InVEST Nutrient Delivery Ratio (NDR) module.

natcap.invest.ndr.ndr.calculate_ic(d_up_path, d_dn_path, target_ic_path)

Calculate IC as log_10(d_up/d_dn).

natcap.invest.ndr.ndr.create_vector_copy(base_vector_path, target_vector_path)

Create a copy of base vector.

natcap.invest.ndr.ndr.d_up_calculation(s_bar_path, flow_accum_path, target_d_up_path)

Calculate d_up = s_bar * sqrt(upslope area).


Nutrient Delivery Ratio.

  • args['workspace_dir'] (string) – path to current workspace

  • args['dem_path'] (string) – path to digital elevation map raster

  • args['lulc_path'] (string) – a path to landcover map raster

  • args['runoff_proxy_path'] (string) – a path to a runoff proxy raster

  • args['watersheds_path'] (string) – path to the watershed shapefile

  • args['biophysical_table_path'] (string) –

    path to csv table on disk containing nutrient retention values.

    For each nutrient type [t] in args[‘calc_[t]’] that is true, must contain the following headers:

    ’load_[t]’, ‘eff_[t]’, ‘crit_len_[t]’

    If args[‘calc_n’] is True, must also contain the header ‘proportion_subsurface_n’ field.

  • args['calc_p'] (boolean) – if True, phosphorus is modeled, additionally if True then biophysical table must have p fields in them

  • args['calc_n'] (boolean) – if True nitrogen will be modeled, additionally biophysical table must have n fields in them.

  • args['results_suffix'] (string) – (optional) a text field to append to all output files

  • args['threshold_flow_accumulation'] – a number representing the flow accumulation in terms of upslope pixels.

  • args['k_param'] (number) – The Borselli k parameter. This is a calibration parameter that determines the shape of the relationship between hydrologic connectivity.

  • args['subsurface_critical_length_n'] (number) – The distance (traveled subsurface and downslope) after which it is assumed that soil retains nutrient at its maximum capacity, given in meters. If dissolved nutrients travel a distance smaller than Subsurface Critical Length, the retention efficiency will be lower than the Subsurface Maximum Retention Efficiency value defined. Setting this value to a distance smaller than the pixel size will result in the maximum retention efficiency being reached within one pixel only. Required if calc_n.

  • args['subsurface_eff_n'] (number) – The maximum nutrient retention efficiency that can be reached through subsurface flow, a floating point value between 0 and 1. This field characterizes the retention due to biochemical degradation in soils. Required if calc_n.

  • args['n_workers'] (int) – if present, indicates how many worker processes should be used in parallel processing. -1 indicates single process mode, 0 is single process but non-blocking mode, and >= 1 is number of processes.