# Overland Flow Distance to Channel Network

(c) 2001 by O.Conrad
This module calculates overland flow distances to a channel network based on gridded digital elevation data and channel network information.
The flow algorithm may be either Deterministic 8 (O'Callaghan & Mark 1984) or Multiple Flow Direction (Freeman 1991)
References:
- Freeman, G.T., 1991: 'Calculating catchment area with divergent flow based on a regular grid', Computers and Geosciences, 17:413-22
- 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

## Parameters

Grid system
Grid system
  Grid system
Elevation
Input Grid
  A grid that contains elevation data.
Channel Network
Input Grid
  A grid providing information about the channel network. It is assumed that no-data cells are not part of the channel network. Vice versa all others cells are recognised as channel network members.
Overland Flow Distance
Output Grid
  The overland flow distance in map units. It is assumed that the (vertical) elevation data use the same units as the (horizontal) grid coordinates.
Vertical Overland Flow Distance
Output Grid
  This is the vertical component of the overland flow
Horizontal Overland Flow Distance
Output Grid
  This is the horizontal component of the overland flow
Flow Algorithm
Choice
  Choose a flow routing algorithm that shall be used for the overland flow distance calculation: - D8 - MFD
  Available choices: D8, MFD