Precipitation is often the most important input data in hydrological models when simulating streamflow. The Soil and Water Assessment Tool (SWAT), a widely used hydrological model, only makes use of ...data from one precipitation gauge station that is nearest to the centroid of each subbasin, which is eventually corrected using the elevation band method. This leads in general to inaccurate representation of subbasin precipitation input data, particularly in catchments with complex topography. To investigate the impact of different precipitation inputs on the SWAT model simulations in Alpine catchments, 13years (1998–2010) of daily precipitation data from four datasets including OP (Observed precipitation), IDW (Inverse Distance Weighting data), CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data) and TRMM (Tropical Rainfall Measuring Mission) has been considered. Both model performances (comparing simulated and measured streamflow data at the catchment outlet) as well as parameter and prediction uncertainties have been quantified. For all three subbasins, the use of elevation bands is fundamental to match the water budget. Streamflow predictions obtained using IDW inputs are better than those obtained using the other datasets in terms of both model performance and prediction uncertainty. Models using the CHIRPS product as input provide satisfactory streamflow estimation, suggesting that this satellite product can be applied to this data-scarce Alpine region. Comparing the performance of SWAT models using different precipitation datasets is therefore important in data-scarce regions. This study has shown that, precipitation is the main source of uncertainty, and different precipitation datasets in SWAT models lead to different best estimate ranges for the calibrated parameters. This has important implications for the interpretation of the simulated hydrological processes.
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•First assessment of precipitation input for SWAT in headwater of Adige basin, Italy.•Four precipitation datasets were tested in three Alpine subbasins.•Elevation band correction was necessary to close the water budget.•IDW model led to the best NS and R2 values considering streamflow data.•The applied precipitation input influenced the estimated model parameters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Uncertainties in hydrologic model outputs can arise for many reasons such as structural, parametric and input uncertainty. Identification of the sources of uncertainties and the quantification of ...their impacts on model results are important to appropriately reproduce hydrodynamic processes in karst aquifers and to support decision-making. The present study investigates the time-dependent relevance of model input uncertainties, defined as the conceptual uncertainties affecting the representation and parameterization of processes relevant for groundwater recharge, i.e. interception, evapotranspiration and snow dynamic, on the lumped karst model LuKARS. A total of nine different models are applied, three to compute interception (DVWK, Gash and Liu), three to compute evapotranspiration (Thornthwaite, Hamon and Oudin) and three to compute snow processes (Martinec, Girons Lopez and Magnusson). All the input model combinations are tested for the case study of the Kerschbaum spring in Austria. The model parameters are kept constant for all combinations. While parametric uncertainties computed for the same model in previous studies do not show pronounced temporal variations, the results of the present work show that input uncertainties are seasonally varying. Moreover, the input uncertainties of evapotranspiration and snowmelt are higher than the interception uncertainties. The results show that the importance of a specific process for groundwater recharge can be estimated from the respective input uncertainties. These findings have practical implications as they can guide researchers to obtain relevant field data to improve the representation of different processes in lumped parameter models and to support model calibration.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Soil and Water Assessment Tool (SWAT) model is generally applied in alpine catchments using a unique set of snow parameters for the entire basin, and calibration is based on discharge records ...only. This technical note presents three calibration procedures for snow parameters of SWAT considering snow water equivalent (SWE) values computed using a dense network of snow depth measurement stations available in the Upper Adige River basin, Italy. The first two procedures calibrate snow parameters according to the average sub-basin SWE: the first one defines a unique set of parameters for the entire basin, while the second allows for sub-basin variability. The last approach includes the elevation band SWE output in the calibration for each sub-basin and qualitatively compares it to the SWE computed from the available snow depth monitoring stations. This last method provides the best agreement between SWAT model results and SWE data.
