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While ongoing climate change is well documented, the impacts exhibit a substantial variability, both in direction and magnitude, visible even at regional and local scales. However, the knowledge of regional impacts is crucial for the design of mitigation and adaptation measures, particularly when changes in the hydrological cycle are concerned. In this paper, we present hydro-meteorological trends based on observations from a hydrological research basin in Eastern Austria between 1979 and 2019. The analyzed variables include air temperature, precipitation, and catchment runoff. Additionally, the number of wet days, trends for catchment evapotranspiration, and computed potential evapotranspiration were derived. Long-term trends were computed using a non-parametric Mann–Kendall test. The analysis shows that while mean annual temperatures were decreasing and annual temperature minima remained constant, annual maxima were rising. Long-term trends indicate a shift of precipitation to the summer, with minor variations observed for the remaining seasons and at an annual scale. Observed precipitation intensities mainly increased in spring and summer between 1979 and 2019. Catchment actual evapotranspiration, computed based on catchment precipitation and outflow, showed no significant trend for the observed time period, while potential evapotranspiration rates based on remote sensing data increased between 1981 and 2019.
Gerald Krebs; David Camhy; Dirk Muschalla. Hydro-Meteorological Trends in an Austrian Low-Mountain Catchment. Climate 2021, 9, 122 .
AMA StyleGerald Krebs, David Camhy, Dirk Muschalla. Hydro-Meteorological Trends in an Austrian Low-Mountain Catchment. Climate. 2021; 9 (8):122.
Chicago/Turabian StyleGerald Krebs; David Camhy; Dirk Muschalla. 2021. "Hydro-Meteorological Trends in an Austrian Low-Mountain Catchment." Climate 9, no. 8: 122.
While the ongoing climate change is well documented, the impacts exhibit a substantial variability, both in direction and magnitude, visible even at regional and local scales. However, the knowledge of regional impacts is crucial for the design of mitigation and adaptation measures, particularly when changes in the hydrological cycle are concerned. In this paper we present hydro-meteorological trends based on observations from a hydrological research basin in Eastern Austria between 1979-2019. The analysed state variables include the air temperature, the precipitation, and the catchment runoff. Additionally, trends for the catchment evapotranspiration were derived. The analysis shows that while the mean annual temperature was decreasing and annual temperature minima remained constant, the annual maxima were rising. The long-term trends indicate a shift of precipitation to the summer with minor variations observed for the remaining seasons and at an annual scale. Observed precipitation intensities mainly increased in spring and summer between 1979-2019. The catchment evapotranspiration, computed based on catchment precipitation and outflow, showed an increasing trend for the observed time period.
Gerald Krebs; David Camhy; Dirk Muschalla. Hydro-Meteorological Trends in an Austrian Low-Mountain Catchment. 2021, 1 .
AMA StyleGerald Krebs, David Camhy, Dirk Muschalla. Hydro-Meteorological Trends in an Austrian Low-Mountain Catchment. . 2021; ():1.
Chicago/Turabian StyleGerald Krebs; David Camhy; Dirk Muschalla. 2021. "Hydro-Meteorological Trends in an Austrian Low-Mountain Catchment." , no. : 1.
Zusammenfassung Hydrologische Simulationen sind ein adäquates Mittel, um wasserwirtschaftliche Maßnahmen im urbanen Raum zu planen und deren Wirkungsweise zu evaluieren. Dieser Beitrag beschreibt die Erstellung eines Niederschlags-Abfluss-Modells für den urbanen Raum durch die Verwendung von Open-Source-Software. Das Stormwater Management Model (SWMM) dient als Simulationssoftware, die Modellerstellung erfolgt mit Open-Source-GIS-Software und die Kalibrierung und Nachbereitung läuft über Pakete in R und Python. Abschließend wird der gesamte Modellaufbau an einem Anwendungsbeispiel erläutert.
Gerald Krebs. Niederschlags-Abfluss-Modellierung im urbanen Raum. Österreichische Wasser- und Abfallwirtschaft 2020, 72, 320 -325.
AMA StyleGerald Krebs. Niederschlags-Abfluss-Modellierung im urbanen Raum. Österreichische Wasser- und Abfallwirtschaft. 2020; 72 (7-8):320-325.
Chicago/Turabian StyleGerald Krebs. 2020. "Niederschlags-Abfluss-Modellierung im urbanen Raum." Österreichische Wasser- und Abfallwirtschaft 72, no. 7-8: 320-325.
