RiverWare User

1
RiverWare Users Group Meeting Pecos River
Adjudication Settlement Application of an
Integrated Surface and Ground Water Modeling
System
June 18, 2003
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Presentation Outline

• Overview of Pecos River Institutions /
  Operational Policies
• Adjudication Settlement Problems and Solutions
• The Pecos River DSS
• Evaluating the Settlement Terms
• Conclusions

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Institutions and Operations

• Pecos River Compact and Amended Decree (New
  Mexico / Texas)
• Water Rights - Prior Appropriation Doctrine
  adjudication and administration
• ESA operations for Pecos Bluntnose Shiner
• 2 NEPA EIS programs
• Carlsbad Project (reservoir operations, GW
  diversions)
• Other diverters (FSID, river pumpers, MI, etc)
• PVACD groundwater diversions

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Santa Rosa Reservoir

• Major Irrigators, Physical Features, and Critical
  Resource Locations in the Pecos Basin

Sumner Reservoir
Fort Sumner Irrigation District
Pecos Valley Artesian Conservancy District
USGS gage PR _at_ Acme
Brantley Reservoir
Carlsbad Irrigation District
NM - TX State Line / Pecos River Compact
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Pecos Adjudication Settlement

• Parties PVACD, CID, NM ISC, United States
• Purpose
• Ensure long-term compliance with the Pecos River
  Compact and Amended Decree
• Avoid need for priority administration of water
  rights
• Maintain or enhance water supplies / aquifer
  storage levels
• Proposal
• NM ISC purchases water rights / land from PVACD
  and CID
• CID water delivered to state line for Compact
  deliveries
• PVACD lands retired, water provides augmentation
  supply when needed

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Pecos Adjudication Settlement - Evaluation of the
Proposal

• Use existing modeling tools to evaluate and
  refine Settlement terms.
• Pecos River DSS integrates RiverWare, two MODFLOW
  models, an accounting model, and numerous I/O
  tools.
• Rules simulate baseline conditions and proposed
  actions.
• Various resource indicators used to quantify
  value of actions by comparing baseline and
  Settlement model results.

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Santa Rosa Reservoir

• Approximate Spatial Domain of Pecos Decision
  Support System Models

Roswell Artesian Basin Groundwater Model
Pecos River RiverWare Model
Brantley Reservoir
Carlsbad Area Groundwater Model
Red Bluff Accounting Model
NM / TX State Line
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Pecos River RiverWare Model

• Rule-based simulation of Pecos River hydrology
  and reservoir operations from Santa Rosa
  Reservoir to Avalon Dam
• USBR, Tetra Tech, Hydrosphere, Pecos HWG

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Roswell Artesian Basin Groundwater Model

• Calibrated MODFLOW model of groundwater flow in
  Roswell Artesian Basin, in both the deep artesian
  and shallow alluvial aquifers
• Simulates areal and stream recharge, pumping
  stress, Pecos River - groundwater interaction
• Predicts base inflows to the Pecos River
• Amy Lewis, NM SEO (Eric Keyes), SSPA, Hydrosphere

10
Carlsbad Area Groundwater Model

• MODFLOW model that simulates groundwater flow in
  the Capitan Reef and overlying alluvial aquifer
  in the Pecos River Basin from Lake Avalon to the
  Malaga Bend
• Simulates surface-water irrigation, groundwater
  diversions, losses, and return flows
• Predicts base inflows to the Pecos River
• Amy Lewis, NM SEO (Peggy Barroll),
  Intera/Hydrosphere

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Red Bluff Accounting Model

• Computes Monthly and Annual Flows at Red Bluff
• Historical (Calibration)
• Current Conditions (Alternative Evaluation)
• Red Bluff Flow Resource Indicator
• Evaluation of Policy Alternatives
• Interstate Compact Implications
• Calculation of Calibration Targets for CAGW

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Data Processing Tool (DPT)

• Input/Output for Models
• Data Archiving/ Metadata
• Alternative Evaluation and Archiving

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Settlement Modeling Challenges

• CID Allotment based on surface water supply
  (RiverWare)
• Augmentation pumping in Roswell Basin conditioned
  on CID water supply pumping occurs when CID
  supplies short of 90Kaf up to 35Kaf/year, 100
  Kaf per 5-year accounting period (Feedback from
  RiverWare to RABGW model)
• Compact credit thresholds computed by Red Bluff
  model drive RiverWare rules for water deliveries
  (Feedback from RBAM, via CAGW, to RiverWare)
• Carlsbad Irrigation District allotment and
  distribution
• Delivery of water to Texas

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Pecos Decision Support System Model Linkages
Feedback Loops Compact deliveries drive
reservoir ops CID Supply drives Roswell
augmentation pumping
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Settlement Model Implementation

