n_vanrijn1984 {HYDROCAL}

Compute channel form roughness following Van Rijn (1984)

Description

n_vanrijn1984 calculate Manning's n using the Van Rijn (1984) method for estimating roughness due to channel form

Usage

n_vanrijn1984(depth, slope, d50, d90, velocity, restrict = TRUE)

Arguments

depth

flow depth (H) in meters. The original model was calibrated for 0.1 < H < 16 m.

slope

channel slope (S) in m/m

d50

grain size (d50) in millimeters. The original model was calibrated for 0.19 mm < d50 < 3.6 mm.

d90

grain size (d90) in millimeters.

velocity

initial channel velocity estimate (U) in meters per second

restrict

allows for function parameters to restrict certain values. Type bool. Default TRUE.

Value

Manning's n

References

van Rijn, L. C. 1984a. Sediment Transport, Part I: Bed Load Transport. Journal of Hydraulic Engineering. ASCE, Vol. 110 (10), pp. 1431-1456.

van Rijn, L. C. 1984b. Sediment Transport, Part II: Suspended Load Transport. Journal of Hydraulic Engineering. ASCE, Vol. 110 (11), pp. 1613-1641.

van Rijn, L. C. 1984c. Sediment Transport, Part III: Bed Forms and Alluvial Roughness. Journal of Hydraulic Engineering. ASCE, Vol. 110 (12), pp. 1733-1754.

Examples

# Result: Manning's n of 0.173
n_vanrijn1984(10,0.025,1,2,6)

# Result: Manning's n of 0.047
n_vanrijn1984(0.33,0.15,0.3,0.5,2)

# Result: Manning's n of 0.028
n_vanrijn1984(1.55,0.033,0.5,0.8,1)

# Result: Depth must be within 0.025 and 17 m.
n_vanrijn1984(0.01,0.033,0.5,0.8,1)