Simulation of snowpack and discharge in an alpine karst basin (original) (raw)
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Simulation of snowmelt runoff in lowland and lower Alpine regions of Switzerland
This study investigates the influence of snowmelt model structure on the overall performance of runoff modelling in basins ranging from 3.2 to 1696 km 2 . For a given basin, melt rates as calculated by various snowmelt models of different complexity are used as input to the same runoff model, and the performance is assessed by linear scale plots of measured and simulated discharge and by a numerical efficiency criterion. In small to medium basins (<1000 km 2 ) there is a noticeable improvement in model performance when moving from a temperature index method to any other method investigated. During advection-melt conditions an energy balance method yields the best results, while during radiation-melt conditions index methods are sufficient. In larger basins (>1000 km ), a noticeable change in model performance is observed only in individual years characterized by an above-normal snow pack. For operational purposes, the combination method according to seems to be the most suitable approach of the methods investigated.
Hydrological Processes, 2011
Mountain water resources management often requires hydrological models that need to handle both snow and ice melt. In this study, we compared two different model types for a partly glacierized watershed in central Switzerland: (1) an energy-balance model primarily designed for snow simulations; and (2) a temperature-index model developed for glacier simulations. The models were forced with data extrapolated from long-term measurement records to mimic the typical input data situation for climate change assessments. By using different methods to distribute precipitation, we also assessed how various snow cover patterns influenced the modelled runoff.
Simulating low and high streamflow driven by snowmelt in an insufficiently gauged alpine basin
Stochastic Environmental Research and Risk Assessment, 2015
Snowmelt and water infiltration are two important processes of the hydrological cycle in alpine basins where snowmelt water is a main contributor of streamflow. In insufficiently gauged basins, hydrologic modeling is a useful approach to understand the runoff formation process and to simulate streamflow. In this study, an existing hydrologic model based on the principles of system dynamics was modified by using the effective cumulative temperature ([0°C) to calculate snowmelt rate, and the soil temperature to adjust the influence of the soil's physical state on water infiltration. This modified model was used to simulate streamflows in the Kaidu River basin from 1982 to 2002, including normal, high, and low flows categorized by the Z index. Sensitivity analyses, visual inspection, and statistical measures were employed to evaluate the capability of the model to simulate various components of the streamflow. Results showed that the modified model was robust, and able to simulate the three categories of flows well. The model's ability to reproduce streamflow in low-flow and normal-flow years was better than that in high-flow years. The model was also able to simulate the baseflow. Further, its ability to simulate spring-peak flow was much better than its ability to simulate the summer-peak flow. This study could provide useful information for water managers in determining water allocations as well as in managing water resources.
Sequential Development of a Conceptual Hydrological Model Considering Alpine Basin Processes
2002
In the frame of an applied research project the authors had to develop a runoff forecast tool to enable a prediction of the hydropower potential with a lead time of four days. Therefore procedures for runoff, snow accumulation and snowmelt were sequentially generated, leading to model types ranging from a statistical approach via one storage/single outflow type, one storage/two outflow model to a two storage/triple outflow concept. This contribution presents a procedure to adapt model complexity as far as necessary to improve runoff simulation while still keeping the type of a parsimonious, conceptual model. The improvements of the results are interpreted in terms of hydrological process consideration and are evaluated by means of temporal efficiency criteria like the Nash-Sutcliffe and the correlation coefficients. The seasonality of alpine runoff processes could only be achieved with consideration of snowmelt and evaporation concepts. The model reliability increased with increasin...
A comparative study in modelling runoff and its components in two mountainous catchments
Hydrological Processes, 2003
In mountainous catchments the quality of runoff modelling depends strongly on the assessment of the spatial differences in the generation of the various runoff components and of the flow paths as coupled with the amount and intensity of precipitation and/or the snow melting. These catchments are also suitable for the intercomparison of different kinds of hydrological models, particularly of different approaches for the simulation of runoff generation. Two differently structured catchment models were applied on the pre-alpine Rietholzbach research catchment (3Ð2 km 2 ) within the period 1981-98 and on the high-alpine Dischmabach catchment (43 km 2 ) within the period 1981-96 for the simulation of hydrological processes and of the runoff hydrographs. The models adopted are the more physically based WaSiM-ETH model, with grid-oriented computation of the water balance elements, and the rather conceptual PREVAH model, based on hydrological response units. The simulation results and the differences resulting from the application of the two models are discussed and compared with the observed catchment discharges, with measurements of evapotranspiration, soil moisture, outflow of a lysimeter, and of groundwater levels in three access tubes. The model intercomparison indicates that the two approaches for determining runoff generation with different degrees of complexity performed with similar statistical efficiency over a period longer than 15 years. The analysis of the simulated runoff components shows that the interflow is the main runoff component and that the portion of the runoff components depends strongly on the approach used. The snowmelt model component is of decisive importance in the snowmelt season and needs to take into account the role of air temperature and radiation for simulating runoff generation in a spatially distributed manner.
