TY  - THES
A1  - Creutzfeldt, Noah Angelo Benjamin
T1  - The effect of water storages on temporal gravity measurements and the benefits for hydrology
T1  - Der Effekt von Wasserspeicher auf zeitabhängige Gravitationsmessungen und der Nutzen für die Hydrologie
N2  - Temporal gravimeter observations, used in geodesy and geophysics to study variation of the Earth’s gravity field, are influenced by local water storage changes (WSC) and – from this perspective – add noise to the gravimeter signal records. At the same time, the part of the gravity signal caused by WSC may provide substantial information for hydrologists. Water storages are the fundamental state variable of hydrological systems, but comprehensive data on total WSC are practically inaccessible and their quantification is associated with a high level of uncertainty at the field scale. This study investigates the relationship between temporal gravity measurements and WSC in order to reduce the hydrological interfering signal from temporal gravity measurements and to explore the value of temporal gravity measurements for hydrology for the superconducting gravimeter (SG) of the Geodetic Observatory Wettzell, Germany. A 4D forward model with a spatially nested discretization domain was developed to simulate and calculate the local hydrological effect on the temporal gravity observations. An intensive measurement system was installed at the Geodetic Observatory Wettzell and WSC were measured in all relevant storage components, namely groundwater, saprolite, soil, top soil and snow storage. The monitoring system comprised also a suction-controlled, weighable, monolith-filled lysimeter, allowing an all time first comparison of a lysimeter and a gravimeter. Lysimeter data were used to estimate WSC at the field scale in combination with complementary observations and a hydrological 1D model. Total local WSC were derived, uncertainties were assessed and the hydrological gravity response was calculated from the WSC. A simple conceptual hydrological model was calibrated and evaluated against records of a superconducting gravimeter, soil moisture and groundwater time series. The model was evaluated by a split sample test and validated against independently estimated WSC from the lysimeter-based approach. A simulation of the hydrological gravity effect showed that WSC of one meter height along the topography caused a gravity response of 52 µGal, whereas, generally in geodesy, on flat terrain, the same water mass variation causes a gravity change of only 42 µGal (Bouguer approximation). The radius of influence of local water storage variations can be limited to 1000 m and 50 % to 80 % of the local hydro¬logical gravity signal is generated within a radius of 50 m around the gravimeter. At the Geodetic Observatory Wettzell, WSC in the snow pack, top soil, unsaturated saprolite and fractured aquifer are all important terms of the local water budget. With the exception of snow, all storage components have gravity responses of the same order of magnitude and are therefore relevant for gravity observations. The comparison of the total hydrological gravity response to the gravity residuals obtained from the SG, showed similarities in both short-term and seasonal dynamics. However, the results demonstrated the limitations of estimating total local WSC using hydrological point measurements. The results of the lysimeter-based approach showed that gravity residuals are caused to a larger extent by local WSC than previously estimated. A comparison of the results with other methods used in the past to correct temporal gravity observations for the local hydrological influence showed that the lysimeter measurements improved the independent estimation of WSC significantly and thus provided a better way of estimating the local hydrological gravity effect. In the context of hydrological noise reduction, at sites where temporal gravity observations are used for geophysical studies beyond local hydrology, the installation of a lysimeter in combination with complementary hydrological measurements is recommended. From the hydrological view point, using gravimeter data as a calibration constraint improved the model results in comparison to hydrological point measurements. Thanks to their capacity to integrate over different storage components and a larger area, gravimeters provide generalized information on total WSC at the field scale. Due to their integrative nature, gravity data must be interpreted with great care in hydrological studies. However, gravimeters can serve as a novel measurement instrument for hydrology and the application of gravimeters especially designed to study open research questions in hydrology is recommended.
