Hydrological EXtreme Events in Changing Climate: The HEX Events project

Abstract

Chronological control of Late Pleistocene and Holocene fluvial archives has much improved during the past decades, and this is renewing their use in order to improve records of extreme hydrological events worldwide. A extreme hydrological event is here defined in the sense given by Gregroy et al., (2006), meaning any past process or phenomena related to the hydrological cycle (e.g. rainfall, runoff, snowmelt, flood, water recharge) with a magnitude higher/lower than the mean and probably above or below a critical threshold. An hydrological event may relate to periods ranging from minutes, up to several years (for the case of droughts); clustering of events with higher or lower frequency is analysed The INQUA funded HEX Events project aims to combine extended regional records of hydrological events (above average stream flow and discrete flood events) from multiple proxies and to establish in-phase and out-of-phase periods of hydrological activity in response to climate and atmospheric circulation variability. The project approach is based on combined meta-analysis of large sets of dates (C- 14, OSL, IRSL) from diverse fluvial contexts, allowing series of fluvial activity periods to be more objectively defined, and to better facilitate their characterization in terms of forcing hydrological conditions (climate or human changes).