EXHIBIT 120 Walker River Basin Decision Support Tool (DST) Version - - PDF document

EXHIBIT 120

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Walker River Basin Decision Support Tool (DST) Version 2.0

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Original DST Mission – ca. 2006-7

What: Develop a Decision Support Tool (DST) that includes the important spatial, temporal, and vertical complexities of the hydrologic behaviors of the of Walker River Basin to inform proposed water right acquisitions aimed at increasing flows to Walker Lake. Why: Options for water right acquisitions (purchases and/or leases) are being obtained. DST will provide an estimate of how much additional water will make it to Walbuska based on different acquisitions and climate conditions.

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Our Modeling Approach

• 1. Understand the process, scale, and data

needs/constraints of the Walker River Basin - supply and demand.

• 2. Identify and evaluate existing and previous modeling

and data collection efforts.

• 3. Identify and obtain available hydrologic information

for the system.

• 4. Develop physically realistic hydrologic models of the

supply and demand components of the system.

• 5. Create and test a DST, based on the physical models,

that can be used to inform water acquisition decisions.

• 6. Use the DST.

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Phase I & II

• 1. Development and initial testing of DST completed

December 2008. Phase I completed.

• 2. The “Water Group” formed in January 2010. Designed,

conducted, analyzed and discussed experiments with DST aimed at understanding Walker River basin behavior.

• 3. Phase II started in August 2010. Based on needs of

Water Group, effort to improve DST started in January 2011.

• 4. DST version 2.0 presented to Water Group in January
• 2012. Continued interactions with Water Group planned

through CY 2013.

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Overview of DST 2.0 Model Components

MODFLOW models

• f Mason & Smith

(Demand Side) PRMS models of headwater areas (Supply Side) MODSIM River Basin Management system

Douglas P. Boyle Department of Geography, University of Nevada, Reno

What is MODSIM?

MODSIM River Basin Management Decision Support System Network comprised of nodes and links Includes tools for priority, variable colors of water, and optimization. Provides user with access to all variables and parameters within time loop. Capable of linking with other hydrologic models (e.g., MODFLOW, PRMS, etc.). GeoMODSIM implemented in GIS software. Agricultural Demand

GW 20% New Lands 5% Flood 5% Decree Storage 10% Decree 60%

Douglas P. Boyle Department of Geography, University of Nevada, Reno

MODSIM Conceptual Model

Boundary Conditions: Obst = 100 Boundary Conditions: Obst = 30

HRU 1 HRU 2 HRU 3

P2: High D2: 30 P3: Low D3: 25 P1: Med. D1: 35 PB: Very High DB: 30

30 35 30 5 5 5 15

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Application of MODSIM to Walker River Basin

MODSIM upstream boundary conditions - driven with

• bserved monthly streamflow

for 1996 through 2011. Reservoir storage and evaporation simulated at Bridgeport and Topaz. Diversion node for each ditch in Mason and Smith Valleys; HRUs defined by agricultural area served by each ditch. Agricultural areas with primary pumping defined as separate HRUs.

Douglas P. Boyle Department of Geography, University of Nevada, Reno

MODSIM Mode 1: Historic Ditch Demand

Dx: Decree, storage, and flood water diverted at each ditch based

• n historic delivery records

according to priority, Px. Water balance computed at each HRU on 100m grid scale based on crop type, NSE net water requirement, supplemental pumping, farm efficiency, ditch loss, etc. Water applied becomes ET, infiltration, or runoff.

Iterative MODSIM/MODFLOW convergence

MODSIM – partitioning and distribution

• f all surface water

MODFLOW – interaction of surface and groundwater

HRU 1 HRU 2 HRU 3

P2, D2 P3, D3 P1, D1 R1 R2 R3

Douglas P. Boyle Department of Geography, University of Nevada, Reno

MODSIM Mode 2: Crop Demand

Dx: Decree, storage, and flood water diverted at each ditch based

• n crop demand and ditch level

priority, Px. Historic diversions used to evaluate model. Water balance computed at each HRU on 100m grid scale based on crop type, NSE net water requirement, supplemental pumping, farm efficiency, ditch loss, etc. Water applied becomes ET, infiltration, or runoff.

Iterative MODSIM/MODFLOW convergence

MODSIM – partitioning and distribution

• f all surface water

MODFLOW – interaction of surface and groundwater

HRU 1 HRU 2 HRU 3

P2, D2 P3, D3 P1, D1 R1 R2 R3

Douglas P. Boyle Department of Geography, University of Nevada, Reno

MODSIM Network

MODSIM Streams & Drains MODSIM Ditches

Legend

Douglas P. Boyle Department of Geography, University of Nevada, Reno

West Hyland HRU

MODSIM Streams & Drains MODSIM Ditches

Legend

West Hyland HRU

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Water Balance Modeling Units

MODSIM Streams & Drains MODSIM Ditches

Legend

West Hyland HRU Model Grid

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Primary GW HRU & GW POU

MODSIM Streams & Drains MODSIM Ditches

Legend

West Hyland HRU Model Grid Primary GW HRU GW POU GW Well

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Portion of West Hyland With Supplemental GW

