This page has only limited features, please log in for full access.

Dr. Søren Thorndahl
Aalborg Universitet, Department of Civil Engineering, Aalborg, Denmark

Basic Info


Research Keywords & Expertise

0 rainfall
0 Urban Hydrology
0 urban drainage modelling
0 numerical modelling
0 Uncertainty Assessment

Fingerprints

rainfall
Urban Hydrology
urban drainage modelling
Uncertainty Assessment
numerical modelling

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Research article
Published: 19 June 2020 in Hydrology and Earth System Sciences
Reads 0
Downloads 0

Weather radar has become an invaluable tool for monitoring rainfall and studying its link to hydrological response. However, when it comes to accurately measuring small-scale rainfall extremes responsible for urban flooding, many challenges remain. The most important of them is that radar tends to underestimate rainfall compared to gauges. The hope is that by measuring at higher resolutions and making use of dual-polarization radar, these mismatches can be reduced. Each country has developed its own strategy for addressing this issue. However, since there is no common benchmark, improvements are hard to quantify objectively. This study sheds new light on current performances by conducting a multinational assessment of radar's ability to capture heavy rain events at scales of 5 min up to 2 h. The work is performed within the context of the joint experiment framework of project MUFFIN (Multiscale Urban Flood Forecasting), which aims at better understanding the link between rainfall and urban pluvial flooding across scales. In total, six different radar products in Denmark, the Netherlands, Finland and Sweden were considered. The top 50 events in a 10-year database of radar data were used to quantify the overall agreement between radar and gauges as well as the bias affecting the peaks. Results show that the overall agreement in heavy rain is fair (correlation coefficient 0.7–0.9), with apparent multiplicative biases on the order of 1.2–1.8 (17 %–44 % underestimation). However, after taking into account the different sampling volumes of radar and gauges, actual biases could be as low as 10 %. Differences in sampling volumes between radar and gauges play an important role in explaining the bias but are hard to quantify precisely due to the many post-processing steps applied to radar. Despite being adjusted for bias by gauges, five out of six radar products still exhibited a clear conditional bias, with intensities of about 1 %–2 % per mmh−1. As a result, peak rainfall intensities were severely underestimated (factor 1.8–3.0 or 44 %–67 %). The most likely reason for this is the use of a fixed Z–R relationship when estimating rainfall rates (R) from reflectivity (Z), which fails to account for natural variations in raindrop size distribution with intensity. Based on our findings, the easiest way to mitigate the bias in times of heavy rain is to perform frequent (e.g., hourly) bias adjustments with the help of rain gauges, as demonstrated by the Dutch C-band product. An even more promising strategy that does not require any gauge adjustments is to estimate rainfall rates using a combination of reflectivity (Z) and differential phase shift (Kdp), as done in the Finnish OSAPOL product. Both approaches lead to approximately similar performances, with an average bias (at 10 min resolution) of about 30 % and a peak intensity bias of about 45 %.

ACS Style

Marc Schleiss; Jonas Olsson; Peter Berg; Tero Niemi; Teemu Kokkonen; Søren Thorndahl; Rasmus Nielsen; Jesper Ellerbæk Nielsen; Denica Bozhinova; Seppo Pulkkinen. The accuracy of weather radar in heavy rain: a comparative study for Denmark, the Netherlands, Finland and Sweden. Hydrology and Earth System Sciences 2020, 24, 3157 -3188.

AMA Style

Marc Schleiss, Jonas Olsson, Peter Berg, Tero Niemi, Teemu Kokkonen, Søren Thorndahl, Rasmus Nielsen, Jesper Ellerbæk Nielsen, Denica Bozhinova, Seppo Pulkkinen. The accuracy of weather radar in heavy rain: a comparative study for Denmark, the Netherlands, Finland and Sweden. Hydrology and Earth System Sciences. 2020; 24 (6):3157-3188.

Chicago/Turabian Style

Marc Schleiss; Jonas Olsson; Peter Berg; Tero Niemi; Teemu Kokkonen; Søren Thorndahl; Rasmus Nielsen; Jesper Ellerbæk Nielsen; Denica Bozhinova; Seppo Pulkkinen. 2020. "The accuracy of weather radar in heavy rain: a comparative study for Denmark, the Netherlands, Finland and Sweden." Hydrology and Earth System Sciences 24, no. 6: 3157-3188.

