| 1. |
- Moghadas, Shahab, et al.
(författare)
-
Laboratory study of infiltration into two frozen engineered (sandy) soils recommended for bioretention
- 2016
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 30:8, s. 1251-1264
-
Tidskriftsartikel (refereegranskat)abstract
- Infiltration of water into two frozen engineered soils of different gradation was studied in laboratory soil columns 1.2 m long and 0.1 m in diameter. Prior to testing, the soil moisture was adjusted to two levels, described by the gravimetric water content of 5 or 10%, soils were compacted to about 80-90% of the maximum dry density, and refrigerated to temperatures ranging from −8 to −2 °C. Water with temperatures 8-9 °C was thereafter fed on the top of columns at a constant head and the times of water break through the column and reaching a steady percolation rate, as well as the percolation rate, were recorded. The soil water content was a critical factor affecting the thawing process; during freezing, soil moisture was converted into ice, which blocked pores, and its melting required high amounts of energy supplied by infiltrating water. Hence, the thawing of soils with higher initial water content was much slower than in lower moisture soils, and water breakthrough and the attainment of steady percolation required much longer times in higher moisture soils. Heat transfer between infiltrating water, soil ice and frozen soil particles was well described by the energy budget equations, which constitute a parsimonious model of the observed processes. The finer grained soil and more compacted soil columns exhibited reduced porosity and required longer times for soil thawing. Practical implications of study results for design of bioretention facilities (BFs) in cold climate include the use of coarse engineered soils and fitting BFs with a drain facilitating soil drainage before the onset of freezing weather. This article is protected by copyright. All rights reserved.
|
|
| 2. |
- Berggren, Karolina, et al.
(författare)
-
Hydraulic impacts on urban drainage systems due to changes in rainfall, caused by climatic change
- 2012
-
Ingår i: Journal of hydrologic engineering. - 1084-0699 .- 1943-5584. ; 17:1, s. 92-98
-
Tidskriftsartikel (refereegranskat)abstract
- The changes in climate were of a growing concern in the last decade, and will be even more so in the coming years. When investigating impacts on urban drainage systems due to changes in the climate, two challenges are (1) what type of input rainfall data to use, and (2) what parameters to measure the impacts. The overall objective of this study is to investigate the hydraulic performances ofurban drainage systems related to changes in rainfall, and through these hydraulic parameters describe impacts of climate change. Input rainfall data represents today's climate, as well as three future time periods (2011-2040, 2041-2070, and 2071-2100). The hydraulic parameters used were water levels in nodes (e.g. as the number of floods, frequency and duration of floods), and pipe flow ratio. For the study area, the number of flooded nodes and the geographical distribution of floods will increase in the future, as will both the flooding frequency and the duration of floods.
|
|
| 3. |
|
|
| 4. |
- Borris, Matthias, et al.
(författare)
-
Continuous simulations of urban stormwater runoff and total suspended solids loads: influence of varying climatic inputs and catchment imperviousness
- 2014
-
Ingår i: Journal of Water and Climate. - : IWA Publishing. - 2040-2244 .- 2408-9354. ; 5:4, s. 593-609
-
Tidskriftsartikel (refereegranskat)abstract
- Potential implications of climate change for future stormwater management were addressed by undertaking continuous simulations of runoff and total suspended solids (TSS) loads for three urban catchments, with imperviousness varying from 23 to 63%, which were exposed to five rainfall regimes during the snow-free part of the year: the current climate and four climate change scenarios projecting higher rainfalls. Simulated runoff volumes increased in all the future scenarios, particularly in the sub-arctic climate and the fixed uplift scenario (plus20) indicating appreciable rainfall increases. Simulated runoff volumes increased depending on the projected increases in rainfall and increasing runoff contributions from pervious areas when more intense future rainfalls exceeded hydrologic abstractions. The increased runoff volumes then contributed higher TSS loads, which were highly variable for the rainfall regimes tested. In cold climate regions, residues of solids from winter road maintenance may contribute to high initial accumulations of TSS on the catchment surface and high washed off loads. In general, the study suggests that intermediate design-life stormwater management facilities require flexible design allowing for future step-wise adaptation by gradually increasing design capacities and modifying treatment trains.
|
|
| 5. |
- Borris, Matthias, et al.