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BFBNIB, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this article, we perform a parameter study for a recently developed karst hydrological model. The study consists of a high‐dimensional Bayesian inverse problem and a global sensitivity analysis. ...For the first time in karst hydrology, we use the active subspace method to find directions in the parameter space that dominate the Bayesian update from the prior to the posterior distribution in order to effectively reduce the dimension of the problem and for computational efficiency. Additionally, the calculated active subspace can be exploited to construct sensitivity metrics on each of the individual parameters and be used to construct a natural model surrogate. The model consists of 21 parameters to reproduce the hydrological behavior of spring discharge in a karst aquifer located in the Kerschbaum spring recharge area at Waidhofen a.d. Ybbs in Austria. The experimental spatial and time series data for the inference process were collected by the water works in Waidhofen. We show that this case study has implicit low dimensionality, and we run an adjusted Markov chain Monte Carlo algorithm in a low‐dimensional subspace to construct samples of the posterior distribution. The results are visualized and verified by plots of the posterior's push‐forward distribution displaying the uncertainty in predicting discharge values due to the experimental noise in the data. Finally, a discussion provides hydrological interpretation of these results for the Kerschbaum area.
Key Points
Quantification of uncertainties via Bayesian inference of a high‐dimensional karst aquifer model
Dimension reduction and global sensitivity analysis with active subspaces
Detection of parameter correlations and their hydrological interpretation
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Raised bog “Königsdorfer-Weidfilz”, Bavaria, Germany.
This study investigates effects of different rewetting scenarios on water levels in raised bog peat under varying climatic conditions. We apply ...physically-based models with high temporal and spatial resolutions to compare seasonal and annual water levels. The results were evaluated to determine the significance of these water level changes. Based on these water levels, a qualitative assessment was conducted to determine the percentage of areas that are more or less likely contributing to climate change through greenhouse gas emissions.
Our study demonstrates the potential for investigating the rewetting of small peatland areas using high-resolution three-dimensional hydrological models. By utilizing a partially rewetted raised bog as a case study, we successfully modeled areas with different drainage states. Our results indicate that the areas rewetted in the respective scenarios behave similarly to the areas that have already been rewetted on site. Our study highlights that additional rewetting measures have a positive impact on reducing climate-active areas with low water levels in raised bogs. When combined with natural vegetation succession and changes in soil properties resulting from the formation of a new functional acrotelm layer after rewetting, these changes further enhance the effectiveness of the rewetting process. Although the influence of relevant dry periods after rewetting remains significant, our results suggest that the resilience of the peatland increases.
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•Physically-based modeling is a promising tool for small catchments and peatland restoration.•Different rewetting scenarios can be simulated to determine the resulting increase in water level.•Different climate conditions can be evaluated regarding their impact on the water level.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Reduction of snow cover duration (SCD) and mean seasonal snow depth (HS) after 1987.•HS and SCD sensitivity towards temperature increase decreases with site elevation.•Wavelet coherence between HS ...or SCD and climate indices (NAOI, MOI) depends on elevation.
The Upper and Middle Adige catchment, Trentino-South Tyrol, Italy.
We provide evidence of changes in mean seasonal snow depth and snow cover duration in the region occurred in the period from 1980 to 2009.
Stations located above and below 1650 m a.s.l. show different dynamics, with the latter experiencing in the last decades a larger reduction of average snow depth and snow cover duration, than the former. Wavelet analyses show that snow dynamics change with elevation and correlate differently with climatic indices at multiple temporal scales. We also observe that starting from the late 1980s snow cover duration and mean seasonal snow depth are below the average in the study area. We also identify an elevation dependent correlation with the temperature. Moreover, correlation with the Mediterranean Oscillation Index and with the North Atlantic Oscillation Index is identified.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mixing, entropy and reactive solute transport Chiogna, Gabriele; Hochstetler, David L.; Bellin, Alberto ...
Geophysical research letters,
28 October 2012, Volume:
39, Issue:
20
Journal Article
Peer reviewed
Open access
Mixing processes significantly affect reactive solute transport in fluids. For example, contaminant degradation in environmental aquatic systems can be limited either by the availability of one or ...more reactants, brought into contact by physical mixing, or by the kinetics of the (bio)chemical transformations. Appropriate metrics are needed to accurately quantify the interplay between mixing and reactive processes. The exponential of the Shannon entropy of the concentration probability distribution has been proposed and applied to quantify the dilution of conservative solutes either in a given volume (dilution index) or in a given water flux (flux‐related dilution index). In this work we derive the transport equation for the entropy of a reactive solute. Adopting a flux‐related framework, we show that the degree of uniformity of the solute mass flux distribution for a reactive species and its rate of change are informative measures of physical and (bio)chemical processes and their complex interaction.