Journal article
Published: 30 August 2019 in Hydrological Processes
Reads 0
Downloads 0
ACS Style

Kristoffer T. Nielsen; Per Moldrup; Søren Thorndahl; Jesper E. Nielsen; Lene B. Duus; Søren H. Rasmussen; Mads Uggerby; Michael R. Rasmussen. Automated rainfall simulator for variable rainfall on urban green areas. Hydrological Processes 2019, 33, 3364 -3377.

AMA Style

Kristoffer T. Nielsen, Per Moldrup, Søren Thorndahl, Jesper E. Nielsen, Lene B. Duus, Søren H. Rasmussen, Mads Uggerby, Michael R. Rasmussen. Automated rainfall simulator for variable rainfall on urban green areas. Hydrological Processes. 2019; 33 (26):3364-3377.

Chicago/Turabian Style

Kristoffer T. Nielsen; Per Moldrup; Søren Thorndahl; Jesper E. Nielsen; Lene B. Duus; Søren H. Rasmussen; Mads Uggerby; Michael R. Rasmussen. 2019. "Automated rainfall simulator for variable rainfall on urban green areas." Hydrological Processes 33, no. 26: 3364-3377.

Preprint content
Published: 15 August 2019
Reads 0
Downloads 0

Weather radar has become an invaluable tool for monitoring rainfall and studying its link to hydrological response. However, when it comes to accurately measuring small-scale rainfall extremes responsible for urban flooding, many challenges remain. The most important of them is that radar tends to underestimate rainfall compared to gauges. The hope is that by moving to higher resolution and making use of dual-polarization, these mismatches can be reduced. Each country has developed its own strategy for addressing this issue. But since there is no common benchmark, improvements are hard to quantify objectively. This study sheds new light on current performances by conducting a multinational assessment of radar's ability to capture heavy rain events at scales of 5 min up to 2 hours. The work is performed within the context of the joint experiment framework of project MUFFIN (Multiscale Urban Flood Forecasting), which aims at better understanding the link between rainfall and urban pluvial flooding across scales. In total, 6 different radar products in Denmark, the Netherlands, Finland and Sweden were considered. The top 50 events for each country were used to quantify the overall agreement between radar and gauges and the errors affecting the peaks. Results show that the overall agreement between radar and gauges in heavy rain is fair, with multiplicative biases in the order of 1.41–1.66 (i.e., radar underestimates by 29–39.8 %) and correlation coefficients of 0.71–0.83 across countries. However, the bias increases with intensity, reaching 45.9 %–66.2 % during the peaks. Only part of the bias (i.e., roughly 13 %–30 % depending on the radar product) can be explained by differences in measurement areas between gauges and radar. Radar products with higher spatial and temporal resolutions agreed better with the gauges, highlighting the importance of high-resolution radar for urban hydrology. However, for capturing peak intensity and reducing the bias during the most intense part of a storm, the ability to combine measurements from multiple overlapping radars to help mitigate attenuation seemed to play a more important role than resolution. The use of dual-polarization and phase information (e.g., Kdp) in the experimental Finnish OSAPOL product also seemed to provide a slight advantage in heavy rain. But improvements were hard to quantify and similarly good results were achieved in the Netherlands by applying a simple Z–R relation together with a mean field bias-correction.

ACS Style

Marc Schleiss; Jonas Olsson; Peter Berg; Tero Niemi; Teemu Kokkonen; Søren Thorndahl; Rasmus Nielsen; Jesper Ellerbæk Nielsen; Denica Bozhinova; Seppo Pulkkinen. The accuracy of weather radar in heavy rain: a comparative study for Denmark, the Netherlands, Finland and Sweden. 2019, 1 .

AMA Style

Marc Schleiss, Jonas Olsson, Peter Berg, Tero Niemi, Teemu Kokkonen, Søren Thorndahl, Rasmus Nielsen, Jesper Ellerbæk Nielsen, Denica Bozhinova, Seppo Pulkkinen. The accuracy of weather radar in heavy rain: a comparative study for Denmark, the Netherlands, Finland and Sweden. . 2019; ():1.

