Arne Arns | University of Siegen (original) (raw)

Papers by Arne Arns

Research paper thumbnail of Entwicklung eines neuen Verfahrens zur automatischen Erkennung und Festlegung von Tidescheiteln im Bereich der Deutschen Bucht und der Ästuare

Research paper thumbnail of Determining return water levels at ungauged coastal sites: a case study for northern Germany

Ocean Dynamics, 2015

We estimate return periods and levels of extreme still water levels for the highly vulnerable and... more We estimate return periods and levels of extreme still water levels for the highly vulnerable and historically and culturally important small marsh islands known as the Halligen, located in the Wadden Sea offshore of the coast of northern Germany. This is a challenging task as only few water level records are available for this region and they are currently too short to apply traditional extreme value analysis methods. Therefore, we use the Regional Frequency Analysis (RFA) approach. This originates from hydrology but has been used before in several coastal studies and is also currently applied by the local federal administration responsible for coastal protection in the study area. The RFA enables us to indirectly estimate return levels by transferring hydrological information from gauged to related un-gauged sites. Our analyses highlight that this methodology has some drawbacks and may over-or underestimated return levels compared to direct analyses using station data.

Research paper thumbnail of Measuring sediment deposition and accretion on anthropogenic marshland – Part I: Methodical evaluation and development

Estuarine, Coastal and Shelf Science, 2014

ABSTRACT Low coastlands, marshlands and islands all over the world are challenged by rising water... more ABSTRACT Low coastlands, marshlands and islands all over the world are challenged by rising water levels due to climatic changes. The adaptation capacity of such lowlands is based on frequent inundations and according sedimentation processes. Exemplarily, a system of small islands west of Northern Germany was investigated over three years. At three out of ten so-called Halligen located in the Wadden Sea, the adaptation capacity of the anthropogenic marshland was determined. The Halligen Hooge, Langeness and Nordstrandischmoor have surface elevations only a few decimetres above mean high water and have to cope with an inundation frequency of nowadays up to 22 times per year. By use of methods introduced in Schindler et al. (2014, this volume) in combination with a 137Cs and 210Pb dating campaign on 12 sediment cores, vertical accretion rates were measured and detailed sediment accretion patterns presented. A good agreement was found between the used methods to calculate long term and short term marshland accretion rates. Sediment deposition and vertical marshland accretion is mainly controlled by the high tide events (single storm surges). Coastal protection structures, established in the early 20th century, decrease the inundation frequency and hinder the efficiency of the sediment transport by the tidal channel system on the Halligen. Vertical marshland accretion based on 210Pb dating for the time span 1915 - 2011 (1.0 ± 0.3 mm/a, Hooge, 1.2 ± 0.3 mm/a, Langeness and 2.6 ± 0.9 mm/a, Nordstrandischmoor) is in disequilibrium with the fast increasing mean high water level (MHW, 5.0 ± 0.3 mm/a). Projections until 2100 revealed that the extreme values (highest high waters, HHW) tend to rise much faster than the MHW or relative mean sea level (RMSL). Therefore an increasing hazard potential for the Halligen has to be expected if vertical marshland accretion does not accelerate in the future.

Research paper thumbnail of Mean sea level variability in the North Sea: Processes and implications

Journal of Geophysical Research: Oceans, 2014

• North Sea mean sea level variability over the past 140 years is analyzed • The variability is m... more • North Sea mean sea level variability over the past 140 years is analyzed • The variability is mainly related to local and remote atmospheric forcing • The variability hampers early detection of sea level rise acceleration Allan, M.R., and L.A. Smith (1994), Investigating the origins and significance of lowfrequency modes of climate variability, Geophys. The effect of the 18.6-year lunar nodal cycle on regional sea level rise estimates, J. Coast. Res., 28, 511-516. Bingham, R.J., and C.W. Hughes (2012), Local diagnostics to estimate density-induced sea level variations over topography and along coastlines, J. Geophys. Res., 117, C01013. Bromirski, P.D., A.J. Miller, R,E, Flick, and G. Auad (2011), Dynamical suppression of sea level rise along the Pacific coast of North America: Indications for imminent acceleration, J Geophys. Res, 116, C07005, (2013a), Characteristics of intra-, inter-annual and decadal variability and the role of meteorological forcing: the long record of Cuxhaven,

Research paper thumbnail of North Sea sea level rise and the role of inter-annual to multi-decadal variability since the late 19th century

Research paper thumbnail of Determination of regionalised extreme water levels for the North Sea Coast of Schleswig-Holstein

Research paper thumbnail of Ermittlung regionalisierter Extremwasserstände für die Schleswig-Holsteinische Nordseeküste

Research paper thumbnail of EVALUATION AND DEVELOPMENT OF COASTAL PROTECTION MEASURES FOR SMALL ISLANDS IN THE WADDEN SEA

