sedFlow modelling tool

The bedload transport modelling tool sedFlow has been designed especially for the application in mountain streams. It includes the following main features: (i) implementation of state of the art approaches for the application in steep channels accounting for macro-roughness effects; (ii) individual calculations for several grain diameter fractions i.e. fractional transport; (iii) fast calculations for modelling entire catchments and for scenario studies with automated calculation of many variations; and (iv) consideration of the effects of adverse slopes in terms of ponding e.g. due to sudden sediment deposition by debris flow inputs. Moreover, sedFlow is (v) provided together with its complete source code free of charge and (vi) features an easy and straightforward pre- and post-processing of simulation data.

A detailed description of the model structure and the numerical implementation is given in Heimann et al. (2014a). The sedFlow modelling tool was calibrated for two Swiss mountain rivers (Heimann et al. 2014b), the Kleine Emme River (20 km study reach, five year calibration period) and the Brenno River (25 km study reach, ten year calibration period).

The bedload transport modelling tool sedFlow provides the option to choose among two approaches for the calculation of the flow resistance and among three methods for the calculation of channel hydraulics. Furthermore, sedFlow can be used with different formulae for the estimation of bedload transport capacity. The range of various approaches implemented in the model is given below.

Flow resistance:

• Variable power equation VPE (Ferguson, 2007; Rickenmann & Recking, 2011)
• Manning-Strickler equation (fixed power equation)

Channel hydraulics:

• Spatially uniform discharge (considering the effects of ponding)
• Kinematic wave routing (implicit and explicit version)

Formulae for the estimation of bedload transport:

• Transport equation according to Rickenmann (2001)
• Transport equation according to Wilcock & Crowe (2003)
• Transport equation according to Recking (2010)

Selection of hiding functions:

• Power law hiding function according to Parker (2008), with a fixed exponent (to be selected)
• Power law hiding function with a hiding exponent according to Wilcock and Crowe (2003)

Definition of initiation of bedload transport:

• Constant threshold value (Shields value) (to be selected)
• Slope-dependent critical Shields value according to Lamb et al. (2008), combined with a minimum critical Shields value (to be selected)