Doctoral Thesis , 2002
Severe floods regularly occur at different places all over the world including the European Alps and Prealps. They are responsible for important damages and a large number of fatalities. Consequently, research activities in physical and engineering sciences have long focused on understanding the underlying physical processes and on developing methods to reproduce and predict floods. Despite considerable progress in both fields over the last few years, a number of questions still remain open. The frequent over- or underestimation of both structural and non-structural measures for flood mitigation are, however, only partially caused by this fact. Recent and more sophisticated methods of flood estimation do not often penetrate to everyday hydrological practice in engineering companies and federal agencies. These methods are abandoned in favour of simple empirical methods, mainly due to their extended demand in input data. The reliability of the results obtained by these simple methods is, however, often unsatisfactory and there is a strong demand for better performing practice-oriented methods. This work intends to add a step towards the solution of this problem. The overall goal consists in developing / adapting a methodology for the estimation of overland flow suited to the Swiss alpine and prealpine context. The methodology should further exclusively rely on widely available geographic information. It was decided in this respect to work with the geographic database GEOSTAT. GEOSTAT is operated by the Swiss Federal Statistical Office (Bundesamt für Statistik) and covers the whole country. The highest spatial resolution of the maps is 1 hectare. For overland flow estimation the Curve Number method is used. The Curve Number method was developed by the US Natural Resources Conservation Service (formerly known as Soil Conservation Service) and allows for the estimation of direct runoff for a given rainfall input based only on qualitative information on soil type and land use. The goal then consists in adapting the Curve Number method in order to allow for a correct reproduction of overland flow for all types of hydrological different reacting areas which can be differentiated based on information from the GEOSTAT maps. This goal is addressed by reproducing hydrographs of annual flood events observed in four alpine and prealpine catchments by means of a spatially distributed Rainfall-Runoff model. The spatial resolution of the model corresponds to the spatial resolution of the information from the GEOSTAT maps (1ha). For each single grid cell, the overland flow is further calculated separately by the Curve Number equation. The simulations then allow for indications on the performance and the parameterisation of the Curve Number equation for single hydrological different reacting areas. These indications are however exposed to larger uncertainties. The simulated hydrograph is influenced by different hydrological areas which react similarly and different modules of the model (e.g. subsurface flow module). Therefore the single hydrological different reacting areas cannot be analysed independently. In order to reduce the uncertainty, the performance of the Curve Number equation was also analysed based on data from a number of small scale 6800$5< rainfall experiments. These experiments are of interest in the context of the present study, as the runoff processes and the soil characteristics at the plot sites were observed and measured in detail. Consequently, the performance of the Curve Number equation can be investigated separately for single soil types. The results from the analysis at this plot scale show that the equation mainly performs well for rainfall plots in which Hortonian runoff processes dominate and which are located on Cambisols and Gleysols. The equation shows a lower performance for plots on soils such as Rendzina, Ranker and Podsol. In terms of reparameterisation, only preliminary indications are gained from the analysis mainly due to the limited number of experiments. For a number of plot sites the runoff behaviour is furthermore dominated by local structures such as macropores. At basin scale the Rainfall-Runoff model in general and the Curve Number equation in particular show a satisfactory performance in reproducing the flood runoff observed in the prealpine catchments. In the alpine catchment considered a reproduction of the flood events was however not successful due to the large uncertainty of the spatial rainfall distribution and the influence of snow on the flood events. The simulations generally result in rough indications on the performance and the parameterisation of the Curve Number equation for a number of hydrological different reacting areas. For storm events characterised by rainfall peaks interrupted by periods of rainfall of low intensity, modification of the Curve Number method is further required and proposed. A comparison of the resulting parameterisation with event characteristics then shows that the relation of parameterisation and antecedent wetness conditions presented in the original Curve Number method are not valid in the alpine and prealpine context. The found Curve Number values further decline with increasing storm rainfall volume. The indications on the parameterisation of the Curve Number equation are however exposed to larger uncertainties. The findings from the analysis at plot scale are partially helpful in reducing these uncertainties. This study represents a first important step towards the modification of the Curve Number method to a method for the estimation of the overland flow in the Swiss alpine and prealpine environment. Further steps mainly consist in extending the analysis / adaptation of the Curve Number method to a large number of additional mesoscale catchments of the Swiss Plateau and the Prealps. When selecting the catchments, similar hydrological different reacting areas should be present in several catchments. This permits a more precise idea on the performance of the Curve Number equation for single hydrological different reacting areas. The simulations of flood events from additional catchments may also serve to refine the proposed modification of the Curve Number equation and gain insight into how the parameterisation relates with the antecedent wetness conditions.
