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A strategy to simulate rainfall by the means of different Multiplicative random Cascades (MRC) was developed to evaluate their applicability to produce inputs for green roof infrastructures models taking into account climate change. The MRC reproduce a (multi)fractal distribution of precipitation through an iterative and multiplicative random process. The initial model was improved with a temperature dependency and an additional function to improve its capability to reproduce the temporal structure of rainfall. The structure of the models with depth and temperature dependency was found to be applicable in eight locations studied across Norway (N) and France (F). The resulting time-series from both reference period and projection based on RCP 8.5 were applied to two green roofs (GR) with different properties. The different models lead to a slight change in the performance of GR, but this was not significant compared to the range of outcomes due to ensemble uncertainty in climate modelling and the stochastic uncertainty due to nature of the process. The moderating effect of the green infrastructure was found to decrease in most of the Norwegian cities, especially Bergen (N), while increasing in Lyon (F).
Vincent Pons; Rasmus Benestad; Edvard Sivertsen; Tone Merete Muthanna; Jean-Luc Bertrand-Krajewski. Temporal downscaling of precipitation time-series projections to forecast green roofs future detention performance. 2021, 2021, 1 -24.
AMA StyleVincent Pons, Rasmus Benestad, Edvard Sivertsen, Tone Merete Muthanna, Jean-Luc Bertrand-Krajewski. Temporal downscaling of precipitation time-series projections to forecast green roofs future detention performance. . 2021; 2021 ():1-24.
Chicago/Turabian StyleVincent Pons; Rasmus Benestad; Edvard Sivertsen; Tone Merete Muthanna; Jean-Luc Bertrand-Krajewski. 2021. "Temporal downscaling of precipitation time-series projections to forecast green roofs future detention performance." 2021, no. : 1-24.
As climate change in the Nordic region brings an increase in extreme precipitation events, blue-green roofs have emerged as a solution for stormwater management, hereafter referred to as “blue-green roofs”. The addition of blue-green layers on a conventional compact roof represents several multi-disciplinary technical challenges and quality risks that must be managed. This paper aims to list and address the key building technical challenges associated with blue-green roofs and to present a framework for managing these risks. Literature and document studies as well as qualitative interviews and expert meetings have been conducted to collect research data on defects in blue-green roofs and causes thereof. A list of nine key challenges has been extracted along with recommendations on how to address them. The recommendations are structured around a framework developed for practical use in building projects. For ease of use, the nine key challenges are presented on a general level, with references to detailed recommendations. The framework is intended to be used to reduce the building technical risks of blue-green roofs, by addressing the most important quality risk elements.
Erlend Andenæs; Berit Time; Tone Muthanna; Silje Asphaug; Tore Kvande. Risk Reduction Framework for Blue-Green Roofs. Buildings 2021, 11, 185 .
AMA StyleErlend Andenæs, Berit Time, Tone Muthanna, Silje Asphaug, Tore Kvande. Risk Reduction Framework for Blue-Green Roofs. Buildings. 2021; 11 (5):185.
Chicago/Turabian StyleErlend Andenæs; Berit Time; Tone Muthanna; Silje Asphaug; Tore Kvande. 2021. "Risk Reduction Framework for Blue-Green Roofs." Buildings 11, no. 5: 185.
Green roofs are increasingly popular measures to permanently reduce or delay stormwater runoff. Conceptual and physically-based hydrological models are powerful tools to estimate their performance. However, physically-based models are associated with a high level of complexity and computation costs while parameters of conceptual models are more difficult to obtain when measurements are not available for calibration. The main objective of the study was to examine the potential of using machine learning (ML) to simulate runoff from green roofs to estimate their hydrological performance. Four machine learning methods, Artificial Neural Network (ANN), M5 Model tree, Long Short-Term Memory (LSTM) and k-Nearest Neighbour (kNN) were applied to simulate stormwater runoff from sixteen extensive green roofs located in four Norwegian cities across different climatic zones. The potential of these ML methods for estimating green roof retention was assessed by comparing their simulations with a proven conceptual retention model. Furthermore, the transferability of ML models between the different green roofs in the study was tested to investigate the potential of using ML models as a tool for planning and design purposes. The ML models yielded low volumetric errors that were comparable with the conceptual retention models, which indicates good performance in estimating annual retention. The ML models yielded satisfactory modelling results (NSE > 0.5) in both training and validation data which indicates an ability to estimate green roof detention. The variations in ML models' performance between the cities was larger than between the different configurations, which was attributed to the different climatic characteristics between the four cities. Transferred ML models between cities with similar rainfall events characteristics (Bergen–Sandnes, Trondheim–Oslo) could yield satisfactory modelling performance (NSE > 0.5, |PBIAS|
Elhadi Mohsen Hassan Abdalla; Vincent Pons; Virginia Stovin; Simon De-Ville; Elizabeth Fassman-Beck; Knut Alfredsen; Tone Merete Muthanna. Evaluating different machine learning methods to simulate runoff from extensive green roofs. 2021, 2021, 1 -24.
