Sensitivity of river flow models to environmental factors and its quantitative assessment

New methods (a) to assess the sensitivity of river runoff models to natural variations of environmental factors and (b) to analyze the components of their residual variance are proposed. Using a simulation model of mountain river flow, built with the help of system-analytical modeling, the sensitivity to the factors mentioned is calculated. The sensitivity decreases in the precipitation - air temperature - landscape structure series, comprising 22-8-6 explained percent of the observed runoff variance. Every component of the residual variance, including that formed by error of the model equations themselves, is evaluated. The latter does not exceed 34% of the observed runoff variance. Such calculation error meets the Nash-Sutcliffe efficiency NSE=0,66 and means a good model performance.