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Publications (10 of 15) Show all publications
Mantilla, I., Flanagan, K., Broekhuizen, I., Muthanna, T. & Viklander, M. (2023). Evaluating the infiltration performance of grassed swales : Comparison between point measurements and a full-scale infiltration method: [Évaluation des performances d'infiltration d'une noue enherbée : Comparaison entre des mesures ponctuelles et une méthode d'infiltration grandeur nature]. In: : . Paper presented at 11th Novatech international conference, Lyon, France, July 3-7, 2023.
Open this publication in new window or tab >>Evaluating the infiltration performance of grassed swales : Comparison between point measurements and a full-scale infiltration method: [Évaluation des performances d'infiltration d'une noue enherbée : Comparaison entre des mesures ponctuelles et une méthode d'infiltration grandeur nature]
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2023 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Due to large spatial and temporal variations of soil properties that govern swale infiltration capacities, traditional methods for estimating saturated hydraulic conductivity (ksat) values could potentially lead to erroneous estimation of the total system infiltration capacity. To increase the knowledge of grassed swale infiltration performance and the relationship between hydraulic properties related to the spatial variation within the swale, two methods were applied to estimate ksat values: 1) point measurements using the Modified Philip Dunne (MPD) Infiltrometer, and 2) a full-scale infiltration test (FSIT). A large variation in calculated ksat values was found, ranging from 22 to 1382 mm/hr, with lower/higher values at the swale bottom, and right swale slope respectively. Infiltration point measurements, with a geometric mean of 81 mm/hr, showed higher infiltration rates than those obtained from FSIT, which yielded 34 and 22 mm/hr (for test 1 and 2 respectively). Moreover, FSIT results showed an agreement with ksat values obtained from MPD infiltrometer at the swale bottom. In addition, infiltration rates are significantly reduced as the groundwater mound gets closer to the bottom of the grassed swale.

Abstract [fr]

En raison des grandes variations spatiales et temporelles des propriétés du sol qui régissent les capacités d'infiltration des noues, les méthodes traditionnelles d'estimation des valeurs de conductivité hydraulique saturée (ksat) pourraient potentiellement conduire à une estimation erronée de la capacité d'infiltration totale du système. Afin d'accroître la connaissance des capacités d'infiltration des noues enherbées et de la relation entre les propriétés hydrauliques liées aux classes de texture du sol, deux méthodes ont été appliquées pour estimer les valeurs de ksat : 1) des mesures ponctuelles à l'aide de l'infiltromètre Philip Dunne modifié (MPD), et 2) un test d’infiltration à pleine échelle (FSIT). Une grande variation dans les valeurs calculées de ksat a été trouvée, allant de 22 à 1382 mm/h, avec des valeurs inférieures/élevées au fond de la noue et à droite de la pente de la noue respectivement. Les mesures des points d'infiltration, avec une moyenne géométrique de 81 mm/h, ont montré des taux d'infiltration plus élevés que ceux obtenus à partir du FSIT, avec 34 et 22 mm/h (pour les tests 1 et 2 respectivement). De plus, les résultats du FSIT ont montré un accord avec les valeurs de ksat obtenues au fond de la noue. De plus, les taux d'infiltration diminuent considérablement à mesure que le niveau de la nappe phréatique se rapproche du fond de la noue enherbée.

Keywords
Hydraulic conductivity, full-scale infiltration test, swale, groundwater mouding, Conductivité hydraulique, test d'infiltration à grande échelle, rigole, mouding des eaux souterraines
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-101380 (URN)
Conference
11th Novatech international conference, Lyon, France, July 3-7, 2023
Available from: 2023-09-19 Created: 2023-09-19 Last updated: 2024-01-25Bibliographically approved
Kjellin, J., Ekeroth, S., Erdal, D., Olsson, J. & Broekhuizen, I. (2023). The coupling between urban floodings and soil moisture in green areas forpresent and future climate. In: : . Paper presented at Nordic Wastewater Conference, 2023 (NORDIWA 2023), September 5-7, 2023.
Open this publication in new window or tab >>The coupling between urban floodings and soil moisture in green areas forpresent and future climate
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2023 (English)Conference paper, Oral presentation only (Refereed)
National Category
Water Engineering Oceanography, Hydrology and Water Resources
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-101816 (URN)
Conference
Nordic Wastewater Conference, 2023 (NORDIWA 2023), September 5-7, 2023
Projects
SECURE
Funder
Vinnova, 2021-02458
Available from: 2023-10-27 Created: 2023-10-27 Last updated: 2023-10-31Bibliographically approved
Hedlund Nilsson, E., Broekhuizen, I., Muthanna, T. M. & Viklander, M. (2022). Evaluation of Snow Management using Green Infrastructure in Subarctic Climate. In: : . Paper presented at EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022. Copernicus GmbH
Open this publication in new window or tab >>Evaluation of Snow Management using Green Infrastructure in Subarctic Climate
2022 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

