def watershed_delineation(np, dem, outlet_file=None, thresh=0, singlebasin=False,
                              workingdir=None, mpi_bin=None, bin_dir=None,
                              logfile=None, runtime_file=None, hostfile=None):
        """Watershed Delineation."""
        # 1. Check directories
        if not os.path.exists(dem):
            TauDEM.error('DEM: %s is not existed!' % dem)
        dem = os.path.abspath(dem)
        if workingdir is None:
            workingdir = os.path.dirname(dem)
        namecfg = TauDEMFilesUtils(workingdir)
        workingdir = namecfg.workspace
        UtilClass.mkdir(workingdir)
        # 2. Check log file
        if logfile is not None and FileClass.is_file_exists(logfile):
            os.remove(logfile)
        # 3. Get predefined intermediate file names
        filled_dem = namecfg.filldem
        flow_dir = namecfg.d8flow
        slope = namecfg.slp
        flow_dir_dinf = namecfg.dinf
        slope_dinf = namecfg.dinf_slp
        dir_code_dinf = namecfg.dinf_d8dir
        weight_dinf = namecfg.dinf_weight
        acc = namecfg.d8acc
        stream_raster = namecfg.stream_raster
        default_outlet = namecfg.outlet_pre
        modified_outlet = namecfg.outlet_m
        stream_skeleton = namecfg.stream_pd
        acc_with_weight = namecfg.d8acc_weight
        stream_order = namecfg.stream_order
        ch_network = namecfg.channel_net
        ch_coord = namecfg.channel_coord
        stream_net = namecfg.streamnet_shp
        subbasin = namecfg.subbsn
        dist2_stream_d8 = namecfg.dist2stream_d8

        # 4. perform calculation
        UtilClass.writelog(logfile, '[Output] %d..., %s' % (10, 'pitremove DEM...'), 'a')
        TauDEM.pitremove(np, dem, filled_dem, workingdir, mpi_bin, bin_dir,
                         log_file=logfile, runtime_file=runtime_file, hostfile=hostfile)
        UtilClass.writelog(logfile, '[Output] %d..., %s' %
                           (20, 'Calculating D8 and Dinf flow direction...'), 'a')
        TauDEM.d8flowdir(np, filled_dem, flow_dir, slope, workingdir,
                         mpi_bin, bin_dir, log_file=logfile,
                         runtime_file=runtime_file, hostfile=hostfile)
        TauDEM.dinfflowdir(np, filled_dem, flow_dir_dinf, slope_dinf, workingdir,
                           mpi_bin, bin_dir, log_file=logfile,
                           runtime_file=runtime_file, hostfile=hostfile)
        DinfUtil.output_compressed_dinf(flow_dir_dinf, dir_code_dinf, weight_dinf)
        UtilClass.writelog(logfile, '[Output] %d..., %s' % (30, 'D8 flow accumulation...'), 'a')
        TauDEM.aread8(np, flow_dir, acc, None, None, False, workingdir, mpi_bin, bin_dir,
                      log_file=logfile, runtime_file=runtime_file, hostfile=hostfile)
        UtilClass.writelog(logfile, '[Output] %d..., %s' %
                           (40, 'Generating stream raster initially...'), 'a')
        min_accum, max_accum, mean_accum, std_accum = RasterUtilClass.raster_statistics(acc)
        TauDEM.threshold(np, acc, stream_raster, mean_accum, workingdir,
                         mpi_bin, bin_dir, log_file=logfile,
                         runtime_file=runtime_file, hostfile=hostfile)
        UtilClass.writelog(logfile, '[Output] %d..., %s' % (50, 'Moving outlet to stream...'), 'a')
        if outlet_file is None:
            outlet_file = default_outlet
            TauDEM.connectdown(np, flow_dir, acc, outlet_file, wtsd=None,
                               workingdir=workingdir, mpiexedir=mpi_bin, exedir=bin_dir,
                               log_file=logfile, runtime_file=runtime_file, hostfile=hostfile)
        TauDEM.moveoutletstostrm(np, flow_dir, stream_raster, outlet_file,
                                 modified_outlet, workingdir, mpi_bin, bin_dir,
                                 log_file=logfile, runtime_file=runtime_file, hostfile=hostfile)
        UtilClass.writelog(logfile, '[Output] %d..., %s' %
                           (60, 'Generating stream skeleton...'), 'a')
        TauDEM.peukerdouglas(np, filled_dem, stream_skeleton, workingdir,
                             mpi_bin, bin_dir, log_file=logfile,
                             runtime_file=runtime_file, hostfile=hostfile)
        UtilClass.writelog(logfile, '[Output] %d..., %s' %
                           (70, 'Flow accumulation with outlet...'), 'a')
        tmp_outlet = None
        if singlebasin:
            tmp_outlet = modified_outlet
        TauDEM.aread8(np, flow_dir, acc_with_weight, tmp_outlet, stream_skeleton, False,
                      workingdir, mpi_bin, bin_dir, log_file=logfile,
                      runtime_file=runtime_file, hostfile=hostfile)

        if thresh <= 0:  # find the optimal threshold using dropanalysis function
            UtilClass.writelog(logfile, '[Output] %d..., %s' %
                               (75, 'Drop analysis to select optimal threshold...'), 'a')
            min_accum, max_accum, mean_accum, std_accum = \
                RasterUtilClass.raster_statistics(acc_with_weight)
            if mean_accum - std_accum < 0:
                minthresh = mean_accum
            else:
                minthresh = mean_accum - std_accum
            maxthresh = mean_accum + std_accum
            numthresh = 20
            logspace = 'true'
            drp_file = namecfg.drptxt
            TauDEM.dropanalysis(np, filled_dem, flow_dir, acc_with_weight,
                                acc_with_weight, modified_outlet, minthresh, maxthresh,
                                numthresh, logspace, drp_file, workingdir, mpi_bin, bin_dir,
                                log_file=logfile, runtime_file=runtime_file, hostfile=hostfile)
            if not FileClass.is_file_exists(drp_file):
                raise RuntimeError('Dropanalysis failed and drp.txt was not created!')
            with open(drp_file, 'r', encoding='utf-8') as drpf:
                temp_contents = drpf.read()
                (beg, thresh) = temp_contents.rsplit(' ', 1)
            print(thresh)
        UtilClass.writelog(logfile, '[Output] %d..., %s' % (80, 'Generating stream raster...'), 'a')
        TauDEM.threshold(np, acc_with_weight, stream_raster, float(thresh),
                         workingdir, mpi_bin, bin_dir, log_file=logfile,
                         runtime_file=runtime_file, hostfile=hostfile)
        UtilClass.writelog(logfile, '[Output] %d..., %s' % (90, 'Generating stream net...'), 'a')
        TauDEM.streamnet(np, filled_dem, flow_dir, acc_with_weight, stream_raster,
                         modified_outlet, stream_order, ch_network,
                         ch_coord, stream_net, subbasin, workingdir, mpi_bin, bin_dir,
                         log_file=logfile, runtime_file=runtime_file, hostfile=hostfile)
        UtilClass.writelog(logfile, '[Output] %d..., %s' %
                           (95, 'Calculating distance to stream (D8)...'), 'a')
        TauDEM.d8hdisttostrm(np, flow_dir, stream_raster, dist2_stream_d8, 1,
                             workingdir, mpi_bin, bin_dir, log_file=logfile,
                             runtime_file=runtime_file, hostfile=hostfile)
        UtilClass.writelog(logfile, '[Output] %d.., %s' %
                           (100, 'Original subbasin delineation is finished!'), 'a')