AMA StyleElhadi Mohsen Hassan Abdalla, Vincent Pons, Virginia Stovin, Simon De-Ville, Elizabeth Fassman-Beck, Knut Alfredsen, Tone Merete Muthanna. Evaluating different machine learning methods to simulate runoff from extensive green roofs. . 2021; 2021 ():1-24.
Chicago/Turabian StyleElhadi Mohsen Hassan Abdalla; Vincent Pons; Virginia Stovin; Simon De-Ville; Elizabeth Fassman-Beck; Knut Alfredsen; Tone Merete Muthanna. 2021. "Evaluating different machine learning methods to simulate runoff from extensive green roofs." 2021, no. : 1-24.
Climate change and urbanization increase the pressure on combined sewer systems in urban areas resulting in elevated combined sewer overflows, degraded water quality in receiving waters, and changing stream flows. Permeable surfaces offer infiltration potential, which can contribute to alleviate the runoff to combined sewer systems. The variation in urban soil characteristics and the initial moisture conditions before a rainfall event are important factors affecting the infiltration process and consequently runoff characteristics. In this study, the urban hydrological models SWMM and STORM are used to evaluate the Green-Ampt, Horton, and Holtan infiltration methods for three urban sandy soils. A sensitivity analysis was carried out on a set of key parameter values. In addition, long-term simulations were conducted to evaluate the ability to account for initial soil moisture content. The results showed that the Holtan method's ability to account for both available storage capacity and maximum infiltration rate, as well as evapotranspiration in the regeneration of infiltration capacity, gave the best result with regard to runoff behaviour, especially for long-term simulations. Furthermore, the results from the urban sandy soils with different infiltration rate at saturation, together with a high sensitivity to the degree of sensitivity for maximum infiltration rate under dry conditions and minimum infiltration rate under wet conditions, indicate that field measurements of infiltration rate should be carried out at saturation for these soils.
Frida E. Å. Parnas; Elhadi M. H. Abdalla; Tone M. Muthanna. Evaluating three commonly used infiltration methods for permeable surfaces in urban areas using the SWMM and STORM. Water Policy 2021, 52, 160 -175.
AMA StyleFrida E. Å. Parnas, Elhadi M. H. Abdalla, Tone M. Muthanna. Evaluating three commonly used infiltration methods for permeable surfaces in urban areas using the SWMM and STORM. Water Policy. 2021; 52 (1):160-175.
Chicago/Turabian StyleFrida E. Å. Parnas; Elhadi M. H. Abdalla; Tone M. Muthanna. 2021. "Evaluating three commonly used infiltration methods for permeable surfaces in urban areas using the SWMM and STORM." Water Policy 52, no. 1: 160-175.
Climate change is one of the greatest threats currently facing the world's environment. In Norway, a change in climate will strongly affect the pattern, frequency, and magnitudes of stream flows. However, it is challenging to quantify to what extent the change will affect the flow patterns and floods from small rural catchments due to the unavailability or inadequacy of hydro-meteorological data for the calibration of hydrological models and due to the tailoring of methods to a small-scale level. To provide meaningful climate impact studies at the level of small catchments, it is therefore beneficial to use high-spatial- and high-temporal-resolution climate projections as input to a high-resolution hydrological model. In this study, we used such a model chain to assess the impacts of climate change on the flow patterns and frequency of floods in small ungauged rural catchments in western Norway. We used a new high-resolution regional climate projection, with improved performance regarding the precipitation distribution, and a regionalized hydrological model (distance distribution dynamics) between a reference period (1981–2011) and a future period (2070–2100). The flow-duration curves for all study catchments show more wet periods in the future than during the reference period. The results also show that in the future period, the mean annual flow increases by 16 % to 33 %. The mean annual maximum floods increase by 29 % to 38 %, and floods of 2- to 200-year return periods increase by 16 % to 43 %. The results are based on the RCP8.5 scenario from a single climate model simulation tailored to the Bergen region in western Norway, and the results should be interpreted in this context. The results should therefore be seen in consideration of other scenarios for the region to address the uncertainty. Nevertheless, the study increases our knowledge and understanding of the hydrological impacts of climate change on small catchments in the Bergen area in the western part of Norway.
Aynalem T. Tsegaw; Marie Pontoppidan; Erle Kristvik; Knut Alfredsen; Tone M. Muthanna. Hydrological impacts of climate change on small ungauged catchments – results from a global climate model–regional climate model–hydrologic model chain. Natural Hazards and Earth System Sciences 2020, 20, 2133 -2155.
AMA StyleAynalem T. Tsegaw, Marie Pontoppidan, Erle Kristvik, Knut Alfredsen, Tone M. Muthanna. Hydrological impacts of climate change on small ungauged catchments – results from a global climate model–regional climate model–hydrologic model chain. Natural Hazards and Earth System Sciences. 2020; 20 (8):2133-2155.
