DHSVM Sediment Module
Model Overview
Examples Running the Model
DHSVM Watershed Sediment Module
DHSVM
Qsed
SURFACE EROSION
Q
OUTPUT
CHANNEL EROSION
MASS WASTING

The variables can be assigned to one of four distributions:


The parameter distributions are randomly sampled for each of “Maximum Iterations” times to define a range of potential failure scenarios.
Probability of slope failure before and after Fourth of July Fire
Pre-fire
Approximate extent of August 2001 fire
Post-fire
Icicle Creek Vegetation
Simulated soil saturation
[OPTIONS] Format
SEM
= =
# Model Options # BIN, BYTESWAP or NETCDF
# TRUE or FALSE; run SEM
MWM Input File: Model Area
[AREA] Coordinate System = Extreme North = Extreme West = Center Latitude = Center Longitude = Time Zone Meridian = Number of Rows = Number of Columns = Grid spacing = Mass wasting spacing # # # # # # # # # # = Model area UTM or USER_DEFINED Coordinate for northern edge of grid Coordinate for western edge of grid Central parallel of basin Central meridian of basin Time zone meridian for area Number of rows Number of columns Grid resolution in m # Grid resolution of the mass wasting model in m
Roads and streams
Hillslope and road surface erosion module
Run at the hydrology model resolution. Maps of surface sediment type are supplied to the SEM from the MWM. Runoff generation for each model pixel (“effective precipitation”) is determined from DHSVM. Overland flow is modeled using an explicit finite difference solution of the diffusive wave equation. Sediment supply for transport determined by: Soil particle detachment from raindrop and leaf drip impact, and Soil particle detachment via overland flow.
Watershed Sediment Module
Mass Wasting Module
Multiple realizations of total failure locations
Soil depth DEM Soil info Vegetation info P(cohesion, etc.)
MWM - Stochastic Nature
Four variables are input as probability distributions:


soil cohesion,
angle of internal friction, root cohesion, and vegetation surcharge. uniform, normal, triangular or lognormal.
Effective Root Cohesion
Effect of wildfire on simulated root cohesion
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 1 2 3 4 5 6 7 8 9 10 Years since wildfire Root decay Root regrowth Total root strength
0 1
Channel Erosion
Similar approach as for upland areas, but:
Splash erosion neglected Lateral inflows become important Allows selective entrainment of finer material, leading to the formation of an armour layer
Rainy Creek Current vegetation November 28, 1995 storm event
Saturated Fraction
Simulated probability of slope failure
Rainy Creek Current vegetation November 28, 1995 storm event
MASS WASTING
Multiple time series of sediment supply
Mass Wasting Module
Dynamic relative soil saturation predicted by DHSVM
Nested grids for fine resolution failure computation Slope instability indicated by the factor of safety (ratio of resisting forces to driving forces) Uncertainty in failure predictions is assumed to be primarily due to uncertainty in the spatial variability of soil and vegetation characteristics.
Examples
Simulated streamflow
Icicle Creek, October 1995 - September 1996
Simulated soil saturation

Icicle Creek

November 1995
Simulated probability of slope failure
Surface Erosion Module - Hillslopes
Multiple time series of sediment supply Soil Precipitation Vegetation DEM
SURFACE EROSION
Overland flow
Distribution of sediment delivery to channels (roads and streams)
MWM Input File: Constants
[CONSTANTS] Ground Roughness Reference Height Maximum Iterations # = # = # = # # # Model constants Roughness of soil surface (m) Wind speed reference height Number of iterations for stochastic failure predictions; 1 =deterministic
Total erosion is limited by overland flow transport capacity.
Surface Erosion Module - Channels
23.9 19.2 19.7 21.9 19.8 17.1 18.0 19.5 19.3 18.9
CHANNEL EROSION
MWM Input File: Time
[TIME] Time Step Model Start
Model End
= = =
# Model period # Model time step (hours) # Model start time (MM/DD/YYYY-HH) # Model end time (MM/DD/YYYY-HH)
Channel flow
Distribution of sediment delivery to channels (roads and streams)