Nora SillanpääAalto University · Department of Built Environment
Nora Sillanpää
D.Sc. (Tech.)
About
56
Publications
14,298
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825
Citations
Citations since 2017
Introduction
My research topics include urban hydrology, urban runoff quality, and sustainable urban runoff management with a special focus on cold climatic conditions. I have been involved in many urban runoff monitoring studies (construction sites, residential and industrial areas, urban snow, city centres, biofiltration), statistical analyses and runoff modelling (SWMM). At the moment, I am working as a researcher at Aalto University. Previously I worked as a project manager at the University of Helsinki.
Additional affiliations
December 2020 - present
August 2019 - present
Sitowise
Position
- Manager
July 2014 - July 2019
Aalto University School of Engineering
Position
- PostDoc Position
Publications
Publications (56)
The impacts of urbanization on catchment hydrology are widely studied by comparing how different urban catchments respond to storm events, but rarely by realising long-term observations of hydrological changes during the construction process at urbanizing small catchments. In this study, the changes occurring in runoff generation were monitored in...
This study quantifies the effects of common stormwater management techniques on urban runoff generation. Simulated flow rates for different low impact development (LID) scenarios were compared with observed flow rates during different urban construction phases in a catchment (12.3 ha) that was developed from natural forest to residential area over...
Permeable Pavement Systems (PPS) are an alternative to conventional paving systems that allow water to filter through their layers instead of running off them. They are structural source control Sustainable Drainage System (SuDS), which can contribute to reducing increased flood risk due to the combination of two of the greatest challenges with whi...
Urban hydrology is characterized by increased runoff and various pollutant sources. We studied the spatio-temporal patterns of stormwater metal (Al, V, Cr, Mn, Fe, Cu, Zn, and Pb) concentrations and loads in five urbanized and one rural catchment in Southern Finland. The two-year continuous monitoring revealed a non-linear seasonal relationship bet...
Urbanization modifies the natural water cycle particularly by reducing the water storage capacity. We analysed the storage capacity of three stormwater management designs in south-western Finland to demonstrate how an urban catchment releases stormwater and how storage contributes to flood resilience. The analysis relies on EPA SWMM5.1 simulations...
By changing the hydrological cycle, urbanisation has led to frequent flooding worldwide. These phenomena, combined with Climate Change, threaten the capacity of sewer networks for safe conveyance of runoff. In this context, there is a need for efficient methods of modelling sewer networks, which are the main drainage systems used to deal with runof...
Flood modelling in urban areas is usually undertaken using stormwater tools, which are complex and time-consuming in terms of parametrization. To replace them, this research developed a methodology for predicting flooding probability in urban watersheds (sewersheds) through the modelling of peak flow rates from a set of watershed and sewer network-...
Availability of remotely sensed and openly available land cover datasets is rapidly improving. This opens promising possibilities for utilizing such data in urban hydrological assessments. However, it remains unknown how the performance of readily available land cover data compares with manually collated information when used to construct detailed...
Constructing hydrological models for large urban areas is time consuming and laborious due to the requirements for high-resolution data and fine model detail. An open-source algorithm using adaptive subcatchments is proposed to automate Storm Water Management Model (SWMM) construction. The algorithm merges areas with homogeneous land cover and a co...
Decentralized urban runoff management requires detailed information about pollutant sources and pathways. However, scarce data of local water quality compel simplified approaches in water quality modelling. This study investigated the use of constant source concentrations in modelling pollutant loads. The source area contributions of total suspende...
Low impact development (LID) has received significant attention in supplementing urban drainage designs. This study demonstrates the effects of LID-based urban designs on water balance components for an urban catchment. Two LID-based urban designs (A, B) are simulated for short term (E1) and long term (E2) periods and the effects of the various des...
Simple and automatic optimization approaches were used to create Low Impact Development (LID) scenarios for a residential catchment in Espoo, Finland. Ten LID scenarios were simulated with the Storm Water Management Model (SWMM) to evaluate their impact on urban runoff and pollutant load on a catchment scale. Permeable pavements and bioretention ce...
Roadside filters can be used to treat polluted stormwater. In this study, sand and sand-biochar filters were investigated in full-scale field conditions during three rain events. Stormwater influent and effluent of the filters were sampled with high frequency and up to 29 water quality parameters were determined. The obtained field data was analyze...
The overall objectives of urban stormwater management are appropriate drainage to minimize urban flood risk and erosion, and protection of groundwater and surface water quality. Urban systems of green infrastructure such as rain gardens, green roofs, permeable pavements, swales, wetlands, and other designed to reduce stormwater surface runoff volume...
