Abstract
In this work, the maximum spring flood flow was calculated, statistical parameters of flow were estimated and independent runoff rates were determined. The statistical parameters of the spring flow depth and maximum water flow were determined for different characteristic periods. The methods of integrated and different integrated curves have been used to identify the features of the multi-year runoff in different basins. For the water basins under study the norms and coefficient of variation of the spring flow depth and maximum water discharge were calculated in 2 variants: based on actual observation data; for the last forty-five-year period (1970-2015); and for the conditionally-natural period (from the beginning of the representative period up to 1970), respectively on gauging stations: Selety river - Isobilnoye village, Yesil river - Turgenevka village, Moyildy river - Nikolaevka village, Zhabai river - Atbasar village, Zhabai river - Balkashino village, Selety river - Prirechnoye village, Yesil river - Astana city, Yesil river - Petropavlovsk city. The analysis of the agreement of empirical and analytical distribution functions has shown that the distribution of spring flow characteristics of most rivers corresponds to the Kritsky - Menkel frequency curve. The analysis of the mutual arrangement of the empirical frequency curve and the theoretical as well as the integral curves showed that the curve deviates least from the empirical points of the curve corresponding to the ratio Cs /Cv =2. This curve was taken as a rated value.