Chicago/Turabian StyleAynalem T. Tsegaw; Marie Pontoppidan; Erle Kristvik; Knut Alfredsen; Tone M. Muthanna. 2020. "Hydrological impacts of climate change on small ungauged catchments – results from a global climate model–regional climate model–hydrologic model chain." Natural Hazards and Earth System Sciences 20, no. 8: 2133-2155.
Paved surfaces, increased precipitation intensities in addition to limited capacity in the sewer systems, cause a higher risk of combined sewer overflows (CSOs). Sustainable drainage systems (SUDS) offer an alternative approach to mitigate CSO by managing the stormwater locally. Seven SUDS scenarios, developed based on the concept of effective impervious area reduction, have been implemented in the Grefsen catchment using the Mike Urban model. This study evaluated the hydrological performance of two SUDS controls (i.e. green roof (GR) and rain garden (RG)) modules of the model and the effect of the SUDS scenarios on the CSOs using event-based and continuous simulations. The Nash–Sutcliffe efficiency (NSE) along with flow duration curves (FDCs) has been used for evaluating the model performance. Event-based evaluations revealed the superior performance of the RG in reducing CSOs for larger precipitation events, while GRs were proven to have beneficial outcomes during smaller events. The study illustrated another way of assessing the continuous simulations by employing the FDCs. The FDCs were assessed against a discharge threshold at the outlet (which authorities can set as design criteria) of the catchment in terms of the extent, each scenario reduced occurrence and duration of outflow that invokes flow in the overflow pipe.
Ragni R. Hernes; Ashenafi S. Gragne; Elhadi M. H. Abdalla; Bent C. Braskerud; Knut Alfredsen; Tone M. Muthanna. Assessing the effects of four SUDS scenarios on combined sewer overflows in Oslo, Norway: evaluating the low-impact development module of the Mike Urban model. Water Policy 2020, 51, 1437 -1454.
AMA StyleRagni R. Hernes, Ashenafi S. Gragne, Elhadi M. H. Abdalla, Bent C. Braskerud, Knut Alfredsen, Tone M. Muthanna. Assessing the effects of four SUDS scenarios on combined sewer overflows in Oslo, Norway: evaluating the low-impact development module of the Mike Urban model. Water Policy. 2020; 51 (6):1437-1454.
Chicago/Turabian StyleRagni R. Hernes; Ashenafi S. Gragne; Elhadi M. H. Abdalla; Bent C. Braskerud; Knut Alfredsen; Tone M. Muthanna. 2020. "Assessing the effects of four SUDS scenarios on combined sewer overflows in Oslo, Norway: evaluating the low-impact development module of the Mike Urban model." Water Policy 51, no. 6: 1437-1454.
Climate change combined with urbanization increases the performance demand on urban drainage systems. Green roofs are one of the most used green infrastructure measures to alleviate the pressure on the urban drainage system through the detention and retention of runoff. The rational method with the runoff coefficient (C) is one of the most commonly used design tools for stormwater design in Norway. This method relies on a runoff coefficient being available for green roofs, which is typically not the case. This paper compares laboratory and experimental field studies to investigate runoff coefficients from different types of detention-based roofs. The methodology described in the German ‘FLL Guideline’, one of the world's most commonly used green roof standards, was used to measure the runoff coefficients for the different components making up a typical green roof. The contribution from each layer is reflected in the runoff coefficients. The runoff coefficients from the field experiments were calculated using observed precipitation and runoff from existing green roofs in Oslo, Trondheim, Sandnes, and Bergen, Norway. Events that had a cumulative precipitation comparable to the laboratory events, but longer durations, were selected. These events gave significantly lower and varying runoff coefficients, clearly demonstrating the limitation of choosing a suitable runoff coefficient for a given roof. However, laboratory experiments are important in understanding the underlying flow processes in the different layers in a detention-based roof.
Lotte Askeland Schärer; Jan Ove Busklein; Edvard Sivertsen; Tone M. Muthanna. Limitations in using runoff coefficients for green and gray roof design. Water Policy 2020, 51, 339 -350.
AMA StyleLotte Askeland Schärer, Jan Ove Busklein, Edvard Sivertsen, Tone M. Muthanna. Limitations in using runoff coefficients for green and gray roof design. Water Policy. 2020; 51 (2):339-350.
Chicago/Turabian StyleLotte Askeland Schärer; Jan Ove Busklein; Edvard Sivertsen; Tone M. Muthanna. 2020. "Limitations in using runoff coefficients for green and gray roof design." Water Policy 51, no. 2: 339-350.