Chicago/Turabian Style

Marc Schleiss; Jonas Olsson; Peter Berg; Tero Niemi; Teemu Kokkonen; Søren Thorndahl; Rasmus Nielsen; Jesper Ellerbæk Nielsen; Denica Bozhinova; Seppo Pulkkinen. 2019. "The accuracy of weather radar in heavy rain: a comparative study for Denmark, the Netherlands, Finland and Sweden." , no. : 1.

Journal article
Published: 29 May 2019 in Water
Reads 0
Downloads 0

In the design practice of urban hydrological systems, e.g., storm-water drainage systems, design rainfall is typically assumed spatially homogeneous over a given catchment. For catchments larger than approximately 10 km2, this leads to significant overestimation of the design rainfall intensities, and thus potentially oversizing of urban drainage systems. By extending methods from rural hydrology to urban hydrology, this paper proposes the introduction of areal reduction factors in urban drainage design focusing on temporal and spatial scales relevant for urban hydrological applications (1 min to 1 day and 0.1 to 100 km2). Storm-centred areal reduction factors are developed based on a 15-year radar rainfall dataset from Denmark. From the individual storms, a generic relationship of the areal reduction factor as a function of rainfall duration and area is derived. This relationship can be directly implemented in design with intensity–duration–frequency curves or design storms.

ACS Style

Søren Thorndahl; Jesper Ellerbæk Nielsen; Michael R. Rasmussen. Estimation of Storm-Centred Areal Reduction Factors from Radar Rainfall for Design in Urban Hydrology. Water 2019, 11, 1120 .

AMA Style

Søren Thorndahl, Jesper Ellerbæk Nielsen, Michael R. Rasmussen. Estimation of Storm-Centred Areal Reduction Factors from Radar Rainfall for Design in Urban Hydrology. Water. 2019; 11 (6):1120.

Chicago/Turabian Style

Søren Thorndahl; Jesper Ellerbæk Nielsen; Michael R. Rasmussen. 2019. "Estimation of Storm-Centred Areal Reduction Factors from Radar Rainfall for Design in Urban Hydrology." Water 11, no. 6: 1120.

Journal article
Published: 14 May 2018 in Water Science and Technology
Reads 0
Downloads 0

The technical lifetime of urban water infrastructure has a duration where climate change has to be considered when alterations to the system are planned. Also, models for urban water management are reaching a very high complexity level with, for example, decentralized stormwater control measures being included. These systems have to be evaluated under as close-to-real conditions as possible. Long term statistics (LTS) modelling with observational data is the most close-to-real solution for present climate conditions, but for future climate conditions artificial rainfall time series from weather generators (WGs) have to be used. In this study, we ran LTS simulations with four different WG products for both present and future conditions on two different catchments. For the present conditions, all WG products result in realistic catchment responses when it comes to the number of full flowing pipes and the number and volume of combined sewer overflows (CSOs). For future conditions, the differences in the WGs representation of the expectations to climate change is evident. Nonetheless, all future results indicate that the catchments will have to handle more events that utilize the full capacity of the drainage systems. Generally, WG products are relevant to use in planning of future changes to sewer systems.

ACS Style

Hjalte Jomo Danielsen Sørup; Steffen Davidsen; Roland Löwe; Søren Liedtke Thorndahl; Morten Borup; Karsten Arnbjerg-Nielsen. Evaluating catchment response to artificial rainfall from four weather generators for present and future climate. Water Science and Technology 2018, 77, 2578 -2588.

AMA Style

Hjalte Jomo Danielsen Sørup, Steffen Davidsen, Roland Löwe, Søren Liedtke Thorndahl, Morten Borup, Karsten Arnbjerg-Nielsen. Evaluating catchment response to artificial rainfall from four weather generators for present and future climate. Water Science and Technology. 2018; 77 (11):2578-2588.

Chicago/Turabian Style

Hjalte Jomo Danielsen Sørup; Steffen Davidsen; Roland Löwe; Søren Liedtke Thorndahl; Morten Borup; Karsten Arnbjerg-Nielsen. 2018. "Evaluating catchment response to artificial rainfall from four weather generators for present and future climate." Water Science and Technology 77, no. 11: 2578-2588.

