## bdrc - Bayesian
Discharge Rating Curves

This software package fits a discharge rating curve based on the
power-law and the generalized power-law from data on paired water
elevation and discharge measurements in a given river using a Bayesian
hierarchical model as described in Hrafnkelsson et al. (2022). Four
models are implemented:

`plm0()`

- Power-law model with a constant error variance.
This is a Bayesian hierarchical implementation of the most commonly used
discharge rating curve model in hydrological practice.

`plm()`

- Power-law model with error variance that varies
with water elevation.

`gplm0()`

- Generalized power-law model with a constant
error variance. The generalized power-law is introduced in Hrafnkelsson
et al. (2022).

`gplm()`

- Generalized power-law model with error variance
that varies with water elevation. The generalized power-law is
introduced in Hrafnkelsson et al. (2022).

## Installation

```
# Install release version from CRAN
install.packages("bdrc")
# Install development version from GitHub
devtools::install_github("sor16/bdrc")
```

## Getting started

It is very simple to fit a discharge rating curve with the
*bdrc* package. All you need are two mandatory input arguments,
formula and data. The formula is of the form y~x where y is discharge in
m![^3/](https://latex.codecogs.com/png.image?%5Cdpi%7B110%7D&space;%5Cbg_white&space;%5E3%2F
“^3/”)s and x is water elevation in m (it is very important that the
data is in the correct units). data is a data.frame which must include x
and y as column names. As an example, we will use data from the Swedish
gauging station *Krokfors*, which is one of the datasets that
come with the package. In this table, the Q column denotes discharge
while W denotes water elevation:

`gplm.fit <- gplm(Q~W,krokfors)`

To dig deeper into the functionality of the package and the different
ways to visualize a discharge rating curve model for your data, we
recommend taking a look at our two vignettes.

## References

Hrafnkelsson, B., Sigurdarson, H., and Gardarsson, S. M. (2022).
*Generalization of the power-law rating curve using hydrodynamic
theory and Bayesian hierarchical modeling*, Environmetrics,
33(2):e2711.