Study of hydro-sedimentary variability of the Radicatel karst system influenced by climate signal fluctuations (Normandy, France)
Résumé
This study relies on the use and analysis of hydro-meteorological variables, long turbidity time series (from 1988 to 2009, 21 years) and a sedimentary record to provide better understanding of the hydro-sedimentary variability of the karst system near the town of Radicatel, France. Wavelet analysis of rainfall, piezometric level and turbidity, as well as the sediment archive, show common modes of variability. A common spectral composition emphasizes the influence of climate controls. Comparison of the wavelet spectra with the North Atlantic Oscillation (NAO) spectrum clearly highlights the control of the latter on hydro-meteorological variables at the regional level. Climatic fluctuations are recorded in the turbidity signal and in sedimentary fill, as revealed by the 5- to 8-year frequency band, which is characteristic of the NAO index. A climatic signal is recorded in both rainfall events and piezometric levels, and also in sediment transport and deposition at the scale of the local karst system. The overall climate control is also present beyond the local variations and heterogeneities.