Runoff events and related rainfall variability in the Southern Carpathians during the last 2000 years

Jack Longman,Vasile Ersek,Daniel Veres,Volker Wennrich,Aritina Haliuc

doi:10.1038/s41598-019-41855-1

Abstract

The occurrence of heavy rainfall events is expected to undergo significant changes under increasing anthropogenic forcing. South-eastern Europe is reacting rapidly to such changes, therefore understanding and forecasting of precipitation variability is vital to better comprehending environmental changes in this area. Here we present a sub-decadal reconstruction of enhanced rainfall events for the past 2000 years from the Southern Carpathians, Romania using peat geochemistry. Five clear periods of enhanced rainfall are identified at 125–250, 600–900, 1050–1300, 1400–1575 and 1725–1980 CE. Significant runoff is observed during the second half of the Medieval Warm Period, whilst the Little Ice Age was characterised by significant variability. The North Atlantic Oscillation appears to be the main control on regional precipitation, but changes in solar irradiance also seem to play a significant role, together with the Siberian High. Comparison of the data presented here with model outputs confirms the ability of models to predict general trends, and major shifts, but highlights the complexity of the region’s hydrological history.

Highlights

Understanding the causes and effects of wetter periods and associated hydro-meteorological events is of great interest in climate science[1], as the majority of modelling studies predict higher incidence of such events in the near future[2]
To ensure the X-Ray Fluorescence Core-Scanning (XRF-CS) data discussed here provide a reliable method of geochemical screening for the Sureanu peat record, comparison of ITRAX results with those from destructive Inductively Coupled Plasma Optical Emission Spectrometry www.nature.com/scientificreports
We present the first record of sub-decadal fluctuations in runoff activity in the Southern Carpathians, Romania for the last 2000 years using XRF-CS and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) derived lithogenic elemental data

Summary

Introduction

Understanding the causes and effects of wetter periods and associated hydro-meteorological events (heavy precipitation, flooding) is of great interest in climate science[1], as the majority of modelling studies predict higher incidence of such events in the near future[2]. South-eastern Europe is one of the most rapidly reacting areas to current climate change[2,5] and to understand the long-term hydroclimate variability in this region, high-resolution and well-dated records are needed. Further high-resolution palaeoclimate data from south-eastern Europe may strengthen our understanding of long-term patterns and amplitudes of change in the pressure systems mentioned above, as well as their environmental impact across the continent as a whole[30]. We present a new high-resolution geochemical record of sediment input onto Sureanu bog (Southern Carpathians, Romania, Fig. 1) linked to precipitation variability in the catchment area, and associated runoff erosion for the last 2000 years. Such work builds on a previous, low-resolution study into the paleoclimatic history of this area, which demonstrated a clear link between variations in lithogenic element concentrations and land erosion

Methods

Results

Conclusion