(författare)
-
Modelling the effects of changes in rainfall event characteristics on TSS loads in urban runoff
- 2014
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 28:4, s. 1787-1796
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of changes in rainfall event characteristics on urban stormwater quality, which was described by total suspended solids (TSS), was studied by means of computer simulations conducted with the Storm Water Management Model for a climate change scenario for northern Sweden. The simulation results showed that TSS event loads depended mainly on rainfall depth and intensity, but not on antecedent conditions. Storms with low-to-intermediate depths and intensities showed the highest sensitivity to changes in rainfall input, both for percentage and absolute changes in TSS wash-off loads, which was explained by the contribution of pervious areas and supply limitations. This has significant implications for stormwater management, because those relatively frequent events generally carry a high percentage of the annual pollutant load
|
|
| 6. |
- Borris, Matthias, et al.
(författare)
-
Simulating future trends in urban stormwater quality for changing climate, urban land use and environmental controls
- 2013
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 68:9, s. 2082-2089
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of climatic changes, progressing urbanization and improved environmental controls on the simulated urban stormwater quality in a northern Sweden community were studied. Future scenarios accounting for those changes were developed and their effects simulated with the Storm Water Management Model (SWMM). It was observed that the simulated stormwater quality was highly sensitive to the scenarios, mimicking progressing urbanization with varying catchment imperviousness and area. Thus, land use change was identified as one of the most influential factors and in some scenarios, urban growth caused changes in runoff quantity and quality exceeding those caused by a changing climate. Adaptation measures, including the reduction of directly connected impervious surfaces (DCIS) through the integration of more green spaces into the urban landscape, or disconnection of DCIS were effective in reducing runoff volume and pollutant loads. Furthermore, pollutant source control measures, including material substitution, were effective in reducing pollutant loads and significantly improving stormwater quality
|
|
| 7. |
- Borris, Matthias, et al.
(författare)
-
Using urban runoff simulations for addressing climate change impacts on urban runoff quality in a Swedish town
- 2012
-
Ingår i: Urban Drainage Modelling. - Belgrade : Faculty of Civil Engineering, University of Belgrade. - 9788675181569
-
Konferensbidrag (refereegranskat)abstract
- The effect of climate change on urban stormwater quality was studied by means of computer simulations conducted with the Stormwater Management Model (SWMM) for common climate change scenarios developed for northern Sweden. The simulation results showed that stormwater quality depended on rainfall characteristics; a climate scenario implying increased rainfall depths and intensities produced higher pollutant loads carried by stormwater, but reduced concentrations, particularly for medium to high intensity storm events. This type of stormwater quality response was explained by pollutant supply limited transport processes and the resulting dilution of such pollutants. Medium intensity events showed the highest sensitivity to climatic changes, since such events strongly affected the contributions of pervious surfaces. This has significant implications for stormwater management, because those relatively frequent events generally carry a high percentage of the annual pollutant load.
|
|
| 8. |
- Broekhuizen, Ico, et al.
(författare)
-
Improving hydrological modelling of urban drainage swales through use of soil water content observations
- 2020
-
Ingår i: Journal of Hydrology X. - 2589-9155.
-
Tidskriftsartikel (refereegranskat)abstract
- Flow observations alone may not provide sufficient information for calibration of detailed hydrological models of urban drainage swales. Therefore this study investigated the added value of using soil water content (SWC) observations made throughout the swale. This can be done by (1) including SWC in the likelihood function that is used to quantify model performance or (2) by using the SWC observations to set initial conditions in the model. The results show that combining outflow and SWC in the likelihood function is necessary to obtain reliable and precise predictions for both variables, and that this increases the number of parameters that are identifiable from the data. Using SWC observations to set initial model conditions improves model performance and affects the degree to which soil hydraulic parameters are identifiable. Overall, it is concluded that SWC observations may be a valuable complement to outflow observations in the modelling of urbanswales.
|
|
| 9. |
- Broekhuizen, Ico, et al.
