TY - JOUR A1 - Selle, Benny A1 - Graeff, Thomas A1 - Salzmann, Thomas A1 - Oswald, Sascha Eric A1 - Walther, Marc A1 - Miegel, Konrad T1 - Investigation of a renatured fen catchment on the Baltic Sea coast of Mecklenburg - Part II: Salt dynamics and water balance JF - Hydrologie und Wasserbewirtschaftung N2 - Coastal fens like the nature reserve "Hutelmoor und Heiligensee" (north-eastern Germany) are important landscape elements along the southern Baltic coast, which exchange fresh water and brackish water with the Baltic Sea. These exchange processes can be understood as experiments with a natural tracer, which may be used to investigate the hydrologic behaviour of these fen systems. With the establishment of coastal protection measures such as dunes and dikes, the installation of surface drainage and, more recently, also nature conservation measures, the hydrologic regime of these coastal wetlands has constantly altered over the last centuries.The rehabilitated wetland "Hutelnnoor und Heiligensee" is suitable for an analysis of hydrologic change as it has been monitored over the time period since nature conservation measures started in the 1990s. Collected data sets included observation of groundwater levels and electrical conductivities, weather data as well as discharge at the outlet of the drainage catchment. In this article, as a second part of the dual publication, processes and quantified process magnitudes have been identified that govern the salt balance of the study area including its variability in space and time. It was detected that - over the period of rehabilitation - salt water entered the catchment with an episodic storm surge by wave overtopping of dunes in 1995. The intruded brackish water was then diluted, which was a slow process extending over decades. It was governed by local groundwater recharge from precipitation and the inflow of relatively fresh groundwater from the hinterland. It is concluded that salt inputs from the Baltic Sea provide a natural tracer of hydrological processes, which can be readily monitored via electrical conductivity measurements. KW - Baltic Sea KW - coastal wetland KW - drainage of the catchment area KW - groundwater flow KW - management effects KW - system analysis KW - water balance Y1 - 2016 U6 - https://doi.org/10.5675/HyWa_2016.4_2 SN - 1439-1783 VL - 60 SP - 259 EP - 268 PB - Bundesanst. für Gewässerkunde CY - Koblenz ER - TY - JOUR A1 - Miegel, Konrad A1 - Gräff, Thomas A1 - Franck, Christian A1 - Salzmann, Thomas A1 - Bronstert, Axel A1 - Walther, Marc A1 - Oswald, Sascha Eric 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 - TY - GEN A1 - Jing, Miao A1 - Heße, Falk A1 - Kumar, Rohini A1 - Wang, Wenqing A1 - Fischer, Thomas A1 - Walther, Marc A1 - Zink, Matthias A1 - Zech, Alraune A1 - Samaniego, Luis A1 - Kolditz, Olaf A1 - Attinger, Sabine T1 - Improved regional-scale groundwater representation by the coupling of the mesoscale Hydrologic Model (mHM v5.7) to the groundwater model OpenGeoSys (OGS) T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - Most large-scale hydrologic models fall short in reproducing groundwater head dynamics and simulating transport process due to their oversimplified representation of groundwater flow. In this study, we aim to extend the applicability of the mesoscale Hydrologic Model (mHM v5.7) to subsurface hydrology by coupling it with the porous media simulator OpenGeoSys (OGS). The two models are one-way coupled through model interfaces GIS2FEM and RIV2FEM, by which the grid-based fluxes of groundwater recharge and the river-groundwater exchange generated by mHM are converted to fixed-flux boundary conditions of the groundwater model OGS. Specifically, the grid-based vertical reservoirs in mHM are completely preserved for the estimation of land-surface fluxes, while OGS acts as a plug-in to the original mHM modeling framework for groundwater flow and transport modeling. The applicability of the coupled model (mHM-OGS v1.0) is evaluated by a case study in the central European mesoscale river basin - Nagelstedt. Different time steps, i.e., daily in mHM and monthly in OGS, are used to account for fast surface flow and slow groundwater flow. Model calibration is conducted following a two-step procedure using discharge for mHM and long-term mean of groundwater head measurements for OGS. Based on the model summary statistics, namely the Nash-Sutcliffe model efficiency (NSE), the mean absolute error (MAE), and the interquartile range error (QRE), the coupled model is able to satisfactorily represent the dynamics of discharge and groundwater heads at several locations across the study basin. Our exemplary calculations show that the one-way coupled model can take advantage of the spatially explicit modeling capabilities of surface and groundwater hydrologic models and provide an adequate representation of the spatiotemporal behaviors of groundwater storage and heads, thus making it a valuable tool for addressing water resources and management problems. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 851 KW - travel-time distributions KW - surface-water KW - land-surface KW - surface/subsurface flow KW - parameter-estimation KW - subsurface flow KW - transport model KW - climate-change KW - river-basins KW - catchment Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-427030 SN - 1866-8372 IS - 851 SP - 1989 EP - 2007 ER - TY - JOUR A1 - Jing, Miao A1 - Hesse, Falk A1 - Kumar, Rohini A1 - Wang, Wenqing A1 - Fischer, Thomas A1 - Walther, Marc A1 - Zink, Matthias A1 - Zech, Alraune A1 - Samaniego, Luis A1 - Kolditz, Olaf A1 - Attinger, Sabine T1 - Improved regional-scale groundwater representation by the coupling of the mesoscale Hydrologic Model (mHM v5.7) to the groundwater model OpenGeoSys (OGS) JF - Geoscientific model development : an interactive open access journal of the European Geosciences Union N2 - Most large-scale hydrologic models fall short in reproducing groundwater head dynamics and simulating transport process due to their oversimplified representation of groundwater flow. In this study, we aim to extend the applicability of the mesoscale Hydrologic Model (mHM v5.7) to subsurface hydrology by coupling it with the porous media simulator OpenGeoSys (OGS). The two models are one-way coupled through model interfaces GIS2FEM and RIV2FEM, by which the grid-based fluxes of groundwater recharge and the river-groundwater exchange generated by mHM are converted to fixed-flux boundary conditions of the groundwater model OGS. Specifically, the grid-based vertical reservoirs in mHM are completely preserved for the estimation of land-surface fluxes, while OGS acts as a plug-in to the original mHM modeling framework for groundwater flow and transport modeling. The applicability of the coupled model (mHM-OGS v1.0) is evaluated by a case study in the central European mesoscale river basin - Nagelstedt. Different time steps, i.e., daily in mHM and monthly in OGS, are used to account for fast surface flow and slow groundwater flow. Model calibration is conducted following a two-step procedure using discharge for mHM and long-term mean of groundwater head measurements for OGS. Based on the model summary statistics, namely the Nash-Sutcliffe model efficiency (NSE), the mean absolute error (MAE), and the interquartile range error (QRE), the coupled model is able to satisfactorily represent the dynamics of discharge and groundwater heads at several locations across the study basin. Our exemplary calculations show that the one-way coupled model can take advantage of the spatially explicit modeling capabilities of surface and groundwater hydrologic models and provide an adequate representation of the spatiotemporal behaviors of groundwater storage and heads, thus making it a valuable tool for addressing water resources and management problems. Y1 - 2018 U6 - https://doi.org/10.5194/gmd-11-1989-2018 SN - 1991-959X SN - 1991-9603 VL - 11 IS - 5 SP - 1989 EP - 2007 PB - Copernicus CY - Göttingen ER -