Calculation of slope effect and secondary currents only based on skin friction

Summary

At the moment the bed shear stress used for calculating the slope effect and secondary currents is based on the total bed friction coming from Telemac. When vegetation is accounted for in hydromorphological simulations, the total bed friction is probably not the right variable for calculating slope effect and secondary currents. For Calculating the slope effect and secondary currents we suggest to eliminate the effect of the vegetation friction (vegetation drag) from the total bed shear stress and suggest to rather use the skin friction to calculate the slope effect and secondary currents.

Why is this feature useful?

The calculation of slope effect and seconadry current was established for hydromorphological simulations without vegetation. Accounting for the hydraulic resistance of vegetation, the total friction changes significantly and therefore the calculation of slope effect and secondary currents is not accurate anymore.

How to implement it?

We suggest to use the skin friction instead of the total bed shear stress when calculating the slope effect and secondary currents by multiplying the total bed shear stress with the skin friction correction factor mu.