Key Points
Application of information entropy to reactive solute transport problems
Metrics for mixing: flux‐related dilution index and its rate of change
Quantification of complex interplay between dilution and reaction processes
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Plume dilution and reactive mixing can be considerably enhanced by helical flows occurring in three-dimensional anisotropic porous media. In this study, we perform conservative and reactive transport ...simulations considering different anisotropy structures of a single inclusion with the objective of exploring the effect of the inclusion’s geometry and orientation on the patterns of twisted streamlines and on the overall dilution and reaction of solute plumes. We analyzed 100 different scenarios by varying key parameters such as the angle of the anisotropic structures with respect to the average flow velocity, the spacing between alternated heterogeneous zones of coarse and fine materials, the permeability contrast between such matrices, and the magnitude of the seepage velocity. Entropy conservation equations and entropy-based metrics for both conservative and reactive species were adopted to quantify dilution, reactive mixing and their interactions with the helical flow patterns in the considered three-dimensional anisotropic setups. The results allowed identifying optimal anisotropic configurations maximizing mixing and reactions, and yielding enhancement factors up to 15 times the outcomes of analogous simulations in homogeneous media. Furthermore, the effects of compound-specific diffusive/dispersive properties of the transported species were found to be relevant for both plume dilution and reactive mixing in helical flows.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•The water of the Vermigliana creek mainly derives from snowpack and glacier melting.•Identification of annual periodicity in hydrological cycle.•Estimation of mean residence time in the catchment.
...Characterizing the hydrological behavior of streams in small Alpine catchments spanning a wide range of elevations is a difficult task, often hampered by the intrinsic variability of streamwater sources. Stable isotope ratios of oxygen and hydrogen have been sampled monthly in order to determine the spatial and temporal hydrological behavior and the mean residence time of water in the Vermigliana catchment, North-Eastern Italy. This study aims at separating contributions to streamflow originating from Presena and Presanella glaciers, both exerting a strong control on the hydrologic budget of the study site. The isotopic signature of precipitation has been collected at two locations at different altitudes (1176m a.s.l. and 2731m a.s.l.), while stream water was sampled at 11 locations, 8 along the main course of the Vermigliana creek and 3 along the two tributaries of the Vermigliana creek: the Presanella and Presena creeks. Groundwater was sampled monthly in a single location, whilst the waters of two small lakes, Capanna Presena and Cantiere, both located in the proximity of the Presena glacier, were sampled during summer, when the sites were accessible. Isotope analysis evidenced that Presena and Presanella creeks are the main contributors to the Vermigliana creek. The contribution of the Presanella creek is 44% of the total flow at the confluence with the Vermigliana, while the contribution of the Presena creek rises to 75% of the total flow immediately after the confluence. The mean residence times computed for the Vermigliana and the tributaries vary between 7 and 5months, respectively. This work allows us to investigate the main components in the hydrological cycle of the Vermigliana catchment and constitutes the basis for future modeling and climate change impact studies on this important Alpine catchment. The methodology can be exported to other sites with the aim to provide additional data, with respect to streamflow at the catchment outlet, to reduce epistemic uncertainty of hydrological models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This article aims to present the structure and the workflow of a new software DeMa (Decision Support Software and Database for Wellfield Management), to support wellfield managers in their ...decision-making processes. There is a recognized need to improve the management of groundwater resources, especially with the increased demand for fresh water in arid and semi-arid regions. DeMa differentiates from other available software, by combining data collected for the well’s maintenance, operation, design, installations, and cost data with the collected hydrological field measurements. Additionally, DeMa links the different information and provides an effective graphical representation of the data. We applied the software to the Wadi Al Arab wellfield case study to support wellfield managers in the decision-making process of three typical problems: identification of missing data and information concerning the wells, identification of maintenance needs for a well, and identification of a suitable location for a new well. In the application to the Wadi Al Arab wellfield (Jordan), we collected data and documents from the Yarmouk Water Company (YWC), the Jordan Ministry of Water and Irrigation (MWI), and private drilling companies. The software application highlights the beneficial effects of the digitalization of water resources management by improving data availability and management and achieving data and research-based decisions on the wellfield.
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