In subarctic regions, a significant part of annual precipitation occurs as snow. This creates challenges since (a) the occurrence of rain on snow during melting season might increase runoff peak flow and cause flooding in urban areas and (b) snow needs to be removed from roofs and streets. Current snow management practice includes removal of snow to large deposits outside of cities. Downsides of this approach are the carbon footprint and air pollution caused by transport and the release of untreated polluted melt water to nearby water bodies. One strategy to reduce transport and increase treatment of meltwater could be to integrate snow deposits with existing green infrastructure that manages stormwater within the urban environment, i.e. multifunctional areas.

When studying the potential performance of multifunctional areas with respect to snow management it is important to consider the flood risk that comes with increased snowmelt and rain on snow. Prior studies have evaluated the combined effect of frozen soils, snowmelt and rainfall during the melting season on runoff from urban catchments, but there are no similar studies on facility scale. Hydrological models can be used to investigate these factors and the snow deposit potential, without risking flooding. It is, however, unclear to what extent current urban hydrological models are suited to this purpose. This study aims to explore how hydrological models can be used to predict snow deposition volumes in multifunctional areas and the effect on runoff.

This study used EPA SWMM because it is a commonly used urban hydrological model with a relatively advanced snow management module. The modelled facility was a grassed swale in Luleå, Northern Sweden, receiving runoff from a 60 ha catchment with commercial and light industrial land use.  The swale was separated into 6 identical parts to test different scenarios for the amount and distribution of snow deposited in the swale. The long-term performance of the swale with regard to stormwater quantity was investigated with historical rain and temperature data. Runoff from the catchment to the swales was calibrated based on observed data from late spring 2021.

Hydrological models as a support tool for snow management using green infrastructure shows promising results. Using the model, it was possible to evaluate the effect of snow volume and placement within the swale. Such information can be of great use when designing green infrastructure and snow management strategies. However, SWMM has some limitations in this regard. For example, pollutants such as sediments (gravel, sand and micro plastics) affect the properties and melting behavior of urban snow and the release of pollutants, yet these factors are not represented in SWMM. Differences in the actual melt rate will affect the total volume of snow that can be deposited in the swale, hence this topic requires further research.

Place, publisher, year, edition, pages
Copernicus GmbH, 2022
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-94330 (URN)10.5194/egusphere-egu22-9977 (DOI)
Conference
EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022
Available from: 2022-11-29 Created: 2022-11-29 Last updated: 2023-09-05Bibliographically approved
Broekhuizen, I. (2021). Hydrological modelling of green urban drainage systems: Advancing the understanding and management of uncertainties in data, model structure and objective functions. (Doctoral dissertation). Luleå University of Technology
Open this publication in new window or tab >>Hydrological modelling of green urban drainage systems: Advancing the understanding and management of uncertainties in data, model structure and objective functions
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Hydrologisk modellering av gröna dagvattensystem : Förbättrad förståelse av osäkerheter i data, modellstruktur och målfunktioner
Abstract [en]

