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A Dynamical-Systems Approach for Computing Ice-Affected Streamflow, 1996

By David J. Holtschlag


A dynamical-systems approach was developed and evaluated for computing ice-affected streamflow. The approach provides for dynamic simulation and parameter estimation of site-specific equations relating ice effects to routinely measured environmental variables. The form of the site-specific equations are user specified. Parameters are estimated by minimizing an objective function, which is also user specified. Error correction is used to prorate the error in the simulation estimates so that final estimates match daily mean discharge computed on days of direct streamflow measurements.

The accuracy of the dynamical-systems approach was evaluated by use of an extensive data set that provides detailed information on ice-affected streamflow for three streams in Iowa during the winter of 1987-88. The report expands on the work of previous investigators, who originally obtained the data and compared 11 analytical methods that are proposed or commonly used for estimating ice-affected streamflow.

Comparison indicates that the results from the dynamical-systems approach ranked higher than the results from 11 analytical methods previously investigated on the basis of accuracy and feasibility criteria. Given the modest data requirements, ease of computer application, and the reproducibility and objectivity of the method, the dynamical-systems approach has the potential to become an important method for computing streamflow records. Research on alternative forms of site-specific equations, choice of objective functions and optimization methods, simultaneous simulation of ice-effects in a network of stream-flow-gaging stations, and the effect of time-step length will likely lead to further improvements in the dynamical-systems approach.

Holtschlag, D.J., 1996, A Dynamical-Systems Approach for Computing Ice-Affected Streamflow: U.S. Geological Survey Water-Supply Paper 2473, 14 p.

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