, F. Burjachs, T. Schmidt, P. Rubio, H. Veit, 2014.

CLIMATE FORCING OF PALEOFLOODS IN THE SWISS ALPS

Avances de la Geomorfología en España 2012-2014. Editores: Susanne Schnabel y Álvaro Gómez Gutiérrez. XIII Reunión Nacional de Geomorfología, Cáceres, 2014. pp. 143-146

Universitat de BarcelonaICREA - Institució Catalana de Recerca i Estudis AvançatsUniversität BernServei Meteorològic de CatalunyaGobierno de España - Ministerio de Educación y CienciaAlexander von Humboldt Foundation