environmentaltools.processes.unit_hydrograph_model

environmentaltools.processes.unit_hydrograph_model(df, info)

Transform rainfall to discharge using SCS Unit Hydrograph method.

Applies unit hydrograph theory to convert effective precipitation into surface runoff hydrographs. Supports multiple concentration time formulas.

Parameters:

• df (pd.DataFrame) – DataFrame with effective precipitation (‘net_pr’ column)

• info (dict) –

  Dictionary with watershed parameters:

  • modelstr

    Concentration time model (‘SCS’, ‘Temez’, ‘Kirpich’, ‘Kirpich-natural_slope’)

  • lonfloat

    Main river length (km)

  • slopefloat

    Main river slope (m/m)

  • cn2float

    Curve Number for average conditions

  • areafloat

    Watershed area (km²)

  • dtfloat

    Time step (hours)

Returns:

Updated DataFrame with ‘sup_flow’ column containing surface flow (m³/s)

Return type:

pd.DataFrame

Raises:

ValueError – If the specified unit hydrograph model is not implemented

Notes

Concentration time formulas:

• SCS: tc = 0.071 * L^0.8 / (S^0.25) * (1000/CN - 9)^0.7

• Temez: tc = 0.3 * (L / S^0.25)^0.76

• Kirpich: tc = 0.066 * L^0.77 / S^0.385

• Kirpich-natural_slope: tc = 0.13 * L^0.77 / S^0.385