Coastal cold climates experience frequent intermittent melting and freezing periods over the cold period. This intermittent freezing in stormwater systems affects the infiltration capacity and hence the performance. This paper investigates the infiltration capacity of engineered filter media (composed of sand mixed with charcoal, pine bark, or olivine) under freezing temperatures in a column-based laboratory setup. Infiltration into partially frozen filter media was replicated using a climate room. The filter media in the columns were brought to −2.5 °C, and water at +2 °C was percolated through the columns with a constant head of 5 cm. Infiltration performance was assessed by observing the time until breakthrough, and the infiltration rate 24 h after breakthrough. The results were compared to the observed hydraulic conductivity for the unfrozen filter media. A novel approach combining the unfrozen water content curves with X-ray tomographic (XRT) images of the materials was adopted to better understand the thermal and infiltration processes. Breakthrough was observed between ca. 21 and 56 h in all columns. The column with homogeneously mixed filter media with sand yielded the quickest breakthrough. The infiltration rates were higher than recommendations for infiltration-based systems in cold climates, making them a suitable option in cold climates.
Carlos Monrabal-Martinez; Elena Scibilia; Sønke Maus; Tone M. Muthanna. Infiltration Response of Adsorbent Amended Filters for Stormwater Management under Freezing/Thawing Conditions. Water 2019, 11, 2619 .
AMA StyleCarlos Monrabal-Martinez, Elena Scibilia, Sønke Maus, Tone M. Muthanna. Infiltration Response of Adsorbent Amended Filters for Stormwater Management under Freezing/Thawing Conditions. Water. 2019; 11 (12):2619.
Chicago/Turabian StyleCarlos Monrabal-Martinez; Elena Scibilia; Sønke Maus; Tone M. Muthanna. 2019. "Infiltration Response of Adsorbent Amended Filters for Stormwater Management under Freezing/Thawing Conditions." Water 11, no. 12: 2619.
Climate change is one of the greatest threats to the World's environment. In Norway, the change will strongly affect the pattern, frequency and magnitudes of stream flows. However, it is highly challenging to quantify to what extent it will affect flow patterns and floods from small ungauged rural catchments due to unavailability or inadequacy of hydro-meteorological data for the calibration of hydrological models and tailoring methods to a small-scale level. To provide meaningful climate impact studies at small catchments, it is therefore beneficial to use high spatial and temporal resolution climate projections as input to a high-resolution hydrological model. Here we use such a model chain to assess the impacts of climate change on flow patterns and frequency of floods in small ungauged rural catchments in western Norway using a new high-resolution regional climate projection, with improved performance with regards to the precipitation distribution, and the regionalized hydrological model (Distance Distribution Dynamics) between the reference period (1981–2011) and a future period (2071–2100). The FDCs of all study catchments show there will be more wetter periods in the future than the reference period. The results also show that in the future period, the mean annual flow increases by 16.5 % to 33.3 %, and there will be an increase in the mean autumn, mean winter and mean spring flows ranging from 4.3 % to 256.3 %. The mean summer flow decreases by 7.2 % to 35.2 %. The mean annual maximum floods increase by 28.9 % to 38.3 %, and floods of 2 to 200 years return periods increase by 16.1 % to 42.7 %. The findings of this study could be of practical use to regional decision-makers if considered alongside other previous and future findings.
Aynalem T. Tsegaw; Marie Pontoppidan; Erle Kristvik; Knut Alfredsen; Tone M. Muthanna. Hydrological impacts of climate change on small ungauged catchments-results from a GCM-RCM-hydrologic model chain. 2019, 1 -56.
AMA StyleAynalem T. Tsegaw, Marie Pontoppidan, Erle Kristvik, Knut Alfredsen, Tone M. Muthanna. Hydrological impacts of climate change on small ungauged catchments-results from a GCM-RCM-hydrologic model chain. . 2019; ():1-56.
Chicago/Turabian StyleAynalem T. Tsegaw; Marie Pontoppidan; Erle Kristvik; Knut Alfredsen; Tone M. Muthanna. 2019. "Hydrological impacts of climate change on small ungauged catchments-results from a GCM-RCM-hydrologic model chain." , no. : 1-56.
Mathematical stormwater models are often used as tools for planning and analysing urban drainage systems. However, the inherent uncertainties of the models must be properly understood in order to make optimal use of them. One source of uncertainty that has received relatively little attention, particularly for increasingly popular green areas as part of urban drainage systems, is the mathematical model structure. This paper analyses the differences between three different widely-used models (SWMM, MOUSE and Mike SHE) when simulating rainfall runoff from green areas over a 26-year period. Eleven different soil types and six different soil depths were used to investigate the sensitivity of the models to changes in both. Important hydrological factors such as seasonal runoff and evapotranspiration, the number of events that generated runoff, and the initial conditions for rainfall events, varied significantly between the three models. MOUSE generated the highest runoff volumes, while it was rather insensitive to changes in soil type and depth. Mike SHE was mainly sensitive to changes in soil type. SWMM, which generated the least runoff, was sensitive to changes in both soil type and depth. Explanations for the observed differences were found in the descriptions of the mathematical models. The differences in model outputs could significantly impact the conclusions from studies on the design or analysis of urban drainage systems. The amount and frequency of runoff from green areas in all three models indicates that green areas cannot be simply ignored in urban drainage modelling studies.