Journal article
Published: 13 April 2018 in Journal of Hydroinformatics
Reads 0
Downloads 0

Intense rainfall in urban areas can often generate severe flood impacts. Consequently, it is crucial to design systems to minimize potential flood damages. Traditional, simple design of urban drainage systems assumes agreement between rainfall return period and its consequent flood return period; however, this does not always apply. Hydraulic infrastructures found in urban drainage systems can increase system heterogeneity and perturb the impact of severe rainfall response. In this study, a surface flood return period assessment was carried out at Lystrup (Denmark), which has received the impact of flooding in recent years. A 35 years' rainfall dataset together with a coupled 1D/2D surface and network model was used to analyse and assess flood return period response. Results show an ambiguous relation between rainfall and flood return periods indicating that linear rainfall–runoff relationships will, for the analysed case study, be insufficient for flood estimation. Simulation-based mapping of return periods for flood area and volume has been suggested, and moreover, a novel approach has been developed to map local flood response time and relate this to rainfall characteristics. This approach allows to carefully analyse rainfall impacts and flooding response for a correct flood return period assessment in urban areas.

ACS Style

Damian Murla Tuyls; Søren Thorndahl; Michael R. Rasmussen. Return period assessment of urban pluvial floods through modelling of rainfall–flood response. Journal of Hydroinformatics 2018, 20, 829 -845.

AMA Style

Damian Murla Tuyls, Søren Thorndahl, Michael R. Rasmussen. Return period assessment of urban pluvial floods through modelling of rainfall–flood response. Journal of Hydroinformatics. 2018; 20 (4):829-845.

Chicago/Turabian Style

Damian Murla Tuyls; Søren Thorndahl; Michael R. Rasmussen. 2018. "Return period assessment of urban pluvial floods through modelling of rainfall–flood response." Journal of Hydroinformatics 20, no. 4: 829-845.

Journal article
Published: 07 September 2017 in Hydrology and Earth System Sciences
Reads 0
Downloads 0

Continuous and long rainfall series are a necessity in rural and urban hydrology for analysis and design purposes. Local historical point rainfall series often cover several decades, which makes it possible to estimate rainfall means at different timescales, and to assess return periods of extreme events. Due to climate change, however, these series are most likely not representative of future rainfall. There is therefore a demand for climate-projected long rainfall series, which can represent a specific region and rainfall pattern as well as fulfil requirements of long rainfall series which includes climate changes projected to a specific future period. This paper presents a framework for resampling of historical point rainfall series in order to generate synthetic rainfall series, which has the same statistical properties as an original series. Using a number of key target predictions for the future climate, such as winter and summer precipitation, and representation of extreme events, the resampled historical series are projected to represent rainfall properties in a future climate. Climate-projected rainfall series are simulated by brute force randomization of model parameters, which leads to a large number of projected series. In order to evaluate and select the rainfall series with matching statistical properties as the key target projections, an extensive evaluation procedure is developed.

ACS Style

Søren Thorndahl; Aske Korup Andersen; Anders Badsberg Larsen. Event-based stochastic point rainfall resampling for statistical replication and climate projection of historical rainfall series. Hydrology and Earth System Sciences 2017, 21, 4433 -4448.

AMA Style

Søren Thorndahl, Aske Korup Andersen, Anders Badsberg Larsen. Event-based stochastic point rainfall resampling for statistical replication and climate projection of historical rainfall series. Hydrology and Earth System Sciences. 2017; 21 (9):4433-4448.

Chicago/Turabian Style

Søren Thorndahl; Aske Korup Andersen; Anders Badsberg Larsen. 2017. "Event-based stochastic point rainfall resampling for statistical replication and climate projection of historical rainfall series." Hydrology and Earth System Sciences 21, no. 9: 4433-4448.

Review
Published: 05 July 2017
Reads 0
Downloads 0
ACS Style

Søren Thorndahl. Review of ten Veldhuis et al. ” The role of storm dynamics and scale in controlling urban flood response”. 2017, 1 .

AMA Style

Søren Thorndahl. Review of ten Veldhuis et al. ” The role of storm dynamics and scale in controlling urban flood response”. . 2017; ():1.

Chicago/Turabian Style

Søren Thorndahl. 2017. "Review of ten Veldhuis et al. ” The role of storm dynamics and scale in controlling urban flood response”." , no. : 1.

Preprint content
Published: 01 July 2017
Reads 0
Downloads 0
ACS Style

Søren Thorndahl. Reply to review by Patrick Willems. 2017, 1 .

AMA Style

Søren Thorndahl. Reply to review by Patrick Willems. . 2017; ():1.

