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Stage-dependent hydraulic and hydromorphologic properties in stream networks translated into response functions of compartmental models
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Hydraulic Engineering.ORCID iD: 0000-0002-9202-3159
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Hydraulic Engineering.
2012 (English)In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 420-421, 25-36 p.Article in journal (Refereed) Published
Abstract [en]

A distributed non-uniform routing model was constructed and applied to two stream networks in southern Sweden to investigate the effects of stage, topology and morphology on advective travel times within the stream networks.Using particle-tracking, we found markedly non-linear relationships between travel time distributions and discharge for both catchments under a range of hydraulic conditions, represented by discharges comprising percentiles between 30 and 99.9 extracted from the discharge data set for the two catchments in this study.The travel time distributions from the particle tracking were used to numerically parameterise the response function of a lumped hydrological model, which resulted in improvements, particularly in the prediction of high flows. A sensitivity analysis was performed on the routing procedure, particularly regarding the choice of Manning's friction coefficient and the choice of generic cross-sectional areas along the two stream networks showing that the uncertainty in routing parameters did not have a major effect on the final hydrograph. The new parameterisation performed better than the conventional model in every modelled case.A theoretical demonstration shows that correct descriptions of streamflow processes becomes more important with increased watershed scale, because the travel time within the stream network relative to the travel time on hillslopes increases with the watershed scale. The topology and topography of the stream network were shown to be the major factors influencing the network averaged travel time. These results demonstrate that physically based response functions (and model parameters) can be superior to compartmental model parameters that are based on numerical calibration and that are extrapolated to account for conditions during hydrological extremes.

Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 420-421, 25-36 p.
Keyword [en]
Streamflow; Hydrological model; Distributed routing; Response function; Geomorphologic; Hydrodynamic
National Category
Oceanography, Hydrology, Water Resources
Identifiers
URN: urn:nbn:se:kth:diva-58433DOI: 10.1016/j.jhydrol.2011.11.015ISI: 000301082000003Scopus ID: 2-s2.0-84856212851OAI: oai:DiVA.org:kth-58433DiVA: diva2:473045
Funder
StandUp
Note

QC 20120402

Available from: 2012-01-05 Created: 2012-01-05 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Hydraulic- hydromorphologic analysis as an aid for improving peak flow predictions
Open this publication in new window or tab >>Hydraulic- hydromorphologic analysis as an aid for improving peak flow predictions
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Conventional hydrological compartmental models have been shown to exhibit a high degree of uncertainty for predictions of peak flows, such as the design floods for design of hydropower infrastructure. One reason for these uncertainties is that conventional models are parameterised using statistical methods based on how catchments have responded in the past. Because the rare occurrence of peak flows, these are underrepresented during the periods used for calibration. This implies that the model has to be extrapolated beyond the discharge intervals where it has been calibrated.

In this thesis, hydromechanical approaches are used to investigate the properties of stream networks, reflecting mechanisms including stage dependency, damming effects, interactions between tributaries (network effects) and the topography of the stream network. Further, it is investigated how these properties can be incorporated into the streamflow response functions of compartmental hydrological models.

The response of the stream network was shown to vary strongly with stage in a non-linear manner, an effect that is commonly not accounted for in model formulation. The non-linearity is particularly linked to the flooding of stream channels and interactions with the flow on flood-plains.

An evaluation of the significance of using physically based response functions on discharge predictions in a few sub-catchments in Southern Sweden show improvements (compared to a conventional model) in discharge predictions – particularly when modelling peak discharges.

An additional benefit of replacing statistical parameterisation methods with physical parameterisation methods is the possibility of hydrological modelling during non-stationary conditions, such as the ongoing climate change.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. viii, 31 p.
Series
Trita-LWR. LIC, ISSN 1650-8629 ; 2051
Keyword
Hydrological modelling, peak flow predictions, distributed routing, parameterisation, stage-dependency
National Category
Oceanography, Hydrology, Water Resources
Identifiers
urn:nbn:se:kth:diva-25425 (URN)978-91-7415-760-4 (ISBN)
Presentation
2010-11-02, L43, Drottning Kristinas väg 30, KTH, Stockholm, 10:52 (English)
Opponent
Supervisors
Note
QC 20101022Available from: 2010-10-22 Created: 2010-10-21 Last updated: 2012-01-23Bibliographically approved
2. Peakflow response of stream networks: implications of physical descriptions of streams and temporal change
Open this publication in new window or tab >>Peakflow response of stream networks: implications of physical descriptions of streams and temporal change
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Through distributed stream network routing, it has quantitatively been shown that the relationship between flow travel time and discharge varies strongly nonlinearly with stream stage and with catchment-specific properties.

Physically derived distributions of water travel times through a stream network were successfully used to parameterise the streamflow response function of a compartmental hydrological model. Predictions were found to improve compared to conventional statistically based parameterisation schemes, for most of the modelled scenarios, particularly for peakflow conditions.

A Fourier spectral analysis of 55-110 years of daily discharge time series from 79 unregulated catchments in Sweden revealed that the discharge power spectral slope has gradually increased over time, with significant increases for 58 catchments. The results indicated that the catchment scaling function power spectrum had steepened in most of the catchments for which historical precipitation series were available. These results suggest that (local) land-use changes within the catchments may affect the discharge power spectra more significantly than changes in precipitation (climate change).

A case study from an agriculturally intense catchment using historical (from the 1880s) and modern stream network maps revealed that the average stream network flow distance as well as average water levels were substantially diminished over the past century, while average bottom slopes increased. The study verifies the hypothesis that anthropogenic changes (determined through scenario modelling using a 1D distributed routing model) of stream network properties can have a substantial influence on the travel times through the stream networks and thus on the discharge hydrographs.

The findings stress the need for a more hydrodynamically based approach to adequately describe the variation of streamflow response, especially for predictions of higher discharges. An increased physical basis of response functions can be beneficial in improving discharge predictions during conditions in which conventional parameterisation based on historical flow patterns may not be possible - for example, for extreme peak flows and during periods of nonstationary conditions, such as during periods of climate and/or land use change.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. x, 74 p.
Series
TRITA-HYD, 2015:2
Keyword
Streamflow routing, peakflow predictions, parameterization, hydrological response, stage-dependency, flooded cross-sections, stream networks, backwater effects, temporal change, land use change
National Category
Oceanography, Hydrology, Water Resources
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-172939 (URN)978-91-7595-672-5 (ISBN)
Public defence
2015-09-29, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20150903

Available from: 2015-09-03 Created: 2015-09-02 Last updated: 2015-09-28Bibliographically approved

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