Ico Broekhuizen; Tone Merete Muthanna; Günther Leonhardt; Maria Viklander. Urban drainage models for green areas: Structural differences and their effects on simulated runoff. Journal of Hydrology X 2019, 5, 100044 .
AMA StyleIco Broekhuizen, Tone Merete Muthanna, Günther Leonhardt, Maria Viklander. Urban drainage models for green areas: Structural differences and their effects on simulated runoff. Journal of Hydrology X. 2019; 5 ():100044.
Chicago/Turabian StyleIco Broekhuizen; Tone Merete Muthanna; Günther Leonhardt; Maria Viklander. 2019. "Urban drainage models for green areas: Structural differences and their effects on simulated runoff." Journal of Hydrology X 5, no. : 100044.
Rooftop retrofitting targets the largest land-use type available for reduction in impervious surfaces area in urban areas. Extensive green and grey roofs offer solution for retention and detention of stormwater in densely developed urban areas. Among the available green roof types, the extensive green roof has become a popular selection and commonly adopted choice. These solutions provide multiple benefits for stormwater and environmental management due to stormwater retention and detention capacities. The Storm Water Management Model (SWMM) 5.1.012 with Low Impact Development (LID) Controls was used to model the hydrological performance of a green and a grey (non-vegetated detention roof based on extruded lightweight aggregates) roof (located in the coastal area of Trondheim, Norway) by defining the physical parameters of individual layers in LID Control editor. High-resolution 1-min data from a previously monitored green and grey roof were used for calibration. Six parameters within the individual LID layers: soil (four parameters) and drainage mat (two parameters) were selected for calibration. After calibration, the SWMM model simulated runoff with a Nash-Sutcliffe model efficiency (NSME) of 0.94 (green roof) and 0.78 (grey roof) and a volume error of 3% for the green roof, and 10% for the grey roof. Validation of the calibrated model indicates good fit between observed and simulated runoff with a NSME of 0.88 (green roof) and 0.81 (grey roof) and with volume errors of 29% (green roof) and 11% (grey roof). Concerning the snowmelt modelling, the calibrated model showed a NSME of 0.56 (green roof) and 0.37 (grey roof) through the winter period. However, regarding volume errors, additional model development for winter conditions is needed; 30% (green roof) and 11% (grey roof). Optimal parameter sets were proposed within both the green and grey configurations. The results from calibration and especially validation indicated that SWMM could be used to simulate the performance of different rooftop solutions. The study provides insight for urban planners of how to target and focus the implementation of rooftop solutions as stormwater measures.
Vladimír Hamouz; Tone Merete Muthanna. Hydrological modelling of green and grey roofs in cold climate with the SWMM model. Journal of Environmental Management 2019, 249, 109350 .
AMA StyleVladimír Hamouz, Tone Merete Muthanna. Hydrological modelling of green and grey roofs in cold climate with the SWMM model. Journal of Environmental Management. 2019; 249 ():109350.
Chicago/Turabian StyleVladimír Hamouz; Tone Merete Muthanna. 2019. "Hydrological modelling of green and grey roofs in cold climate with the SWMM model." Journal of Environmental Management 249, no. : 109350.
Streamflow data is important for studies of water resources and flood management, but an inherent problem is that many catchments of interest are ungauged. The lack of data is particularly the case for small catchments, where flow data with high temporal resolution is needed. This paper presents an analysis of regionalizing parameters of the Distance Distribution Dynamics (DDD) rainfall-runoff model for predicting hourly flows at small-ungauged rural catchments. The performance of the model with hourly time resolution has been evaluated (calibrated and validated) for 41 small gauged catchments in Norway (areas from 1 km2 – 50km2). The model parameters needing regionalization have been regionalized using three different methods: multiple regression, physical similarity (single-donor and pooling-group based methods), and a combination of the two methods. Seven independent catchments, which are not used in the evaluation, are used for validation of the regionalization methods. All the three methods (the multiple regression, pooling-group, and combined methods) perform satisfactorily (0.5 ≤ KGE < 0.75). The combined method (which combines multiple regression and pooling-group) performed slightly better than the other methods. Some model parameters, namely those describing recession characteristics, estimated by the regionalization methods, appear to be a better choice than those estimated locally from short period of hydro-meteorological data for some test catchments. The single-donor method did not perform satisfactorily. The satisfactory performance of the combined method shows that regionalization of DDD model parameters is possible by combining multiple regression and physical similarity methods.
Aynalem Tassachew Tsegaw; Knut Alfredsen; Thomas Skaugen; Tone M. Muthanna. Predicting hourly flows at ungauged small rural catchments using a parsimonious hydrological model. Journal of Hydrology 2019, 573, 855 -871.
