rfactor package

rfactor.rfactor module

exception rfactor.rfactor.RFactorInputError

Bases: Exception

Raise when input data are not conform the rfactor required input format.

exception rfactor.rfactor.RFactorKeyError

Bases: Exception

Raise when input data missing required column names.

exception rfactor.rfactor.RFactorTypeError

Bases: Exception

Raise when input data data type of a data column is wrong.

rfactor.rfactor.compute_erosivity(rain, energy_method=<function rain_energy_verstraeten2006>, intensity_method=<function maximum_intensity>, **kwargs)

Calculate erosivity for each year/station combination

Parameters:

• rain (pandas.DataFrame) –

  DataFrame with rainfall time series. Need to contain the following columns:

  • datetime (pandas.Timestamp): Time stamp

  • rain_mm (float): Rain in mm

  • station (str): Measurement station identifier

• energy_method (Callable, default rain_energy_per_unit_depth_verstraeten2006) – Function to compute the rain energy per unit depth

• intensity_method (Callable, default maximum_intensity) – Function to derive the maximal rain intensity (over 30min).

Returns:

all_erosivity – DataFrame with erosivity output for each event.

• station* (str)

• year (int)

• tag (str): unique tag for year, station-couple.

• event_rain_cum (float): Cumulative rain for each event

• all_events_cum (float): Cumulative rain over the whole timeseries

• max_30min_intensity (float): Maximal 30min intensity for each event

• event_energy (float): Rain energy per unit depth for each event

• erosivity (float): Erosivity for each event

• erosivity_cum (float): Cumulative erosivity over all events together

Return type:

pandas.DataFrame

Notes

1. NaN- and 0-values are removed from the input timeseries.

rfactor.rfactor.maximum_intensity(df)

Maximum rain intensity for 30-min interval (Pandas rolling) expressed as mm/hour

The implementation uses a rolling window of the chosen interval to derive the maximal intensity.

Parameters:

df (pandas.DataFrame) –

DataFrame with rainfall time series. Needs to contain the following columns:

• datetime (pandas.Timestamp): Timestamp

• rain_mm (float): Rain in mm. No NaN or 0-values allowed

Returns:

maxprecip_30min – Maximal 30-minute intensity during event (in mm/h).

Return type:

float

rfactor.rfactor.maximum_intensity_interpolate(df)

Maximum rain intensity for 30-min interval (Matlab clone Fix). This implementation is a fixed version of the Python-translation of the original Matlab implementation by [3].

Changes to the original script are:

• In the if-statement ‘if timestamps[-1] - timestamps[0] <= 30:’ this methode calculates the total amount of rain during the interval while the original method only looks at the first rainfall entry.

• In the same if-statement, the *2 was removed, since this is already done in the ‘return’ step of the model. This *2 causes the model to steeply over estimate the rainfall during short rainfall events.

Parameters:

df (pandas.DataFrame) – DataFrame with rainfall time series. Needs to contain the following columns: - datetime (pandas.Timestamp): Time stamp - rain_mm (float): Rain in mm. No NaN or 0-values allowed - event_rain_cum (float): Cumulative rain in mm

Returns:

maxprecip_30min – Maximal 30-minute intensity during event (in mm/h).

Return type:

float

Notes

The Python and original Matlab implementation linearly interpolate zero and NaN-values within one event.

rfactor.rfactor.maximum_intensity_matlab_clone(df)

Maximum rain intensity for 30-min interval (Matlab clone).

The implementation is a direct Python-translation of the original Matlab implementation by Verstraeten et al. (2006) [3].

Parameters:

df (pandas.DataFrame) – DataFrame with rainfall time series. Needs to contain the following columns: - datetime (pandas.Timestamp): Time stamp - rain_mm (float): Rain in mm. No NaN or 0-values allowed - event_rain_cum (float): Cumulative rain in mm

Returns:

maxprecip_30min – Maximal 30-minute intensity during event (in mm/h).

Return type:

float

Notes

The Python and original Matlab implementation linearly interpolate zero and NaN-values within one event.

rfactor.rfactor.rain_energy_brown_and_foster1987(rain)

Calculate rain energy per unit depth according to Brown and Foster.

Brown and Foster is applied considering a 10-minute interval input rainfall data set.

Parameters:

rain (numpy.ndarray) – Rain (mm)

Returns:

energy – Energy per unit depth.