Flood assessment in urban catchments is usually addressed through the combination of Geographic Information Systems (GIS) and stormwater models. However, the coupled use of these tools involves a level of detail in terms of hydrological modelling which can be beyond the scope of overall flood management planning strategies. This research consists o...
This research developed a methodology for optimising the stormwater modelling of ur-ban areas using Design of Experiments (DOE), and tested it through a case study of a catchment located in the city of Espoo (Finland), which validated its applicability under real conditions. The use of DOE enabled identifying the most influential parameters on catc...
Urban drainage is being affected by Climate Change, whose effects are likely to alter the intensity of rainfall events and result in variations in peak discharges and runoff volumes which stationary-based designs might not be capable of dealing with. Therefore, there is a need to have an accurate and reliable means to model the response of urban ca...
Multiple natural and anthropogenic factors affect urban water chemistry. However, little is known about the abundance or temporal variation of major ions in urban runoff. This study explores the spatio-temporal variation of major dissolved ions (Na, K, Ca, Mg, Cl, NO3, SO4) and total dissolved solids (TDS) in cold climate urban stormwater. Three wa...
Accurate quantification of the amount, quality and sources of urban stormwater runoff are a prerequisite for effective stormwater management. The goal of this study was to estimate city-scale stormwater pollutant export, examine the effect of data sources on export estimates, and develop an optimization method for stormwater monitoring. The results...
Stormwater biofiltration was studied at a large-scale lysimeter facility in southern Finland. Biofiltration systems, constructed within eight lysimeters, consisted of an organic topsoil, a sand layer and three gravel layers of varying gravel size underneath. Six of the lysimeter systems were vegetated with Phalaris arundinacea, Salix glauca var. ca...
The source area contributions of total suspended solids, total phosphorus and total nitrogen were simulated with SWMM using event mean concentrations (EMCs) from literature for different surface types. Simulated loads were compared against measured loads at the catchment outlet in a residential catchment in Espoo, Finland. A high variability in the...
This study explored the hydrological impacts of urbanization, rainfall pattern and magnitude in a developing catchment. The Stormwater Management Model (SWMM) was parameterized, calibrated and validated in three development phases which had a same catchment area (12.3 ha) but different land use intensities. The model calibration and validation by u...
Urban runoff contains various pollutants and has the potential of deteriorating the quality of aquatic ecosystems. In this study our objective is to shed light on the factors that control the runoff water quality in urbanized catchments. The effects of runoff event characteristics, land use type and catchment imperviousness on event mass loads (EML...
Urbanization strongly changes natural catchment by increasing impervious coverage and by creating a need for efficient drainage systems. Such land cover changes lead to more rapid hydrological response to storms and change distribution of peak and low flows. This study aims to explore and assess how gradual hydrological changes occur during urban d...
Research on the water quality of urban runoff has so far focussed on the post-development phase of urban catchments, whereas water quality in developing areas under construction has remained less understood. The construction phase, however, may constitute a considerable source of diffuse pollution in urban areas. This study investigated mechanisms...
This study investigates the impacts of suburban development on the direct runoff response to a range of storm events using hydrological data from a developing catchment under construction and two residential control catchments in the capital area in Finland. Construction works caused the largest relative changes in the runoff response to frequently...
http://meetingorganizer.copernicus.org/EGU2014/EGU2014-9718.pdf
http://meetingorganizer.copernicus.org/EGU2014/EGU2014-6743.pdf
The effects of urbanization on runoff pollutant concentrations and pollutant loading were studied in three urban catchments of varying imperviousness and land use type in the city of Lahti, Finland. Imperviousness of the catchments were 19% (“Low”), 62% (“Intermediate”) and 89% (“High”). During the 2-year study period, runoff quantity was measured...
The impacts of land use intensity, here defined as the degree of imperviousness, on stormwater volumes, runoff rates and their temporal occurrence were studied at three urban catchments in a cold region in southern Finland. The catchments with ‘High’ and ‘Intermediate’ land use intensity, located around the city centre, were characterized by 89% an...
http://www.lamk.fi/english/rd/research/sivut/tuote.aspx?pid=3360
Despite the crucial role of snow in the hydrological cycle in cold climate conditions, monitoring studies of urban snow quality often lack discussions about the relevance of snow in the catchment-scale runoff management. In this study, measurements of snow quality were conducted at two residential catchments in Espoo, Finland, simultaneously with c...
