Abstract
Floods comprise a dominant hydroclimatic phenomenon in aridlands with significant implications for humans, infrastructure, and landscape evolution worldwide. The study of short-term hydroclimatic variability, such as floods, and its forecasting for episodes of changing climate therefore poses a dominant challenge for the scientific community, and predominantly relies on modeling. Testing the capabilities of climate models to properly describe past and forecast future short-term hydroclimatic phenomena such as floods requires verification against suitable geological archives. However, determining flood frequency during changing climate is rarely achieved, because modern and paleoflood records, especially in arid regions, are often too short or discontinuous. Thus, coeval independent climate reconstructions and paleoflood records are required to further understand the impact of climate change on flood generation. Dead Sea lake levels reflect the mean centennial-millennial hydrological budget in the eastern Mediterranean. In contrast, floods in the large watersheds draining directly into the Dead Sea, are linked to short-term synoptic circulation patterns reflecting hydroclimatic variability. These two very different records are combined in this study to resolve flood frequency during opposing mean climates. Two 700-year-long, seasonally-resolved flood time series constructed from late Pleistocene Dead Sea varved sediments, coeval with significant Dead Sea lake level variations are reported. These series demonstrate that episodes of rising lake levels are characterized by higher frequency of floods, shorter intervals between years of multiple floods, and asignificantly larger number of years that experienced multiple floods. In addition, floods cluster into intervals of intense flooding, characterized by 75% and 20% increased frequency above their respective background frequencies during rising and falling lake-levels, respectively. Mean centennial precipitation in the eastern Mediterranean is therefore coupled with drastic changes in flood frequencies. These drastic changes in flood frequencies are linked to changes in the track, depth, and frequency of mid-latitude eastern Mediterranean cyclones, determining mean climatology resulting in wetter and drier regional climatic episodes.
| Original language | American English |
|---|---|
| Article number | 8445 |
| Journal | Scientific Reports |
| Volume | 8 |
| Issue number | 1 |
| DOIs | |
| State | Published - 1 Dec 2018 |
Bibliographical note
Funding Information:This study is a contribution to the PALEX project "Paleohydrology and Extreme Floods from the Dead Sea ICDP core", funded by the DFG (grant no. BR2208/13-1/-2). The authors acknowledge the support and contribution of laboratory staff and technicians in the GFZ, where preparation of thin-sections and photography were carried. We thank J. Mingram, N. Nowaczyk, B. Brademann, F. Ott, N. Dräger and M. Köppel for technical support and fruitful discussions. We thank I. Sirota and L. Ben-Moshe for flood imagery presented in Fig. S6, and E. Wajnberg for statistical assistance. The study is also supported by an Excellence Center of the Israel Science Foundation grant 1436/14. Y.B. is also grateful for a scholarship from the Advanced School of Environmental Studies, Hebrew University. We acknowledge the use of imagery from the NASA Worldview application (https://worldview. earthdata.nasa.gov/) operated by the NASA/Goddard Space Flight Center Earth Science Data and Information System (ESDIS) project, and the use of The Blue Marble Next Generation, provided by NASA's Earth Observatory. Map in Fig. 1d was created using ArcGIS® software by Esri, and includes World Imagery basemap (Sources: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community).
Funding Information:
This study is a contribution to the PALEX project “Paleohydrology and Extreme Floods from the Dead Sea ICDP core”, funded by the DFG (grant no. BR2208/13-1/-2). The authors acknowledge the support and contribution of laboratory staff and technicians in the GFZ, where preparation of thin-sections and photography were carried. We thank J. Mingram, N. Nowaczyk, B. Brademann, F. Ott, N. Dräger and M. Köppel for technical support and fruitful discussions. We thank I. Sirota and L. Ben-Moshe for flood imagery presented in Fig. S6, and E. Wajnberg for statistical assistance. The study is also supported by an Excellence Center of the Israel Science Foundation grant 1436/14. Y.B. is also grateful for a scholarship from the Advanced School of Environmental Studies, Hebrew University. We acknowledge the use of imagery from the NASA Worldview application (https://worldview. earthdata.nasa.gov/) operated by the NASA/Goddard Space Flight Center Earth Science Data and Information System (ESDIS) project, and the use of The Blue Marble Next Generation, provided by NASA’s Earth Observatory. DigitalGlobe, GeoEye, Earthstar GeograMap in Fig. 1d was created using ArcGIS®phics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GISsoftware by Esri, and includes World Imagery basemap (Sources: Esri,
Publisher Copyright:
© 2018 The Author(s).
