TY - JOUR A1 - Ganguli, Poulomi A1 - Paprotny, Dominik A1 - Hasan, Mehedi A1 - Güntner, Andreas A1 - Merz, Bruno T1 - Projected changes in compound flood hazard from riverine and coastal floods in northwestern Europe JF - Earth's future N2 - Compound flooding in coastal regions, that is, the simultaneous or successive occurrence of high sea levels and high river flows, is expected to increase in a warmer world. To date, however, there is no robust evidence on projected changes in compound flooding for northwestern Europe. We combine projected storm surges and river floods with probabilistic, localized relative sea-level rise (SLR) scenarios to assess the future compound flood hazard over northwestern coastal Europe in the high (RCP8.5) emission scenario. We use high-resolution, dynamically downscaled regional climate models (RCM) to drive a storm surge model and a hydrological model, and analyze the joint occurrence of high coastal water levels and associated river peaks in a multivariate copula-based approach. The RCM-forced multimodel mean reasonably represents the observed spatial pattern of the dependence strength between annual maxima surge and peak river discharge, although substantial discrepancies exist between observed and simulated dependence strength. All models overestimate the dependence strength, possibly due to limitations in model parameterizations. This bias affects compound flood hazard estimates and requires further investigation. While our results suggest decreasing compound flood hazard over the majority of sites by 2050s (2040-2069) compared to the reference period (1985-2005), an increase in projected compound flood hazard is limited to around 34% of the sites. Further, we show the substantial role of SLR, a driver of compound floods, which has frequently been neglected. Our findings highlight the need to be aware of the limitations of the current generation of Earth system models in simulating coastal compound floods. KW - compound flood KW - storm surge KW - river floods KW - sea level rise KW - climate KW - change KW - Europe Y1 - 2020 U6 - https://doi.org/10.1029/2020EF001752 SN - 2328-4277 VL - 8 IS - 11 PB - Wiley-Blackwell CY - Hoboken, NJ ER - TY - JOUR A1 - Miegel, Konrad A1 - Gräff, Thomas A1 - Franck, Christian A1 - Salzmann, Thomas A1 - Bronstert, Axel A1 - Walther, Marc A1 - Oswald, Sascha T1 - Auswirkungen des Sturmhochwassers der Ostsee am 4./5. Januar 2017 auf das renaturierte Nieder- moor „Hütelmoor und Heiligensee“ an der deut- schen Ostseeküste BT - Effects of the January 4/5 2017 storm surge on a restored fen at the German Baltic Sea coast JF - Hydrologie und Wasserbewirtschaftung N2 - Entlang der Küstenniederung des Naturschutzgebietes „Hütelmoor und Heiligensee“, ca. 6 km nordöstlich von Rostock-Warnemünde gelegen, wird seit dem Jahr 2000 die Küstendüne nicht mehr instand gehalten. Im Rahmen der Renaturierung des Gebietes werden so grundsätzlich wieder Überflutungen bei Ostseehochwassern zugelassen, was bisher jedoch noch nicht eingetreten ist. Am 4./5. Januar 2017 ereignete sich ein Sturmhochwasser der Ostsee, mit einem Scheitelwasserstand in Warnemünde, der sich zwischen dem 10- und 20-jährlichen Hochwasserstand einordnet. Dennoch kam es bei diesem Ereignis nicht zum Dünendurchbruch und zur seeseitigen Überflutung, wohl aber zum binnenseitigen Einstrom von Salz- bzw. Brackwasser. Dieser erfolgte über den Graben, durch den das Gebiet normalerweise über die Warnow in die Ostsee entwässert. Durch das Einströmen über die Sohlschwelle, sonst Auslass des Gebietes, stiegen die Wasserstände und Salzkonzentrationen in der südwestlichen Hälfte der Niederung an. Mit zunehmender Entfernung zur Sohlschwelle waren diese Auswirkungen jedoch geringer spürbar. Dies gilt wegen der Retentionswirkung der Niederung mehr für den Wasserstand als für die Salzkonzentration. Während der Wasserstand durch den Einstau der Niederung und Überschwemmungen flächenhaft anstieg, breitete sich die Salzfront präferentiell in den ehemaligen Entwässerungsgräben, die trotz des Einstaus nach wie vor hydraulisch aktiv sind, eher linienhaft aus. Diese Interpretation beruht auf Messergebnissen von Wasserstand, elektrischer Leitfähigkeit und Wassertemperatur. N2 - Maintenance and repair of the coastal dunes of the conservation area, Hutelmoor und Heiligensee" have been ceased for renaturation purposes since the year 2000 to aid flooding of the area during high water levels of the Baltic Sea. On January 4th and 5th 2017, the Baltic Sea experienced a storm surge resulting in a water level in Warnemunde with a 10-to 20-year reoccurrence rate. Nevertheless, the event caused neither a dune failure nor a sea-sided flooding, but did result in an upstream inflow of salt and brackwater through the trench which normally drains the area into the Baltic Sea via the Warnow. Water levels and salinity concentrations rose in the south-western part of the area due to the influx via a ground sill, which normally acts as the outlet of the lowland. The effects within the lowland were less pronounced with increasing distance to the ground sill, which proved to be even more significant for the water levels than for salinities due to the retention capabilities of the area. While water levels increased extensively as a result of the flooding, the salinity front is presumed to have spread primarily along the former draining channels. This interpretation is based on monitoring data of the water level as well as the environmental tracers electrical conductivity and water temperature. KW - Baltic Sea KW - storm surge KW - coastal lowland KW - flooding KW - salinization KW - environmental tracer KW - process analysis KW - Ostsee KW - Sturmhochwasser KW - Küstenniederung KW - Überflutung KW - Versalzung KW - Umwelttracer KW - Prozessgeschehen Y1 - 2017 U6 - https://doi.org/10.5675/HyWa_2017,4_2 SN - 1439-1783 VL - 61 IS - 4 SP - 232 EP - 243 PB - Bundesanst. für Gewässerkunde CY - Koblenz ER -