Rainfall runoff models are frequently used for design processes for urban infrastructure. The most sensitive input for these models is precipitation data. Therefore, it is crucial to account for temporal and spatial variability of rainfall events as accurately as possible to avoid misleading simulation results. This paper aims to show the significant errors that can occur by using rainfall measurement resolutions in urban environments that are too coarse. We analyzed the spatial variability of rainfall events from two years with the validated data of 22 rain gauges spread out over an urban catchment of 125 km2. By looking at the interstation correlation of the rain gauges for different classes of rainfall intensities, we found that rainfall events with low and intermediate intensities show a good interstation correlation. However, the correlation drops significantly for heavy rainfall events suggesting higher spatial variability for more intense rainstorms. Further, we analyzed the possible deviation from the spatial rainfall interpolation that uses all available rain gauges when reducing the number of rain gauges to interpolate the spatial rainfall for 24 chosen events. With these analyses we found that reducing the available information by half results in deviations of up to 25% for events with return periods shorter than one year and 45% for events with longer return periods. Assuming uniformly distributed rainfall over the entire catchment resulted in deviations of up to 75% and 125%, respectively. These findings are supported by the work of past research projects and underline the necessity of a high spatial measurement density in order to account for spatial variability of intense rainstorms.
Roman Maier; Gerald Krebs; Markus Pichler; Dirk Muschalla; Günter Gruber. Spatial Rainfall Variability in Urban Environments—High-Density Precipitation Measurements on a City-Scale. Water 2020, 12, 1157 .
AMA StyleRoman Maier, Gerald Krebs, Markus Pichler, Dirk Muschalla, Günter Gruber. Spatial Rainfall Variability in Urban Environments—High-Density Precipitation Measurements on a City-Scale. Water. 2020; 12 (4):1157.
Chicago/Turabian StyleRoman Maier; Gerald Krebs; Markus Pichler; Dirk Muschalla; Günter Gruber. 2020. "Spatial Rainfall Variability in Urban Environments—High-Density Precipitation Measurements on a City-Scale." Water 12, no. 4: 1157.
Urbanization induces an increase of runoff volume and decrease of evapotranspiration and groundwater recharge. Low impact development (LID) strategies aim to mitigate these adverse impacts. Hydrologic simulation is a reasonable option to assess the LID performance with respect to the water balance and is applicable to planning purposes. Current LID design approaches are based on design storm events and focus on the runoff volume and peak, neglecting evapotranspiration and groundwater recharge. This contribution presents a model-based design approach for the selection of cost-effective LID strategies. The method is based on monitored precipitation time series and considers the complete water balance and life-cycle-costs, as well as the demand for land. The efficiency of LID strategies (ELID) is introduced as an evaluation measure which also accounts for emphasizing different goals. The results show that there exist several pareto-optimal LID strategies providing a reasonable basis for decision-making. Additionally, the application of LID treatment trains emerges as an option of high potential.
Johannes Leimgruber; Gerald Krebs; David Camhy; Dirk Muschalla. Model-Based Selection of Cost-Effective Low Impact Development Strategies to Control Water Balance. Sustainability 2019, 11, 2440 .
AMA StyleJohannes Leimgruber, Gerald Krebs, David Camhy, Dirk Muschalla. Model-Based Selection of Cost-Effective Low Impact Development Strategies to Control Water Balance. Sustainability. 2019; 11 (8):2440.
Chicago/Turabian StyleJohannes Leimgruber; Gerald Krebs; David Camhy; Dirk Muschalla. 2019. "Model-Based Selection of Cost-Effective Low Impact Development Strategies to Control Water Balance." Sustainability 11, no. 8: 2440.
Low impact development (LID) strategies aim to mitigate the adverse impacts of urbanization, like the increase of runoff and the decrease of evapotranspiration. Hydrological simulation is a reasonable option to evaluate the LID performance with respect to the complete water balance. The sensitivity of water balance components to LID parameters is important for the modeling and planning process of LIDs. This contribution presents the results of a global sensitivity analysis of model-based water balance components (runoff volume, evapotranspiration, groundwater recharge/storage change) using the US Environmental Protection Agency Storm Water Management Model to the parameters (e.g., soil thickness, porosity) of a green roof, an infiltration trench, and a bio-retention cell. All results are based on long-term simulations. The water balance and sensitivity analyses are evaluated for the long-term as well as single storm events. The identification of non-influential and most influential LID parameters for the water balance components is the main outcome of this work. Additionally, the influence of the storm event characteristics precipitation depth and antecedent dry period on the sensitivity of water balance components to LID parameters is shown.