N2  - Zeitabhängigen Gravimetermessungen, die in der Geodäsie und der Geophysik eingesetzt werden, um Variationen des Erdschwerefelds zu messen, werden durch lokale Wasserspeicheränderungen beeinflusst und verursachen – aus dieser Perspektive – ein hydrologisches Störsignal in den Gravimetermessungen. Gleichzeitig bietet der Teil des Gravimetersignals, der durch Wasserspeicheränderungen hervorgerufen wird, das Potential wichtige Informationen über hydrologische Speicher zu gewinnen, da zwar Wasserspeicher eine grundlegende Zustandsgröße hydrologischer Systeme darstellt, jedoch ihre Quantifizierung mit einem hohen Maß an Unsicherheiten auf der Feldskala behaftet ist. Diese Studie untersucht die Beziehung zwischen zeitabhängigen Gravimetermessungen und Wasserspeicheränderungen, um die Gravimetermessungen von dem hydrologischen Störsignal zu bereinigen und um den Nutzen der Gravimetermessungen für die Hydrologie zu erkunden. Dies geschieht am Beispiel des Supraleitgravimeters (SG) des Geodätischen Observatoriums Wettzell in Deutschland. Ein 4D Vorwärtsmodel mit einer räumlich genesteten Diskretisierungsdomäne wurde entwickelt, um die lokalen hydrologischen Masseneffekte auf Gravimetermessungen zu simulieren. Des Weiteren wurde ein intensives Messsystem am Geodätischen Observatorium Wettzell installiert, um die Wasserspeicheränderungen in allen relevanten Speicherkomponenten, also im dem Grundwasser, in der ungesättigten Zone und im Schneespeicher zu messen. Das Monitoringsystem beinhaltete auch einen wägbaren, monolithischen Lysimeter mit Matrixpotentialübertragung, der es uns ermöglichte, zum ersten Mal einen Lysimeter direkt mit einem Gravimeter zu vergleichen. Die Lysimetermessungen wurden in Kombination mit komplementären hydrologischen Beobachtungen und einem 1D-Modell verwendet, um die Wasserspeicheränderungen auf der Feldskala zu bestimmen. Die Gesamtwasserspeicheränderungen wurden bestimmt, Unsicherheiten abgeschätzt und der hydrologische Masseneffekt auf Gravimetermessungen berechnet. Schlussendlich wurde ein einfaches, konzeptionelles, hydrologisches Modell mittels der Zeitreihen von dem SG, Bodenfeuchte- und Grundwassermessungen kalibriert und evaluiert. Das Modell wurde durch einen “Split-Sample-Test” evaluiert und basierend auf unabhängig bestimmten Wasserspeicheränderungen bestimmt auf Grundlage der Lysimetermessungen validiert. Die Simulation des hydrologischen Masseneffektes auf Gravimetermessungen zeigte, dass Wasserspeicheränderungen von einem Meter Höhe entlang der Topographie, einen Erdschwereeffekt von 52 µGal hervorriefen, während in der Geodäsie im Allgemeinen die gleiche Wassermassenvariation in flachem Terrain eine Erdschwereeffekt von nur 42 µGal (Bouguer-Platte) hervorruft. Der Einflussradius der lokalen Wasserspeicheränderungen kann auf 1000 m begrenzt werden, und 50 % bis 80 % des lokalen hydrologischen Erdschweresignals wird in einem Radius von 50 m um den Gravimeter generiert. Wasserspeichervariationen in der Schneedecke, im Oberboden, dem ungesättigten Saprolith und im gelüfteten Aquifer, sind allesamt wichtige Größen der lokalen Wasserbilanz. Mit der Ausnahme von Schnee beeinflussen alle Speicheränderungen die Gravimetermessungen in derselben Größenordnung und sind daher für die Gravimetermessungen von Bedeutung. Ein Vergleich des lokalen hydrologischen Gravitationseffektes mit den SG Residuen zeigte sowohl ereignisbezogene als auch saisonalen Übereinstimmungen. Weiterhin zeigten die Ergebnisse jedoch auch die Grenzen bei der Bestimmung der gesamten lokalen Wasserspeichervariationen mithilfe hydrologischer Punktmessungen auf. Die Ergebnisse des Lysimeter-basierten Ansatzes zeigten, dass SG Residuen mehr noch, als bisher aufgezeigt, durch lokale Wasserspeicheränderungen hervorgerufen werden. Ein Vergleich der Resultate mit anderen Methoden, die in der Vergangenheit zur Korrektur zeitabhängiger Erdschwerebeobachtungen durch Bestimmung des lokalen hydrologischen Masseneffekte verwendet wurden, zeigte, dass die unabhängige Berechnung von Wasserspeicheränderungen durch Lysimetermessungen erheblich verbessert werden kann und dass diese somit eine verbesserte Methode zur Bestimmung des lokalen hydrologischen Erdschwereeffekts darstellt. Die Installation eines Lysimeters ist somit im Zusammenhang mit einer Reduzierung des hydrologischen Störsignals und an Standorten, wo zeitabhängige Erdschwerebeobachtungen für geophysikalische Studien, die über die lokale Hydrologie hinausgehen verwendet werden, zu empfehlen. Aus hydrologischer Sicht zeigte diese Studie, dass die Verwendung von zeitabhängigen Gravimetermessungen als Kalibrierungsdaten die Modellergebnisse im Vergleich zu hydrologischen Punktmessungen verbesserten. Auf Grund ihrer Fähigkeit, über verschiedene Speicherkomponenten und ein größeres Gebiet zu integrieren, bieten Gravimeter verallgemeinerte Informationen über die Gesamtwasserspeicherveränderungen auf der Feldskala. Diese integrative Eigenschaft macht es notwendig, Erdschweredaten in hydrologischen Studien mit großer Vorsicht zu interpretieren. Dennoch können Gravimeter der Hydrologie als neuartiges Messinstrument dienen und die Nutzung von Gravimetern, die speziell für die Beantwortung noch offener Forschungsfragen der Hydrologie entwickelt wurden wird hier empfohlen.