Return type:

float

Notes

The rain energy per unit depth \(e_r\) (\(\text{MJ}.\text{mm}^{-1}. \text{ha}^{-1}\)) is defined by [4] and [5]:

\[e_r = 0.29*(1-0.72*exp(-0.05*i_r)\]

with

• \(i_r\) the rain intensity for every 10-min increment (mm \(\text{h}^{-1}\) ).

The rain energy is multiplied by the volume of rain (per 10 minutes) and summed per event to compute the total energy of the event. The formula applies for a 10 minute rainfall input data set.

References

[4]

Brown, L.C., Foster, G.R., 1987. Storm erosivity using idealized intensity distributions. Transactions of the ASAE 30, 0379–0386. https://doi.org/10.13031/2013.31957.

[5]

Renard, K.G., Foster, G.R., Weesies, G.A., McCool, D.K., Yoder, D.C., 1997, Predicting soil erosion by water: a guide to conservation planning with the revised universal soil loss equation (RUSLE), Agriculture Handbook. U.S. Department of Agriculture, Washington. https://www.ars.usda.gov/ARSUserFiles/64080530/RUSLE/AH_703.pdf

rfactor.rfactor.rain_energy_mcgregor1995(rain)

Calculate rain energy per unit depth according to McGregor with 10 minute interval data.

McGregor is applied considering a 10-minute interval input rainfall data set.

Parameters:

rain (numpy.ndarray) – Rain (mm)

Returns:

energy – Energy per unit depth.

Return type:

float

Notes

The rain energy per unit depth \(e_r\) (\(\text{MJ}.\text{mm}^{-1}. \text{ha}^{-1}\)) is defined by [6]:

\[e_r = 0.29*(1-0.72*exp(-0.08*i_r)\]

with

• \(i_r\) the rain intensity for every 10-min increment (mm \(\text{h}^{-1}\) ).

The rain energy is multiplied by the volume of rain (per 10 minutes) and summed per event to compute the total energy of the event. The formula applies for a 10 minute rainfall input data set.

References

[6]

McGregor, K.C., Bingner, R.L., Bowie, A.J. and Foster, G.R., 1995. Erosivity index values for northern Mississippi. Transactions of the ASAE,

38(4), pp.1039-1047. 10.13031/2013.27921

rfactor.rfactor.rain_energy_verstraeten2006(rain)

Calculate rain energy per unit depth according to Salles/Verstraeten with 10 minute interval data.

Verstraeten is applied considering a 10-minute interval input rainfall data set.

Parameters:

rain (numpy.ndarray) – Rain (mm)

Returns:

energy – Energy per unit depth.

Return type:

float

Notes

The rain energy per unit depth \(e_r\) (\(\text{MJ}.\text{mm}^{-1}. \text{ha}^{-1}\)) for an application for Flanders/Belgium is defined by [1] , [2] and [3]:

\[e_r = 0.1112i_r^{0.31}\]

with

• \(i_r\) the rain intensity for every 10-min increment (mm \(\text{h}^{-1}\) ).

The rain energy is multiplied by the volume of rain (per 10 minutes) and summed per event to compute the total energy of the event. The formula applies for a 10 minute rainfall input data set.

References

[1]

Salles, C., Poesen, J., Pissart, A., 1999, Rain erosivity indices and drop size distribution for central Belgium. Presented at the General Assembly of the European Geophysical Society, The Hague, The Netherlands, p. 280.

[2]

Salles, C., Poesen, J., Sempere-Torres, D., 2002. Kinetic energy of rain and its functional relationship with intensity. Journal of Hydrology 257, 256–270.

[3] (1,2,3)

Verstraeten, G., Poesen, J., Demarée, G., Salles, C., 2006, Long-term (105 years) variability in rain erosivity as derived from 10-min rainfall depth data for Ukkel (Brussels, Belgium): Implications for assessing soil erosion rates. Journal Geophysysical Research, 111, D22109.

rfactor.process module

rfactor.process.compute_diagnostics(rain)

Compute diagnostics for input rainfall.

This function computes coverage (per year, station) and missing rainfall for each month (per year, station).

