slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Long-Term Salinity Prediction with Uncertainty Analysis: Application for Colorado River Above Glenwood Springs, CO PowerPoint Presentation
Download Presentation
Long-Term Salinity Prediction with Uncertainty Analysis: Application for Colorado River Above Glenwood Springs, CO

Loading in 2 Seconds...

play fullscreen
1 / 48

Long-Term Salinity Prediction with Uncertainty Analysis: Application for Colorado River Above Glenwood Springs, CO - PowerPoint PPT Presentation


  • 136 Views
  • Uploaded on

Long-Term Salinity Prediction with Uncertainty Analysis: Application for Colorado River Above Glenwood Springs, CO. Hydrology Days 2002. James Prairie

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Long-Term Salinity Prediction with Uncertainty Analysis: Application for Colorado River Above Glenwood Springs, CO' - kitra


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Long-Term Salinity Prediction with Uncertainty Analysis:Application for Colorado River Above Glenwood Springs, CO

Hydrology Days 2002

James Prairie

Water Resources Division, Civil, Architectural, and Environmental Engineering Department, and U.S. Bureau of Reclamation, University of Colorado, Boulder

Balaji Rajagopalan

Water Resources Division, Civil, Architectural, and Environmental Engineering Department, University of Colorado, Boulder

Terry Fulp

U.S. Bureau of Reclamation, University of Colorado, Boulder

Edith Zagona

Center for Advanced Decision Support for Water and Environmental Sysytems (CADSWES), University of Colorado, Boulder

motivation
Motivation
  • Colorado River Basin
    • arid and semi-arid climates
    • irrigation demands for agriculture
  • “Law of the River”
    • Mexico Treaty Minute No. 242
    • Colorado River Basin Salinity Control Act of 1974
stochastic simulation
Stochastic Simulation
  • Simulate from the conditional probability function
    • joint over the marginal densities
parametric par 1
Parametric PAR(1)
  • Periodic Auto Regressive model (PAR)
    • developed a lag(1) model
    • Stochastic Analysis, Modeling, and Simulation (SAMS) (Salas, 1992)
  • Data must fit a Gaussian distribution
  • Expected to preserve
    • mean, standard deviation, lag(1) correlation
    • skew dependant on transformation
    • gaussian probability density function
modified nonparametric k nn natural flow model
Modified Nonparametric K-NN Natural Flow Model
  • Improvement on traditional K-NN
  • keeps modeling simple yet creates values not seen in the historic record
  • perturbs the historic record within its representative neighborhood
  • allows extrapolation beyond sample
residual resampling

e

*

t

y

*

t

y

t-1

Residual Resampling

yt = yt* + et*

statistical nonparametric model for natural salt estimation
Statistical Nonparametric Model for Natural Salt Estimation
  • Based on calculated natural flow and natural salt mass from water year 1941-85
    • calculated natural flow = observed historic flow + total depletions
    • calculated natural salt = observed historic salt - salt added from agriculture + salt removed with exports
  • Nonparametric regression (local regression)
    • natural salt = f (natural flow)
  • Residual resampling
crss simulation model for historic validation
CRSS Simulation Model for Historic Validation

Natural flow 1906-95

Natural salt 1941-95

Constant salinity pickup 137,000 tons/year

Exports removed @ 100 mg/L

Compare results to observed historic for validation

annual model with resampling
Annual Model With Resampling
  • Based on 1941-1995 natural flow
  • 1941-1995 annual salt model
  • Simulates 1941-1995
  • Historic Flow and Concentration
modified and existing crss comparison historic salt mass
Modified and Existing CRSS ComparisonHistoric Salt Mass
  • Based on 1906-1995 natural flows
  • 1941-1995 monthly salt models
  • Simulates 1941-1995
policy analysis historic simulation
Policy AnalysisHistoric Simulation