AMA StyleAynalem Tassachew Tsegaw, Knut Alfredsen, Thomas Skaugen, Tone M. Muthanna. Predicting hourly flows at ungauged small rural catchments using a parsimonious hydrological model. Journal of Hydrology. 2019; 573 ():855-871.
Chicago/Turabian StyleAynalem Tassachew Tsegaw; Knut Alfredsen; Thomas Skaugen; Tone M. Muthanna. 2019. "Predicting hourly flows at ungauged small rural catchments using a parsimonious hydrological model." Journal of Hydrology 573, no. : 855-871.
Low-impact development (LID) structures are combined with traditional measures to manage stormwater and cope with increased runoff rates originating from heavy urbanization and climate change. As the use of LIDs for climate adaptation increases, practitioners need more knowledge on LID performance in future climates for successful planning and implementation. In this study, temporal downscaling of regional climate projections for three cities in Norway is performed, using the concept of scale invariance to downscale the distribution of extreme precipitation from daily to sub-daily timescales. From this, local-scale intensity-duration-frequency (IDF) curves for future precipitation were obtained. Using climate projections of daily temporal resolution as input to water balance models and the obtained IDF relationships as input to event-based models allowed for assessing the retention capacity, peak flow reduction potential and pollution control of three different types of LIDs: green roofs, bioretention cells, and detention basins. The downscaling resulted in large local variations in presumed increase of both precipitation amount and intensity, contradicting current design recommendations in Norway. Countrywide, a decrease in the overall LID performance was found, although some positive effects of temperature rises were detected. The study illustrated the importance of evapotranspiration- and infiltration-based processes in future stormwater management and how coupling of LID structures in series can significantly reduce required detention volumes.
Erle Kristvik; Birgitte Gisvold Johannessen; Tone Merete Muthanna. Temporal Downscaling of IDF Curves Applied to Future Performance of Local Stormwater Measures. Sustainability 2019, 11, 1231 .
AMA StyleErle Kristvik, Birgitte Gisvold Johannessen, Tone Merete Muthanna. Temporal Downscaling of IDF Curves Applied to Future Performance of Local Stormwater Measures. Sustainability. 2019; 11 (5):1231.
Chicago/Turabian StyleErle Kristvik; Birgitte Gisvold Johannessen; Tone Merete Muthanna. 2019. "Temporal Downscaling of IDF Curves Applied to Future Performance of Local Stormwater Measures." Sustainability 11, no. 5: 1231.
While extensive green roofs are popular measures for reducing and delaying stormwater runoff, design tools are needed to better predict roof performance based on material properties, geometry and climate. This paper investigates the EPA’s Storm Water Management Model’s (SWMM) green roof module for this purpose based on observed runoff from several roofs with different build-ups, geometry, and climates. First, the general model performance was investigated and secondly transferability of model parameters for similar roofs but different geometries and climates was tested. Individual models reproduced runoff hydrographs well (NSE 0.56-0.96), while the long-term modelling showed relatively large volume errors most likely due to insufficient representation of evapotranspiration in the model. Model parameters obtained at one site were only partly transferable to similar roof build-up at other sites. Transferability was better from models calibrated with wetter climates and higher intensity events to drier climates, than the opposite way. Multi-site calibration resulted in model parameters performing well for most sites, giving model parameters that could be used for the design of similar roof build-ups in comparable climates. However, large variability in obtained model parameters, large volume errors and the fact that the calibrated model parameters did not directly correspond to measured material properties, place concerns on the generality of the SWMM green roof module as a design tool.
Birgitte Gisvold Johannessen; Vladimír Hamouz; Ashenafi Seifu Gragne; Tone Merete Muthanna. The transferability of SWMM model parameters between green roofs with similar build-up. Journal of Hydrology 2019, 569, 816 -828.
AMA StyleBirgitte Gisvold Johannessen, Vladimír Hamouz, Ashenafi Seifu Gragne, Tone Merete Muthanna. The transferability of SWMM model parameters between green roofs with similar build-up. Journal of Hydrology. 2019; 569 ():816-828.
Chicago/Turabian StyleBirgitte Gisvold Johannessen; Vladimír Hamouz; Ashenafi Seifu Gragne; Tone Merete Muthanna. 2019. "The transferability of SWMM model parameters between green roofs with similar build-up." Journal of Hydrology 569, no. : 816-828.
Urbanization and increased precipitation volumes and intensities due to climate change add pressure to the urban drainage system, resulting in increased flooding frequencies of urban areas and deteriorating water quality in receiving waters. Infiltration practices and the use of blue green infrastructure, also called Sustainable Urban Drainage Systems (SUDS), can limit, and, in some cases, reverse the effects of urbanization. However, adequate infiltration capacity is an essential parameter for the successful implementation. In this paper, a Geographical Information System (GIS)-based hydrology analysis for SUDS placements is coupled with field measurements using Modified Phillip Dunne infiltrometer tests. The case study area is the expansion of the campus at the Norwegian University of Science and Technology (NTNU) over the next decade. Infiltration in urban soils can be highly heterogenous over short distances. When comparing measured infiltration rates with physical characteristics of the soils showed that the physical characteristics are not a good indication of the infiltration potential in urban soils with a large degree of compaction. The results showed that measuring the infiltration potential combined with flow path analysis can greatly enhance the benefits of blue green infrastructure, with an up to 70% difference in area required for SUDS solutions for managing 90% of the annual precipitation.