Chicago/Turabian Style

Søren Thorndahl. 2017. "Reply to review by Patrick Willems." , no. : 1.

Preprint content
Published: 01 July 2017
Reads 0
Downloads 0
ACS Style

Søren Thorndahl. Reply to review by Lars Bengtsson. 2017, 1 .

AMA Style

Søren Thorndahl. Reply to review by Lars Bengtsson. . 2017; ():1.

Chicago/Turabian Style

Søren Thorndahl. 2017. "Reply to review by Lars Bengtsson." , no. : 1.

Review
Published: 01 June 2017
Reads 0
Downloads 0
ACS Style

Søren Thorndahl. Review of Kaspersen et al.: Comparison of the impacts of urban development and climate change in exposing European cities to pluvial flooding. 2017, 1 .

AMA Style

Søren Thorndahl. Review of Kaspersen et al.: Comparison of the impacts of urban development and climate change in exposing European cities to pluvial flooding. . 2017; ():1.

Chicago/Turabian Style

Søren Thorndahl. 2017. "Review of Kaspersen et al.: Comparison of the impacts of urban development and climate change in exposing European cities to pluvial flooding." , no. : 1.

Journal article
Published: 07 March 2017 in Hydrology and Earth System Sciences
Reads 0
Downloads 0

Application of weather radar data in urban hydrological applications has evolved significantly during the past decade as an alternative to traditional rainfall observations with rain gauges. Advances in radar hardware, data processing, numerical models, and emerging fields within urban hydrology necessitate an updated review of the state of the art in such radar rainfall data and applications. Three key areas with significant advances over the past decade have been identified: (1) temporal and spatial resolution of rainfall data required for different types of hydrological applications, (2) rainfall estimation, radar data adjustment and data quality, and (3) nowcasting of radar rainfall and real-time applications. Based on these three fields of research, the paper provides recommendations based on an updated overview of shortcomings, gains, and novel developments in relation to urban hydrological applications. The paper also reviews how the focus in urban hydrology research has shifted over the last decade to fields such as climate change impacts, resilience of urban areas to hydrological extremes, and online prediction/warning systems. It is discussed how radar rainfall data can add value to the aforementioned emerging fields in current and future applications, but also to the analysis of integrated water systems.

ACS Style

Søren Thorndahl; Thomas Einfalt; Patrick Willems; Jesper Ellerbæk Nielsen; Marie-Claire Ten Veldhuis; Karsten Arnbjerg-Nielsen; Michael R. Rasmussen; Peter Molnar. Weather radar rainfall data in urban hydrology. Hydrology and Earth System Sciences 2017, 21, 1359 -1380.

AMA Style

Søren Thorndahl, Thomas Einfalt, Patrick Willems, Jesper Ellerbæk Nielsen, Marie-Claire Ten Veldhuis, Karsten Arnbjerg-Nielsen, Michael R. Rasmussen, Peter Molnar. Weather radar rainfall data in urban hydrology. Hydrology and Earth System Sciences. 2017; 21 (3):1359-1380.

Chicago/Turabian Style

Søren Thorndahl; Thomas Einfalt; Patrick Willems; Jesper Ellerbæk Nielsen; Marie-Claire Ten Veldhuis; Karsten Arnbjerg-Nielsen; Michael R. Rasmussen; Peter Molnar. 2017. "Weather radar rainfall data in urban hydrology." Hydrology and Earth System Sciences 21, no. 3: 1359-1380.

Preprint content
Published: 01 March 2017
Reads 0
Downloads 0

Continuous and long rainfall series are a necessity in rural and urban hydrology for analysis and design purposes. Local historical point rainfall series often cover several decades which makes it possible to estimate rainfall means at different time scales, and to assess return periods of extreme events. Due to climate change, however, these series are most likely not representative for future rainfall. There is therefore a demand for climate projected long rainfall series, which can represent a specific region and rainfall pattern as well as fulfill requirements of long rainfall series which includes climate changes projected to a specific future period. This paper presents a framework for resampling of historical point rainfall series in order to generate synthetic rainfall series, which has the same statistical properties as an original series. Using a number of key target predictions for the future climate, such as winter and summer precipitation, representation of extreme events, the resampled historical series are projected to represent rainfall properties in a future climate. Climate projected rainfall series are simulated by brute force randomization of model parameters which leads to a large number of projected series. In order to evaluate and select the rainfall series with matching statistical properties as the key target projections, an extensive evaluation procedure is developed.

