SYSTEM-ANALYTICAL MODELLING: 2. ASSESSMENT OF RUNOFF MODEL SENSITIVITY TO ENVIRONMENTAL FACTOR VARIATIONS

To evaluate the performance of deterministic models in earth science, an elemen- tary method for assessing their sensitivity to natural variations of environmental factors and the subsequent uncertainty analysis (the evaluation of residual variance components) are pro- posed. Using a regional model of mountain river runoff as an example, the model sensitivity and all the components of its residual variance are calculated. It is shown that the sensitivity decreases in the sequence “precipitation – air temperature – landscape structure of the river basin” making 22–8–6 explained percent of the observed runoff variance respectively. Model inaccuracy does not exceed 34% of this variance. The most probable river runoff can be forecasted for 3–4 months ahead with a twice reduced variance as compared to the similar forecast based on the observed mean runoff.