Coastal Engineering Proceedings, 2014

Research paper thumbnail of A study on the interactions of the MSL and the movement of amphydromic points and their impact on the mean tidal range in the North Sea

According to IPCC (2007), the global average sea level rise projections are significant to the en... more According to IPCC (2007), the global average sea level rise projections are significant to the end of the century. Even the current time series analyses of the North Sea show, that there have been significant changes in the tidal regime starting from 1955 to 1960. While one can observe an appreciable increase in the mean tidal high water (MHW) from then on, the mean tidal low water (MLW) behaves contrary; as difference between the MHW and the MLW, the mean tidal range (MTR) in the German Bight rises (JENSEN and MUDERSBACH 2007). The reason for this behaviour is not as yet clarified entirely, but there have been many theoretical approaches ascribing the changes in the MTR either to anthropogenic or natural processes. The changes in the MTR can not only be observed in the German Bight, but also along the British east coast. However the MTR along the British coast shows a small decrease being the largest in the area of Aberdeen and reduces in northern and southern direction respectivel...

Research paper thumbnail of Estimating extreme water level probabilities: A comparison of the direct methods and recommendations for best practise

Coastal Engineering, 2013

Research paper thumbnail of The impact of sea level rise on storm surge water levels in the northern part of the German Bight

Coastal Engineering, 2015

The impact of mean sea level rise (SLR) on extreme water levels is investigated using a numerical... more The impact of mean sea level rise (SLR) on extreme water levels is investigated using a numerical model that covers the entire North Sea, but has its highest spatial resolution in the northern part of the German Bight. A 40-year hindcast covering the period 1970 to 2009 is conducted using observed mean sea level (MSL) changes, tides and atmospheric forcing as boundary conditions. The model reproduces the observed water levels well for this control period. A second 40-year run is then conducted considering the same atmospheric forcing but adding +0.54 m to the MSL to explore the effects of sea level rise on storm surges in the investigation area. At most locations, the second model run leads to changes in the storm surge water levels that are significantly different from the changes in MSL alone. The largest increases of the order of 15 cm (in addition to the MSL changes) occur in the shallow water areas of the Wadden Sea. These increases in storm surge water levels are caused by nonlinear changes in the tidal constituents which are spatially not coherent. The response of the tidal propagation to SLR is investigated based on the results from a tidal analysis of each individual event. These analyses point to an increase in the M 2 amplitude and decrease in the amplitudes of frictional and overtides accompanied by less tidal wave energy dissipation.

Research paper thumbnail of Entwicklung eines neuen Verfahrens zur automatischen Erkennung und Festlegung von Tidescheiteln im Bereich der Deutschen Bucht und der Ästuare

Research paper thumbnail of Determining return water levels at ungauged coastal sites: a case study for northern Germany

Ocean Dynamics, 2015

We estimate return periods and levels of extreme still water levels for the highly vulnerable and... more We estimate return periods and levels of extreme still water levels for the highly vulnerable and historically and culturally important small marsh islands known as the Halligen, located in the Wadden Sea offshore of the coast of northern Germany. This is a challenging task as only few water level records are available for this region and they are currently too short to apply traditional extreme value analysis methods. Therefore, we use the Regional Frequency Analysis (RFA) approach. This originates from hydrology but has been used before in several coastal studies and is also currently applied by the local federal administration responsible for coastal protection in the study area. The RFA enables us to indirectly estimate return levels by transferring hydrological information from gauged to related un-gauged sites. Our analyses highlight that this methodology has some drawbacks and may over-or underestimated return levels compared to direct analyses using station data.

Research paper thumbnail of Measuring sediment deposition and accretion on anthropogenic marshland – Part I: Methodical evaluation and development

Estuarine, Coastal and Shelf Science, 2014

ABSTRACT Low coastlands, marshlands and islands all over the world are challenged by rising water... more ABSTRACT Low coastlands, marshlands and islands all over the world are challenged by rising water levels due to climatic changes. The adaptation capacity of such lowlands is based on frequent inundations and according sedimentation processes. Exemplarily, a system of small islands west of Northern Germany was investigated over three years. At three out of ten so-called Halligen located in the Wadden Sea, the adaptation capacity of the anthropogenic marshland was determined. The Halligen Hooge, Langeness and Nordstrandischmoor have surface elevations only a few decimetres above mean high water and have to cope with an inundation frequency of nowadays up to 22 times per year. By use of methods introduced in Schindler et al. (2014, this volume) in combination with a 137Cs and 210Pb dating campaign on 12 sediment cores, vertical accretion rates were measured and detailed sediment accretion patterns presented. A good agreement was found between the used methods to calculate long term and short term marshland accretion rates. Sediment deposition and vertical marshland accretion is mainly controlled by the high tide events (single storm surges). Coastal protection structures, established in the early 20th century, decrease the inundation frequency and hinder the efficiency of the sediment transport by the tidal channel system on the Halligen. Vertical marshland accretion based on 210Pb dating for the time span 1915 - 2011 (1.0 ± 0.3 mm/a, Hooge, 1.2 ± 0.3 mm/a, Langeness and 2.6 ± 0.9 mm/a, Nordstrandischmoor) is in disequilibrium with the fast increasing mean high water level (MHW, 5.0 ± 0.3 mm/a). Projections until 2100 revealed that the extreme values (highest high waters, HHW) tend to rise much faster than the MHW or relative mean sea level (RMSL). Therefore an increasing hazard potential for the Halligen has to be expected if vertical marshland accretion does not accelerate in the future.