ACS Style

Søren Thorndahl; Aske Korup Andersen; Anders Badsberg Larsen. Event-based stochastic point rainfall resampling for statistical replication and climate projection of historical rainfall series. 2017, 1 -26.

AMA Style

Søren Thorndahl, Aske Korup Andersen, Anders Badsberg Larsen. Event-based stochastic point rainfall resampling for statistical replication and climate projection of historical rainfall series. . 2017; ():1-26.

Chicago/Turabian Style

Søren Thorndahl; Aske Korup Andersen; Anders Badsberg Larsen. 2017. "Event-based stochastic point rainfall resampling for statistical replication and climate projection of historical rainfall series." , no. : 1-26.

Journal article
Published: 11 October 2016 in Water Science and Technology
Reads 0
Downloads 0

Flooding produced by high-intensive local rainfall and drainage system capacity exceedance can have severe impacts in cities. In order to prepare cities for these types of flood events – especially in the future climate – it is valuable to be able to simulate these events numerically, both historically and in real-time. There is a rather untested potential in real-time prediction of urban floods. In this paper, radar data observations with different spatial and temporal resolution, radar nowcasts of 0–2 h leadtime, and numerical weather models with leadtimes up to 24 h are used as inputs to an integrated flood and drainage systems model in order to investigate the relative difference between different inputs in predicting future floods. The system is tested on the small town of Lystrup in Denmark, which was flooded in 2012 and 2014. Results show it is possible to generate detailed flood maps in real-time with high resolution radar rainfall data, but rather limited forecast performance in predicting floods with leadtimes more than half an hour.

ACS Style

Søren Thorndahl; Jesper E. Nielsen; David Getreuer Jensen. Urban pluvial flood prediction: a case study evaluating radar rainfall nowcasts and numerical weather prediction models as model inputs. Water Science and Technology 2016, 74, 2599 -2610.

AMA Style

Søren Thorndahl, Jesper E. Nielsen, David Getreuer Jensen. Urban pluvial flood prediction: a case study evaluating radar rainfall nowcasts and numerical weather prediction models as model inputs. Water Science and Technology. 2016; 74 (11):2599-2610.

Chicago/Turabian Style

Søren Thorndahl; Jesper E. Nielsen; David Getreuer Jensen. 2016. "Urban pluvial flood prediction: a case study evaluating radar rainfall nowcasts and numerical weather prediction models as model inputs." Water Science and Technology 74, no. 11: 2599-2610.

Preprint content
Published: 06 October 2016
Reads 0
Downloads 0

Application of weather radar data in urban hydrological applications has evolved significantly during the past decade as an alternative to traditional rainfall observations with rain gauges. Advances in radar hardware, data processing, numerical models, and emerging fields within urban hydrology, necessitate an updated review of the state of the art in radar rainfall for urban hydrological applications. Three key areas of research have been identified as especially important in application of radar data in urban hydrology, given their significant advances over the past decade: 1) Temporal and spatial resolution of rainfall data required for different hydrological applications, 2) Rainfall estimation, radar data adjustment and data quality, and 3) Nowcasting of radar rainfall and real-time applications. Based on these three fields of research, the paper provides recommendations based on an updated overview of shortcomings, gains, and novel developments in relation to urban hydrological applications. The paper reviews how the focus in urban hydrology as a field of research has shifted over the last decade to fields such as urban resilience to hydrological extremes, climate change impacts, and on-line warning/prediction systems. It is discussed how radar rainfall data can contribute to existing hydrological fields and add value to the aforementioned emerging fields in current and future applications.

ACS Style

Søren Thorndahl; Thomas Einfalt; Patrick Willems; Jesper Ellerbæk Nielsen; Marie-Claire Ten Veldhuis; Karsten Arnbjerg-Nielsen; Michael R. Rasmussen; Peter Molnar. Weather radar rainfall data in urban hydrology. 2016, 2016, 1 -37.

AMA Style

Søren Thorndahl, Thomas Einfalt, Patrick Willems, Jesper Ellerbæk Nielsen, Marie-Claire Ten Veldhuis, Karsten Arnbjerg-Nielsen, Michael R. Rasmussen, Peter Molnar. Weather radar rainfall data in urban hydrology. . 2016; 2016 ():1-37.

