CRDSS_Task1_15-1_SummaryofModelRecommendation

• Title: CRDSS Task 1.15-1 - Water Rights Planning Model - Summary of Model Recommendation
• Description: This memorandum summarizes the results of the Task 1.15 ‎(a)‎ work effort and the final recommendation.
• Decision Support - Doc Type: Task Memorandum
• Date: 5/10/1994
• DSS Category: Surface Water
• DSS: Colorado River
• Basin: Colorado Mainstem
• Contract/PO #: C153658, C153727, C153752
• Grant Type: Non-Reimbursable
• Bill Number: SB92-87, HB93-1273, SB94-029, HB95-1155, SB96-153, HB97-008
• Prepared By: Riverside Technology inc.

HYDROSS
HYDROSS was developed and is maintained by the USBR and is considered to be in the public
domain. However, there are certain costs related to acquiring the source code and subscribing
for continued support and upgrades. It is not clear whether these costs would be waived for the
CRDSS. The model has many attributes, including very good documentation and excellent
commenting in the source code. Based on the Level One and Level Two decision criteria, there
are a number of deficiencies in the model's functionality for the CRDSS, including the
following:
The model is not structured to accommodate water right exchanges.
?
The model does not readily allow for multiple storage accounts/ownerships within a
?
reservoir.
..Virgin flows, required by the model in order to allocate water to priorities, must be generated
?
external to the model. Although the USBR has developed a virgin flow database for the
Colorado River basin for CRSS, the level of work effort by the CRDSS Project Team to add
to or modify this database is unknown.
..The model allows return flows to accrue to the river in the same time-step. Under certain
?
circumstances, this may result in an erroneous estimate of the flow available for diversion by
the water right that generates those return flows. The model cannot iteratively solve for this
potential problem.
The model HYDROSS was determined to be unacceptable for the CRDSS because of the stated
deficiencies in the functionality as related to the CRDSS objectives; see Task Memorandum
1.15-4.
MODSIM
The model MODSIM differs from the BESTSM and HYDROSS models in that the entire river
basin is treated as a unified system wherein all of the inflows, diversions, return flows, storage,
outflows, etc. are represented as a single flow network. All diversions are constrained by
physical bounds established by the user and the water right priority. MODSIM then employs
an optimization algorithm (Lagrangian Relaxation) to interactively solve the entire flow
network to achieve a "minimum cost" while satisfying mass balance and maintaining flows
throughout the network within the required limits; see Task Memorandum 1.15-5.
From the review of the model, including the Level One and Level Two decision criteria,
MODSIM appears capable of accommodating the majority of the water rights planning issues
contemplated in the CRDSS. In addition:
..The MODSIM source code, including the recently developed workstation version (UNIX), is
?
available for use by the State for the CRDSS.
..The model appears to address the majority of issues of functionality required to satisfy the
?
objectives of the CRDSS, with little or no modifications of the source code.
3
A275 05.10.94 1.15-1 Fosha, Hyre