Tone M. Muthanna; Edvard Sivertsen; Dennis Kliewer; Lensa Jotta. Coupling Field Observations and Geographical Information System (GIS)-Based Analysis for Improved Sustainable Urban Drainage Systems (SUDS) Performance. Sustainability 2018, 10, 4683 .
AMA StyleTone M. Muthanna, Edvard Sivertsen, Dennis Kliewer, Lensa Jotta. Coupling Field Observations and Geographical Information System (GIS)-Based Analysis for Improved Sustainable Urban Drainage Systems (SUDS) Performance. Sustainability. 2018; 10 (12):4683.
Chicago/Turabian StyleTone M. Muthanna; Edvard Sivertsen; Dennis Kliewer; Lensa Jotta. 2018. "Coupling Field Observations and Geographical Information System (GIS)-Based Analysis for Improved Sustainable Urban Drainage Systems (SUDS) Performance." Sustainability 10, no. 12: 4683.
This paper characterizes stormwater runoff in a coastal cold climate urban area regarding metal fractionation and particle size distribution to understand the implications for sustainable urban drainage system (SuDS) design. Strong temporal and spatial variations were found for all studied parameters. Suspended and dissolved solids showed up to 10-fold and 44-fold increase, respectively, during salting periods (air temperature 1.2 µm), which increased during the salting periods (>97%). Use of snow-tyres and de-icers (gritting sand and NaCl) are more likely to explain the temporal fluctuations, rather than contributions from nearby snow piles. Residential streets might serve as a source of pollutants during the winter months when street sweeping is minimal. These results imply that protection against clogging from excessive sediment loads and use of salts during winter should be the primary focus for SuDS design.
Carlos Monrabal-Martinez; Thomas Meyn; Tone Merete Muthanna. Characterization and temporal variation of urban runoff in a cold climate - design implications for SuDS. Urban Water Journal 2018, 16, 451 -459.
AMA StyleCarlos Monrabal-Martinez, Thomas Meyn, Tone Merete Muthanna. Characterization and temporal variation of urban runoff in a cold climate - design implications for SuDS. Urban Water Journal. 2018; 16 (6):451-459.
Chicago/Turabian StyleCarlos Monrabal-Martinez; Thomas Meyn; Tone Merete Muthanna. 2018. "Characterization and temporal variation of urban runoff in a cold climate - design implications for SuDS." Urban Water Journal 16, no. 6: 451-459.
The urban drainage system experiences increasing challenges due to limited capacity, increased precipitation amount, and intensity cause a higher risk of urban flooding and frequent combined sewer overflows (CSOs). This is a common problem in Norwegian cities, and around the world. The gully pots in the urban drainage system should trap sediments that is transported with stormwater and function as a pollutant trap for low flow events. However, this is dependent on regular maintenance for proper function. If poorly maintained the gully pots in the drainage systems can become a source of resuspension of accumulated sediments during high intensity rain events that. This can be a significant source of polluted sediment transported to receiving waters. This study investigates the pathways and occurrence of remobilization of sediments through the use of a SWMM model and a case study area in Damsgaard, Bergen. Steep slopes characterize the research catchment, with elevation ranges from sea level to 468 m above mean sea level. Built-up areas (i.e. buildings and roads) cover about 48.3% of the area while about 44.5% of the catchment is forested. The case study illustrates how poorly maintained gully pots can be a net source of pollutants to receiving waters, in this case the Puddefjord fjord, where the City of Bergen wishes to establish swimmable water quality in the inner harbor areas.
Tone Merete Muthanna; Maria Viklander. Remobilization of Sediments in Gully Pots During High Intensity Precipitation Events. Smart and Sustainable Planning for Cities and Regions 2018, 993 -996.
AMA StyleTone Merete Muthanna, Maria Viklander. Remobilization of Sediments in Gully Pots During High Intensity Precipitation Events. Smart and Sustainable Planning for Cities and Regions. 2018; ():993-996.
Chicago/Turabian StyleTone Merete Muthanna; Maria Viklander. 2018. "Remobilization of Sediments in Gully Pots During High Intensity Precipitation Events." Smart and Sustainable Planning for Cities and Regions , no. : 993-996.
