Endre søk
Begrens søket
1 - 6 of 6
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Broekhuizen, Ico
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Rujner, Hendrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Roldin, Maria
    DHI Sweden.
    Leonhardt, Günther
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Towards using soil water content observations for calibration of distributed urban drainage models2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 2.
    Rujner, Hendrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Green Urban Drainage Infrastructure: Hydrology and Modelling of Grass Swales2018Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The management of urban runoff has evolved along with the advancement of understanding of runoff environmental impacts. Besides the impacts on water quality in the receiving waters, the impacts on the urban hydrologic regime include reduced infiltration by the sealing of pervious land, reduced evapotranspiration by removal of vegetation, and the resulting increase of stormwater runoff peaks and volumes causing flooding, and ultimately degradation of receiving waters. In such considerations, urban stormwater management benefits from the implementation of Green Infrastructure which includes decentralized vegetative controls that capture and infiltrates rain where it falls and thus reduces and improves stormwater runoff. An example of small scale elements of Green Infrastructure are traditional grass swales. Through shallow depressions with mild side slopes grass swales collect and infiltrate stormwater from parking lots and roads, while runoff flows are attenuated and further conveyed depending on the hydraulic loading. Grass swales usually operate reliably and their maintenance needs are well understood. Their hydrological performance is, beside their dimensions and the contributing area, determined mainly by hydraulic and soil-related hydrological parameters that change with the intensity of the storm. Yet, because swales discharge to downstream drainage elements, either to the conventional sewer system or to other stormwater management facilities, the knowledge of the underlying inter-related processes and influential factors that govern the hydraulic and hydrological performance of grass swales is required.

    Against this background, this thesis is devoted to such questions as (i) what are the differences in the hydraulic and hydrological performance of the studied swales, (ii) how do soil characteristics, including the antecedent soil moisture, influence the swale water balance for various hydraulic loadings; and (iii) how can the related hydrological processes be simulated in high-resolution and reliably predicted using a grid-based, distributed model. For this purpose, full-scale studies were performed in three 30-m grass swale sections in Luleå, Northern Sweden, by collecting hydraulic and hydrological data based on routine storm events mimicking block-rainfall storm events of 2 months and 3 years recurrence. The resulting runoff and soil moisture data were used to calculate the swale water balance, to derive event hydrographs and to obtain calibration and validation data for model simulations. The experimental results showed that the relative swale flow volume reduction decreased with an increasing soil moisture and indicated the transition in dominating swale functions: at low initial SWC, runoff was highly attenuated (up to 74%), but for high SWC, the conveyance function dominated (with attenuation as low as 17%). Runoff flow peaks were reduced, proportionally to the volume reductions. Swale outflow hydrograph lag times varied between 5 to 15 minutes and decreased with increasing soil moisture. The swale wetness affected runoff formation, attenuation and subsequent outlet discharge and, for the short-duration events tested, only the top soil layer contributed to these findings. In the three swales tested, soils, initial soil water content, saturated hydraulic conductivity and topography varied spatially significantly. Double-ring infiltrometer measurements resulted in values of 1.78, 4.04 and 9.41 cm/hr (n=9) in the three swales tested and deviated from estimates from averages of spatially integrated infiltration rates. However, with regard to spatial variability, only the topography, described as irregularities in the swale bottom slopes affected the swale runoff dissipation and conveyance in the early phase of the events. Together with estimates of the water stored in the top soil layer, 4-32% of runoff volumes from the mimicked 2-month storm were temporarily stored. The distributed model Mike SHE was found capable of simulating swale drainage processes, when properly calibrated. Close agreement (NSE>0.8) was found not only for the measured and simulated swale outlet hydrographs, but also for the changes of the soil moisture in the top soil layer, which shows rapid increase up to the saturated soil water content, but minor or no progression in depths of 0.2 m. The model output was little sensitive to the initial soil water content, especially for low inflow which resulted in larger residuals in simulated runoff peak flows and volumes. As in field measurements, spatial variability of the initial soil water content had no effect on the swale outflow, but the accuracy of the topographical representation. The thesis findings include several implications regarding effects of the assessed parameters in the application of the model for swale flow simulation and eventually the design of grass swales.

