Analytic Vs Numeric Analytic Vs Numeric Ground Water ModelsGround Water Models

Ray R. Bennett, PERay R. Bennett, PEColorado Division of Water Colorado Division of Water

ResourcesResources

Example Analytic (Glover) Example Analytic (Glover) ApplicationApplication

Analytic (Glover)Analytic (Glover)

Depletion (q) is a function of:Depletion (q) is a function of:–– Pumping (Q)Pumping (Q)–– Transmissitivity (T)Transmissitivity (T)–– Specific Yield (Sy)Specific Yield (Sy)–– Distance from well to river (x)Distance from well to river (x)–– Distance to Aquifer Boundary (w)Distance to Aquifer Boundary (w)

Data is assigned by Aquifer (1 value)Data is assigned by Aquifer (1 value)RELATIVELY SIMPLERELATIVELY SIMPLE

Analytical (Glover) Analytical (Glover) Key AssumptionsKey Assumptions

Conductivity (K) is ConstantConductivity (K) is ConstantUniform Aquifer ThicknessUniform Aquifer Thickness–– Transmissitivity is ConstantTransmissitivity is Constant

Flat Water TableFlat Water TableStream is Fully PenetratingStream is Fully Penetrating

Analytical (Glover) ResultsAnalytical (Glover) ResultsResponse from Pumping in Month 1 OnlyResponse from Pumping in Month 1 Only

URF 6400511

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Example Numeric ModelExample Numeric Model

Numerical (Modflow) ModelNumerical (Modflow) ModelDepletion is still a function of:Depletion is still a function of:–– Pumping (Q)Pumping (Q)–– Hydraulic Conductivity (K)Hydraulic Conductivity (K)–– Aquifer Thickness (b)Aquifer Thickness (b)–– Specific Yield (Specific Yield (Sy) or StorageSy) or Storage Coefficient (S)Coefficient (S)–– Distance from well to river (x)Distance from well to river (x)–– Distance to Boundary (w)Distance to Boundary (w)

Data is assigned by Model Cell (1,000Data is assigned by Model Cell (1,000’’s)s)Might include complex geometry, multiple layers, Might include complex geometry, multiple layers, boundary conditions, partially penetrating boundary conditions, partially penetrating streams, ET from GW, subirrigation, impact on streams, ET from GW, subirrigation, impact on canals, canals, ……..LOTS of WORKLOTS of WORK

Numerical (Modflow) ResultsNumerical (Modflow) ResultsStream DepletionStream Depletion–– By stream Reach (not a point)By stream Reach (not a point)

Water LevelsWater LevelsGround Water BalanceGround Water BalanceStream Water BalanceStream Water Balance–– Phreatophyte CUPhreatophyte CU–– SubirrigationSubirrigation–– Complex Geology (faulting)Complex Geology (faulting)–– Complex BoundariesComplex Boundaries–– Multiple, Layered AquifersMultiple, Layered Aquifers

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Comparison SummaryComparison Summary

Item Analytical NumericalStream Depletion Yes Yes

Assumptions High Low-HighWater Levels No Yes

Complex Geology No YesDry Stream No Yes

Multiple Aquifers No YesEffort Low Med-High

South Platte DSS

Republican River

Division 1 except Republican (WD 65) and North Platte (WD 47)North

Platte

South Platte

Colorado Water Conservation Board and Division of Water Resources

SPDSS SPDSS Major ComponentsMajor Components

Data Data -- Tabular and MapsTabular and MapsNew Data New Data -- Irrigated Lands, Irrigated Lands, stream gages, aquifer data, and stream gages, aquifer data, and observation wellsobservation wellsTools Tools –– CU, SW, GWCU, SW, GWUser Involvement User Involvement Documentation & Product Documentation & Product DistributionDistribution

DSS Components

HydroBaseHydroBase Field and Historical Datadmis

dmis

dmis

dmis

d mi s

dmis

dmis

dmis

Surface WaterPlanningModel

TSTools

Water BudgetModel

Water RightsAdminCU Model

Other UserComponents

GroundwaterPlanningModel

= DSS Integration Component

Tabular DataTabular DataStationsStations–– StreamflowStreamflow–– Climate (temp, Climate (temp,

ppt., evap.)ppt., evap.)

