Runoff Efficiency and Seasonal Streamflow Predictability in the U.S. Southwest

Project ID: 8730
Principal Investigator: Dagmar Llewellyn
Research Topic: Water Operation Models and Decision Support Systems
Priority Area Assignments: 2015 (Climate Change and Variability Research), 2016 (Climate Change and Variability Research)
Funded Fiscal Years: 2015, 2016 and 2017
Keywords: streamflow forecasting, decision support, kalman filtering, bayesian algorithm, analog forcasting, quantile regression, mtom, hindcast, uncertainty

Research Question

Streamflow forecasts sometime disagree with real-time conditions observed by Reclamation operators. Recent studies show that changes in climatic conditions have resulted in changes to temperature and precipitation patterns throughout the West. Anecdotal evidence suggests that differences between streamflow forecasts versus observation is increasing, such that existing forecast methodologies incorporate increasing variability and uncertainty, and extreme weather events.

This research seeks to identify and research web-based data assimilation methodologies that improve streamflow forecasts, including, but not limited to, (1) a Bias Aware Ensemble Kalman Filter (EnKF), (2) a Bayesian correction algorithm that combines historical climatological datasets with datasets used to create model based forecasts, (3) statistical methodologies such as quantile regression of forecast emsembles, and (4) analog forecast of hydrologic conditions from existing streamflow time series data.

Given the web-based assimilation methodologies identified above, a research question may be framed as follows:

What web-based assimilation methodologies if implemented, would significantly improve streamflow forecast accuracy?

Need and Benefit

As Reclamation's Dam Safety program estimates risk and downstream consequences for High Hazard Dams throughout the West, dam operations, operations forecasts, and hydrology are all important aspects of this risk assessment. Although risk and loss of life estimates are focused mostly on dam failure, many Reclamation dams are frequently required to pass non-failure releases that exceed safe channel capacities, potentially posing a threat to life and property. Reclamation operators also need to address short term operations adjusting operations in a real-time, dynamic environment. Increased hydrologic variability as a result of climate change increases the need for rapid optimal decision making, serving as a key driver for the proposed research.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Independent Peer Review

The following documents were reviewed by qualified Bureau of Reclamation employees. The findings were determined to be achieved using valid means.

Assessing recent declines in Upper Rio Grande River runoff efficiency from a paleoclimate perspective (final, PDF, 928KB)
By Douglas Blatchford, Dagmar Llewellyn
Research Product completed on May 01, 2017

This research product summarizes the research results and potential application to Reclamation's mission.

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Runoff Efficiency and Seasonal Streamflow Predictability in the U.S. Southwest (final, PDF, 3.7MB)
By Dagmar Llewellyn, Andy Wood, Flavio Lehner
Research Product completed on September 30, 2018

This research product summarizes the research results and potential application to Reclamation's mission.


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Last Updated: 4/4/17