@staticmethod
def _initialise_states(dict_desc, dict_param, kwa):
    """
        This function initialises the model states before starting the simulations.
        If a warm-up run is used, this initialisation happens before the start of the warm-up run.
        If no warm-up is used, this initialisation happens before the start of the actual simulation run.
        """
    area_m2 = dict_desc['area']
    my_dict = dict()
    try:
        my_dict.update({'r_s_v_h2o': kwa['aar'] * kwa['r-o_ratio'] / 1000 *
            area_m2 / 8766 * dict_param['r_p_k_h2o']})
    except KeyError:
        my_dict.update({'r_s_v_h2o': 0.0})
    return my_dict