Johannes Leimgruber; Gerald Krebs; David Camhy; Dirk Muschalla. Sensitivity of Model-Based Water Balance to Low Impact Development Parameters. Water 2018, 10, 1838 .
AMA StyleJohannes Leimgruber, Gerald Krebs, David Camhy, Dirk Muschalla. Sensitivity of Model-Based Water Balance to Low Impact Development Parameters. Water. 2018; 10 (12):1838.
Chicago/Turabian StyleJohannes Leimgruber; Gerald Krebs; David Camhy; Dirk Muschalla. 2018. "Sensitivity of Model-Based Water Balance to Low Impact Development Parameters." Water 10, no. 12: 1838.
Manually constructing hydrological model descriptions for urban areas tends to be laborious due to the detailed mosaic land cover and the required high-resolution model setup. Here, the performance of a novel automated subcatchment generator with a detailed DEM-based surface flow routing is assessed against observations and manually constructed models. In general, the auto-generated models perform well against observations and comparably to manually constructed models regardless of the detail of land cover information input. The introduced inter-subcatchment connections may require previously acquired model parameters to be re-calibrated. This is due to the calibrated parameters in manually constructed models, even with high-resolution landuse, partly compensating for missing flow routes due to the larger scale used in subcatchment description.
Tero J. Niemi; Gerald Krebs; Teemu Kokkonen. Automated Approach for Rainfall-Runoff Model Generation. Smart and Sustainable Planning for Cities and Regions 2018, 597 -602.
AMA StyleTero J. Niemi, Gerald Krebs, Teemu Kokkonen. Automated Approach for Rainfall-Runoff Model Generation. Smart and Sustainable Planning for Cities and Regions. 2018; ():597-602.
Chicago/Turabian StyleTero J. Niemi; Gerald Krebs; Teemu Kokkonen. 2018. "Automated Approach for Rainfall-Runoff Model Generation." Smart and Sustainable Planning for Cities and Regions , no. : 597-602.
The hydraulic verification of combined sewer systems as well as the assessment of combined sewer overflows (CSOs) can be conducted using a hydrodynamic model. Unfortunately, long-term simulations with hydrodynamic models for the assessment of CSOs can cause unacceptably long computation times. Using only a series of storm events instead of a precipitation continuum can reduce this time and enables parallel simulation of single storm events. We introduce a method to select this series of storm events. The method’s parameters have been optimized to replicate the overflow volume of the continuous simulation and to minimize the overall computation time. This optimization revealed a generally applicable parameter set that results in series of storm events that are shorter than the precipitation continuum by 86.2–95.2% for the investigated cases. Additionally, the deviation of overflow volume between continuous simulation and series simulation ranges between only 0.1% and 4.1%.
Johannes Leimgruber; David B. Steffelbauer; Gerald Krebs; Franz Tscheikner-Gratl; Dirk Muschalla. Selecting a series of storm events for a model-based assessment of combined sewer overflows. Urban Water Journal 2018, 15, 453 -460.
AMA StyleJohannes Leimgruber, David B. Steffelbauer, Gerald Krebs, Franz Tscheikner-Gratl, Dirk Muschalla. Selecting a series of storm events for a model-based assessment of combined sewer overflows. Urban Water Journal. 2018; 15 (5):453-460.
Chicago/Turabian StyleJohannes Leimgruber; David B. Steffelbauer; Gerald Krebs; Franz Tscheikner-Gratl; Dirk Muschalla. 2018. "Selecting a series of storm events for a model-based assessment of combined sewer overflows." Urban Water Journal 15, no. 5: 453-460.
An open source subcatchment generator program was developed for the Stormwater Management Model (SWMM) to automate tedious stages in the model construction process. The generator divides the investigated area into subcatchments using a uniform computation grid and connects the grid cells together and to the underlying stormwater network. The system was tested by applying it to two small urban catchments with different fractions of impervious surfaces in Helsinki, Finland, using mostly openly available data. The simulated discharge results were compared to measured data and to results obtained from manually built models. The proposed system significantly accelerated the setup of a SWMM modelling project, as the routing between the subcatchments as well as the subcatchment slopes and flow widths were directly derived from the computation grid. Automatically generated and manually constructed SWMM models produced discharge results that differed only slightly from each other.