Rooftops retrofitting, typically extensive green roofs, is a favoured sustainable drainage system technology in densely developed urban areas. They provide multiple benefits in terms of stormwater retention and runoff detention. The latest version of Storm Water Management Model (SWMM) 5.1.012 with Low Impact Development (LID) Controls was used to model hydrological the performance of a green and grey (non-vegetated) roof by defining the physical parameters of individual layers in LID Control editor. In this study, high-resolution 1-min data from a previously monitored green and grey roof were used to calibrate the SWMM LID Green Roof module. Results from the un-calibrated model were unsatisfactory considering the hydrological response of the green and grey roof. After calibration, the observed and simulated runoff had Nash-Sutcliffe model efficiency (NSME) of 0.88 (green roof) 0.68 (grey roof). This indicates that better fit between observed and modelled runoff could be achieved with calibration, primarily of the grey roof. Ideally the calibrated parameter set of the LID modules should be transferable between watersheds given the same LID structural build up. This should be investigated through further research finding the optimal parameter set, and data validation of proposed parameters across catchments.
Vladimír Hamouz; Tone Merete Muthanna. Modelling of Green and Grey Roofs in Cold Climates Using EPA’s Storm Water Management Model. Smart and Sustainable Planning for Cities and Regions 2018, 385 -391.
AMA StyleVladimír Hamouz, Tone Merete Muthanna. Modelling of Green and Grey Roofs in Cold Climates Using EPA’s Storm Water Management Model. Smart and Sustainable Planning for Cities and Regions. 2018; ():385-391.
Chicago/Turabian StyleVladimír Hamouz; Tone Merete Muthanna. 2018. "Modelling of Green and Grey Roofs in Cold Climates Using EPA’s Storm Water Management Model." Smart and Sustainable Planning for Cities and Regions , no. : 385-391.
This paper studies the hydraulic performance of two swales composed of filters for stormwater management (filtering swales) in a large-scale experimental study and compares them to the performance of a swale composed of traditional bioretention soil (bioswale). Using experimental data, dimensionless formulations are derived to reflect the influence of swale design parameters on hydraulic performance. The developed formulas can be used to design swales accounting for practical factors for decision makers such as local rainfall patterns, volume capture requirements, and drainage area. The experimental data show that while the bioswale is characterized by large overland flows, the tested filtering swales manage, in the majority of cases, the complete inflow volume without overland flow. The longitudinal slope of the swales does not affect the infiltration capacity of the filtering swales for the tested experimental boundary conditions, only the inflow rate and media water content are found to be statistically significant. As an example, filtering swales tested in this study captured 90% of the runoff generated by a 12.2 mm/h storm (approximately a 5-year return period 1-h duration storm event in the city of Trondheim) on a road 40 times larger than the swale. This highlights the capacity of such swales for handling infrequent events.
C. Monrabal-Martinez; J. Aberle; T.M. Muthanna; M. Orts-Zamorano. Hydrological benefits of filtering swales for metal removal. Water Research 2018, 145, 509 -517.
AMA StyleC. Monrabal-Martinez, J. Aberle, T.M. Muthanna, M. Orts-Zamorano. Hydrological benefits of filtering swales for metal removal. Water Research. 2018; 145 ():509-517.
Chicago/Turabian StyleC. Monrabal-Martinez; J. Aberle; T.M. Muthanna; M. Orts-Zamorano. 2018. "Hydrological benefits of filtering swales for metal removal." Water Research 145, no. : 509-517.
Climate change coupled with increasing urbanization has made extensive green roofs, both for retrofitting and new developments, an attractive way to bring nature back to cities, while managing stormwater. This study has investigated extensive green roof retention and detention performance based on 3–8 years of field data from four Norwegian locations representing typical cold and wet Nordic climates, also comparing several different commercial configurations. Accumulated retention was found to be 11–30% annually and 22–46% in May through October. The performance was found to be strongly dependent in evapotranspiration and less dependent on material storage capacities. Estimates for available storage capacities for precipitation events larger than 5 mm are given and can be useful for design purposes. Median observed peak attenuation compared to the precipitation ranged from 65–90% depending on locations and configurations. The event-based approach for evaluating detention was found to be challenging due to the nature of the precipitation in the studied locations. An alternative approach using flow duration curves based on the observed time series was tested and found to give valuable information on runoff patterns from green roofs and to be useful for evaluating green roof performance in relation to local requirements.
Birgitte Gisvold Johannessen; Tone Merete Muthanna; Bent Christen Braskerud. Detention and Retention Behavior of Four Extensive Green Roofs in Three Nordic Climate Zones. Water 2018, 10, 671 .
AMA StyleBirgitte Gisvold Johannessen, Tone Merete Muthanna, Bent Christen Braskerud. Detention and Retention Behavior of Four Extensive Green Roofs in Three Nordic Climate Zones. Water. 2018; 10 (6):671.
Chicago/Turabian StyleBirgitte Gisvold Johannessen; Tone Merete Muthanna; Bent Christen Braskerud. 2018. "Detention and Retention Behavior of Four Extensive Green Roofs in Three Nordic Climate Zones." Water 10, no. 6: 671.