hydraulic_geometry: Compute discharge and hyrdaulic geometry

In flee-group/watershed: Tools for Watershed Delineation

Compute discharge and hyrdaulic geometry

Description

Compute discharge and hyrdaulic geometry

Usage

hydraulic_geometry(Ac, Qc, Ap, use_prior = TRUE)

Arguments

Ac	Vector of catchment area for calibration points in $m^2$
Qc	Vector of discharge for calibration points in $m^3/s$
Ap	Vector or raster of catchment area for prediction
use_prior	Logical, use the prior for scaling? See 'details'

Details

Computes discharge from catchment area as \log Q = \log b + m \log A. If a single point in calib is included, the relationship will be re-parameterised by adjusting the intercept parameter b so that the calibration point falls on the line (while keeping the slope the same).

	With multiple points, a regression model is fit. If `use_prior == TRUE`, this is a Bayesian model
	using the parameters from Burgers et al (2014). These priors are calibrated from a variety of rivers,
	and the prior is quite strong, so it is possible with a small number of calibration points that the line
	is quite far from the calibration. In this case, either re-run this function with a single calibration point,
	or run with `use_prior = FALSE` (but this is only recommended if `range(Ac)` is similar to `range(Ap)`.

	For discharge scaling, catchment area units are expected to be in
	\eqn{m^2}, and discharge will be computed in \eqn{m^3 s^{-1}}.

	Following computation of discharge, other aspects of hydralic geometry are computed following Raymond et al (2012).

Value

A data.frame with the following variables: * CA; the input catchment area * Q; discharge * v; water velocity * z; water depth * w; width * Ax; stream cross-sectional area

References

Burgers HE et al. 2014. Size relationships of water discharge in rivers: scaling of discharge with catchment area, main-stem lengthand precipitation. Hydrological Processes. 28:5769-5775.

Raymond, PA et al. 2012. Scaling the gas transfer velocity and hydraulic geometry in streams and small rivers. Limnology and Oceanography: Fluids and Environments. 2:41-53.

Examples

    library(sf)
    data(kamp_q)
    data(kamp_dem)

    kamp = delineate(kamp_dem)
    kamp_Tp = pixel_topology(kamp)
    CA = catchment(kamp, type = 'reach', Tp = kamp_Tp)

    ## need to transform coordinate system for kamp_q to match
    ## need to snap to stream
    ## need to make sure this works
    ## should probably update kamp_q projection to match kamp_dem

    kamp_q$ca = catchment(kamp, type = 'points', y = st_geometry(kamp_q), Tp = kamp_Tp)
    x = hydraulic_geometry(kamp_q$ca, kamp_q$discharge, CA)

flee-group/watershed documentation built on July 25, 2022, 12:46 p.m.