This paper summarizes the major findings on variations of the individual components of the water balance in the head watershed of the Linth River, situated in the high alpine region of Glarus, north-eastern Switzerland, where direct measurements have been available since the beginning of this century. In the current discussion of possible climate changes, the natural variability of the water balance components may help to put today's research results in perspective. In a first step, the individual components of basin precipitation, snow accumulation, glacier mass balance and discharge are assessed. Special emphasis is placed on a comprehensive interpretation of the results. In a second step, a conceptual precipitation-runoff model running on a daily time step is applied. The required data input are daily values of precipitation and air temperature as measured at standard meteorological stations, which facilitates the transfer of this modelling approach to other mountainous regions where data are scarce. The results obtained using the various methods compare favourably with one another. It can be concluded that the high alpine Linth-Limmern region is well suited for the assessment of the water balance components thanks to the long-term series of available data. It is recommended to continue the various measurement programmes being conducted by federal agencies, hydro-power companies and private individuals, and to engage in further detailed investigations concerning runoff processes and pathways.
Hydrological Sciences Bulletin, 1981
This paper describes and compares various approaches to modelling a high mountain basin with dominant snow yields. Three different conceptual models were thus applied to the same test basin over the same test periods, and with identical calibration: (a) one specially developed for the given basin, using a refined description of the physiographic features and including a snowmelt routine based on energy budgets at 12 h intervals; (b) a general purpose hydrological model (HSP model), partially standardized and applied to the basin considered following the users' manual; (c) an intermediate model, much like the HSP model except for the snowmelt routine. Conclusions have been drawn about the structure of models such as the usefulness of introducing some routines far more sophisticated than those of the average model, but mostly about estimations of missing input data required by the model. Some variables such as thermometric gradients or spatial distribution of precipitation are much more crucial than the possible choices between different approaches for modelling évapotranspiration and even snowmelt.
Multi-Variable Calibration of a Conceptual Rainfall-Runoff Model in the Selected Alpine Catchment
2017
MULTI-VARIABLE CALIBRATION OF A CONCEPTUAL RAINFALLRUNOFF MODEL IN THE SELECTED ALPINE CATCHMENT PATRIK SLEZIAK, JÁN SZOLGAY, KAMILA HLAVČOVÁ, JURAJ PARAJKA Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology, Radlinského 11, 810 05, Bratislava, Slovakia; Institute of Hydraulic Engineering and Water Resource Management, Vienna University of Technology, Karlsplatz 13/222, Vienna, Austria
Forest
An application of the Precipitation Runoff Modelling System (PRMS) based on the concept of Hydrological Response Units (HRUs) is presented for hydrological modelling of an alpine catchment. This is the Aare River catchment upstream of the Lake Thun, in the Bernese Oberland Region, Switzerland, which is characterised by large glacierised areas. Accounting for these areas required to develop further the original PRMS, which was rarely used in alpine regions. Particular attention was devoted to the analysis of the temporal and spatial distribution of temperature and rainfall within the catchment. The derivation of distributed model's parameters was based on an extensive database of catchment characteristics available for the region, thereby including a 25 m resolution Digital Elevation Model (DEM), and digital maps of geotechnical properties, soil and landuse. The encouraging results in spite of the highly complex catchment morphology underline the importance of the availability of spatially distributed data to be used for HRUs identification and parameterisation. Such availability allowed transferring the parameter set from one subcatchment to another without significant loss of model efficiency. However, as expected, the model was strongly sensitive to the parameters describing the runoff generation processes (retention capacity of the unsaturated storage, snowmelt infiltration capacity) and the routing of water in subsurface and groundwater reservoirs. This is due to the intrinsic variability of these parameters, but may be enhanced by the general lack of specific distributed data that could be used to improve calibration. Accordingly, the study concludes about the evident need for enlarging data availability in relation to subsurface and groundwater processes, or, alternatively, in fostering the development of robust parameter calibration methods, which rely on data that are generally available.