Assessing the precision of the iGrav superconducting gravimeter for hydrological models and karstic hydrological process identification

Hydrological signatures aim at extracting information about certain aspects of hydrological behaviour. They can be used to quantify hydrological similarity, to explore catchment functioning and to evaluate hydrological models. Relating hydrological signatures to hydrological processes is, however, still a challenge and many signatures remain poorly understood.We propose a flexible approach for linking hydrological signatures to hydrological processes, which might help to improve our understanding and hence the usefulness of certain hydrological signatures. As a first step, we should build a perceptual model describing the hydrological process of interest. We should then try to find or create relevant &#8211; and ideally widely available &#8211; catchment attributes that target the process of interest, and hence have the potential to explain the signature in a process-based way. We should control for climate by either incorporating it into our perceptual model or by analysing sub-climates individually, to disentangle the influences of forcing and catchment form. Lastly, simple conceptual models might be a useful tool to systematically explore the controlling factors (parameters, forcing) of a signature. Focusing on hydrological processes and explaining hydrological signatures in a process-based way will make hydrological signatures more meaningful, useful and robust.The proposed approach is tested on signatures related to baseflow and groundwater processes, such as the baseflow index. Baseflow generation has been studied extensively, and while many regional studies could identify landscape controls on baseflow generation (e.g. soils and geology), continental or global studies have resulted in a less clear picture, partially because of the masking influence of climate at these scales. Furthermore, the relationship between controls, such as climate and catchment form, and baseflow response has often been only described statistically (e.g. by means of regression-type approaches). &#160;A mechanistic theory based on widely available catchment attributes (e.g. soils, geology, topography) would thus be a major step towards improved understanding and transferability.

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The impact of hydrological model structure on the simulation of extreme runoff events

Natural Hazards and Earth System Science ◽

10.5194/nhess-21-961-2021 ◽

2021 ◽

Vol 21 (3) ◽

pp. 961-976

Author(s):

Gijs van Kempen ◽

Karin van der Wiel ◽

Lieke Anna Melsen

Keyword(s):

Hydrological Model ◽

Low Flow ◽

Temperate Climate ◽

Hydrological Process ◽

Model Structure ◽

Hydrological Models ◽

Climate Zones ◽

The Impact ◽

Model Structures ◽

Runoff Events

Abstract. Hydrological extremes affect societies and ecosystems around the world in many ways, stressing the need to make reliable predictions using hydrological models. However, several different hydrological models can be selected to simulate extreme events. A difference in hydrological model structure results in a spread in the simulation of extreme runoff events. We investigated the impact of different model structures on the magnitude and timing of simulated extreme high- and low-flow events by combining two state-of-the-art approaches: a modular modelling framework (FUSE) and large ensemble meteorological simulations. This combination of methods created the opportunity to isolate the impact of specific hydrological process formulations at long return periods without relying on statistical models. We showed that the impact of hydrological model structure was larger for the simulation of low-flow compared to high-flow events and varied between the four evaluated climate zones. In cold and temperate climate zones, the magnitude and timing of extreme runoff events were significantly affected by different parameter sets and hydrological process formulations, such as evaporation. In the arid and tropical climate zones, the impact of hydrological model structures on extreme runoff events was smaller. This novel combination of approaches provided insights into the importance of specific hydrological process formulations in different climate zones, which can support adequate model selection for the simulation of extreme runoff events.

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Hydrological Signals in Tilt and Gravity Residuals at Conrad Observatory (Austria)

10.5194/hess-2020-316 ◽

2020 ◽

Author(s):

Bruno Meurers ◽

Gábor Papp ◽

Hannu Ruotsalainen ◽

Judit Benedek ◽

Roman Leonhardt

Keyword(s):