Research paper thumbnail of Mean sea level variability in the North Sea: Processes and implications

Journal of Geophysical Research: Oceans, 2014

• North Sea mean sea level variability over the past 140 years is analyzed • The variability is m... more • North Sea mean sea level variability over the past 140 years is analyzed • The variability is mainly related to local and remote atmospheric forcing • The variability hampers early detection of sea level rise acceleration Allan, M.R., and L.A. Smith (1994), Investigating the origins and significance of lowfrequency modes of climate variability, Geophys. The effect of the 18.6-year lunar nodal cycle on regional sea level rise estimates, J. Coast. Res., 28, 511-516. Bingham, R.J., and C.W. Hughes (2012), Local diagnostics to estimate density-induced sea level variations over topography and along coastlines, J. Geophys. Res., 117, C01013. Bromirski, P.D., A.J. Miller, R,E, Flick, and G. Auad (2011), Dynamical suppression of sea level rise along the Pacific coast of North America: Indications for imminent acceleration, J Geophys. Res, 116, C07005, (2013a), Characteristics of intra-, inter-annual and decadal variability and the role of meteorological forcing: the long record of Cuxhaven,

Research paper thumbnail of North Sea sea level rise and the role of inter-annual to multi-decadal variability since the late 19th century

Research paper thumbnail of Determination of regionalised extreme water levels for the North Sea Coast of Schleswig-Holstein

Research paper thumbnail of Ermittlung regionalisierter Extremwasserstände für die Schleswig-Holsteinische Nordseeküste

Research paper thumbnail of EVALUATION AND DEVELOPMENT OF COASTAL PROTECTION MEASURES FOR SMALL ISLANDS IN THE WADDEN SEA

Coastal Engineering Proceedings, 2014

Research paper thumbnail of A study on the interactions of the MSL and the movement of amphydromic points and their impact on the mean tidal range in the North Sea

According to IPCC (2007), the global average sea level rise projections are significant to the en... more According to IPCC (2007), the global average sea level rise projections are significant to the end of the century. Even the current time series analyses of the North Sea show, that there have been significant changes in the tidal regime starting from 1955 to 1960. While one can observe an appreciable increase in the mean tidal high water (MHW) from then on, the mean tidal low water (MLW) behaves contrary; as difference between the MHW and the MLW, the mean tidal range (MTR) in the German Bight rises (JENSEN and MUDERSBACH 2007). The reason for this behaviour is not as yet clarified entirely, but there have been many theoretical approaches ascribing the changes in the MTR either to anthropogenic or natural processes. The changes in the MTR can not only be observed in the German Bight, but also along the British east coast. However the MTR along the British coast shows a small decrease being the largest in the area of Aberdeen and reduces in northern and southern direction respectivel...

Research paper thumbnail of Estimating extreme water level probabilities: A comparison of the direct methods and recommendations for best practise

Coastal Engineering, 2013

Research paper thumbnail of The impact of sea level rise on storm surge water levels in the northern part of the German Bight

Coastal Engineering, 2015

The impact of mean sea level rise (SLR) on extreme water levels is investigated using a numerical... more The impact of mean sea level rise (SLR) on extreme water levels is investigated using a numerical model that covers the entire North Sea, but has its highest spatial resolution in the northern part of the German Bight. A 40-year hindcast covering the period 1970 to 2009 is conducted using observed mean sea level (MSL) changes, tides and atmospheric forcing as boundary conditions. The model reproduces the observed water levels well for this control period. A second 40-year run is then conducted considering the same atmospheric forcing but adding +0.54 m to the MSL to explore the effects of sea level rise on storm surges in the investigation area. At most locations, the second model run leads to changes in the storm surge water levels that are significantly different from the changes in MSL alone. The largest increases of the order of 15 cm (in addition to the MSL changes) occur in the shallow water areas of the Wadden Sea. These increases in storm surge water levels are caused by nonlinear changes in the tidal constituents which are spatially not coherent. The response of the tidal propagation to SLR is investigated based on the results from a tidal analysis of each individual event. These analyses point to an increase in the M 2 amplitude and decrease in the amplitudes of frictional and overtides accompanied by less tidal wave energy dissipation.