(författare)
-
Towards using soil water content observations for calibration of distributed urban drainage models : [Vers l’utilisation d'observations de teneur en eau du sol pour le calage de modèles distribués d’assainissement urbain]
- 2019
-
Ingår i: 10e Conférence internationale L'eau dans la ville. - : GRAIE. ; , s. 124-124
-
Konferensbidrag (refereegranskat)abstract
- Fully distributed urban drainage models can be used to analyse and predict the behaviour of green urban drainage infrastructure such as swales, but they need to be calibrated for specific study sites. Using only drainage outflow measurements may not provide enough information to do this in an optimal way, so additional types of measurements have to be considered. This study identifies different approaches to including soil water content (SWC) observations in the calibration process and investigates how they affect parameter identifiability and the predictive uncertainty of the calibrated model. This is done using the Generalized Likelihood Uncertainty Estimation methodology applied to a model of a large urban swale. It was found that setting initial conditions based on the SWC measurements improved the fit between observed and simulated SWC, but also reduced the accuracy of the simulated amount of infiltration. Including SWC observations allowed to identify one parameter (saturated moisture content of the swale bottom) that was not identifiable from outflow measurements alone. Including SWC observations in the derivation of predictive uncertainty bounds made those bounds narrower (more precise), but where SWC had been used to set initial conditions the uncertainty bound failed to capture the observations. It is concluded that SWC observations can provide useful information for the calibration of distributed urban drainage models.
|
|
| 10. |
- Gustafsson, Anna-Maria, et al.
(författare)
-
Metoder för att undersöka extrema regnhändelsers påverkan på dagvattensystemet
- 2014
-
Rapport (refereegranskat)abstract
- Detta projekt har genomförts av Luleå Tekniska Universitet i samarbete med 5 kommuner; Arvika, Skellefteå, Sundsvall, Trelleborg samt Växjö. Projektets syfte har varit att studera hur olika metoder kan användas för att utvärdera dagvattensystemets påverkan av extrema regnhändelser. Rapporten har skrivits i syfte att ge en övergripande bild av olika metoder och de osäkerheter som finns när de olika metoderna används. Materialet i rapporten är hämtat från aktuellt projekt samt från parallella studier vid forskningsgruppen Stadens vatten, LTU och från internationella och nationella studier för att ge ett så brett perspektiv på olika metoder som möjligt. De metoder som beskrivs i rapporten går från en väldigt enkel analys baserat på vanliga dimensioneringsekvationer som kan utföras i ett excelark eller för hand till analyser som kräver komplexa modeller som simulerar vattenföringen i ledningsnätet samt ytavrinning kopplat till infiltration. Alla metoder kräver någon form av nederbördsinformation och därför inkluderas i rapporten ett avsnitt om regn och framtida regn kopplat till klimatförändring. För att genomföra en analys krävs även parametrar att studera effekterna av olika körningar och i slutet presenteras ett kort avsnitt om indikationer som är lämpliga att använda vid utvärdering av dagvattensystemet. När en metod ska väljas är det viktigt att syfte med undersökning och resurser i form av tid, existerande data och pengar ställs mot varandra. En avancerad modell har ett större krav på indata, datakapacitet och på mätdata som den kan verifieras mot. I vissa fall är det bättre att använda en enklare modell med kontinuerligt, historiskt regndata medan i andra fall krävs en komplex modell som inkluderar t.ex. infiltration i permeabla ytor och att då använda sig av designregn för att klara av de begränsningar som ev. finns i datakapacitet och simuleringstid. Innan beslut tas om modell eller metod bör det noggrant funderas över varför modellen ska tas fram, hur den ska användas samt vilka data som finns tillgängliga eller kan tas fram med nya mätningar. Om metoderna beskrivna i rapporten används på korrekt sätt och verifieras med tillräckligt data kan dessa utvärderingar av dagvattensystemet ge en bra bild av hur systemet fungerar samt hur det påverkas av olika scenarier.
|
|