MODSIM Streams & Drains MODSIM Ditches

Legend

West Hyland HRU Model Grid Primary GW HRU GW POU GW Well West Hyland Modeling Units With Supplemental GW

Douglas P. Boyle Department of Geography, University of Nevada, Reno

• 1. Determine available surface water at POD (Surf1)
• 2. Surf2 = Surf1*(1-DCL)
• 3. CD = Ag. Area * NIWR (State Engineer)
• 4. CIWR = CD / (EFarm)
• 5. PReq = CIWR – Surf2
• 6. SPMax = f(Permits)
• 7. PAct = PReq or Balance of SPMax
• 8. App = PAct + Surf2
• 9. OFL = App*(1-EFarm)

10.RO = RFactor*(OFL) 11.RCH = (1-RFactor)*OFL

Hudson Gage Strosnider Gage Wabuska Gage HRU

Uncertainty Parameter

Surf1 = Surface Supply at POD DCL = Ditch Conveyance Loss Surf2 = Surface Supply at Ag. Area CD = Crop Demand EFarm = Farm Efficiency NIWR = Net Irrigation Water Req. CIWR = Crop Irrigation Water Req. SPMax = Seasonal Pumping Maximum

Surf1 Surf2 DCL

# Acres AF A 4 SPMax = *

PAct App

PReq = Pumping Required PAct = Pumping Actual App = Application OFL = On Farm Loss RFactor= Runoff Factor RO = Runoff RCH = Recharge

Terms and Definitions

Walker DST Water Balance 2.0 RO

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Consumptive Use Comparison (2007)

West Hyland Non-NDOW

0.1 0.2 0.3 0.4 0.5 0.6 0.7 Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07 Oct-07 Feet METRIC ET NIWR DST Consumptive Use

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Example Wabuska Calibration Streamflow

20000 40000 60000 80000 100000 120000 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Acre-Feet Simulated Observed

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Basin-wide GW Pumping (Mason and Smith)

20 40 60 80 100 120 140 160 1996 1997 1998 1999 2000 2001 2002 2003 2004 Thousand Acre-Feet

Walker Basinwide GW Pumping Comparison

Observed DST (53,15,35)

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Example West Hyland Demands & Deliveries

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Application No. 80700

• Summary

– 646.16 Acres of West Hyland HRU – 7.745 CFS of Decree Rights – Claim Numbers: 23, 23A, 35, 44, 67, 89 – Priority Dates: 1874, 1877, 1880, 1881, 1887, 1888, 1891, 1894, 1896, 1900, 1901, 1904, 1906

MODSIM Streams & Drains Change App. Parcels West Hyland HRU

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Application No. 80700 – DST Methods

• The DST was modified from the baseline model run to reflect, as closely as

possible, the effects of the proposed change over calendar years 1996 through 2011. The results from the scenario model run are then compared to the results from the baseline model run.

• The change application parcels are removed from the DST modeling grid

(i.e. fallowed) & supplemental pumping is retired for the parcels.

• The volume of surface water that is not applied in the scenario run (i..e.,

Application 80700 water) is calculated based on the fraction of the areas taken out of production relative to the total non-NDOW HRU area. It is equal to the sum of the decree, flood and storage water delivered to the same areas in the baseline run.

• The Application 80700 water is “protected” at the West Hyland point of

diversion and allowed to flow to Wabuska.

• The 80700 Wabuska water is the amount of Application 80700 water that

makes it to Wabuska

Douglas P. Boyle Department of Geography, University of Nevada, Reno 26,834 29,500 25,344 221 92 5,000 10,000 15,000 20,000 25,000 30,000 35,000 Total Acre-Feet (1996 - 2011) Retired GW Pumping

• App. 80700 Water

80700 Wabuska Water Shortage Surplus

Scenario Results (1996-2011)

Decree = 20,762 Flood = 3,111 Storage = 5,627

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Scenario Results (Annual)

1,000 2,000 3,000 4,000 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Acre-Feet Retired GW Pumping

• App. 80700 Water

80700 Wabuska Water Shortage Surplus

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Shortage By Demand (1996-2011)

5 10 15 20 25 30 35 40 45 50 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Acre Feet RP_Stanley PF MSW_Wabuska

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Surplus

5 10 15 20 25 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Acre Feet Surplus

Douglas P. Boyle Department of Geography, University of Nevada, Reno

Summary of Application No. 80700 DST Run

• Results from the scenario model run were then compared to

the results from the baseline model run.

• An analysis of the results indicates that, within the

assumptions and limitations of the DST and the scenario method, 86% of the Application 80700 water makes it to Wabuska over the sixteen-year time period with an annual range between 77.3% and 92.9%.

• The analysis also indicates that there were no shortages in

surface water delivered to the remaining areas of the West Hyland HRU but that there are occasional minor shortages and surpluses within the system.