Vertical Component ◽

Gravitational Effect ◽

Heavy Rain ◽

Superconducting Gravimeter ◽

Gravity Potential ◽

Hydrological Process ◽

Wide Range ◽

Site Water ◽

Set Up

Abstract. The Superconducting Gravimeter GWR C025 monitors the vertical component of the gravity vector at the Conrad Observatory (Austria) since autumn 2007. Two tilt meters operate continuously since spring 2016: a 5.5 m long interferometric water level tilt meter and a Lippmann-type 2D pendulum tilt sensor. The co-located and co-oriented set up enables a wide range of investigations because tilts are sensitive both to geometrical solid Earth deformations and to gravity potential changes. The tide free residuals of the SG and both tilt meters clearly reflect the gravity/deformation effects associated with short- and long-term environmental processes and reveal a complex water transport process at the observatory site. Water accumulation on the terrain surface causes short-term (a few hours) effects which are clearly imaged by the SG gravity and N-S tilt residuals. Long-term (> a few days/weeks) tilt and gravity variations occur frequently after long-lasting rain, heavy rain or rapid snowmelt. Gravity and tilt residuals are associated to the same hydrological process but have different physical causes. SG gravity residuals reveal the gravitational effect of water mass transport, while modelling results exclude a purely gravitational source of the observed tilts. Tilt residuals show the response on surface loading instead. N-S tilt signals are much stronger than those of the E-W component most probably due to the well-known cavity effect of the 150 m long tunnel oriented in E-W direction.

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Hydrological signals in tilt and gravity residuals at Conrad Observatory (Austria)

Hydrology and Earth System Sciences ◽

10.5194/hess-25-217-2021 ◽

2021 ◽

Vol 25 (1) ◽

pp. 217-236

Author(s):

Bruno Meurers ◽

Gábor Papp ◽

Hannu Ruotsalainen ◽

Judit Benedek ◽

Roman Leonhardt

Keyword(s):

Gravitational Effect ◽

Heavy Rain ◽

Superconducting Gravimeter ◽

Gravity Potential ◽

Hydrological Process ◽

Wide Range ◽

Site Water ◽

Set Up ◽

Cavity Effect

Abstract. The superconducting gravimeter (SG) GWR C025 has monitored the time variation in gravity at the Conrad Observatory (Austria) since autumn 2007. Two tiltmeters have operated continuously since spring 2016, namely a 5.5 m long interferometric water level tiltmeter and a Lippmann-type 2D pendulum tilt sensor. The co-located and co-oriented set up enables a wide range of investigations because the tilts are sensitive to both geometrical solid Earth deformations and to gravity potential changes. The tide-free residuals of the SG and both tiltmeters clearly reflect the gravity and/or deformation effects associated with short- and long-term environmental processes and reveal a complex water transport process at the observatory site. Water accumulation on the terrain surface causes short-term (a few hours) effects which are clearly imaged by the SG gravity and N–S tilt residuals. Long-term (> a few days/weeks) tilt and gravity variations occur frequently after long-lasting rain, heavy rain or rapid snowmelt. Gravity and tilt residuals are associated with the same hydrological process but have different physical causes. SG gravity residuals reveal the gravitational effect of water mass transport, while modelling results exclude a purely gravitational source of the observed tilts. Tilt residuals show the response on surface loading instead. Tilts can be strongly affected by strain–tilt coupling (cavity effect). N–S tilt signals are much stronger than those of the E–W component, which is most probably due to the cavity effect of the 144 m long tunnel being oriented in an E–W direction.

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The impact of hydrological model structure on the simulation of extreme runoff events

10.5194/nhess-2020-154 ◽

2020 ◽

Author(s):

Gijs van Kempen ◽

Karin van der Wiel ◽

Lieke Anna Melsen

Keyword(s):

Hydrological Model ◽

Low Flow ◽

Temperate Climate ◽

Hydrological Process ◽

Model Structure ◽

Hydrological Models ◽

Climate Zones ◽

The Impact ◽

Model Structures ◽

Runoff Events

Abstract. Hydrological extremes affect societies and ecosystems around the world in many ways, stressing the need to make reliable predictions using hydrological models. However, several hydrological models can be selected to simulate extreme events. A difference in hydrological model structure results in a spread in the simulation of extreme runoff events. We investigated the impact of different model structures on the magnitude and timing of simulated extreme high- and low-flow events, by combining two state-of-the-art approaches; a modular modelling framework (FUSE) and large ensemble meteorological simulations. This combination of methods created the opportunity to isolate the impact of specific hydrological process formulations at long return periods without relying on statistical models. We showed that the impact of hydrological model structure was larger for the simulation of low-flow compared to high-flow events and varied between the four evaluated climate zones. In cold and temperate climate zones, the magnitude and timing of extreme runoff events were significantly affected by different parameter sets and hydrological process formulations, such as evaporation. The impact of hydrological model structures on extreme runoff events was smaller in the arid and tropical climate zones. This novel combination of approaches provided insights into the importance of specific hydrological processes formulations in different climate zones, which can support adequate model selection for the simulation of extreme runoff events.