  • 3.
    Rujner, Hendrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Goedecke, Manfred
    AG Goedecke & Welsch, Berlin.
    Urban Water Management: Spatial Assessment of the Urban Water Balance2016Inngår i: Sustainable Ho Chi Minh City: Climate Policies for Emerging Mega Cities, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 133-150Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    For fast emerging Asian megacities, knowledge of water resource conditions is indispensable for sustainable water balance management and planning. Urbanisation results in the sealing of surfaces to different degrees in relation to the urban densities and structures developed and ultimately to an alteration of the urban hydrograph. In recent decades urban flooding in Ho Chi Minh City has become one of the most pressing issues. To support the Ho Chi Minh City’s planning authorities, within the frame of this the research project TP. Ho Chi Minh, the rainfall-runoff regime of the southern Vietnamese metropolis of Ho Chi Minh City was investigated. On the basis of high resolution digital databases as well with a previously generated urban structure type map, a German water balance model ABIMO was used to calculate the long-term annual means of individual water balance components for the entire administrative area of the city. Current conditions and further time-series of future urban development scenarios as set out in the draft land use plan up to the year 2020/25 over static climate conditions were modelled. The results were mapped for each of the individual 16,282 land-use blocks of the city’s official land use plan and construed to planning recommendations. The results showed that for the current conditions from a total annual precipitation input of 1573 mm, 117 mm or approximately 7 % is unable to infiltrate or evaporate and converts into surface run-off. Evidence, that urbanization is one of the main cause of increased flooding, could be given by the finding that currently 212 million m3 and based on the simulation for the year 2020/2025 overland flow of 586 million m3 will occur. Finally on the basis of modelled results, a planning recommendation map was compiled displaying zones as planning priorities, targets and measures.

  • 4.
    Rujner, Hendrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Leonhardt, Günther
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Marsalek, Jiri
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Perttu, Anna-Maria
    SENS Sustainable Energy Solutions, 12154 Nacka, Sweden.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    The effects of initial soil moisture conditions on swale flow hydrographs2018Inngår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 32, nr 5, s. 644-654Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of soil water content (SWC) on the formation of run‐off in grass swales draining into astorm sewer system were studied in two 30‐m test swales with trapezoidal cross sections. Swale1 was built in a loamy fine‐sand soil, on a slope of 1.5%, and Swale 2 was built in a sandy loam soil,on a slope of 0.7%. In experimental runs, the swales were irrigated with 2 flow rates reproducing run‐off from block rainfalls with intensities approximately corresponding to 2‐month and 3‐year events. Run‐off experiments were conducted for initial SWC (SWCini) ranging from 0.18 to 0.43 m3/m3. For low SWCini, the run‐off volume was greatly reduced by up to 82%, but at highSWCini, the volume reduction was as low as 15%. The relative swale flow volume reductions decreased with increasing SWCini and, for the conditions studied, indicated a transition of the dominating swale functions from run‐off dissipation to conveyance. Run‐off flow peaks were reduced proportionally to the flow volume reductions, in the range from 4% to 55%. The swale outflow hydrograph lag times varied from 5 to 15 min, with the high values corresponding tolow SWCini. Analysis of swale inflow/outflow hydrographs for high SWCini allowed estimations of the saturated hydraulic conductivities as 3.27 and 4.84 cm/hr in Swales 1 and 2, respectively. Such estimates differed from averages (N = 9) of double‐ring infiltrometer measurements (9.41 and 1.78 cm/hr). Irregularities in swale bottom slopes created bottom surface depression storage of 0.35 and 0.61 m3 for Swales 1 and 2, respectively, and functioned similarly as check bermscontributing to run‐off attenuation. The experimental findings offer implications for drainage swale planning and design: (a) SWCini strongly affect swale functioning in run‐off dissipation and conveyance during the early phase of run‐off, which is particularly important for design storms and their antecedent moisture conditions, and (b) concerning the longevity of swale operation, Swale 1 remains fully functional even after almost 60 years of operation, as judged from its attractive appearance, good infiltration rates (3.27 cm/hr), and high flow capacity.

