From rainfall to spring discharge: Coupling conduit flow, subsurface matrix flow and surface flow in karst systems using a discrete–continuum model

2013 ◽  
Vol 61 ◽  
pp. 29-41 ◽  
Author(s):  
Rob de Rooij ◽  
Pierre Perrochet ◽  
Wendy Graham
Keyword(s):  
Continuum Model ◽  
Surface Flow ◽  
Spring Discharge ◽  
Conduit Flow ◽  
Matrix Flow ◽  
Karst Systems

scholarly journals The Effects of Exchange Flow on the Karst Spring Hydrograph under the Different Flow Regimes: A Synthetic Modeling Approach

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1189
Author(s):  
Malihe Shirafkan ◽  
Zargham Mohammadi ◽  
Vianney Sivelle ◽  
David Labat
Keyword(s):  
Flow Regime ◽  
Spring Discharge ◽  
Exchange Flow ◽  
Flow Conditions ◽  
Spring Hydrograph ◽  
Conduit Flow ◽  
Discharge Fluctuations ◽  
Recession Coefficient ◽  
The Matrix ◽  
Synthetic Modeling

In this study, a synthetic modeling approach is proposed to quantify the effect of the amount and direction of the exchange flow on the karstic spring discharge fluctuations under different hydrologic conditions corresponding to high and low flow conditions. We hypothesis that the spring discharge fluctuations constitute a valuable proxy to understand the internal processes of the karst system. An ensemble of spring hydrographs was synthetically produced to highlight the effect of exchange flow by exploring the plausible range of variability of coefficients of exchange flow, conduit diameter, and matrix hydraulic conductivity. Moreover, the change of the rate of point recharge through the karst conduit allows for the quantifying of the sensibility of the spring hydrograph to the directions of exchange flow. We show that increasing the point recharge lies to a remarkable linear recession coefficient (β) as an indication of the conduit flow regime. However, a reduction in and/or lack of the point recharge caused the recession coefficient to change to exponential (α) due to the dominant effect of the matrix restrained flow regime and/or conduit-influenced flow regime. The simulations highlight that the exchange flow process from the conduit to the matrix occurred in a short period and over a restricted part of the conduit flow regime (CFR). Conversely, the exchange flow dumped from the matrix to the conduit occurs as a long-term process. A conceptual model is introduced to compare spring hydrographs’ characteristics (i.e., the peak discharge, the volume of baseflow, and the slope of the recession curve) under the various flow conditions with the directions of the exchange flow between the conduit and the matrix.

Proposal of a typology of karst systems functioning based on relevant indicators of karst springs hydrodynamics

2021 ◽  
Author(s):  
Guillaume Cinkus ◽  
Naomi Mazzilli ◽  
Hervé Jourde
Keyword(s):  
Time Series ◽  
Resource Management ◽  
Water Resource ◽  
Water Resource Management ◽  
Spring Discharge ◽  
Karst Water ◽  
Discharge Time ◽  
Wide Range ◽  
Karst Systems ◽  
Hydrological Functioning

<p>10% of the world’s population is dependent on karst water resources for drinking water. Understanding the functioning of these complex and heterogeneous systems is therefore a major challenge for long term water resource management. Over the past century, different methods have been developed to analyse hydrological series, and subsequently characterize the functioning of karst systems. These methods can be considered as a preliminary step in the development and design of hydrological models of karst functioning for sustainable water resource management. Recent progress in analytical tools, as well as the emergence of data bases of discharge time series (e.g. the French SNO KARST database and the WoKaS database at global scale) allow reconsidering former typology of karst system hydrodynamic responses. Ten karst systems and associated spring discharge time series were considered for developing the typology. The systems are well-known with a high-quality monitoring and they cover a wide range of hydrological functioning, which ensure the relevance of the analyses. The methodology for the assessment and the development of the typology consisted in (i) the analysis of springs discharge time series according to four different methods, (ii) the selection or proposal of the most relevant indicators of karst systems hydrodynamics, and (iii) the interpretation of the information from these indicators based on principal component analysis and clustering techniques. A typology of karst systems accounting for 6 different classes is finally proposed, based on 3 aspects of functioning: the capacity of dynamic storage, the draining dynamic of the capacitive function and the variability of the hydrological functioning. The typology was applied to a wider dataset composed of spring discharge of 78 karst systems. The results show a relevant distribution of the systems among the different classes.</p>

scholarly journals Hydraulic-Hydrology Analysis of the Turbulent Seepage Flow within Karst Aquifer of the Golubinka Spring Catchment