The use of green urban drainage systems such as green roofs, swales and pervious areas has in recent years become a popular option to reduce flood risk and water quality problems in a more sustainable way than with traditional pipe-based drainage systems. Computer models are valuable tools for the management of such systems. While uncertainties associated with these models have been investigated for pipe-based systems, their adaptation and application to green areas requires re-examination of these uncertainties, as additional hydrological processes become relevant and new opportunities for model calibration arise. The overall aim of this thesis is to contribute to understanding and reducing of uncertainties in the mathematical modelling of green urban drainage studies. Specific topics adressed are field measurements, data processing, data selection, model structures and objective functions.Weighing-bucket precipitation sensors were confirmed on multiple occasions to be accurate to within ±1% of accumulated precipitation. A new signal processing method was able to convert accumulated precipitation to noise-free 1-minute rainfall rates that reproduced total rainfall volumes with only minor errors.Area-velocity flow sensors were tested and their measurement uncertainties quantified in laboratory experiments for flow rates up to 9 L s-1. Total flow rate uncertainty was ±0.34 L s-1 in optimal conditions (flat pipe), increasing to 0.60 and 0.83 L s-1 for pipe slopes of 2% and 4% respectively. In the presence of an upstream obstacle the uncertainty was 2 to 3 times larger, although in the case of no pipe slope this could be reduced to the same as the optimal conditions by increasing water levels in the pipe.Three different urban drainage models for green areas were compared using long-term simulations of synthetic catchments with different soil types and depth. In all models surface runoff formed a significant component of the annual water balance for some soil profiles, while the models reacted differently to changes in soil type an depth. Inter-model variation was large compared to the variation between different soil profiles.Four different models were tested for the simulation of runoff from two full-scale green roofs. More complex models showed better performance in reproducing observed runoff, while the magnitude and source of model predictive uncertainties varied between the models. It was also found that for all models calibration periods with high inter-event variability in terms of runoff retention provided more information in the calibration process.The use of soil water content observations (SWC) was investigated for the calibration of a detailed model of an urban swale. SWC observations were found to be useful for improving the identifiability of certain model parameters and the model predictions of SWC, and for setting the initial SWC in simulations. Different approaches to combining SWC and outflow observations were compared, revealing that the precision and reliability of model predictions could in some cases be improved by using a different way of determining which parameter sets to use for the generation of uncertain model predictions.The influence of calibration data selection was investigated using a model of a small green urban catchment. Performance of the model when calibrated using different sets of events varied significantly. Two-stage calibration strategies (where first small rainfall events were used to calibrate impervious area parameters, followed by using larger events to calibrate green area parameters) showed good performance especially in terms of runoff volume and peak flow. Finally it was found that the benefits of the two-stage calibration were greater when using a model with a low spatial resolution than with a high spatial resolution.For the same catchment tests were also carried out of an objective function that explicitly allows for timing errors, rather than comparing only simulated and observed values for the same time step. Model predictions generated using this objective function were equally reliable, but more precise and therefore of more practical value.Finally, drawing upon the practical experience from working with different models and drainage systems an overview is provided of the applicability of the modelling techniques used in this thesis for different models and what features may be desirable to add to models to improve this.

Place, publisher, year, edition, pages
Luleå University of Technology, 2021
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Water Engineering
Research subject
Urban Water Engineering; Centre - Centre for Stormwater Management (DRIZZLE)
Identifiers
urn:nbn:se:ltu:diva-82916 (URN)978-91-7790-758-9 (ISBN)978-91-7790-759-6 (ISBN)
Public defence
2021-04-08, E632, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2021-02-12 Created: 2021-02-11 Last updated: 2023-09-05Bibliographically approved
Broekhuizen, I., Sandoval, S., Gao, H., Mendez-Rios, F., Leonhardt, G., Bertrand-Krajewski, J.-L. & Viklander, M. (2021). Performance comparison of green roof hydrological models for full-scale field sites. Journal of Hydrology X, 12, Article ID 100093.
Open this publication in new window or tab >>Performance comparison of green roof hydrological models for full-scale field sites
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2021 (English)In: Journal of Hydrology X, ISSN 2589-9155, Vol. 12, article id 100093Article in journal (Refereed) Published
Abstract [en]

Green roofs can be valuable components in sustainable urban drainage systems, and hydrological models may provide useful information about the runoff from green roofs for planning purposes. Various models have been proposed in the literature, but so far no papers have compared the performance of multiple models across multiple full-size green roofs. This paper compared 4 models: the conceptual models Urbis and SWMM and the physically-based models Hydrus-1D and Mike SHE, across two field sites (Lyon, France and Umeå, Sweden) and two calibration periods for each site. The uncertainty and accuracy of model predictions were dependent on the selected calibration site and period. Overall model predictions from the simple conceptual model Urbis were least accurate and most uncertain; predictions from SWMM and Mike SHE were jointly the best in terms of raw percentage observations covered by their flow prediction intervals, but the uncertainty in the predictions in SWMM was smaller. However, predictions from Hydrus were more accurate in terms of how well the observations conformed to probabilistic flow predictions. Mike SHE performed best in terms of total runoff volume. In Urbis, SWMM and Hydrus uncertainty in model predictions was almost completely driven by random uncertainty, while parametric uncertainty played a significant role in Mike SHE. Parameter identifiability and most likely parameter values determined with the DREAM Bayesian algorithm were found to be inconsistent across calibration periods in all models, raising questions about the generalizability of model applications. Calibration periods where rainfall retention was highly variable between events were more informative for parameter values in all models.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Green roof, modeling, predictive uncertainty, parameter identifiability, model structure
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-82915 (URN)10.1016/j.hydroa.2021.100093 (DOI)000688440100001 ()2-s2.0-85111252417 (Scopus ID)
Funder
Swedish Research Council Formas, 2015-121, 2015-778Vinnova, 2016-05176
Note

Validerad;2021;Nivå 2;2021-08-12 (alebob);

