Recent Activities

Significant enhancements to URGWOM have been completed recently. Development has been completed to improve the physical representation of the system and improve the efficiency for applying the model. The Middle Valley Upgrade was recently incorporated into the Planning Model to include a better representation of surface water-groundwater interaction in the Middle Valley and the physical system. New synthetic hydrologic sequences were developed to use for planning studies, and an update to the URGWOM database was recently completed. Database work has also entailed utilizing the new DSS direct connection capability in RiverWare. The URGWOM ruleset was updated to better represent potential new agreements and actions in the Basin and changes were made to the rules to improve the performance of the model. Reclamation has been implementing enhancements to the Accounting Model, and the URGWOM Technical Team has continued to work with Sandia National Laboratory on modeling with their monthly timestep Powersim model.

The segment of URGWOM from Cochiti Dam to Elephant Butte Reservoir was modified to include groundwater-surface water interaction between the regional aquifer, the shallow aquifer, the river, and system of canals and drains (Refer to the sample picture of the system to the right and a schematic of the representation in URGWOM below). The system includes representation for riparian evapotranspiration which has a significant effect on the river during low flows. Several diversions along the Middle Rio Grande between Cochiti Dam and Elephant Butte Reservoir divert river flows to the system of canals and drains, and seepage from the river may flow into the drains or vice versa. The structure of the physical system in URGWOM with the Middle Valley Upgrade provides a more physically based representation of the groundwater-surface water interaction along the Middle Rio Grande.

New algorithms for simulating head dependent groundwater movement between river reaches or drains and the adjacent shallow aquifer were set up in the existing groundwater objects in RiverWare by the software developers at the CADSWES. Riparian evapotranspiration and deep percolation from the aquifer are also simulated. Deep aquifer heads are input based on simulations completed with the regional MODFLOW model for the Albuquerque basin used as a pre-processor for URGWOM. 

Groundwater flow from river reaches or drains to groundwater objects is computed as a function of the difference in heads and a calibrated aquifer conductance. Flow between groundwater objects is also represented. The modified model structure from Cochiti Dam to San Marcial consists of nineteen separate groundwater reaches linked to separate surface water reaches where individual groundwater objects represent the shallow aquifer below the river and the shallow aquifer to the left and right of the river (Refer to the screen capture of the upper portion of the Middle Valley in URGWOM to the right). 

While model data requirements are greater for this new configuration of the physical system, improved results from URGWOM for simulated river flows and the system water budget should continue to be evident as calibration and potential improvements to the method for open water evaporation loss are implemented, but most importantly, the physical system is now represented more accurately.

Given the fairly short historical period when data are available as needed to complete URGWOM runs (1975 to present), synthetic hydrologic sequences were developed to represent a wider variation of potential hydrologic conditions based on a review of paleo-data. Tree ring data from 604 historical years were referenced to develop hydrologic sequences that are composed of more recent years when data are available but years are sorted to reflect the occurrence of wet years and dry years as evident in the paleo-data and also reflect the transition probability between year classifications such that potential wet and drought periods are represented. Amec Environmental consulting developed a stochastic simulation of the flow at Otowi gage and produced 1000 ensembles of 100 years flow sequences based on paleo climate data, and can be accessed with the link below:

The planning module of URGWOM is computationally intensive, so the focus for analyses is often on 10-year periods to minimize any potential efficiency or performance issues. Ultimately, five 10-year sequences were selected such that the hydrology is exceeded 10%, 30%, 50%, 70%, and 90% of the time based on the references to the paleo-data. An evaluation of monsoon season inflows to the Middle Valley for the sequences was also completed and each of the five sequences includes a good distribution of wet and dry monsoon season runoff volumes. Charts for the five sequences and annual Otowi flow volumes for each year are presented, and a full report on the analysis and sequence selection process can be accessed with the link below.

Report on the Selection of the Five Sequences

Data needed to complete rulebased simulations with URGWOM include series for upstream inflows and inflows from tributaries along the system. Crop evapotranspiration rates and irrigated areas for each crop type are required. Data from the ET Toolbox are a large and important component of the database. ET Toolbox maintenance and development is an ongoing task key to meeting the continued needs of URGWOM (Refer to the following link for more details on the ET Toolbox: http://www.usbr.gov/pmts/rivers/awards/Nm2/riogrande.html). Reservoir precipitation and pan evaporation data are needed and reservoir climate and ice coverage data are needed if reservoir evaporation is to be computed. Assumptions for irrigation diversions from the Rio Chama are needed, and values for demands and diversions in the Middle Valley are required. Maintaining the database with historical values is a significant regular maintenance task. Data needs have become more intensive for groundwater-surface water interaction calculations with the Middle Valley Upgrade. An update was recently completed to the database through 2005 for all these parameters which is maintained in electronic files having the format of the Corps of Engineers Hydrologic Engineering Center Data Storage System (HEC-DSS).

