This multi-year effort was aimed at benefiting the Bureau of Reclamation from the integration of stochastic simulation techniques into planning and the development of the new Midterm Operations Model for the Colorado River Basin. To understand how streamflow has varied at interannual and interdecadal time scales, WWA researchers Rajagopalan, Nowak, Zagona, and Bracken empoyed suite of methodologies. At the interdecadal time scale, wavelet analysis was used to demonstrate the climatic drivers of streamflow variability, and a stochastic simulation of multisite streamflow with nonstationary spectral features was developed. At the interannual time scale, hidden Markov models were used to demonstrate that short-term changes in streamflow are greater than indicated by standard time-series analysis. In addition, development of a new probabilistic Midterm Operations Model was completed and is now in use by the Bureau of Reclamation.

Bracken, C. (2011). Seasonal to Inter-Annual Streamflow Simulation and Forecasting on the Upper Colorado River Basin and Implications for Water Resources Management. M.S. Thesis, Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder.

Bracken, C., B. Rajagopalan, and J. Prairie. (2010). A Multi-Site Seasonal Ensemble Streamflow Forecasting Technique. Water Resources Research 46: W03302.

Nowak, K., M. Hoerling, B. Rajagopalan, E. and Zagona. (2012). Colorado River Basin Hydroclimatic Variability. Journal of Climate 25(12): 4389.

Nowak, K. (2011). Stochastic Streamflow Simulation at Interdecadal Times Scales and Implications for Water Resources Management in the Colorado River Basin. Ph.D. Thesis, Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder.

Nowak, K., B. Rajagopalan, and E. Zagona. (2011). Wavelet Auto-Regressive Method (WARM) for multi-site streamflow simulation of data with non-stationary spectra. Journal of Hydrology, 410 (1-2): 1-12.

Nowak, K., J. Prairie, B. Rajagopalan, and U. Lall, (2010). A nonparametric stochastic approach for multisite disaggregation of annual to daily streamflow. Water Resources Research 46: W08529