Urbanization leads to changes in natural catchment characteristics by increasing the impervious coverage and drainage efficiency, which enhance flooding, erosion and water quality problems in the receiving waters. Year-round monitoring of catchment-scale hydrological and water quality variables is needed to produce data resources for the developmen...
http://lib.tkk.fi/TIEDE_TEKNOLOGIA/2012/isbn9789526045559.pdf
This paper describes the current situation concerning stormwater management in Finland. Also
presented is a research program “StormWater” in which several organisations cooperated. How the
governance issues have affected the research programs case studies are examined. Based on a review
of the current state of stormwater management in Finland and o...
Stormwater biofiltration structures were tested in cold climate conditions in a large scale lysimeter facility located in Lahti, southern Finland. Structures consisted of organic topsoil layer, sand filter layer and various gravel layers in the bottom. Retention for nitrate, phosphate, zinc, copper and aluminium was studied during three seasons. Al...
The main theme of this paper is to assess the complexity of rainfall‐runoff process in urbanized areas. Effects of paved and impervious surfaces on rainfall‐runoff process and storm water quality are described in three different urban study areas. Conclusions on the hydrological and water quality effects of urbanization were drawn from the results...
Questions
Questions (5)
Dear all,
Are there publications/guidelines about methodologies for identifying critical areas based on stormwater quality? I am especially interested in methods based on GIS analysis and water quality sampling. By sampling I mean quite practical approaches that municipalities can utilize while trying to map critical areas for stormwater quality management, and with city-scale focus. I assume that a city-scale project has to start with a GIS analysis of critical areas and then, as a second phase, continue with a water quality sampling campaing(s) of selected sites.
Dear all,
I am preparing some presentations to promote the use of sustainable stormwater management systems (SUDS/LID/WSUD systems etc.). I would be happy to receive some help about where to find the most interesting case studies. I am particularly interested in visually inspiring examples, because the aim is to capture the audience's interest with a slideshow with plenty of photos etc. from different parts of the world.
Thank you in advance!
Best regards,
Nora
I am interested in finding urban runoff water quality studies, preferably using SWMM. I am working with urban runoff data with continuous flow and rainfall data (2-10 min temporal resolution, 10-30 ha catchments) and water quality data of some common pollutants (TSS, TP, TN, COD) from both wet weather and dry weather flow. I'd be happy to find examples about model calibration (either event-based or continuous modelling) using similar kind of water quality data (flow based sampling, often several samples per event). Also good review papers about the topic are warmly welcome!
Do you have examples about publications discussing stormwater biofiltration during construction works? I think I have heard that if biofiltration or any other vegetated stormwater management practices have been planned for a new residential area, those systems should not be built ready before the contruction works have ended, i.e. the sediments from the construction sites may destroy the structures. For this reason, these stormwater management structures may have some kind of temporary function during the construction period of the resdiential area (e.g. detention pond with some temporary vegetation) and they will be finalized after the construction projects end. But now I am finding it difficult to actually find a publication that really says it is so! Hope you can help me.
I am working with water quality data from a construction site, where elevated total nitrogen concentrations (> 20 mg/l) were observed. There might be several reasons behind the high nitrogen loads, such as illicit waste water discharges and the leaching of nitrogen from the soil after logging, but I would love to have some estimates about the impacts of blasting, which could be an important source.
Projects
Projects (3)
The main objective of the study is to identify and evaluate water quality patterns and pollutant transport mechanisms in urban areas, particularly in cold climatic conditions. Additionally, different modelling methodologies are tested to explore and model pollutant transport mechanisms from source areas to receiving urban streams.
Our project includes runoff and water quality monitoring of two types of filtration systems for urban runoff: roadside biofiltration systems (Espoo, Finland) and an underground filtration unit (Helsinki, Finland). Additionally, we are conducting laboratory tests for developing suitable filter media structures for the treatment of airport runoff (Helsinki Airport). We are involved in the planning of a multifunctional park area with the aim of utilizing online hydrological and water quality data in the everyday operation of the park (Vantaa, Finland).
http://builtenv.aalto.fi/en/current/news/2018-04-04-013/
For a complete project description, please visit the web site http://www.vtt.fi/sites/stormfilter: The STORMFILTER project addresses the societal challenges of urban stormwater management. The research targets are to generate knowhow to provide clean technologies, in the form of engineered materials and designs that can enhance stormwater management by retaining runoff and improving water quality through pollutant sorption or filtering in the soil. The project targets developing material solutions and designs to clean stormwater, with quantitative values and models for the grey (subbase and hard surfacing) and green (vegetation) material solutions. The targets compliment Finnish strategies for green urban living, by promoting vegetation health and improved water quality. The project also provides tools for decision making regarding regional planning and specifications, based on models and smart city monitoring of performance for the new infrastructural solutions.