Forskningsfinansiär: VAKIN

Available from: 2021-02-11 Created: 2021-02-11 Last updated: 2023-09-05Bibliographically approved
Broekhuizen, I., Leonhardt, G. & Viklander, M. (2021). Reducing uncertainties in urban drainage models by explicitly accounting for timing errors in objective functions. Urban Water Journal, 18(9), 740-749
Open this publication in new window or tab >>Reducing uncertainties in urban drainage models by explicitly accounting for timing errors in objective functions
2021 (English)In: Urban Water Journal, ISSN 1573-062X, Vol. 18, no 9, p. 740-749Article in journal (Refereed) Published
Abstract [en]

Traditional hydrological objective functions may penalize models that reproduce hydrograph shapes well, but with some shift in time; especially for urban catchments with a fast hydrological response. Hydrograph timing is not always critical, so this paper investigates alternative objective functions (based on the Hydrograph Matching Algorithm) that try to mimic visual hydrograph comparison. A modified version of the Generalized Likelihood Uncertainty Estimation is proposed to compare regular objective functions with those that account for timing errors. This is applied to 2-year calibration and validation data sets from an urban catchment. Results show that such objective functions provide equally reliable model predictions (they envelop the same fraction of observations), but with more precision, i.e. smaller estimated uncertainty of model predictions. Additionally, identifiability of some model parameters improved. Therefore objective functions based on the Hydrograph Matching Algorithm can be useful to reduce uncertainties in urban drainage modelling.

Place, publisher, year, edition, pages
Taylor & Francis, 2021
Keywords
urban drainage, calibration, objective functions, timing, uncertainty, predictive uncertainty
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-82911 (URN)10.1080/1573062X.2021.1928244 (DOI)000658945300001 ()2-s2.0-85107543190 (Scopus ID)
Funder
Vinnova, 2016-05176Swedish Research Council Formas, 2015-121Swedish Research Council Formas, 2015-778
Note

Validerad;2022;Nivå 2;2022-03-10 (hanlid)

Available from: 2021-02-11 Created: 2021-02-11 Last updated: 2023-09-05Bibliographically approved
Broekhuizen, I., Leonhardt, G. & Viklander, M. (2020). Adapting weighing-bucket rainfall observations to urban applications. In: : . Paper presented at Virtual ICUD2020: Young researcher webinar, Online, December 8-10, 2020.
Open this publication in new window or tab >>Adapting weighing-bucket rainfall observations to urban applications
2020 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

•Data collection and processing approach for 1-minute rain valuesfrom weighing buckets.

•Noise is removed from the record, without affecting event rainfall totals.

National Category
Water Engineering
Research subject
Urban Water Engineering; Centre - Centre for Stormwater Management (DRIZZLE)
Identifiers
urn:nbn:se:ltu:diva-82913 (URN)
Conference
Virtual ICUD2020: Young researcher webinar, Online, December 8-10, 2020
Funder
Swedish Research Council Formas, 2015-778
Note

Presented as one 14 selected abstracts by young researchers at a webinar series organized when conference had to be postponed to 2021.

Available from: 2021-02-11 Created: 2021-02-11 Last updated: 2023-09-05Bibliographically approved
Broekhuizen, I., Leonhardt, G., Marsalek, J. & Viklander, M. (2020). Event selection and two-stage approach for calibrating models of green urban drainage systems. Hydrology and Earth System Sciences, 24, 869-885
Open this publication in new window or tab >>Event selection and two-stage approach for calibrating models of green urban drainage systems
2020 (English)In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 24, p. 869-885Article in journal (Refereed) Published
Abstract [en]

The calibration of urban drainage models is typically performed based on a limited number of observed rainfall–runoff events, which may be selected from a larger dataset in different ways. In this study, 14 single- and two-stage strategies for selecting the calibration events were tested in calibration of a high- and low-resolution Storm Water Management Model (SWMM) of a predominantly green urban area. The two-stage strategies used events with runoff only from impervious areas to calibrate the associated parameters, prior to using larger events to calibrate the parameters relating to green areas. Even though all 14 strategies resulted in successful model calibration (Nash–Sutcliffe efficiency; NSE >0.5), the difference between the best and worst strategies reached 0.2 in the NSE, and the calibrated parameter values notably varied. The various calibration strategies satisfactorily predicted 7 to 13 out of 19 validation events. The two-stage strategies reproduced more validation events poorly (NSE <0) than the single-stage strategies, but they also reproduced more events well (NSE >0.5) and performed better than the single-stage strategies in terms of total runoff volume and peak flow rates, particularly when using a low spatial model resolution. The results show that various strategies for selecting calibration events may lead in some cases to different results in the validation phase and that calibrating impervious and green-area parameters in two separate steps in two-stage strategies may increase the effectiveness of model calibration and validation by reducing the computational demand in the calibration phase and improving model performance in the validation phase.

