Back to search

KLIMAFORSK-Stort program klima

SUstainable URban Flood management- modelling, mitigating and predicting urban and semi-urban flooding

Alternative title: SURF- modellere, redusere og varsle flommer i byer og tettbygde strøk

Awarded: NOK 4.0 mill.

Heavy, intense rainfall and subsequent urban flooding have always posed a threat to urban infrastructure, public health and nature. The cost of damages in Norway caused by urban stormwater are estimated to be between 1.6 and 3.6 bill. NOK per year. Several examples of extreme precipitation with associated heavy damages due to flooding are found in Scandinavia (Copenhagen, Malmø and Mjøndalen). Climate change, leading to an increased intensity and frequency of heavy rainfall and continued urban growth will place even larger demands on urban stormwater management in Norwegian municipalities in the future. A survey of Norwegian municipalities revealed that 60 % had inadequate stormwater capacity for projected future precipitation and lacked local competence, tools and procedures for sustainable management of urban stormwater. The SURF project with its research partners Norwegian Water Resources and Energy Directorate, Norwegian Meteorological Institute and the Municipality of Oslo, intends to increase knowledge and to build expertise and competence in urban hydrology in and for relevant Norwegian institutions and municipalities. SURF will study urban hydrological processes in a water balance context with emphasis on flood-generating processes, response times, extreme values and networks of flow paths as functions of urbanisation. From weather radars and point observations, we produce time series of precipitation of high temporal and spatial resolution. The time series will be used as input to hydrological, hydraulic and geographical information models and for extreme value analysis. SURF will deliver a tool for detailed urban hydrological analysis, quantifying the location of hot spots for inundation and sensitive precipitation thresholds and durations for levels of inundation. Furthermore, SURF will investigate and quantify effects of urban flood mitigating measures, such as rain beds, green roofs etc. and provide a design for streets as secure flood ways. We have selected catchments at Grefsen-Kjelsås and Iladalen in Oslo and Risvollan in Trondheim as test catchments for process understanding and urban hydrologic model development. The test catchments have known urban hydrological problems and data of runoff and precipitation is available. In WP1 available data for the Oslo area is collected and a meta-database is compiled to show periods of existing runoff and precipitation data. The runoff data is further processed in order to identify wastewater so that the hydrological models can be trained solely on runoff due to precipitation. The derived timeseries of runoff are unfortunately not of such a quality that they can be used to estimate subsurface water velocities. WP2 has developed the second generation of a meteorological grid (precipitation and temperature) for Oslo with 250x250 m. spatial- and 10 min temporal resolution for 2 years. A combination of weather radar and conventional precipitation measurements is used. The new grid is being tested for realistic precipitation volumes. A paper on the methodology for estimating design precipitation for the Oslo area has been published. In WP3, GIS analysis of the test catchments is carried out and routines are established for estimating model parameters for the urban rainfall-runoff model DDDUrban, developed during the SURF project. Water velocities of the subsurface are calibrated by DDDUrban and compared to measurements of infiltration. A publication shows that for Grefsen-Kjelsås and Risvollan 1) groundwater flow is a substantial part of runoff measured in the combined flow and stormwater pipes, 2) overland flow from saturated permeable areas contributes to peak runoff and 3) under-designed raingardens may increase flood peaks for sequences close in time of intense precipitation. A Msc study at NMBU has successfully simulated runoff from green roofs at NMBU using DDDUrban. WP4 has, through Msc studies evaluated streets as secure flood ways, the effect of installed raingardens in Oslo, the design and effect of mini-raingardens, and modelling of green roofs. A webinar arranged by SURF and New Water Ways, attended by approximately 90 people was held 1.12.2020. There, main results from the two projects were presented for municipalities and other interested professionals. Presentations are available at https://wordpress.com/page/newwaterways.no/569 and https://www.nve.no/nves-motekalender/sluttseminar-for-surf/

-SURF har jobbet tett sammen med, og bistått NVE's overvannssatsing (Overvannsprosjektet). -SURF har gitt NVE og MET mer kunnskap og fokus på urban hydrometeorologi. -Nedbørsfeltbetraktninger er sentralt også for urbanhydrologiske problemstillinger. -Fuktighets forhold i det urbane nedbørsfelt forut for en regnhendelse er avgjørende for avløpsresponsen. Flom kan forekomme også for ikke-ekstreme nedbørshendelser. -En ny og bedre metode for estimering av ekstremnedbør (IVF kurver) er presentert. -En ny urbanhydrologisk modell er presentert som beregner bidrag til avrenning fra tette og permeable flater. Modellen kan inkludere regnbed og effekten av slike kan analyseres for et nedbørsfelt. -SURF har bidratt til veiledning av 5 MsC studenter ved NMBU og NTNU. -Gjennom foredrag, publikasjoner nasjonalt og internasjonalt og samarbeid med Overvannsprosjektet og utdanningsinstitusjoner mener vi at SURF har vært med på å prege utviklingen av fagfeltet.

Heavy, intense rainfall and subsequent urban flooding have always posed a threat to urban infrastructure, public health and nature. Damages in Norway caused by urban stormwater are estimated to be between 1.6 and 3.6 bill. NOK per year. Several examples of extreme precipitation with associated heavy damages due to flooding are found in Scandinavia (Copenhagen, Malmø and Mjøndalen). Climate change, leading to an increased intensity and frequency of heavy rainfall and continued urban growth will place even larger demands on urban stormwater management in Norwegian municipalities in the future. A survey of Norwegian municipalities revealed that 60 % had inadequate stormwater capacity for projected future precipitation and lacked local competence, tools and procedures for the sustainable management of urban stormwater. The SURF project with its research partners Norwegian Water Resources and Energy Directorate, Norwegian Meteorological Institute and the City of Oslo Agency for Water and Wastewater services, intends to increase knowledge and to build expertise and competence in urban hydrology in and for relevant Norwegian institutions and municipalities. SURF will study urban hydrological processes, their response times, extreme values and their trends and networks of flow paths as functions of urbanisation. From weather radars and point observations, we produce time series of precipitation of high temporal and spatial resolution. The time series will be used as input to hydrological and hydraulic models and for extreme value and trend analysis. SURF will deliver a tool for detailed urban hydrological analysis, quantifying the location of hot spots for inundation and sensitive precipitation thresholds for different runoff. A roadmap for an urban flood forecasting system is planned. Furthermore, SURF will investigate and quantify effects of urban flood mitigating measures, such as rain beds, green roofs etc. and provide a design for streets as secure floodways.

Publications from Cristin

No publications found

No publications found

No publications found

No publications found

Funding scheme:

KLIMAFORSK-Stort program klima