  • 5.
    Rujner, Hendrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Leonhardt, Günther
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Marsalek, Jiri
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    High-resolution modelling of the grass swale response to runoff inflows with Mike SHE2018Inngår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 562, s. 411-422Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The feasibility of simulating the hydrological response of a grass swale to runoff inflows was examined using the hydrological model Mike SHE and the available input data from 12 irrigation events mimicking runoff from block rainfalls. The test swale channel had a trapezoidal cross-section, bottom slope of 1.5%, length of 30 m, and was built in loamy fine sand. The irrigation events consisted in releasing two equal constant inflows to the swale: a concentrated longitudinal flow at the upstream end and a distributed lateral inflow along the swale side slope adjacent to the contributing drainage area. The total inflows approximated runoff from two events with return periods of 2 months and 3 years, respectively, for durations of 30 min. Irrigation experiments were done for two states of the initial soil moisture, dry or wet antecedent moisture conditions (AMC). Mike SHE has been extensively used on catchments of various sizes, but rarely for small stormwater management facilities and their detailed topography investigated in this study. The latter application required high spatial and temporal resolutions, with computational cells of 0.2 × 0.2 m and time steps as short as 0.6 s to avoid computational instabilities. For dominant hydrological processes, the following computational options in Mike SHE were chosen: Soil infiltration – the van Genuchten equation, unsaturated zone flow – the one-dimensional Richards equation, and overland flow – the diffusive wave approximation of the St. Venant equations. For study purposes, the model was calibrated for single events representing one of four combinations of low and high inflows, and dry and wet AMC, and then applied to the remaining 11 events. This was complemented by calibration for two events, representing high inflow on wet AMC and low inflow in dry AMC. The goodness of fit was statistically assessed for observed and simulated peak flows, hydrograph volumes, Nash-Sutcliffe model efficiencies (NSE), and soil water content (SWC) in swale soil layers. The best fit (NSE > 0.8) was obtained for high inflows and wet AMC (i.e., when the primary swale function is flow conveyance); the least fit was noted for low inflows and dry AMC, when the primary swale function is flow attenuation. Furthermore, this observation indicates the overall importance of correct modelling of the soil infiltration. The effects of spatial variation of SWC on the swale discharge hydrograph could not be confirmed from simulation results, but high topographical accuracy was beneficial for reproducing well the locations of the observed water ponding. No significant increases in simulated SWC at 0.3 m or greater depths were noted, which agreed with field observations. Overall, the results indicated that Mike SHE was effective in process-oriented small-scale modelling of grass swale flow hydrographs.

  • 6.
    Rujner, Hendrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Leonhardt, Günther
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten. Unit of Environmental Engineering, University of Innsbruck.
    Perttu, Anna-Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Marsalek, Jiri
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Advancing green infrastructure design: Field evaluation of grassed urban drainage swales2016Inngår i: Novatech proceedings 2016, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Grassed drainage swales, which represent common elements of urban green infrastructures, are designed for different soils, flow capacities, dimensions, slopes and vegetation. Their design is often based on local experience rather than technical guidelines, and consequently, the design and performance of grassed swales, with respect to flow capacity and stormwater management objectives may significantly vary from one jurisdiction to another. To improve this situation and reduce design uncertainties, a field study of grassed swales was conducted by assessing their hydrologic performance. A 30-m section of an urban grassed swale in sandy soils, located in the City of Luleå (Northern Sweden), was equipped with a mobile water supply system and instrumented for measuring swale flow characteristics. The water supply system comprised five containers (~ 1 m3 each) providing controlled longitudinal and lateral inflows into the tested swale section. These inflows were selected to mimic stormwater runoff from a typical drainage area. At the first test site, 14 rainfall events of 30- minute duration were simulated and the resulting swale flows and soil moisture conditions were measured. The experimental variables addressed included wet and dry antecedent conditions, and three inflow rates. The preliminary results indicate that the degree of swale inflow attenuation depended on the magnitude of runoff inflow, on the initial soil moisture conditions and that significant volumes of water can be stored and transmitted during the stormwater drainage process.

1 - 6 of 6
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf