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Uncertainty based approach to simulate groundwater levels in a hillslope upstream of a road
KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. KTH/ The Royal Institute of Technology.ORCID iD: 0000-0002-0378-837X
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Knowledge of the processes governing groundwater dynamics in the areas close to roads is important for sustainable road infrastructure in the face of a changing climate. This study established an uncertainty based approach to simulate groundwater oscillations in a hillslope upstream of a road by using a process based model. Four different soil configurations were analyzed in CoupModel to simulate groundwater dynamics in presence of a road drainage system by implementation of meteorological data as driving factors. An approach similar to GLUE method was applied to analyze the statistical performance of the simulated groundwater level versus high resolution measured groundwater level dynamics. Results of the simulations indicate deviations in simulated results due to different soil stratifications. Uncertainties resulted from the lack of precise information about the geological structure of the site are important contributors to deviated simulation results. Different scenarios showed different model performances in which a simpler soil profile describes better the groundwater dynamics when it is closer to the road drainage system while a more complicated soil profile better describes groundwater dynamics in undisturbed soils. Correlation between hydraulic conductivity of each layer and the model performance was discussed. The results also indicate significance of variables such as physical drainage characteristics of the road in governing level of saturations also the position of the road structure in a hillslope. Texture (hydraulic conductivity) of the soil layers that fluctuation of groundwater occurs in those layers and types of modifications that have been done due to road construction are important driving factors. These factors are suggested as suitable indicators for designing an early warning system based on physical characteristics of a road site.

Keyword [en]
Groundwater Flow · Road drainage · Uncertainty · CoupModel · Sweden
National Category
Geophysical Engineering Other Environmental Engineering
Research subject
Land and Water Resources Engineering
Identifiers
URN: urn:nbn:se:kth:diva-186403OAI: oai:DiVA.org:kth-186403DiVA: diva2:927205
Note

QS 20160512

Available from: 2016-05-11 Created: 2016-05-11 Last updated: 2016-05-12Bibliographically approved
In thesis
1. Road disasters? Modeling and assessment of Swedish roads within crucial climate conditions
Open this publication in new window or tab >>Road disasters? Modeling and assessment of Swedish roads within crucial climate conditions
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

An efficient maintenance of roads to ensure high accessibility and durability of the transport capacity requires an understanding of how the hydrological response depends on both the road and the landscape characteristics. New methods and data were used to identify and explain interaction between roads and surrounding environment and their influence on hydrologic responses both in watershed scale and road-section scale. In the watershed scale, flood hazard probability was made with reference to the most influential physical catchment descriptors and road characteristics. Additionally, a physical based model was used to estimate the effect of road topography on the hydrological responses of 20 watersheds to storms with different intensities. A simple method was developed and discussed to address flood risk probability in the road-stream crossings concerning the correlation between the quantities of the physical catchment descriptors and occurrence/absence of flooding. The most influential factors in describing the probability of flooding along the roads were topographic wetness index, soil properties, road density and channel slopes. A detailed study of simulated flow duration curves showed differences between the 20 watersheds for three different storms based on topography with and without roads. An increase in peak flow and reduced time to pick occurred with existence of roads and increased storm intensity.In the road-section scale, an uncertainty-based simulation approach was used to identify the most influencing processes in controlling the dynamics of the groundwater level. A model (CoupModel) set up with four different geological stratifications was made to model two positions in a slope upstream of a road with drainage pipes and ditches. Results from the simulations indicate the significance of precipitation rate, road drainage and position in hillslope, and soil properties and stratifications in controlling groundwater levels. The same model was also applied to simulate soil moisture and temperature dynamics in two road sections by using groundwater and climate data. Porous media properties were obtained as statistical distribution function that provided the best performance of moisture and temperature dynamic in the road layers and underlying soil.

Abstract [sv]

Ett effektivt vägunderhåll som garanterar tillgänglig och varaktig transportkapacitet förutsätter kunskap om hydrologin i ett område beror av både vägens och landskapets egenskaper. Nya metoder och data utvecklades i projektet och användes för att identifiera och förklara samspelet mellan vägar och omgivande miljö, samt hur detta inverkar på hydrologiska svar på nederbörd, i skalor som avser hela avrinningsområden och/eller enskilda vägsektioner. I avrinningsområdet identifierades de mest betydelsefulla faktorerna för översvämningsrisker, så som fysikaliska avrinningsområdesegenskaper och vägegenskaper. Dessutom användes en fysikalisk modell för att beräkna effekten av hur vägarnas topografi påverkar avrinningens dynamik vid nederbörd för 20 olika avrinningsområden med olika nederbördsintensitet. En metod för detta utvecklades och användes för att diskutera översvämningsrisker i sektioner där vattendrag och väg korsas, genom att sammanföra egenskaper som är korrelerade med förekomst eller avsaknad av översvämnningar. De mest betydelsefulla faktorerna för förekomst av översvämning var topografiskt fuktindex, markegenskaper, vägtäthet och lutning hos vattendragen. En detaljerad studie av simulerad varaktighet av avrinningsintensiteter visade skillnader för de 20 olika områdena och 3 olika nederbördsintensiteter beroende på om områdena innfattade vägar eller ej. En ökning av toppflöden och en reducerad tid för att nå toppflödet erhölls för områden med vägar.För vägsektioner användes en osäkerhetsbaserad metod för att identifiera de mest betydelsfulla processerna som reglerar dynamiken hos grundvattennivån, genom modellen (CoupModel). För ändamålet definierades 4 olika geologiska lagerföljder för 2 positioner i en sluttning uppströms en väg med dräneringsrör och diken. Resultaten från simuleringarna beskrev hur betydelsen av nederbördsintensitet, vägdränering och vägens position i sluttningem samt markegenskaper och dess lagerföljder påverkar grundvattennivåns dynamik. Samma modell användes också för simulera dynamiken hos markvatten och marktemperaturer i 2 vägsektioner genom att använda data om grundvattennivå och klimat som dynamiska styrande randvillkor. Egenskaper hos porösa media erhölls genom statistiska fördelningsfunktioner av parametervärden som på bästa sätt återgav dynamiken av fuktighet och temperatur i vägens olika lager och underliggande mark.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. xii, 43 p.
Series
TRITA-LWR. PHD, ISSN 1650-8602 ; 2016:06
Keyword
Road, Flood, Moisture, Temperature, Groundwater, GIS, Uncertainity, Sweden
National Category
Environmental Management Geophysical Engineering Water Engineering Remote Sensing
Research subject
Land and Water Resources Engineering
Identifiers
urn:nbn:se:kth:diva-186410 (URN)978-91-7729-017-9 (ISBN)
Public defence
2016-06-03, Kollegiesalen, Brinellvägen 8, KTH-campus, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20160512

Available from: 2016-05-12 Created: 2016-05-11 Last updated: 2016-05-12Bibliographically approved

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The full text will be freely available from 2017-05-08 14:00
Available from 2017-05-08 14:00

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