# Catchment Area (Parallel)

O.Conrad (c) 2001-2010, T.Grabs portions (c) 2010
Parallel processing of cells for calculation of flow accumulation and related parameters. This set of algorithms processes a DEM downwards from the highest to the lowest cell.
References:
Deterministic 8
- O'Callaghan, J.F. / Mark, D.M. (1984):
'The extraction of drainage networks from digital elevation data',
Computer Vision, Graphics and Image Processing, 28:323-344
Rho 8:
- Fairfield, J. / Leymarie, P. (1991):
'Drainage networks from grid digital elevation models',
Water Resources Research, 27:709-717
Braunschweiger Reliefmodell:
- Bauer, J. / Rohdenburg, H. / Bork, H.-R. (1985):
'Ein Digitales Reliefmodell als Vorraussetzung fuer ein deterministisches Modell der Wasser- und Stoff-Fluesse',
Landschaftsgenese und Landschaftsoekologie, H.10, Parameteraufbereitung fuer deterministische Gebiets-Wassermodelle,
Grundlagenarbeiten zu Analyse von Agrar-Oekosystemen, (Eds.: Bork, H.-R. / Rohdenburg, H.), p.1-15
Deterministic Infinity:
- Tarboton, D.G. (1997):
'A new method for the determination of flow directions and upslope areas in grid digital elevation models',
Water Ressources Research, Vol.33, No.2, p.309-319
Multiple Flow Direction:
- Freeman, G.T. (1991):
'Calculating catchment area with divergent flow based on a regular grid',
Computers and Geosciences, 17:413-22
- Quinn, P.F. / Beven, K.J. / Chevallier, P. / Planchon, O. (1991):
'The prediction of hillslope flow paths for distributed hydrological modelling using digital terrain models',
Hydrological Processes, 5:59-79
Triangular Multiple Flow Direction
- Seibert, J. / McGlynn, B. (2007):
'A new triangular multiple flow direction algorithm for computing upslope areas from gridded digital elevation models',
Water Ressources Research, Vol. 43, W04501
C++ Implementation into SAGA by Thomas Grabs, Copyrights (c) 2007
Contact: thomas.grabs@natgeo.su.se, jan.seibert@natgeo.su.se

## Parameters

Grid system
Grid system
  Grid system
Elevation
Input Grid
Sink Routes
Input Grid
Weight
Input Grid
Material
Input Grid
Target
Input Grid
Catchment Area
Output Grid
Catchment Height
Output Grid
Catchment Slope
Output Grid
Total accumulated Material
Output Grid
Accumulated Material from _left_ side
Output Grid
Accumulated Material from _right_ side
Output Grid
Step
Integer
  Minimum: 1.0
Catchment Aspect
Output Grid
Flow Path Length
Output Grid
Method
Choice
  Available choices: Deterministic 8, Rho 8, Braunschweiger Reliefmodell, Deterministic Infinity, Multiple Flow Direction, Multiple Triangular Flow Directon
Linear Flow
Boolean
  Use D8 if catchment area becomes higher than specified threshold.
Linear Flow Threshold
Floating point
  Use D8 if catchment area becomes higher than specified threshold (Cells).
Linear Flow Threshold Grid
Input Grid
  (optional) Linear Flow Threshold Grid
Channel Direction
Input Grid
  (optional) Channel Direction Grid. Must contain direction values. For all non-missing grid cells all flow will be routed to the prescribed direction.
Convergence
Floating point
  Convergence factor for Multiple Flow Direction Algorithm (Freeman 1991). Applies also to the Multiple Triangular Flow Directon Algorithm.