This paper presents an assessment of changes in maximum flow values (maximum discharge, m 3 /s) of the spring flood caused by human activities on the rivers Zhayyk, Ilek and Tobyl. Statistical characteristics of the maximum discharge of the spring flood of these rivers for the period of 1940-2012, 1938-2012, before and after the construction of the reservoirs, as well as for the long-term period of supervision were analyzed based on the actual as well as restored data. The values of the maximum discharge of the spring flood of various provisions were calculated. The total integrated curves of the maximum discharge of the spring flood were constructed.

This paper considers the methods and results of determining statistical parameters for spring flood runoff by the main lowland river basins of Kazakhstan for the long-term period. It presents a series of observations made for the long-term period, determines statistical parameters for the depth of spring flood runoff as well as constructs the probability curves of the depth of spring flood runoff by study areas. The paper also gives an estimation of the probability values of the depth of spring flood runoff for the calculation period and for the last period of runoff formation in the context of ongoing climate change. These characteristics are determined by four river basins belonging to the lowland territory of Kazakhstan.

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