import math


def elongation_ratio(area_catchment, max_basin_length):
    """
    Calculates the elongation ration for a given catchment
    Watershed-based Morphometric Analysis: A Review S Sukristiyanti et al
    """
    diameter_catchment_circle = math.sqrt(area_catchment/math.pi) * 2
    return diameter_catchment_circle / max_basin_length