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Seasonality of roughness - the indicator of annual river flow resistance condition in a lowland catchment

Song, Song and Schmalz, Britta and Xu, Y. P. and Fohrer, Nicola (2017):
Seasonality of roughness - the indicator of annual river flow resistance condition in a lowland catchment.
In: Water Resources Management, pp. 3299-3312, 31, (11), DOI: 10.1007/s11269-017-1656-z, [Article]

Abstract

Accurate estimation of flow resistance restricts the quality of the hydraulic model performance. In this study, we try to investigate the seasonal dynamic of the Manning’s roughness coefficient (n) based on the one-dimensional hydraulic model HEC-RAS in a German lowland area. We set up four river section models based on the 1 m digital elevation model and field measurements, in which the seasonal roughness factors were calibrated and validated with the gauge record. The results revealed that: 1) the Manning’s n varied from 46% to 135% from the base value in autumn; 2) adopting the seasonal roughness factor improved the quality of the model output; 3) the vegetation condition and water elevation dominated the Manning’s n in summer (April–September) and winter (October–March) half year respectively. Water temperature increased the flow resistence in winter half year; 4) the peak value of Manning’s n appeared in late summer due to the highest biomass, while the minimum roughness occurred in early-spring because of the combined influence of low biomass, high water level and relatively higher temperature. The involvement of seasonal roughness factor improved the model performance and the results are comparable to the previous research of the same area.

Item Type: Article
Erschienen: 2017
Creators: Song, Song and Schmalz, Britta and Xu, Y. P. and Fohrer, Nicola
Title: Seasonality of roughness - the indicator of annual river flow resistance condition in a lowland catchment
Language: English
Abstract:

Accurate estimation of flow resistance restricts the quality of the hydraulic model performance. In this study, we try to investigate the seasonal dynamic of the Manning’s roughness coefficient (n) based on the one-dimensional hydraulic model HEC-RAS in a German lowland area. We set up four river section models based on the 1 m digital elevation model and field measurements, in which the seasonal roughness factors were calibrated and validated with the gauge record. The results revealed that: 1) the Manning’s n varied from 46% to 135% from the base value in autumn; 2) adopting the seasonal roughness factor improved the quality of the model output; 3) the vegetation condition and water elevation dominated the Manning’s n in summer (April–September) and winter (October–March) half year respectively. Water temperature increased the flow resistence in winter half year; 4) the peak value of Manning’s n appeared in late summer due to the highest biomass, while the minimum roughness occurred in early-spring because of the combined influence of low biomass, high water level and relatively higher temperature. The involvement of seasonal roughness factor improved the model performance and the results are comparable to the previous research of the same area.

Journal or Publication Title: Water Resources Management
Volume: 31
Number: 11
Uncontrolled Keywords: Manning’s n, Seasonal roughness factor, Hydraulic model, German lowland river network
Divisions: 13 Department of Civil and Environmental Engineering Sciences
13 Department of Civil and Environmental Engineering Sciences > Institute of Hydraulic and Water Resources Engineering
13 Department of Civil and Environmental Engineering Sciences > Institute of Hydraulic and Water Resources Engineering > Engineering Hydrology and Water Management
Date Deposited: 31 Jul 2018 06:45
DOI: 10.1007/s11269-017-1656-z
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