A significant update was recently completed to utilize the new capability in RiverWare to set up direct connections to DSS files for importing data to or exporting output from the model. All inputs needed to complete runs are now imported using the direct connection which was set up with mapping between slots in the model and locations of the corresponding inputs in the DSS files. The capability has also been added to RiverWare for direct connection to files having the format of Reclamation’s Hydrologic Database (HDB) which may be utilized as an alternate.

Rulebased simulations are completed with URGWOM using a RiverWare ruleset that represents the policy for operating the facilities represented in the model. Policy is coded using the RiverWare rule policy language (RPL) to represent the priorities for operating dams and diversions based on all the policy factors. Ultimately, the releases from the dams along the Rio Chama and Rio Grande are set for each day in the daily timestep model based on the policy coded in the ruleset. Key policy controls pertain to operations for the San Juan-Chama Project, flood control operations, and the Rio Grande Compact. Diversions from the Rio Grande by the Middle Rio Grande Conservancy District (MRGCD) and Albuquerque Bernalillo County Water Utility Authority are represented along with rules for meeting downstream target flows and for recreational interests. Rules are designated for each of the following dams: Heron, El Vado, Abiquiu, Cochiti, Jemez, Elephant Butte, and Caballo.

The ruleset is maintained as needed to reflect evolving actual policies for operating the system as new agreements and permits and other actions or changes to the system are implemented. Rules are used to set deliveries of water for contractors for San Juan-Chama Project water and other accounts to meet different demands based as input priorities and also assure the mass balance for the accounting reconciles with the total storage. Policy for operating the system is very complex and involves numerous issues. As a result, the code in the ruleset needs to be maintained to assure the code is efficient to help minimize potential computational performance issues with running URGWOM.

Documentation of the policy as represented in the ruleset is currently being updated to reflect all the recent changes to the ruleset which include changes needed for incorporating the Middle Valley upgrade and enhancements to improve the efficiency and performance of the model as a result of evaluations completed by CADSWES. The documentation will include general discussion of all the key controls affecting policy along with separate discussions for each rule in the ruleset.

The Accounting Model utilized to simulate year-to-date conditions in the Basin and provide an updated status of account storage and deliveries made to contractors has recently been enhanced. The separate model for Nambe Reservoir has now been incorporated into the Accounting Model, and post-processing of model results required to prepare annual accounting reports is now completed within RiverWare using expression series slots. This change has eliminated the several steps previously used to export values from the Accounting Model into a spreadsheet that was being used to post-process model results. A different template spreadsheet is now used solely for formatting tables with the results from the new expression series slots exported from the model using a DMI and imported to this spreadsheet using Excel macros. Tables in this spreadsheet are included in annual accounting reports.

Work has begun to export values from the new expression series slots to Reclamation’s Hydrologic Database (HDB) to be used with Crystal Reports to prepare annual accounting reports, and HDB will serve as a data repository for accounting information. Work has also begun to streamline the process for obtaining needed inputs to run the Accounting Model on a daily basis and utilize the Accounting Model with RiverWare on a PC platform. Continued work will include a further review of the approach used for accounting at specific locations in the Basin and reviewing the need to add Caballo Reservoir to the Accounting Model. A plan for completing periodic reviews and QA/QC of the Accounting Model will also be reviewed.

The URGWOM Technical Team is continuing to collaborate with representatives from Sandia National Laboratories on their development and use of a monthly timestep Powersim model that employs the system dynamics computational technique. The model can be used to efficiently evaluate the impact of broad changes in the Basin and was recently used to complete model runs with a thousand 100-year synthetic sequences to evaluate the impact of the sequences developed with reference to paleo-data on different indicators in the Basin. A full report on that analysis can be accessed with the first link below and all needed files for a demo Powersim model can be accessed using the second link below:

Stochastic Hydrologic Analysis of the Upper Rio Grande Surface Water System

MonthlyModel4URGWOMWebsite6.2009.zip (58 MB)