KW  - Hydrogeopyhsik
KW  - zeitabhängige Gravitationsvariation
KW  - Wasserspeicheränderungen
KW  - Supraleitender Gravimeter (SG)
KW  - hydrologische Modellierung
KW  - Hydrogeophysics
KW  - temporal gravity variations
KW  - water storage changes
KW  - superconducting gravimeter (SG)
KW  - hydrological monitoring and modelling
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-48575
ER  - 
TY  - JOUR
A1  - Medeiros, Pedro Henrique Augusto
A1  - de Araujo, Jose Carlos
A1  - Mamede, George Leite
A1  - Creutzfeldt, Benjamin
A1  - Guentner, Andreas
A1  - Bronstert, Axel
T1  - Connectivity of sediment transport in a semiarid environment: a synthesis for the Upper Jaguaribe Basin, Brazil
JF  - Journal of soils and sediments : protection, risk assessment and remediation
N2  - Hydrosedimentological studies conducted in the semiarid Upper Jaguaribe Basin, Brazil, enabled the identification of the key processes controlling sediment connectivity at different spatial scales (10(0)-10(4) km(2)).
 Water and sediment fluxes were assessed from discharge, sediment concentrations and reservoir siltation measurements. Additionally, mathematical modelling (WASA-SED model) was used to quantify water and sediment transfer within the watershed.
 Rainfall erosivity in the study area was moderate (4600 MJ mm ha(-1) h(-1) year(-1)), whereas runoff depths (16-60 mm year(-1)), and therefore the sediment transport capacity, were low. Consequently, similar to 60 % of the eroded sediment was deposited along the landscape, regardless of the spatial scale. The existing high-density reservoir network (contributing area of 6 km(2) per reservoir) also limits sediment propagation, retaining up to 47 % of the sediment at the large basin scale. The sediment delivery ratio (SDR) decreased with the spatial scale; on average, 41 % of the eroded sediment was yielded from the hillslopes, while for the whole 24,600-km(2) basin, the SDR was reduced to 1 % downstream of a large reservoir (1940-hm(3) capacity).
 Hydrological behaviour in the Upper Jaguaribe Basin represents a constraint on sediment propagation; low runoff depth is the main feature breaking sediment connectivity, which limits sediment transference from the hillslopes to the drainage system. Surface reservoirs are also important barriers, but their relative importance to sediment retention increases with scale, since larger contributing areas are more suitable for the construction of dams due to higher hydrological potential.
KW  - Brazil
KW  - Connectivity
KW  - Sediment redistribution
KW  - Semiarid
KW  - Spatial scale
Y1  - 2014
U6  - https://doi.org/10.1007/s11368-014-0988-z
SN  - 1439-0108
SN  - 1614-7480
VL  - 14
IS  - 12
SP  - 1938
EP  - 1948
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - GEN
A1  - Güntner, Andreas
A1  - Reich, Marvin
A1  - Mikolaj, Michal
A1  - Creutzfeldt, Benjamin
A1  - Schroeder, Stephan
A1  - Wziontek, Hartmut
T1  - Landscape-scale water balance monitoring with an iGrav superconducting gravimeter in a field enclosure
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - In spite of the fundamental role of the landscape water balance for the Earth's water and energy cycles, monitoring the water balance and its components beyond the point scale is notoriously difficult due to the multitude of flow and storage processes and their spatial heterogeneity. Here, we present the first field deployment of an iGrav superconducting gravimeter (SG) in a minimized enclosure for long-term integrative monitoring of water storage changes. Results of the field SG on a grassland site under wet-temperate climate conditions were compared to data provided by a nearby SG located in the controlled environment of an observatory building. The field system proves to provide gravity time series that are similarly precise as those of the observatory SG. At the same time, the field SG is more sensitive to hydrological variations than the observatory SG. We demonstrate that the gravity variations observed by the field setup are almost independent of the depth below the terrain surface