Hydrology Modeling in Alaska: Model Documentation Template
(please fill out as much as possible)
Your name: Crane Johnson, USACE Alaska District
Model name: Streamflow Synthesis and Reservoir Regulation (SSARR) Model
HEC-HMS -HEC Hydrological Modeling System
Authors:
SSARR
U.S. Army Corps of Engineers
Columbia Basin Water Management Division
HEC-HMS US Army Corps of Engineers
Hydrologic Engineering Center
Source code location (if public):
SSARR - http://www.nwd-wc.usace.army.mil/ftppub/SSARR_program
HEC-HMS – http://www.hec.usace.army.mil/software/hec-hms/
Citations and URLs for basic documentation:
Source code language: SSARR – Fortran
HEC-HMS - Java
For the following section, you may wish to use appropriate keywords such as:
Physically-based, statistical, lumped parameter, spatially distributed, transitive
model, equilibrium model, implicit, semi-implicit, explicit, TOPMODEL based,
finite element, finite differences, routing, bottom boundary condition, parallel
code, Richardson equation, optimization, forecast, etc
Model type and/or conceptual framework:
Both models are lumped parameter hydrologic models.
Data needed to run the model (inputs):
Spring Snowpack (SWE)
Air Temperature
Precipitation
Discharge
Parameters and how they are derived:
Empirically derived parameters
Spatial element used to lump inputs and outputs:
Sub-basins and elevations bands (SSARR)
Sub-basins and aspects (HEC-HMS)
Sub-models (i.e. snow or ground thermodynamics):
Rainfall/runoff transformation mechanism:
Empirical method based on calculated soil moisture and rainfall intensity
(SSARR)
Runoff routing within spatial elements and to basin outlet: Cascade if reservoirs
for all model routing.(SSARR).
Method for including sub-grid scale processes: N/A
Resolution (possible & prudent):
Method of deriving topography: USGS topographic maps to determine elevation
bands for SSARR model and northern and southern aspect watersheds for HECHMS model
Calibration approaches: Overall model calibrated using historical peak flows
(magnitude/volume). Operational model runs are calibrated to match observed
antecedent hydrographs by adjusting initial conditions (primarily soil moisture).
Treatment of frozen ground: No explicit treatment. Implicitly included in empirical
parameters.
Strengths and Weaknesses in Alaska applications:
Strengths – Robust models that are well documented and generally used
for water control.
Weaknesses – Individual parameters are often difficult to determine
(typically empirically derived) with little in the way or regional guidance. No
explicit treatment of permafrost.