Chicago/Turabian Style

Søren Thorndahl; Thomas Einfalt; Patrick Willems; Jesper Ellerbæk Nielsen; Marie-Claire Ten Veldhuis; Karsten Arnbjerg-Nielsen; Michael R. Rasmussen; Peter Molnar. 2016. "Weather radar rainfall data in urban hydrology." 2016, no. : 1-37.

Journal article
Published: 30 September 2016 in Water Science and Technology
Reads 0
Downloads 0

Combined sewer overflow (CSO) structures are constructed to effectively discharge excess water during heavy rainfall, to protect the urban drainage system from hydraulic overload. Consequently, most CSO structures are not constructed according to basic hydraulic principles for ideal measurement weirs. It can, therefore, be a challenge to quantify the discharges from CSOs. Quantification of CSO discharges are important in relation to the increased environmental awareness of the receiving water bodies. Furthermore, CSO discharge quantification is essential for closing the rainfall-runoff mass-balance in combined sewer catchments. A closed mass-balance is an advantage for calibration of all urban drainage models based on mass-balance principles. This study presents three different software sensor concepts based on local water level sensors, which can be used to estimate CSO discharge volumes from hydraulic complex CSO structures. The three concepts were tested and verified under real practical conditions. All three concepts were accurate when compared to electromagnetic flow measurements.

ACS Style

Malte Ahm; Søren Thorndahl; Jesper E. Nielsen; Michael R. Rasmussen. Estimation of combined sewer overflow discharge: a software sensor approach based on local water level measurements. Water Science and Technology 2016, 74, 2683 -2696.

AMA Style

Malte Ahm, Søren Thorndahl, Jesper E. Nielsen, Michael R. Rasmussen. Estimation of combined sewer overflow discharge: a software sensor approach based on local water level measurements. Water Science and Technology. 2016; 74 (11):2683-2696.

Chicago/Turabian Style

Malte Ahm; Søren Thorndahl; Jesper E. Nielsen; Michael R. Rasmussen. 2016. "Estimation of combined sewer overflow discharge: a software sensor approach based on local water level measurements." Water Science and Technology 74, no. 11: 2683-2696.

Journal article
Published: 27 April 2016 in Hydrological Processes
Reads 0
Downloads 0

Infiltration of groundwater to sewer systems is a problem for the capacity of the system as well as for treatment processes at wastewater treatment plants. This paper quantifies the infiltration of groundwater to a sewer system in Frederikshavn Municipality, Denmark by measurements of sewer flow and novel model setup which simulates the interaction between groundwater and sewer flow.The study area has a separate wastewater sewer system, but the discharged volumes from the system are approx. twice the volumes from a tight system without infiltration. The model setup makes use of two commercial models: Mike SHE for simulation of groundwater transport and Mike Urban for simulation of sewer flow. By simulating the groundwater level and calibrating infiltration coefficients against sewer flow measurements, it has been possible to estimate the average infiltration to the sewer system with satisfying results. The infiltration processes are indeed complicated and to a large degree heterogeneous throughout the sewer system. The paper show contribution from both saturated and unsaturated groundwater zones which makes the modelling process complex. This article is protected by copyright. All rights reserved.

ACS Style

Søren Thorndahl; Jonas Dueholm Balling; Uffe Bay Bøgh Larsen. Analysis and integrated modelling of groundwater infiltration to sewer networks. Hydrological Processes 2016, 30, 3228 -3238.

AMA Style

Søren Thorndahl, Jonas Dueholm Balling, Uffe Bay Bøgh Larsen. Analysis and integrated modelling of groundwater infiltration to sewer networks. Hydrological Processes. 2016; 30 (18):3228-3238.

Chicago/Turabian Style

Søren Thorndahl; Jonas Dueholm Balling; Uffe Bay Bøgh Larsen. 2016. "Analysis and integrated modelling of groundwater infiltration to sewer networks." Hydrological Processes 30, no. 18: 3228-3238.

Journal article
Published: 01 May 2014 in Journal of Hydrology
Reads 0
Downloads 0
ACS Style

Roland Löwe; Søren Thorndahl; Peter Steen Mikkelsen; Michael R. Rasmussen; Henrik Madsen. Probabilistic online runoff forecasting for urban catchments using inputs from rain gauges as well as statically and dynamically adjusted weather radar. Journal of Hydrology 2014, 512, 397 -407.