where water storage changes occur (contrary to SGs in buildings), and thus the field SG system directly observes the total water storage change, i.e., the water balance, in its surroundings in an integrative way. We provide a framework to single out the water balance components actual evapotranspiration and lateral subsurface discharge from the gravity time series on annual to daily timescales. With about 99 and 85% of the gravity signal due to local water storage changes originating within a radius of 4000 and 200m around the instrument, respectively, this setup paves the road towards gravimetry as a continuous hydrological field-monitoring technique at the landscape scale.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 663 
KW  - gravity measurements
KW  - local hydrology
KW  - storage changes
KW  - noise-levels
KW  - time
KW  - system
KW  - attraction
KW  - athmosphere
KW  - surface
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-419105
SN  - 1866-8372
IS  - 663
ER  - 
TY  - JOUR
A1  - Guentner, Andreas
A1  - Reich, Marvin
A1  - Mikolaj, Michal
A1  - Creutzfeldt, Benjamin
A1  - Schroeder, Stephan
A1  - Wziontek, Hartmut
T1  - Landscape-scale water balance monitoring with an iGrav superconducting gravimeter in a field enclosure
JF  - Hydrology and earth system sciences : HESS
Y1  - 2017
U6  - https://doi.org/10.5194/hess-21-3167-2017
SN  - 1027-5606
SN  - 1607-7938
VL  - 21
SP  - 3167
EP  - 3182
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Gräff, Thomas
A1  - Zehe, Erwin
A1  - Schläger, Stefan
A1  - Morgner, Markus
A1  - Bauer, Andreas
A1  - Becker, Rolf
A1  - Creutzfeldt, Benjamin
A1  - Bronstert, Axel
T1  - A quality assessment of spatial TDR soil moisture measurements in homogenous and heterogeneous media with laboratory experiments
N2  - Investigation of transient soil moisture profiles yields valuable information of near- surface processes. A recently developed reconstruction algorithm based on the telegraph equation allows the inverse estimation of soil moisture profiles along coated, three rod TDR probes. Laboratory experiments were carried out to prove the results of the inversion and to understand the influence of probe rod deformation and solid objects close to the probe in heterogonous media. Differences in rod geometry can lead to serious misinterpretations in the soil moisture profile but have small influence on the average soil moisture along the probe. Solids in the integration volume have almost no effect on average soil moisture but result in locally slightly decreased moisture values. Inverted profiles obtained in a loamy soil with a clay content of about 16% were in good agreement with independent measurements.
Y1  - 2010
UR  - http://www.hydrol-earth-syst-sci-discuss.net/volumes_and_issues.html
U6  - https://doi.org/10.5194/hessd-7-269-2010
SN  - 1812-2108
ER  - 
TY  - JOUR
A1  - Gräff, Thomas
A1  - Zehe, Erwin
A1  - Schlaeger, Stefan
A1  - Morgner, Markus
A1  - Bauer, Andreas
A1  - Becker, Rolf
A1  - Creutzfeldt, Benjamin
A1  - Bronstert, Axel
T1  - A quality assessment of Spatial TDR soil moisture measurements in homogenous and heterogeneous media with laboratory experiments
N2  - Investigation of transient soil moisture profiles yields valuable information of near- surface processes. A recently developed reconstruction algorithm based on the telegraph equation allows the inverse estimation of soil moisture profiles along coated, three rod TDR probes. Laboratory experiments were carried out to prove the results of the inversion and to understand the influence of probe rod deformation and solid objects close to the probe in heterogeneous media. Differences in rod geometry can lead to serious misinterpretations in the soil moisture profile, but have small influence on the average soil moisture along the probe. Solids in the integration volume have almost no effect on average soil moisture, but result in locally slightly decreased moisture values. Inverted profiles obtained in a loamy soil with a clay content of about 16% were in good agreement with independent measurements.