Lassi Warsta; Tero J. Niemi; Maija Taka; Gerald Krebs; Kersti Haahti; Harri Koivusalo; Teemu Kokkonen. Development and application of an automated subcatchment generator for SWMM using open data. Urban Water Journal 2017, 14, 954 -963.
AMA StyleLassi Warsta, Tero J. Niemi, Maija Taka, Gerald Krebs, Kersti Haahti, Harri Koivusalo, Teemu Kokkonen. Development and application of an automated subcatchment generator for SWMM using open data. Urban Water Journal. 2017; 14 (9):954-963.
Chicago/Turabian StyleLassi Warsta; Tero J. Niemi; Maija Taka; Gerald Krebs; Kersti Haahti; Harri Koivusalo; Teemu Kokkonen. 2017. "Development and application of an automated subcatchment generator for SWMM using open data." Urban Water Journal 14, no. 9: 954-963.
Tero Niemi; Lassi Warsta; Maija Taka; Brandon Hickman; Seppo Pulkkinen; Gerald Krebs; Dmitri Moisseev; Harri Koivusalo; Teemu Kokkonen. Applicability of open rainfall data to event-scale urban rainfall-runoff modelling. Journal of Hydrology 2017, 547, 143 -155.
AMA StyleTero Niemi, Lassi Warsta, Maija Taka, Brandon Hickman, Seppo Pulkkinen, Gerald Krebs, Dmitri Moisseev, Harri Koivusalo, Teemu Kokkonen. Applicability of open rainfall data to event-scale urban rainfall-runoff modelling. Journal of Hydrology. 2017; 547 ():143-155.
Chicago/Turabian StyleTero Niemi; Lassi Warsta; Maija Taka; Brandon Hickman; Seppo Pulkkinen; Gerald Krebs; Dmitri Moisseev; Harri Koivusalo; Teemu Kokkonen. 2017. "Applicability of open rainfall data to event-scale urban rainfall-runoff modelling." Journal of Hydrology 547, no. : 143-155.
Urbanization leads to the replacement of natural areas by impervious surfaces and affects the catchment hydrological cycle with adverse environmental impacts. Low impact development tools (LID) that mimic hydrological processes of natural areas have been developed and applied to mitigate these impacts. Hydrological simulations are one possibility to evaluate the LID performance but the associated small-scale processes require a highly spatially distributed and explicit modeling approach. However, detailed data for model development are often not available for large urban areas, hampering the model parameterization. In this paper we propose a methodology to parameterize a hydrological model to a large, ungauged urban area by maintaining at the same time a detailed surface discretization for direct parameter manipulation for LID simulation and a firm reliance on available data for model conceptualization. Catchment delineation was based on a high-resolution digital elevation model (DEM) and model parameterization relied on a novel model regionalization approach. The impact of automated delineation and model regionalization on simulation results was evaluated for three monitored study catchments (5.87–12.59 ha). The simulated runoff peak was most sensitive to accurate catchment discretization and calibration, while both the runoff volume and the fit of the hydrograph were less affected.
Gerald Krebs; Teemu Kokkonen; Heikki Setälä; Harri Koivusalo. Parameterization of a Hydrological Model for a Large, Ungauged Urban Catchment. Water 2016, 8, 443 .
AMA StyleGerald Krebs, Teemu Kokkonen, Heikki Setälä, Harri Koivusalo. Parameterization of a Hydrological Model for a Large, Ungauged Urban Catchment. Water. 2016; 8 (10):443.
Chicago/Turabian StyleGerald Krebs; Teemu Kokkonen; Heikki Setälä; Harri Koivusalo. 2016. "Parameterization of a Hydrological Model for a Large, Ungauged Urban Catchment." Water 8, no. 10: 443.
Low Impact Development (LID) aims to mitigate the hydrological impacts of urbanization by replication of processes in natural catchments. Green roofs covered with vegetation and pervious substrate are one alternative among a wide range of LID tools. Water retention of green roofs depends on many factors (e.g. local climate), and measurements remain crucial in evaluating their performance. The simulation of green roof retention by a hydrological model is one option to evaluate their potential benefits before implementation. In this paper, we evaluated the ability of the recently introduced LID green roof module of the stormwater management model to replicate runoff from monitored green roof test beds under Nordic climate conditions. A parameter sensitivity analysis was conducted to identify calibration parameters. The model showed an overall acceptable performance, and the results indicated the importance of accurately estimating potential evapotranspiration rates for inter‐event periods, which is essential in representing the retention capacity regeneration. Copyright © 2015 John Wiley & Sons, Ltd.