AMA Style

Roland Löwe, Søren Thorndahl, Peter Steen Mikkelsen, Michael R. Rasmussen, Henrik Madsen. Probabilistic online runoff forecasting for urban catchments using inputs from rain gauges as well as statically and dynamically adjusted weather radar. Journal of Hydrology. 2014; 512 ():397-407.

Chicago/Turabian Style

Roland Löwe; Søren Thorndahl; Peter Steen Mikkelsen; Michael R. Rasmussen; Henrik Madsen. 2014. "Probabilistic online runoff forecasting for urban catchments using inputs from rain gauges as well as statically and dynamically adjusted weather radar." Journal of Hydrology 512, no. : 397-407.

Journal article
Published: 25 March 2014 in Atmospheric Research
Reads 0
Downloads 0

In this paper, we develop a storm catalog of heavy rainfall events for a region centered on the Milwaukee, Wisconsin WSR-88D (Weather Surveillance Radar — 1988 Doppler) radar. The study region includes portions of southern Wisconsin, northern Illinois and Lake Michigan. The long-term objective of this study is to develop rainfall frequency analysis methods based on a storm catalog of major rain events. The specific objectives of this study are to develop a long-term catalog of high-resolution radar rainfall fields and characterize key features of the space–time variability of rainfall. The research questions that underlie these objectives are: 1) What are the spatial heterogeneities of rainfall over the study region for major flood-producing storm systems? 2) What are the key elements of storm evolution that control the scale-dependent properties of extreme rainfall? The storm catalog contains a record of the 50 “largest” storm days during the 1996–2011 observation period. We show that mean rainfall for the 50 largest storm days exhibits pronounced spatial heterogeneity with a broad maximum in western Wisconsin and a minimum in the eastern portion of the study region over Lake Michigan. We also show that there is a narrow line of maximum mean rainfall extending from west to east along the Wisconsin–Illinois border. This feature is tied to a maximum in the probability of daily rainfall exceeding 100 mm. There are characteristic elements to the storm life cycle of heavy rainfall days that relate to size, structure and evolution of heavy rainfall. Extreme rainfall is also linked with severe weather (tornados, large hail and damaging wind). The diurnal cycle of rainfall for heavy rain days is characterized by an early peak in the largest rainfall rates, an afternoon–evening peak in rain area exceeding 25 mm h− 1 and development of a large stratiform rain area during the night and early morning.

ACS Style

Søren Thorndahl; James A. Smith; Mary Lynn Baeck; Witold F. Krajewski. Analyses of the temporal and spatial structures of heavy rainfall from a catalog of high-resolution radar rainfall fields. Atmospheric Research 2014, 144, 111 -125.

AMA Style

Søren Thorndahl, James A. Smith, Mary Lynn Baeck, Witold F. Krajewski. Analyses of the temporal and spatial structures of heavy rainfall from a catalog of high-resolution radar rainfall fields. Atmospheric Research. 2014; 144 ():111-125.

Chicago/Turabian Style

Søren Thorndahl; James A. Smith; Mary Lynn Baeck; Witold F. Krajewski. 2014. "Analyses of the temporal and spatial structures of heavy rainfall from a catalog of high-resolution radar rainfall fields." Atmospheric Research 144, no. : 111-125.

Journal article
Published: 01 March 2014 in Atmospheric Research
Reads 0
Downloads 0
ACS Style

Jesper E. Nielsen; Søren Thorndahl; Michael R. Rasmussen. A numerical method to generate high temporal resolution precipitation time series by combining weather radar measurements with a nowcast model. Atmospheric Research 2014, 138, 1 -12.

AMA Style

Jesper E. Nielsen, Søren Thorndahl, Michael R. Rasmussen. A numerical method to generate high temporal resolution precipitation time series by combining weather radar measurements with a nowcast model. Atmospheric Research. 2014; 138 ():1-12.

Chicago/Turabian Style

Jesper E. Nielsen; Søren Thorndahl; Michael R. Rasmussen. 2014. "A numerical method to generate high temporal resolution precipitation time series by combining weather radar measurements with a nowcast model." Atmospheric Research 138, no. : 1-12.