# velocity: Streamflow velocity estimation In transfR: Transfer of Hydrograph from Gauged to Ungauged Catchments

## Description

Estimate streamflow velocity in average over the catchment.

## Usage

  1 2 3 4 5 6 7 8 9 10 11 12 13 velocity(hl, ...) ## Default S3 method: velocity(hl, lagtime, method = "loire2016", ...) ## S3 method for class 'units' velocity(hl, lagtime = NULL, method = "loire2016", ...) ## S3 method for class 'stars' velocity(hl, ...) ## S3 method for class 'transfR' velocity(hl, ...) 

## Arguments

 hl hydraulic length of class stars, matrix, vector or transfR. If no unit is provided, hl is assumed to be in [m]. ... further arguments passed to or from other methods lagtime lag time of the catchment. If no unit is provided, lagtime is assumed to be in [h]. method character string describing the method to estimate the velocity. One of "loire2016" (default), "brittany2013" or "lagtime" (see details).

## Details

Estimate the average streamflow velocity of the catchment from three different approaches. Method "lagtime" estimates the velocity from the ratio between the mean hydraulic length and the lag time of the catchment. Method "loire2016" estimates the velocity from a regression based on hydraulic length only:

a \cdot hl^b

where a=4.38e-4 and b=0.69 have been calibrated over the Loire river basin \insertCitedeLavenne2016transfR. Method "brittany2013" used a similar regression calibrated for the French Brittany region where a=8.59e-4 and b=0.61 \insertCitedeLavenne2013transfR.

## Value

A numeric value of class units, or if hl is a transfR object, the same transfR object incremented by the "uc" attribute.

## References

\insertRef

deLavenne2013transfR

\insertRef

deLavenne2016transfR

## Examples

 1 2 3 4 5 6 data(Oudon) velocity(Oudon$hl[[1]], method="loire2016") object <- as_transfr(st=Oudon$obs, hl=Oudon$hl) object <- velocity(object) object$uc 

transfR documentation built on Sept. 8, 2021, 9:08 a.m.