A New Framework to Model Hydraulic Bank Erosion Considering the Effects of Roots

Gasser, Eric; Perona, Paolo; Dorren, Luuk; Phillips, Chris; Hübl, Johannes; Schwarz, Massimiliano (2020). A New Framework to Model Hydraulic Bank Erosion Considering the Effects of Roots Water, 12(3), p. 893. MDPI 10.3390/w12030893

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Floods and subsequent bank erosion are recurring hazards that pose threats to people and can cause damage to buildings and infrastructure. While numerous approaches exist on modeling bank erosion, very few consider the stabilizing effects of vegetation (i.e., roots) for hydraulic bank erosion at catchment scale. Taking root reinforcement into account enables the assessment of the efficiency of vegetation to decrease hydraulic bank erosion rates and thus improve risk management strategies along forested channels. A new framework (BankforNET) was developed to model hydraulic bank erosion that considers the mechanical effects of roots and randomness in the Shields entrainment parameter to calculate probabilistic scenario-based erosion events. The one-dimensional, probabilistic model uses the empirical excess shear stress equation where bank erodibility parameters are randomly updated from an empirical distribution based on data found in the literature. The mechanical effects of roots are implemented by considering the root area ratio (RAR) affecting the material dependent critical shear stress. The framework was validated for the Selwyn/Waikirikiri River catchment in New Zealand, the Thur River catchment and the Sulzigraben catchment, both in Switzerland. Modeled bank erosion deviates from the observed bank erosion between 7% and 19%. A sensitivity analysis based on data of vertically stable river reaches also suggests that the mechanical effects of roots can reduce hydraulic bank erosion up to 100% for channels with widths < 15.00 m, longitudinal slopes < 0.05 m m−1 and a RAR of 1% to 2%. The results show that hydraulic bank erosion can be significantly decreased by the presence of roots under certain conditions and its contribution can be quantified considering different conditions of channel geometry, forest structure and discharge scenarios.

Item Type:

Journal Article (Original Article)

Division/Institute:

School of Agricultural, Forest and Food Sciences HAFL
School of Agricultural, Forest and Food Sciences HAFL > Multifunctional Forest Management
School of Agricultural, Forest and Food Sciences HAFL > Multifunctional Forest Management > Mountain Forests, Natural Hazards and GIS

Name:

Gasser, Eric;
Perona, Paolo;
Dorren, Luuk;
Phillips, Chris;
Hübl, Johannes and
Schwarz, Massimiliano0000-0003-4652-8102

Subjects:

G Geography. Anthropology. Recreation > G Geography (General)
S Agriculture > SD Forestry

ISSN:

2073-4441

Publisher:

MDPI

Language:

English

Submitter:

Simon Lutz

Date Deposited:

13 Jan 2021 12:16

Last Modified:

02 Nov 2021 02:18

Publisher DOI:

10.3390/w12030893

Uncontrolled Keywords:

bank erosion; hydraulic bank erosion; modeling; effects of vegetation; root reinforcement

ARBOR DOI:

10.24451/arbor.14219

URI:

https://arbor.bfh.ch/id/eprint/14219

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