lfstat-package: Calculation of Low Flow Statistics for Daily Stream Flow Data

In lfstat: Calculation of Low Flow Statistics for Daily Stream Flow Data

Calculation of Low Flow Statistics for Daily Stream Flow Data

Description

The "Manual on Low-flow Estimation and Prediction" (Gustard & Demuth (2009, ISBN:978-92-63-11029-9)), published by the World Meteorological Organisation, gives a comprehensive summary on how to analyse stream flow data focusing on low-flows. This packages provides functions to compute the described statistics and produces plots similar to the ones in the manual.

Details

Create an object of class lfobj (Low-Flow-Objects)

The package calculates indices and makes graphics for low flow analysis. It brings its own class 'lfobj', a special data.frame format with columns 'day', 'month', 'year', 'flow', 'hyear' and possibly 'baseflow'.

'day', 'month' and 'year' refer to the date, 'flow' is the measured runoff (unit-independent), 'baseflow' the calculated base flow.

'hyear' refers to the hydrological year. When creating the 'lfobj' you define the month where the stations hydrological year starts. If annual indices are calculated or single years are plotted, the 'hyear' is taken.

Basically there are to options to create an low flow object:

If you have special data format, e.g. GRDC, you can use the function readlfdata, see ?readlfdata to see which formats are currently supported. Otherwise you can use createlfobj. You can apply it for new data in one of two ways: 1) You create a data.frame with columns: 'day', 'month', 'year' and 'flow'. 2) You create a time-series ('ts') from 'flow' and give the start date of the series when calling 'createlfobj'.

Preparation

lfstat does not need to know the unit of the flow, but you might want it to appear in your plots. You can use setlfunit to define how units are labelled in your graphics. Examples are given in '?setlfunit'.

Please check for NA-values using lfnacheck, indices and plots are made as if series were complete. See the manual on how to deal with missing values and, if reasonable, use lfnainterpolate.

Available Indices

• meanflow

• Qxx

• MAM (mean annual minima)

• BFI

• recession (recession constant)

• streamdef (Streamflow deficit)

• tyears (Extreme value - T-years event)

• seasratio

• seasindex

• multistationsreport

Plots

• hydrograph

• recessionplot (Diagnosis for recession)

• fdc (Flow-duration-curve)

• sbplot (seasonal bar chart)

• seglenplot (select recession length for recession)

• streamdefplot (Streamflow deficit)

• rfa (Regional frequency analysis)

• dmcurve (Double mass curve)

Index: This package was not yet installed at build time.

Author(s)

Tobias Gauster [ctb, cre], Gregor Laaha [aut] (<https://orcid.org/0000-0002-6793-9640>), Daniel Koffler [aut]

Maintainer: Tobias Gauster <[e-mail]>

References

Gustard, A. & Demuth, S. (2009) (Eds) Manual on Low-flow Estimation and Prediction. Operational Hydrology Report No. 50, WNO-No. 1029, 136p. https://library.wmo.int/doc_num.php?explnum_id=7699

lfstat documentation built on Nov. 10, 2022, 5:42 p.m.