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The importance of topography controlled sub-grid process heterogeneity in distributed hydrological models

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-13301-2015 ◽

2015 ◽

Vol 12 (12) ◽

pp. 13301-13358 ◽

Cited By ~ 1

Author(s):

R. C. Nijzink ◽

L. Samaniego ◽

J. Mai ◽

R. Kumar ◽

S. Thober ◽

...

Keyword(s):

Expert Knowledge ◽

Model Performance ◽

Hydrologic Model ◽

Low Flow ◽

Evaluation Procedure ◽

Base Case ◽

Hydrological Process ◽

Hydrological Models ◽

Knowledge Based ◽

Distributed Hydrological Models

Abstract. Heterogeneity of landscape features like terrain, soil, and vegetation properties affect the partitioning of water and energy. However, it remains unclear to which extent an explicit representation of this heterogeneity at the sub-grid scale of distributed hydrological models can improve the hydrological consistency and the robustness of such models. In this study, hydrological process complexity arising from sub-grid topography heterogeneity was incorporated in the distributed mesoscale Hydrologic Model (mHM). Seven study catchments across Europe were used to test whether (1) the incorporation of additional sub-grid variability on the basis of landscape-derived response units improves model internal dynamics, (2) the application of semi-quantitative, expert-knowledge based model constraints reduces model uncertainty; and (3) the combined use of sub-grid response units and model constraints improves the spatial transferability of the model. Unconstrained and constrained versions of both, the original mHM and mHMtopo, which allows for topography-based sub-grid heterogeneity, were calibrated for each catchment individually following a multi-objective calibration strategy. In addition, four of the study catchments were simultaneously calibrated and their feasible parameter sets were transferred to the remaining three receiver catchments. In a post-calibration evaluation procedure the probabilities of model and transferability improvement, when accounting for sub-grid variability and/or applying expert-knowledge based model constraints, were assessed on the basis of a set of hydrological signatures. In terms of the Euclidian distance to the optimal model, used as overall measure for model performance with respect to the individual signatures, the model improvement achieved by introducing sub-grid heterogeneity to mHM in mHMtopo was on average 13 %. The addition of semi-quantitative constraints to mHM and mHMtopo resulted in improvements of 13 and 19 % respectively, compared to the base case of the unconstrained mHM. Most significant improvements in signature representations were, in particular, achieved for low flow statistics. The application of prior semi-quantitative constraints further improved the partitioning between runoff and evaporative fluxes. Besides, it was shown that suitable semi-quantitative prior constraints in combination with the transfer function based regularization approach of mHM, can be beneficial for spatial model transferability as the Euclidian distances for the signatures improved on average by 2 %. The effect of semi-quantitative prior constraints combined with topography-guided sub-grid heterogeneity on transferability showed a more variable picture of improvements and deteriorations, but most improvements were observed for low flow statistics.

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Sinkhole Flooding and Aquifer Recharge in Arid to Dry Sub-Humid Regions: A Systematic Review

10.20944/preprints202112.0454.v1 ◽

2021 ◽

Author(s):

Marco Delle Rose

Keyword(s):

Systematic Review ◽

Karst Aquifer ◽

Karst Water ◽

Hydrological Process ◽

Hydrological Models ◽

Aquifer Recharge ◽

Runoff Regulation ◽

Wastewater Recycling ◽

Recycling Policy

Sinkhole flooding is an essential hydrological process to recharge karst aquifer in arid to dry sub-humid regions. On the other hand, the increase of rain extremes is one of the major consequences of the global warming, together with the expansion of drylands. Thus, appropriate runoff regulation in endorheic karst basins in order to reduce the risk of flooding and improve the quantity and quality of the water drained by sinkholes will be more and more crucial. With these premises, a systematic review was performed by using WoS engine to infer the best practices for the karst water management in regions actually or potentially affected by water scarcity. Hydrological models are essential to manage the consequences of climate change on karst water resource, however the review shows that providing the tools necessary for reliable modeling is still challenging. Finally, due to the intrinsic vulnerability of the karst aquifers, pollution reduction and wastewater recycling policy will play key role in the next decades.

