Transient and steady-state river-channel width calculations for both transport- and detachment-limited banks.
| Variable | Description | Typical value(s) |
|---|---|---|
h_banks |
Stream-bank height. This is the thickness of material that must be removed for the river to widen by one unit lateral distance | 1-5 m |
S |
Channel downstream-directed slope. This is used to compute shear stresses and (if necessary) flow depth from water discharge | 10-3<\sup> |
tau_crit |
Critical shear stress required to start eroding muddy banks. At this stress, the flow begins to be able to detach particles. When set up to perform an inversion using data on river widening and past flows, this is one of two key parameters to be estimated. | 1--2 Pa |
k_d |
Erosion-rate coefficient. This determines the rate of erosion as a function of shear stress above critical. When set up to perform an inversion using data on river widening and past flows, this is the other of two key parameters to be estimated. | 10--6<\sup> m / (Pa s) |
lambda_r |
Nikuradse roughness coefficient ( |
0.05 |
D |
Bed-material median grain size Required for rivers with transport-limited banks | 0.002--0.2 m |
Q0 |
Initial discharge Initial discharge to which a channel's width is adjusted | 1--1000 m3<\sup>/s |
b0 |
Initial width Starting width of a channel | 1--1000 m |