Sediment – FEST

History

current version 1.0 - 5th October 2011

version	date	comment
1.0	05/Oct/2011	Original code

License

license: GNU GPL http://www.gnu.org/licenses/

Module Description

compute sediment erosion and deposition The interril and channelerosion are computed according to Sun et al. (2002), which combines the use of USLE data source with storm-based, distributed hydrological model

References:

Sun, H., P. S. Cornish, and T. M. Daniell, Contour-based digital elevation modeling of watershed erosion and sedimentation: Erosion and sedimentation estimation tool (EROSET), Water Resour. Res., 38(11), 1233, doi:10.1029/2001WR000960, 2002.

Imported variables:

Imported routines:

Description:

Uses

Variables

Type	Visibility		Name
type(grid_real),	public	::	QoutSed	output sediment discharge
type(grid_real),	public	::	channelErosion	channel sediment detachment rate (kg/m2/s)
type(grid_real),	public	::	deltaSed	variation of sediment storage (10^6 kg)
type(grid_real),	public	::	interrillErosion	interrill sediment detachment rate (kg/m2/s)
logical,	public	::	routeSediment	flag to route sediment
type(grid_integer),	public	::	sedFlowDirection	map of flow direction to route sediment
type(NetworkSediment),	public	::	sedReach	drainage network to route sediment
type(grid_real),	private	::	PinBL	input discharge of bed load at time t-1
type(grid_real),	private	::	PinSS	input discharge of suspended sediment at time t-1
type(grid_real),	private	::	PoutBL	output discharge of bed load at time t-1
type(grid_real),	private	::	PoutSS	output discharge of suspended sediment at time t-1
type(grid_real),	private	::	QinBL	input discharge of bed load sediment at time t
type(grid_real),	private	::	QinSS	input discharge of suspended sediment at time t
type(grid_real),	private	::	QoutBL	output discharge of bed load at time t
type(grid_real),	private	::	QoutSS	output discharge of suspended sediment at time t
type(grid_real),	private	::	rusleC	crop and management factor (-)
type(grid_real),	private	::	rusleK	soil erodibility factor ( ( tons h) / ( MJ mm))
type(grid_real),	private	::	slope	local slope (radians)
type(grid_real),	private	::	slopeFactor	slope dactor computed by routine ComputeSlopeFactor

Functions

private function ChannelDetachmentRate(flow, s, k, c) result(d)

compute sediment detachment rate per second in channel element (kg/s) using simplified approach by Sun et al. (2002).

Arguments

Type	Intent		Name
real(kind=float),	intent(in)	::	flow	water discharge in channel (m3/s)
real(kind=float),	intent(in)	::	s	channel slope (m/m)
real(kind=float),	intent(in)	::	k	soil erodibility factor ((tons h) / (MJ mm))
real(kind=float),	intent(in)	::	c	crop and management factor (-)

Return Value real(kind=float)

private function CriticalVelocity(d, dp, s) result(cv)

compute critical velocity for incipient motion (m/s)

Arguments

Type	Intent		Name
real(kind=float),	intent(in)	::	d	particle size of bed material (mm)
real(kind=float),	intent(in)	::	dp	water depth (m)
real(kind=float),	intent(in)	::	s	channel slope (m/m)

Return Value real(kind=float)

critical velocity (m/s)

private function FallVelocity(d) result(fv)

compute fall velocity of sediment (m/s)

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=float),	intent(in)			::	d	particle size of bed material (mm)

Return Value real(kind=float)

fall velocity (m/s)

private function ShearVelocity(dp, s) result(sv)

compute shear velocity (m/s)

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=float),	intent(in)			::	dp	water depth (m)
real(kind=float),	intent(in)			::	s	channel slope (m/m)

Return Value real(kind=float)

shear velocity (m/s)

private function Yang1973(flow, s, v, d, dp) result(tc)

compute sediment transport capacity using Yang (1973) approach (kg/s) limitation: Yang1973 equation can be applied for noncohesive natural beds with particle sizes between 0.062 mm and 2 mm, a specific gravity of 2.65 g/cm3, and a shape factor of 0.7