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The importance of topography-controlled sub-grid process heterogeneity and semi-quantitative prior constraints in distributed hydrological models

Hydrology and Earth System Sciences ◽

10.5194/hess-20-1151-2016 ◽

2016 ◽

Vol 20 (3) ◽

pp. 1151-1176 ◽

Cited By ~ 34

Author(s):

Remko C. Nijzink ◽

Luis Samaniego ◽

Juliane Mai ◽

Rohini Kumar ◽

Stephan Thober ◽

...

Keyword(s):

Expert Knowledge ◽

Model Performance ◽

Hydrologic Model ◽

Low Flow ◽

Evaluation Procedure ◽

Base Case ◽

Hydrological Process ◽

Hydrological Models ◽

Knowledge Based ◽

Distributed Hydrological Models

Abstract. Heterogeneity of landscape features like terrain, soil, and vegetation properties affects the partitioning of water and energy. However, it remains unclear to what extent an explicit representation of this heterogeneity at the sub-grid scale of distributed hydrological models can improve the hydrological consistency and the robustness of such models. In this study, hydrological process complexity arising from sub-grid topography heterogeneity was incorporated into the distributed mesoscale Hydrologic Model (mHM). Seven study catchments across Europe were used to test whether (1) the incorporation of additional sub-grid variability on the basis of landscape-derived response units improves model internal dynamics, (2) the application of semi-quantitative, expert-knowledge-based model constraints reduces model uncertainty, and whether (3) the combined use of sub-grid response units and model constraints improves the spatial transferability of the model. Unconstrained and constrained versions of both the original mHM and mHMtopo, which allows for topography-based sub-grid heterogeneity, were calibrated for each catchment individually following a multi-objective calibration strategy. In addition, four of the study catchments were simultaneously calibrated and their feasible parameter sets were transferred to the remaining three receiver catchments. In a post-calibration evaluation procedure the probabilities of model and transferability improvement, when accounting for sub-grid variability and/or applying expert-knowledge-based model constraints, were assessed on the basis of a set of hydrological signatures. In terms of the Euclidian distance to the optimal model, used as an overall measure of model performance with respect to the individual signatures, the model improvement achieved by introducing sub-grid heterogeneity to mHM in mHMtopo was on average 13 %. The addition of semi-quantitative constraints to mHM and mHMtopo resulted in improvements of 13 and 19 %, respectively, compared to the base case of the unconstrained mHM. Most significant improvements in signature representations were, in particular, achieved for low flow statistics. The application of prior semi-quantitative constraints further improved the partitioning between runoff and evaporative fluxes. In addition, it was shown that suitable semi-quantitative prior constraints in combination with the transfer-function-based regularization approach of mHM can be beneficial for spatial model transferability as the Euclidian distances for the signatures improved on average by 2 %. The effect of semi-quantitative prior constraints combined with topography-guided sub-grid heterogeneity on transferability showed a more variable picture of improvements and deteriorations, but most improvements were observed for low flow statistics.

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Process verification of a hydrological model using a temporal parameter sensitivity analysis

Hydrology and Earth System Sciences ◽

10.5194/hess-19-4365-2015 ◽

2015 ◽

Vol 19 (10) ◽

pp. 4365-4376 ◽

Cited By ~ 27

Author(s):

M. Pfannerstill ◽

B. Guse ◽

D. Reusser ◽

N. Fohrer

Keyword(s):

Hydrological Model ◽

Temporal Dynamics ◽

Parameter Sensitivity ◽

Hydrological Processes ◽

Model Parameters ◽

Hydrological Process ◽

Hydrological Models ◽

Parameter Sensitivity Analysis ◽

Process Verification ◽

Process Dynamics

Abstract. To ensure reliable results of hydrological models, it is essential that the models reproduce the hydrological process dynamics adequately. Information about simulated process dynamics is provided by looking at the temporal sensitivities of the corresponding model parameters. For this, the temporal dynamics of parameter sensitivity are analysed to identify the simulated hydrological processes. Based on these analyses it can be verified if the simulated hydrological processes match the observed processes of the real world. We present a framework that makes use of processes observed in a study catchment to verify simulated hydrological processes. Temporal dynamics of parameter sensitivity of a hydrological model are interpreted to simulated hydrological processes and compared with observed hydrological processes of the study catchment. The results of the analysis show the appropriate simulation of all relevant hydrological processes in relation to processes observed in the catchment. Thus, we conclude that temporal dynamics of parameter sensitivity are helpful for verifying simulated processes of hydrological models.

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