def agg_catch(rec_catch):
    """
    Simple function to aggregate rec catchments.

    Parameters
    ----------
    rec_catch : GeoDataFrame
        The output from extract_catch

    Returns
    -------
    GeoDataFrame
    """
    rec_shed = rec_catch[['start', 'geometry']].dissolve('start')
    rec_shed.index = rec_shed.index.astype('int32')
    rec_shed['area'] = rec_shed.area
    rec_shed.crs = rec_catch.crs
    return rec_shed.reset_index()