Parameters:

rain (pandas.DataFrame) –

DataFrame with rainfall time series. Contains at least the following columns:

• rain_mm (float): Rain in mm

• datetime (pandas.Timestamp): Time stamp

• station (str): station name

• year (int): year of the measurement

• tag (str): tag identifier, formatted as STATION_YEAR

Returns:

diagnostics – Diagnostics per station, year with coverage and identifier for no-rain per month. Computed based on non-zero rainfall timeseries.

• station (str): station identifier.

• year (int): year.

• coverage (float): percentage coverage non-zero timeseries (see Notes).

Added with per month (id’s 1 to 12):

• months (int): 1: no rain observed in month, 0: rain observed.

Return type:

pandas.DataFrame

Notes

The coverage is computed as:

\[C = 100*[1-\frac{\text{number of NULL-data}} {\text{length of non-zero timeseries}}]\]

rfactor.process.compute_rainfall_statistics(df_rainfall, df_station_metadata=None)

Compute general statistics for rainfall timeseries.

Statistics (number of records, min, max, median and years data) are computed for each measurement station

Parameters:

• df_rainfall (pandas.DataFrame) – See rfactor.process.load_rain_file()

• df_station_metadata (pandas.DataFrame) –

  Dataframe holding station metadata. This dataframe has one mandatory column:

  • station (str): Name or code of the measurement station

  • x (float): X-coordinate of measurement station.

  • y (float): Y-coordinate of measurement station.

Returns:

df_statistics – Apart from the station, x, y when df_station_metadata is provided, the following columns are returned:

• year (list): List of the years fror which data is available for the station.

• records (int): Total number of records for the station.

• min (float): Minimal measured value for the station.

• median (float): Median measured value for the station.

• max (float): Maximal measured value for the station.

Return type:

pandas.DataFrame

rfactor.process.get_rfactor_station_year(erosivity, stations=None, years=None)

Get R-factor at end of every year for each station from cumulative erosivity.

Parameters:

• erosivity (pandas.DataFrame) – See rfactor.rfactor.compute_erosivity()

• stations (list) – List of stations to extract R for.

• years (list) – List of years to extract R for.

Returns:

erosivity – Updated with:

• year (int): year

• station (str): station

• erosivity_cum (float): cumulative erosivity at end of year and at station.

Return type:

pandas.DataFrame

rfactor.process.write_erosivity_data(df, folder_path)

Write output erosivity to (legacy Matlab format) in folder.

Written data are split-up for each year and station (file name format: SOURCE_STATION_YEAR.txt) and does not contain any headers. The columns (no header!) in the written text files represent the following:

• days_since (float): Days since the start of the year.

• erosivity_cum (float): Cumulative erosivity over events.

• all_event_rain_cum (float): Cumulative rain over events.

Parameters:

• df (pandas.DataFrame) –

  DataFrame with rfactor/erosivity time series. Can contain multiple columns, but should have at least the following:

  • datetime (pandas.Timestamp): Time stamp

  • station (str): Station identifier

  • erosivity_cum (float): Cumulative erosivity over events

  • all_event_rain_cum (float): Cumulative rain over events

• folder_path (pathlib.Path) – Folder path to save data according to legacy Matlab format, see rfactor.process.load_rain_file().

rfactor.valid module

rfactor.valid.valid_column(rain, req_col)

Input dataframe has valid required columns

Parameters:

• rain (pd.DataFrame) – To test dataframe

• req_col (set) – Required columns in dataframe, e.g. {“datetime”, “rain_mm”}

rfactor.valid.valid_const_freq(rain)

Check if rainfall inputdata has constant frequency

Parameters:

rain (pandas.DataFrame)

rfactor.valid.valid_freq(df_freq, req_freq=None)

Test for valid frequency of input data

The frequency of the input data is tested to a defined frequency. Limit usage R-factor package to above 1-minute resolution.

Parameters:

• df_freq (pandas.DatetimeIndex.freq) – Temporal frequency in the rainfall data

• req_freq (int, default None) – Required frequency (minutes). If None, the req_frequence should at least be 1 minute.

rfactor.valid.valid_rainfall_timeseries(func=None, req_col={'datetime', 'rain_mm'}, req_freq=None)

Customisable decorator to check pandas input rainfall data for functions used in

this package.

Parameters:

• func (callable, default None)

• req_col (set) – See rfactor.process.valid_column()

• int (req_freq) – See rfactor.process.valid_freq()

Returns:

decorator – Return the execution of the actual decorator

Return type:

callable

Notes

Use super decorator to allow for decorator inputs