> 650,000 tons salt

> 350 mg/L salt concentration

stochastic planning runs projected future flow and salt mass
Stochastic Planning Runs Projected Future Flow and Salt Mass
  • Passing gauge 09072500
  • Based on 1906-1995 natural flows
  • 1941-1995 monthly salt models
  • Simulating 2002 to 2062
conclusion
Conclusion
  • Developed a modeling framework for long-term salinity with uncertainty in the Colorado River
    • modified nonparametric K-NN natural flow model
    • statistical nonparametric natural salt model
    • validation of historic record
    • demonstrated future projection
future work
Future Work
  • Extend the modified K-NN flow model to perform space-time dissaggregation to simulate flow and salt over the entire basin
  • Move operational policy to an annual time step
  • Further research into the relationship between salt loading and land use
  • Continue work to incorporate climate information in streamflow generation
acknowledgements
Acknowledgements
  • Balaji Rajagopalan, Terry Fulp, Edith Zagona for advising and support
  • Upper Colorado Regional Office

of the US Bureau of Reclamation,

in particular Dave Trueman for funding and support

  • CADSWES personnel for use of their

knowledge and computing facilities

conclusions
Conclusions
  • developed and tested a new statistical nonparametric natural salt model
  • discussed nonparametric techniques
    • flexible and easy to implement
    • can preserve any arbitrary distribution
    • conditioning with additional data
  • validation of historic record
  • preservation of historic salinity violations
case study
Case Study
  • Colorado River above USGS gauge 09072500 (Colorado River near Glenwood Springs, CO)
    • flow data available from water year 1906-1995
    • salt data available from water year 1941-1995
    • model at a monthly timestep to accommodate the reservoirs operating policy in the simulation model
motivation31
Motivation
  • Generating synthetic natural flow
    • future variability
  • Index Sequential Method (ISM)
    • cannot produce values or traces that had not occurred in the past
    • limited variability among traces
enso response in colorado river basin
ENSO response in Colorado River Basin
  • Published by Cayan and Webb, 1992
  • A weak response seen over Upper Colorado River Basin
slide33

Sea Surface Temperature

Correlation

Sea Level Pressure

slide34

Residual Resampling

yt = yt* + et*

et*

yt*

Alpha = 0.4 or k = 18

yt-1

model validation natural flow
Model Validation Natural Flow
  • 1941-1995 natural flow
  • Utilizes subset of available record
model validation natural flow36
Model Validation Natural Flow
  • 1906-1995 natural flow
  • Utilizes entire available record
model validation natural salt mass
Model Validation Natural Salt Mass
  • 1941-1995 natural flow
  • Utilizes subset of available record
  • 1941-1995 monthly and annual salt model
model validation natural salt mass38
Model Validation Natural Salt Mass
  • 1906-1995 natural flow
  • 1941-1995 monthly salt models
annual model with no resampling
Annual model with no resampling
  • 1906-1995 natural flow
  • 1941-1995 annual salt model
  • Historic Flow and Concentration
motivation41
Motivation
  • Salinity Control Forum
    • Federal Water Pollution Control Act Amendments of 1972
    • Numerical salinity criteria
      • 723 mg/L below Hoover Dam
      • 747 mg/L below Parker Dam
      • 879 mg/L at Imperial Dam
      • review standards on 3 year intervals
    • Develop basin wide plan for salinity control
existing colorado river simulation system crss
Existing Colorado River Simulation System (CRSS)
  • Includes three interconnected models
    • salt regression model
      • USGS salt model
    • stochastic natural flow model
      • index sequential method
    • simulation model of entire Colorado River basin
      • implemented in RiverWare
index sequential method
Index Sequential Method
  • Current stochastic hydrology model utilized by the USBR

Adapted from Ouarda, 1997

model evaluation
Model Evaluation
  • Natural flow 1906 to 1995
  • Basic Statistics
    • mean,standard deviation, autocorrelation, skewness
  • Higher Order Statistics
    • probability density function
    • conditional probability
  • Minimum and Maximum Flows
usgs salt model
USGS Salt Model
  • 12 monthly regressions
    • based on observed historic flow and salt mass from water year 1941 to 1983
    • historic salt = f (historic flow, several development variables)
    • natural salt = f (natural flow, development variables set to zero)
policy analysis historic simulation46
Policy AnalysisHistoric Simulation
  • > 350 mg/L salt concentration

Incorporates total depletion as a function of natural flow

crss simulation model for future prediction
CRSS Simulation Model for Future Prediction
  • Natural flows based on 1906-1995
  • Natural salt model based on 1941-1995
  • Projected depletions 2002-2062
  • Constant Ag salt loading of 137,000 tons/year
  • Constant salt removal with exports of 100 mg/L/year
policy analysis future projections
Policy Analysis Future Projections

> 750,000 tons salt

> 600 mg/L salt concentration