• Baseline model w/ Settlement Rules
• Iterate between RiverWare and RABGW to determine
  total augmentation pumping
• Sensitivity analysis in Carlsbad GW model
  results used by RiverWare to estimate compact
  credit
• Simulate basin operations to state line and
  verify estimates used in RiverWare

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Evaluation of Settlement Terms

• Avoid priority administration (50,000 AF Supply
  on March 1)
• Meet Compact delivery requirements (Stateline
  flows and Compact accounting)
• Maintain or enhance CID water supply
• Maintain or enhance Roswell basin aquifer storage
  levels

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Resource Indicator Roswell Basin Aquifer
StorageDerived from RABGW Model
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Resource Indicator CID Supply and Sources -
March 1 Supply - Settlement Scenario
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Resource Indicator Compact Obligations and
Departures Cumulative Departure
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Settlement Gains to Stateline Flows
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Whats Next?

• Settlement parties signed agreement in spring
  2003
• Ongoing applications of PRDSS
• Identification/evaluation of candidate lands for
  retirement (PVACD and CID)
• FWS B.O. on Pecos Bluntnose Shiner
• Identification, evaluation, and refinement of
  alternatives for ongoing Carlsbad Project EIS
• Annual Carlsbad Project water accounting
  (Reclamation)

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Settlement Model Assumptions (example)

• Distribution of water from 6,000 acres of CID
  land purchased by ISC conditioned on cumulative
  Compact credit and current water supply (ISC
  water yield 1.176 x allotment)
• If CID supply lt 50Kaf on March 1, ISC water
  realloted to CID
• If credit lt 50Kaf, deliver ISC water to stateline
  5x annually
• if 50Kaf lt credit lt 115 Kaf, AND current supply gt
  90Kaf, ISC gets all water gt 90 Kaf, up to 24,696
  af (3.5x1.176x6000). Beyond 114,696 af, water is
  alloted to all 25,055 acres equally.
• if 50Kaf lt credit lt 115 Kaf, AND current supply lt
  90Kaf, ISC shall make its CID water available for
  re-distribution to CID irrigators up to 3.5
  af/acre (90Kaf)
• if credit gt 115 Kaf, ISC shall make its CID water
  available for re-distribution to CID irrigators
  up to decreed limit (3.697 af/acre) IF CID
  irrigators have full allotment, excess water to
  be held over in storage

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RiverWare Rulebased Simulation

• Operational policy is simulated using RiverWare
  rules
• Management alternatives can be readily evaluated

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RiverWare - Implementation

• USBR began work in 1991 following FWS B.O.
• Data collection program
• Daily timestep model of river/reservoir
  operations
• Need to evaluate operational alternatives
• HWG review / enhancement process started 1999
• Evaluation of data and methods (side inflows,
  routing, gain/loss, evaporation, bank storage,
  etc.)
• Development of Ruleset representing current
  reservoir operations policy
• Relevance to Settlement
• Impact of reservoir operations and physical
  processes on Texas deliveries and CID allotments
• Long-term water supply implications

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Roswell Artesian Basin Groundwater Model -
Implementation

• RABGW roots Lewis model (1991-1995) Keyes and
  SSPA enhancements
• Calibrated based on 1967-2000 heads, 1967-2000
  pumping data, and 67-2000 Pecos River base
  inflows
• Relevance to NEPA process
• Interrelationships between surface water
  deliveries, well pumping, and climatic drivers
• Direct impact on Pecos River flows from Acme to
  Artesia

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Carlsbad Area Groundwater Model - Implementation

• CAGW roots Lewis model (1991) Bjorklund and
  Motts survey (1959)
• Updated and enhanced by NM OSE and Intera
• Relevance to Settlement
• Interrelationships between surface water
  deliveries, supplemental well pumping, and return
  flows
• Direct impact on Pecos River flows below Avalon
  (and thus stateline deliveries)

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RBAM - Implementation

• Mass-balance calculation of Red Bluff flows
• Input includes RiverWare and CAGW outputs via DPT
• Monthly and annual surface-water budget for the
  Avalon to state-line reach
• Relevance to Settlement
• Pecos Compact obligations and departures
• Impacts of potential changes in reservoir
  operation and CID irrigation supply sources on
  stateline deliveries

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DPT - Implementation

• Coupling of RiverWare, CAGW, and RBAM
• RiverWare post-processing
• CID diversion, Avalon seepage and Avalon releases
• Time-step conversion
• CAGW pre- and post-processing
• Determination of CID supplemental well pumping
  entitlements
• Computation of Pecos River gains below Avalon
• Archiving
• Data
• Policy alternatives