Gerald Krebs; Kirsi Kuoppamäki; Teemu Kokkonen; Harri Koivusalo. Simulation of green roof test bed runoff. Hydrological Processes 2015, 30, 250 -262.
AMA StyleGerald Krebs, Kirsi Kuoppamäki, Teemu Kokkonen, Harri Koivusalo. Simulation of green roof test bed runoff. Hydrological Processes. 2015; 30 (2):250-262.
Chicago/Turabian StyleGerald Krebs; Kirsi Kuoppamäki; Teemu Kokkonen; Harri Koivusalo. 2015. "Simulation of green roof test bed runoff." Hydrological Processes 30, no. 2: 250-262.
Urbanization and associated increase of imperviousness alters the hydrological cycle of urbanizing catchments. Low Impact Development (LID) tools have...
G. Krebs; T. Kokkonen; M. Valtanen; H. Koivusalo. Large-scale urban hydrological modelling at high spatial resolution: requirements and applications. The Sustainable City IX 2014, 1 .
AMA StyleG. Krebs, T. Kokkonen, M. Valtanen, H. Koivusalo. Large-scale urban hydrological modelling at high spatial resolution: requirements and applications. The Sustainable City IX. 2014; ():1.
Chicago/Turabian StyleG. Krebs; T. Kokkonen; M. Valtanen; H. Koivusalo. 2014. "Large-scale urban hydrological modelling at high spatial resolution: requirements and applications." The Sustainable City IX , no. : 1.
Gerald Krebs; T. Kokkonen; M. Valtanen; H. Setälä; Harri Koivusalo. Spatial resolution considerations for urban hydrological modelling. Journal of Hydrology 2014, 512, 482 -497.
AMA StyleGerald Krebs, T. Kokkonen, M. Valtanen, H. Setälä, Harri Koivusalo. Spatial resolution considerations for urban hydrological modelling. Journal of Hydrology. 2014; 512 ():482-497.
Chicago/Turabian StyleGerald Krebs; T. Kokkonen; M. Valtanen; H. Setälä; Harri Koivusalo. 2014. "Spatial resolution considerations for urban hydrological modelling." Journal of Hydrology 512, no. : 482-497.
Low Impact Development (LID) tools and green infrastructure approaches have been developed and applied to mitigate the urbanization impacts on increasing runoff and pollutant washoff. The present work is the first part of a larger effort to simulate LID scenarios for a large scale urban catchment through up-scaling of high-resolution study catchments using the Stormwater Management Model (SWMM). In this study we present the setup, calibration, validation, and the results of a parameter sensitivity analysis of a high-resolution SWMM model for a highly urbanized small catchment located in Southern Finland. The homogenous subcatchments and associated narrow parameter boundaries, which are allowed by the high spatial resolution, result in insensitivity of SWMM to the fraction of impervious cover. The model optimization, using only the two identified key parameters “depression storage” and “Manning's roughness n for conduit flow”, yielded good performance statistics for both calibration and validation of the model.
G. Krebs; T. Kokkonen; M. Valtanen; Harri Koivusalo; H. Setälä. A high resolution application of a stormwater management model (SWMM) using genetic parameter optimization. Urban Water Journal 2013, 10, 394 -410.
AMA StyleG. Krebs, T. Kokkonen, M. Valtanen, Harri Koivusalo, H. Setälä. A high resolution application of a stormwater management model (SWMM) using genetic parameter optimization. Urban Water Journal. 2013; 10 (6):394-410.
Chicago/Turabian StyleG. Krebs; T. Kokkonen; M. Valtanen; Harri Koivusalo; H. Setälä. 2013. "A high resolution application of a stormwater management model (SWMM) using genetic parameter optimization." Urban Water Journal 10, no. 6: 394-410.
Gerald Krebs; Ulla-Maija Rimpiläinen; Outi Salminen. How does imperviousness develop and affect runoff generation in an urbanizing watershed? Fennia - International Journal of Geography 2013, 143 -159.
AMA StyleGerald Krebs, Ulla-Maija Rimpiläinen, Outi Salminen. How does imperviousness develop and affect runoff generation in an urbanizing watershed? Fennia - International Journal of Geography. 2013; ():143-159.
Chicago/Turabian StyleGerald Krebs; Ulla-Maija Rimpiläinen; Outi Salminen. 2013. "How does imperviousness develop and affect runoff generation in an urbanizing watershed?" Fennia - International Journal of Geography , no. : 143-159.