Arguments

Type	Intent		Name
real(kind=float),	intent(in)	::	flow	water discharge in channel (m3/s)
real(kind=float),	intent(in)	::	s	channel slope (m/m)
real(kind=float),	intent(in)	::	v	water flow velocity in channel (m/s)
real(kind=float),	intent(in)	::	d	particle size of bed material (mm)
real(kind=float),	intent(in)	::	dp	water depth (m)

Return Value real(kind=float)

computed transport capacity (kg/s)

private function Yang1979(flow, s, v, d, dp) result(tc)

compute sediment transport capacity using Yang (1979) approach (kg/s) limitation: Yang1979 equation can be applied when the dimensionless unit stream power is relatively small with respect to the prevailing value of unit stream power. Used for finer suspended sediment trasnport in the Yellow River with median particle diameter of 0.067 mm.

Arguments

Type	Intent		Name
real(kind=float),	intent(in)	::	flow	water discharge in channel (m3/s)
real(kind=float),	intent(in)	::	s	channel slope (m/m)
real(kind=float),	intent(in)	::	v	water flow velocity in channel (m/s)
real(kind=float),	intent(in)	::	d	particle size of bed material (mm)
real(kind=float),	intent(in)	::	dp	water depth (m)

Return Value real(kind=float)

computed transport capacity (kg/s)

Subroutines

public subroutine InterrillDetachmentRate(pRate)

compute sediment detachment rate (kg/s). Interril area detachment is considered to be due to the raindrop impact, which breaks the cohesive bonds between particles, making them available for transport.

Arguments

Type	Intent	Optional	Attributes		Name
type(grid_real),	intent(in)			::	pRate	precipitation rate (m/s)

public subroutine SedimentInit(iniFile, dtRoute, fileOutSedimentRouting)

Initialize sediment related variables

Arguments

Type	Intent		Name
character(len=300),	intent(in)	::	iniFile	file containing configuration information
integer(kind=short),	intent(out)	::	dtRoute	time step for sediment routing
character(len=300),	intent(out)	::	fileOutSedimentRouting

public subroutine SedimentRouting(dt, flow, v, dp)

compute sediment routing in channelized drainage network using Muskingum-Cunge method. Interrill erosion is supposed to act as suspended sediment so deposition is not contemplated. Bedload sediment is divided in different grainsize classes and routing is performed for each class separately. Deposition is contemplated comparing sediment discharge to transport capacity. Flow Routing method code remind: 0 --> hillslope, water flow rate is not defined 1,2,3,11,30 --> channel routing, water flow is computed according to different schemes 5 --> Instantaneous mass transferring inside lakes (infinitive celerity) 1000:2000 --> reservoir

Arguments

Type	Intent		Name
integer(kind=short)		::	dt	routing time step
type(grid_real),	intent(in)	::	flow
type(grid_real),	intent(in)	::	v	water flow velocity in channel (m/s)
type(grid_real),	intent(in)	::	dp	water depth (m)

private subroutine ComputeSlopeFactor(slope)

Arguments

Type	Intent	Optional	Attributes		Name
type(grid_real),	intent(in)			::	slope

Sediment Module

Contents

Variables

Functions

Subroutines

History

License

Module Description

Uses

Variables

Functions

private function ChannelDetachmentRate(flow, s, k, c) result(d)

Arguments

Return Value real(kind=float)

private function CriticalVelocity(d, dp, s) result(cv)

Arguments

Return Value real(kind=float)

private function FallVelocity(d) result(fv)

Arguments

Return Value real(kind=float)

private function ShearVelocity(dp, s) result(sv)

Arguments

Return Value real(kind=float)

private function Yang1973(flow, s, v, d, dp) result(tc)

Arguments

Return Value real(kind=float)

private function Yang1979(flow, s, v, d, dp) result(tc)

Arguments

Return Value real(kind=float)

Subroutines

public subroutine InterrillDetachmentRate(pRate)

Arguments

public subroutine SedimentInit(iniFile, dtRoute, fileOutSedimentRouting)

Arguments

public subroutine SedimentRouting(dt, flow, v, dp)

Arguments

private subroutine ComputeSlopeFactor(slope)

Arguments