Tool Quasi-Dynamic Flow Accumulation

This tool estimates the flow distribution at a specified time after a rainfall event. It is based on a standard flow accumulation calculation (e.g. O'Callaghan & Mark 1984, Freeman 1991) that has an additional function to accumulate the flow travel time. Final flow accumulation becomes that part of the total flow through that corresponds to the portion of flow travel time that exceeds the targeted time. The travel time is estimated with the empirical Manning equation (e.g. Dingman 1994, Freeman et al. 1998, Manning 1891).

References

Dingman, S.L. (1994): Physical Hydrology. Macmillan Publishing, 575p.
Freeman, G. E., Copeland, R. R., Rahmeyer, W., & Derrick, D. L. (1998): Field Determination of Manning’s n Value for Shrubs and Woody Vegetation. Engineering Approaches to Ecosystem Restoration. doi:10.1061/40382(1998)7..
Freeman, G.T. (1991): Calculating catchment area with divergent flow based on a regular grid. Computers and Geosciences, 17:413-22. ScienceDirect.
Manning, R. (1891): On the flow of water in open channels and pipes. Transactions of the Institution of Civil Engineers of Ireland. 20: 161–207.
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. ScienceDirect.

Author: O.Conrad (c) 2019
Menu: Simulation|Hydrology

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Elevation	Grid (input)	`DEM`	[m]	-
Input	Manning-Strickler Coefficient (*)	Grid (optional input)	`FLOW_K`	Manning-Strickler coefficient for flow travel time estimation (reciprocal of Manning's Roughness Coefficient)	-
Output	Flow Accumulation	Grid (output)	`FLOW_ACC`	[mm]	-
	Flow Through (*)	Grid (optional output)	`FLOW`	-	-
	Flow Travel Time (*)	Grid (optional output)	`TIME_MEAN`	-	-
	Flow Concentration (*)	Grid (optional output)	`TIME_CONC`	-	-
	Flow Velocity (*)	Grid (optional output)	`VELOCITY`	-	-
Options	Grid System	Grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Default	Floating point	`FLOW_K_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 20.000000
	Time	Floating point	`TIME`	minutes	Minimum: 0.001000 Default: 5.000000
	Flow Routing	Choice	`ROUTING`	-	Available Choices: [0] D8 [1] MFD Default: 1
	Flow Depth	Choice	`FLOW_DEPTH`	-	Available Choices: [0] constant [1] dynamic Default: 1
	Constant Flow Depth	Floating point	`FLOW_CONST`	[mm]	Minimum: 0.000000 Default: 10.000000
	Reset	Boolean	`RESET`	Resets flow accumulation raster.	Default: 1
	Rain	Floating point	`RAIN`	The flow portion [mm] added to each raster cell before simulation starts.	Minimum: 0.000000 Default: 10.000000
(*) optional

Command-line

Usage: saga_cmd sim_hydrology 8 [-DEM <str>] [-FLOW_K <str>] [-FLOW_K_DEFAULT <double>] [-FLOW_ACC <str>] [-FLOW <str>] [-TIME_MEAN <str>] [-TIME_CONC <str>] [-VELOCITY <str>] [-TIME <double>] [-ROUTING <str>] [-FLOW_DEPTH <str>] [-FLOW_CONST <double>] [-RESET <str>] [-RAIN <double>]
  -DEM:<str>              	Elevation
	Grid (input)
  -FLOW_K:<str>           	Manning-Strickler Coefficient
	Grid (optional input)
  -FLOW_K_DEFAULT:<double>	Default
	Floating point
	Minimum: 0.000000
	Default: 20.000000
  -FLOW_ACC:<str>         	Flow Accumulation
	Grid (output)
  -FLOW:<str>             	Flow Through
	Grid (optional output)
  -TIME_MEAN:<str>        	Flow Travel Time
	Grid (optional output)
  -TIME_CONC:<str>        	Flow Concentration
	Grid (optional output)
  -VELOCITY:<str>         	Flow Velocity
	Grid (optional output)
  -TIME:<double>          	Time
	Floating point
	Minimum: 0.001000
	Default: 5.000000
  -ROUTING:<str>          	Flow Routing
	Choice
	Available Choices:
	[0] D8
	[1] MFD
	Default: 1
  -FLOW_DEPTH:<str>       	Flow Depth
	Choice
	Available Choices:
	[0] constant
	[1] dynamic
	Default: 1
  -FLOW_CONST:<double>    	Constant Flow Depth
	Floating point
	Minimum: 0.000000
	Default: 10.000000
  -RESET:<str>            	Reset
	Boolean
	Default: 1
  -RAIN:<double>          	Rain
	Floating point
	Minimum: 0.000000
	Default: 10.000000