How-to: inflows module

Calculating inflows from catchment runoff

The CatchmentRunoffInflows class provides functionality for calculating inflows from catchment runoff during rainfall events. The amount of runoff is calculated as a function of the catchment area, precipitation, and a runoff coefficient/threshold.

To use CatchmentRunoffInflows, you must first have a CSV or pandas.DataFrame object of precipitation data in an hourly or daily frequency. Consider the following timeseries:

import pandas as pd 

met_data = pd.DataFrame({
    'Date': pd.date_range(
        start='1997-01-01',
        end='2004-12-31',
        freq='24h'),
    'Rain': 0.024 #m per day
})

We can now initalise the CatchmentRunoffInflows class by passing in this DataFrame, the catchment area (in m²), the date and rainfall column names, and either a runoff coefficient or a runoff threshold:

from glmpy import inflows

my_inflows = inflows.CatchmentRunoffInflows(
    met_data=met_data,
    catchment_area=1000, # a 1000 m^2 catchment area
    runoff_coef=0.5, 
    precip_col='Rain',
    date_time_col='Date'
)

Inspect the catchment inflows

Upon calling the get_inflows() method, CatchmentRunoffInflows will calculate runoff and return a DataFrame of infows in units of m³/sec:

my_inflows.get_inflows()

time        flow            
1997-01-01  0.000139
1997-01-02  0.000139
1997-01-03  0.000139
1997-01-04  0.000139
1997-01-05  0.000139
...              ...
2004-12-27  0.000139
2004-12-28  0.000139
2004-12-29  0.000139
2004-12-30  0.000139
2004-12-31  0.000139

[2922 rows x 1 columns]

Writing catchment inflows to a CSV

The inflows DataFrame can then be saved to file by simply calling the write_inflows method:

my_inflows.write_inflows(
    file_path="runoff.csv"
)