StructuresStructures–– DiversionsDiversions–– ReservoirsReservoirs–– Instream Flows Instream Flows

Water RightsWater Rights–– TransactionTransaction–– NetNet

Ground WaterGround Water–– Water LevelsWater Levels–– Pumping TestsPumping Tests

CallsCalls–– TributaryTributary–– MainstemMainstem

OtherOther–– Agricultural Agricultural

StatisticsStatistics–– Crop Growth Crop Growth

CoefficientsCoefficients

Tabular DataTabular DataInternet (WWW)Internet (WWW)

Spatial (Map) DataSpatial (Map) DataBasemapBasemap–– HydrologyHydrology–– RoadsRoads–– Cities and TownsCities and Towns–– Public Land Survey Public Land Survey

(T(T--RR--S)S)

StationsStations–– DiversionsDiversions–– ReservoirsReservoirs–– Instream FlowsInstream Flows–– ClimateClimate

Irrigated AcreageIrrigated Acreage–– Water SourceWater Source–– Crop TypeCrop Type–– Irrigation MethodIrrigation Method

OtherOther–– Average Average

precipitationprecipitation–– Average Average

evaporationevaporation–– CanalsCanals–– DrainsDrains

Spatial DataSpatial DataIrrigated Acreage MappingIrrigated Acreage Mapping

Irrigated Area,

Crop Type,

Irrigation Method,

Water Supply

SoilData

Irrigated Acreage and Crop Type

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Climate Data

PARCEL CROP_TYPE IRRIGATION ACREAGE PERIMETER10101 Alfalfa Sprinkler 131.832 2610.94310102 Corn Flood 135.253 2650.78310103 Alfalfa Sprinkler 124.643 3103.06910104 Corn Sprinkler 123.794 2532.17510105 Corn Flood 133.197 2619.83310106 Small Grains Sprinkler 135.335 2649.93310107 Alfalfa Flood 134.877 2637.10510108 Alfalfa Flood 134.181 2637.85210109 Small Grains Flood 125.197 2542.80510110 Alfalfa Sprinkler 122.907 2521.061

Irrigation Method Ditch Efficiencies

Locally Calibrated Blaney-Criddle Crop Coefficients

PCU for Alfalfa at the Fort Collins Climate Station

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ASCE Standardized Modified Blaney-Criddle,TR-21 Coeff.

Bridge on County Road 56 over the Larimer County Canal

Consumptive UseConsumptive UseStateCUStateCU

StateCU Typical ResultsStateCU Typical ResultsCU by Water Supply (SW and GW)CU by Water Supply (SW and GW)

Figure 5Phase 5 CU by Water Supply

0100,000200,000300,000400,000500,000600,000700,000800,000900,000

1,000,000

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CU

(Ac-

Ft)

Surface Water Ground Water

StateModColorado’s Water Resources Planning Model

Ray Bennett, Colorado Division of Water Resources

StateMod Major Features

•Network System

•Monthly or Daily Time Step

•Prior Appropriation Doctrine

•Structure TypesDiversions, Reservoirs,Instream Flows, Wells &Plans

•Operational Rules•Complex water operations

•Graphical User Interface

StateMod Features (cont.....)

•Creates Base or Natural Flows

•Efficient Solution Method– Direct Solution Algorithm– Modified Direct Solution Algorithm•Variable Efficiency

•Soil Moisture Accounting

•Plan Accounting

•Call Reporting

StateMod Typical ResultsStateMod Typical ResultsCompact Delivery Vs Compact CallCompact Delivery Vs Compact Call

9000

9500

10000

10500

11000

11500

12000

1/1/1850 1/1/1930 1/1/1950 1/1/1960 1/1/1970 1/1/1995

Compact Call Date

Yiel

d (K

af/y

r)

Colorado’s Ground Water Model Modflow (USGS)

Alluvial Aquifer

Modflow FeaturesModflow Features

GeologyGeologyAquifer ParametersAquifer ParametersPumpingPumpingRechargeRechargeBoundary ConditionsBoundary ConditionsStreamflows and DiversionsStreamflows and DiversionsSpringsSpringsDrainsDrainsEvapotranspirationEvapotranspirationSubirrigationSubirrigation

Modflow Typical ResultsModflow Typical ResultsProposed Pumping ImpactProposed Pumping Impact

More about SPDSSMore about SPDSSWeb SiteWeb Site–– http://cdss.state.co.ushttp://cdss.state.co.us

DWRDWR–– Ray Bennett (303) 866 Ray Bennett (303) 866 -- 35853585–– ray.bennett@state.co.usray.bennett@state.co.us

CWCBCWCB–– Ray Alvarado (303) 866 Ray Alvarado (303) 866 -- 3517 3517 –– ray.alvarado@state.co.usray.alvarado@state.co.us