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Goran Lončar ◽  
Željko Šreng ◽  
Damir Bekić ◽  
Duška Kunštek
Keyword(s):  
Groundwater Level ◽  
Sea Water ◽  
Karst Aquifer ◽  
Seepage Flow ◽  
Spring Discharge ◽  
Data Set ◽  
Groundwater Levels ◽  
Matrix Flow ◽  
Spring Catchment ◽  
The Difference

This paper shows the results of the hydraulic-hydrologic calculations of karst spring discharges and the groundwater level in the aquifer of spring catchment. The calculations were performed for the Golubinka spring in Zadar area for the 4-year period. The chosen approach was a model using relatively scarce data set, including limnigraphic data on the difference between the sea water level and the freshwater level on the spring itself and the precipitation data from the meteorological station Zadar. The determination of discharge hydrographs, based on inherent assumptions and available data, yields the proportionality coefficients between the discharge and the limnigraphic data on the Golubinka spring itself. Further, based on the discharge hydrograph, groundwater level oscillation was determined. The resulting spring discharge hydrograph and groundwater levels, along with the assumption of Golubinka spring as the only spring on the catchment, were used in creating turbulent seepage model of the fractured system within the aquifer, which evidently extends along the axis of the Golubinka spring catchment. The model yielded suitable turbulent seepage coefficients of the fracture system. By using the numerical model KarstMod it was estimated that, on average, concentrated fracture flow drains around 85% of infiltrated volumes and the remaining 15% accounts for diffuse matrix flow. Finally, the Modflow model was used in order to get insight into the flow field and the distribution of equipotentials in the aquifer of the Golubinka catchment.

scholarly journals Simulation of saturated and unsaturated flow in karst systems at catchment scale using a double continuum approach

2012 ◽  
Vol 16 (10) ◽  
pp. 3909-3923 ◽  
Author(s):  
J. Kordilla ◽  
M. Sauter ◽  
T. Reimann ◽  
T. Geyer
Keyword(s):  
Unsaturated Flow ◽  
Small Scale ◽  
Saturated Model ◽  
Spring Discharge ◽  
Karst Spring ◽  
Continuum Approach ◽  
Catchment Scale ◽  
The Matrix ◽  
Karst Systems ◽  
Linear Exchange

Abstract. The objective of this work is the simulation of saturated and unsaturated flow in a karstified aquifer using a double continuum approach. The HydroGeoSphere code (Therrien et al., 2006) is employed to simulate spring discharge with the Richards equations and van Genuchten parameters to represent flow in the (1) fractured matrix and (2) conduit continuum coupled by a linear exchange term. Rapid vertical small-scale flow processes in the unsaturated conduit continuum are accounted for by applying recharge boundary conditions at the bottom of the saturated model domain. An extensive sensitivity analysis is performed on single parameters as well as parameter combinations. The transient hydraulic response of the karst spring is strongly controlled by the matrix porosity as well as the van Genuchten parameters of the unsaturated matrix, which determine the head dependent inter-continuum water transfer when the conduits are draining the matrix. Sensitivities of parameter combinations partially reveal a non-linear dependence over the parameter space. This can be observed for parameters not belonging to the same continuum as well as combinations, which involve the exchange parameter, showing that results of the double continuum model may depict a certain degree of ambiguity. The application of van Genuchten parameters for simulation of unsaturated flow in karst systems is critically discussed.

scholarly journals Simulation of saturated and unsaturated flow in karst systems at catchment scale using a double continuum approach

2012 ◽  
Vol 9 (2) ◽  
pp. 1515-1546
Author(s):  
J. Kordilla ◽  
M. Sauter ◽  
T. Reimann ◽  
T. Geyer
Keyword(s):  
Unsaturated Flow ◽  
Small Scale ◽  
Saturated Model ◽  
Spring Discharge ◽  
Karst Spring ◽  
Continuum Approach ◽  
Catchment Scale ◽  
The Matrix ◽  
Karst Systems ◽  
Linear Exchange

Abstract. The objective of this work is the simulation of saturated and unsaturated flow in a karstified aquifer using a double continuum approach. The HydroGeoSphere code (Therrien et al., 2006) is employed to simulate spring discharge with the Richards equations and van Genuchten parameters to represent flow in the (1) fractured matrix and (2) conduit continuum coupled by a linear exchange term. Rapid vertical small-scale flow processes in the unsaturated conduit continuum are accounted for by applying recharge boundary conditions at the bottom of the saturated model domain. An extensive sensitivity analysis is performed on single parameters as well as parameter combinations. The transient hydraulic response of the karst spring is strongly controlled by the matrix porosity as well as the van Genuchten parameters of the unsaturated matrix, which determine the head dependent inter-continuum water transfer when the conduits are draining the matrix. Sensitivities of parameter combinations partially reveal a non-linear dependence over the parameter space. This can be observed for parameters not belonging to the same continuum as well as combinations, which involve the exchange parameter, showing that results of the double continuum model may depict a certain degree of ambiguity.

