Abstract
The article considers the possibility of using the results of joint modeling of runoff and runoff- forming factors to assess and forecast the water resources in the Arys River basin. To solve this problem, the canonical decomposition method was used, which allows us to characterize a random process (river runoff) by a set of independent random variables and non–random functions. The method is optimal in the class of linear transformations, decomposition was carried out according to natural orthogonal components. Monthly, annual and vegetative hydrograph of the Arys River runoff were predicted for 2030, 2040 and 2050, according to two scenarios, RCP 4.5 and RCP 8.5. The results of the study showed that changes in river runoff by 2030, 2040, and 2050 fluctuate around the climatic norm of 1974–2019, both downwards and upwards. The use of the canonical decomposition model based on the dependence of runoff on climatic characteristics is fully justified by the results obtained.