Place, publisher, year, edition, pages
Nicolaus Copernicus University Press, 2020
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-77987 (URN)10.5194/hess-24-869-2020 (DOI)000518136600001 ()2-s2.0-85080893882 (Scopus ID)
Funder
Swedish Research Council Formas, 2015-121
Note

Validerad;2020;Nivå 2;2020-03-06 (svasva)

Available from: 2020-03-06 Created: 2020-03-06 Last updated: 2023-09-05Bibliographically approved
Broekhuizen, I., Leonhardt, G., Marsalek, J. & Viklander, M. (2019). Calibration event selection for green urban drainage modelling.
Open this publication in new window or tab >>Calibration event selection for green urban drainage modelling
2019 (English)Manuscript (preprint) (Other (popular science, discussion, etc.))
Abstract [en]

Calibration of urban drainage models is typically performed based on a limited number of observed rainfall-runoff events, which may be selected from a longer time-series of measurements in different ways. In this study, 14 single- and two-stage strategies for selecting these events were tested for calibration of a SWMM model of a predominantly green urban area. The event selection was considered in relation to other sources of uncertainty such as measurement uncertainties, objective functions, and catchment discretization. Even though all 14 strategies resulted in successful model calibration, the difference between the best and worst strategies reached 0.2 in Nash–Sutcliffe Efficiency (NSE) and the calibrated parameter values notably varied. Most, but not all, calibration strategies were robust to changes in objective function, perturbations in calibration data and the use of a low spatial resolution model in the calibration phase. The various calibration strategies satisfactorily predicted 7 to 13 out of 19 validation events. The two-stage strategies performed better than the single-stage strategies when measuring performance using the Root Mean Square Error, flow volume error or peak flow error (but not using NSE); when flow data in the calibration period had been perturbed by ±40 %; and when using a lower model resolution. The two calibration strategies that performed best in the validation period were two-stage strategies. The findings in this paper show that different strategies for selecting calibration events may lead in some cases to different results for the validation period, and that calibrating impermeable and green area parameters in two separate steps may improve model performance in the validation period, while also reducing the computational demand in the calibration phase.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-73294 (URN)10.5194/hess-2019-67 (DOI)
Projects
Reliable modeling of green infrastructure in green urban catchments
Funder
Swedish Research Council Formas, 2015-121
Available from: 2019-03-25 Created: 2019-03-25 Last updated: 2023-09-05Bibliographically approved
Broekhuizen, I., Leonhardt, G., Marsalek, J. & Viklander, M. (2019). Selection of Calibration Events for Modelling Green Urban Drainage. In: Giorgio Mannina (Ed.), New Trends in Urban Drainage Modelling: UDM 2018. Paper presented at International Conference on Urban Drainage Modelling, UDM 2018, Palermo, Italy, 23-26 September 2018 (pp. 608-613). Cham: Springer
Open this publication in new window or tab >>Selection of Calibration Events for Modelling Green Urban Drainage
2019 (English)In: New Trends in Urban Drainage Modelling: UDM 2018 / [ed] Giorgio Mannina, Cham: Springer, 2019, p. 608-613Conference paper, Published paper (Refereed)
Abstract [en]

Urban drainage models are often calibrated using a limited number of rainfall-runoff events, which may be selected in different ways from a longer observation series. This paper compares 13 different single- and two-stage strategies for selecting events used to calibrate a SWMM model of a predominantly green urban area. Most led to successful calibration, but performance varied for various validation events. Most selection strategies were insensitive to the choice of Nash-Sutcliffe Model Efficiency or Root Mean Squared Error as the objective function. Calibrating impervious and green area parameters separately in two-stage strategies can help improve prediction of low-flow events in validation.

Place, publisher, year, edition, pages
Cham: Springer, 2019
Series
Green Energy and Technology
National Category
Water Engineering
Research subject
Urban Water Engineering; Centre - Centre for Stormwater Management (DRIZZLE)
Identifiers
urn:nbn:se:ltu:diva-70715 (URN)10.1007/978-3-319-99867-1_105 (DOI)000482068800105 ()2-s2.0-85071564853 (Scopus ID)978-3-319-99866-4 (ISBN)978-3-319-99867-1 (ISBN)
Conference
International Conference on Urban Drainage Modelling, UDM 2018, Palermo, Italy, 23-26 September 2018
Available from: 2018-09-03 Created: 2018-09-03 Last updated: 2023-09-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6907-8127

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