Towards making karst hydrologic models more user-friendly – The integration of the LuKARS model into FREEWAT

2020 ◽  
Author(s):  
Daniel Bittner ◽  
Ayla Rychlik ◽  
Tobias Klöffel ◽  
Anna Leuteritz ◽  
Markus Disse ◽  
...  
Keyword(s):  
Land Use ◽  
Resource Management ◽  
Open Source ◽  
Water Resource ◽  
Water Resource Management ◽  
Land Use Changes ◽  
Spring Discharge ◽  
Systems Model ◽  
Karst Systems ◽  
User Friendly

<p>Modeling karst spring discharge while considering potential impacts of land use changes in a recharge area is a crucial task for water resource managers worldwide. Generally, such models are based on sophisticated mathematical functions developed and applied by researchers and their complex nature does not allow an intuitive applicability. To overcome this limitation and to make these models applicable for stakeholders, they need to be integrated in an applicable and open source framework that can be used by water managers without losing the original and full modeling functionalities.</p><p>In our work, we introduce a user-friendly modeling environment by integrating the recently proposed LuKARS (Land use change modeling in KARSt systems) model into FREEWAT (FREE and Open Source Software Tools for WATer Resource Management). LuKARS is a lumped, rainfall-discharge model for karst systems that considers impacts of land use changes by changing the area of a so-called hydrotope, representing a landscape unit with homogeneous soil and land use properties. FREEWAT provides an open source toolkit for water resource management that is implemented as a plugin in QGIS. The integration of LuKARS benefits from QGIS’ mapping, visualization and geospatial manipulation capabilities. The plugin of FREEWAT provides a modular concept of pre- and post-processing tools that facilitate the setup, calibration, analysis, storage and sharing of a LuKARS model.</p>

scholarly journals Modeling the discharge behavior of an alpine karst spring influenced by seasonal snow accumulation and melting based on a deep-learning approach

2021 ◽  
Author(s):  
Tanja Liesch ◽  
Andreas Wunsch ◽  
Zhao Chen ◽  
Nico Goldscheider
Keyword(s):  
Neural Networks ◽  
Snow Accumulation ◽  
Spring Discharge ◽  
Learning Approach ◽  
Earth System ◽  
Karst Spring ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Discharge Behavior ◽  
Karst Systems

<p>Karst systems are challenging to model due to their heterogeneous hydraulic properties resulting in highly variable discharge behavior. Distributed models can be applied to karst aquifers but require detailed system knowledge and extensive hydraulic parameter datasets; lumped-parameter models are less complex, but still require parametrization. In this work, we demonstrate the application of a data-driven approach to model the discharge behavior of the Aubach spring in the Gottesacker karst system in the northern Alps, a well-investigated study site for which previous models are available for comparison (Chen et al. 2018; Fandel et al. 2020). Our approach is based on convolutional neural networks (CNN), which have proved to be well suited for time series forecasting in water-related contexts like runoff modelling or groundwater level prediction (Wunsch et al.). The approach is comparably simple in terms of data requirements as we rely mainly on widely available and easy-to-measure parameters such as precipitation and temperature. By implementing Bayesian techniques (Monte-Carlo dropout) we are able to report the predictive uncertainty of the CNN based forecasts. Our results challenge existing modelling results based on lumped-parameter models in terms of common error measures such as Nash-Sutcliffe efficiency. Furthermore, we explore the important role of snow accumulation and melting by coupling our model with a snow-routine to better represent their influence on spring discharge and further improve model performance. Our results demonstrate that the presented machine-learning approach can be applied to simulate karst spring discharge and has certain advantages in comparison with conventional karst modelling approaches, which require hydraulic parameters that are often not available.</p><p>Chen, Z.; Hartmann, A.; Wagener, T.; Goldscheider, N. (2018) Dynamics of water fluxes and storages in an Alpine karst catchment under current and potential future climate conditions. Hydrology and earth system sciences, 22 (7), 3807–3823.</p><p>Fandel, C.; Ferré, T.; Chen, Z.; Renard, P.; Goldscheider, N. (2020) A model ensemble generator to explore structural uncertainty in karst systems with unmapped conduits. Hydrogeology journal, published online.</p><p>Wunsch, A.; Liesch, T.; Broda, S. (2020) Groundwater Level Forecasting with Artificial Neural Networks: A Comparison of LSTM, CNN and NARX. Hydrology and Earth System Sciences Discussions 2020:1–23. https://doi.org/10/ghtcz3</p>

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