Y1  - 2010
UR  - http://www.copernicus.org/EGU/hess/hess.html
U6  - https://doi.org/10.5194/hess-14-1007-2010
SN  - 1027-5606
ER  - 
TY  - JOUR
A1  - Bronstert, Axel
A1  - Creutzfeldt, Benjamin
A1  - Gräff, Thomas
A1  - Hajnsek, Irena
A1  - Heistermann, Maik
A1  - Itzerott, Sibylle
A1  - Jagdhuber, Thomas
A1  - Kneis, David
A1  - Lueck, Erika
A1  - Reusser, Dominik
A1  - Zehe, Erwin
T1  - Potentials and constraints of different types of soil moisture observations for flood simulations in headwater catchments
JF  - Natural hazards : journal of the International Society for the Prevention and Mitigation of Natural Hazards
N2  - Flood generation in mountainous headwater catchments is governed by rainfall intensities, by the spatial distribution of rainfall and by the state of the catchment prior to the rainfall, e. g. by the spatial pattern of the soil moisture, groundwater conditions and possibly snow. The work presented here explores the limits and potentials of measuring soil moisture with different methods and in different scales and their potential use for flood simulation. These measurements were obtained in 2007 and 2008 within a comprehensive multi-scale experiment in the Weisseritz headwater catchment in the Ore-Mountains, Germany. The following technologies have been applied jointly thermogravimetric method, frequency domain reflectometry (FDR) sensors, spatial time domain reflectometry (STDR) cluster, ground-penetrating radar (GPR), airborne polarimetric synthetic aperture radar (polarimetric SAR) and advanced synthetic aperture radar (ASAR) based on the satellite Envisat. We present exemplary soil measurement results, with spatial scales ranging from point scale, via hillslope and field scale, to the catchment scale. Only the spatial TDR cluster was able to record continuous data. The other methods are limited to the date of over-flights (airplane and satellite) or measurement campaigns on the ground. For possible use in flood simulation, the observation of soil moisture at multiple scales has to be combined with suitable hydrological modelling, using the hydrological model WaSiM-ETH. Therefore, several simulation experiments have been conducted in order to test both the usability of the recorded soil moisture data and the suitability of a distributed hydrological model to make use of this information. The measurement results show that airborne-based and satellite-based systems in particular provide information on the near-surface spatial distribution. However, there are still a variety of limitations, such as the need for parallel ground measurements (Envisat ASAR), uncertainties in polarimetric decomposition techniques (polarimetric SAR), very limited information from remote sensing methods about vegetated surfaces and the non-availability of continuous measurements. The model experiments showed the importance of soil moisture as an initial condition for physically based flood modelling. However, the observed moisture data reflect the surface or near-surface soil moisture only. Hence, only saturated overland flow might be related to these data. Other flood generation processes influenced by catchment wetness in the subsurface such as subsurface storm flow or quick groundwater drainage cannot be assessed by these data. One has to acknowledge that, in spite of innovative measuring techniques on all spatial scales, soil moisture data for entire vegetated catchments are still today not operationally available. Therefore, observations of soil moisture should primarily be used to improve the quality of continuous, distributed hydrological catchment models that simulate the spatial distribution of moisture internally. Thus, when and where soil moisture data are available, they should be compared with their simulated equivalents in order to improve the parameter estimates and possibly the structure of the hydrological model.
KW  - Soil moisture
KW  - Remote sensing
KW  - Hydrological modelling
KW  - Flood forecasting
KW  - Soil moisture measurement comparison
Y1  - 2012
U6  - https://doi.org/10.1007/s11069-011-9874-9
SN  - 0921-030X
SN  - 1573-0840
VL  - 60
IS  - 3
SP  - 879
EP  - 914
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Creutzfeldt, Benjamin
A1  - Troch, Peter A.
A1  - Guentner, Andreas
A1  - Ferre, Ty P. A.
A1  - Gräff, Thomas
A1  - Merz, Bruno
T1  - Storage-discharge relationships at different catchment scales based on local high-precision gravimetry
JF  - Hydrological processes
N2  - In hydrology, the storage-discharge relationship is a fundamental catchment property. Understanding what controls this relationship is at the core of catchment science. To date, there are no direct methods to measure water storage at catchment scales (10(1)-10(3)km(2)). In this study, we use direct measurements of terrestrial water storage dynamics by means of superconducting gravimetry in a small headwater catchment of the Regen River, Germany, to derive empirical storage-discharge relationships in nested catchments of increasing scale. Our results show that the local storage measurements are strongly related to streamflow dynamics at larger scales (> 100km(2); correlation coefficient=0.78-0.81), but at small scale, no such relationship exists (similar to 1km(2); correlation coefficients=-0.11). The geologic setting in the region can explain both the disconnection between local water storage and headwater runoff, and the connectivity between headwater storage and streams draining larger catchment areas. More research is required to understand what controls the form of the observed storage-discharge relationships at the catchment scale. This study demonstrates that high-precision gravimetry can provide new insights into the complex relationship between state and response of hydrological systems.
KW  - water storage
KW  - high-precision gravimeter
KW  - storage-discharge relationship
KW  - nested catchments
Y1  - 2014
U6  - https://doi.org/10.1002/hyp.9689
SN  - 0885-6087
SN  - 1099-1085
VL  - 28
IS  - 3
SP  - 1465
EP  - 1475
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -