The technique of channel deformations of the Western Siberia Rivers

The technique for estimating channel deformations is offered. The technique suggests selection of data from the long-term hydrological supervision, which corresponds to fixed water levels Hi (Hi=Hmin+i-AH, i=1,..., m; AH - a constant increment; Hmin - the minimal value of a water level). If there is no fixed value of water level Hi, then values of parameters of a stream are interpolation between nearest dates. Then for each data selection, values of amplitude and standard deviations for width and maximum depth are determined at a fixed water level Hi. To evaluate vertical deformations, the top limit of the greatest standard deviation of the maximum stream depth ob(hmax) is used, whereas the top limit of the greatest standard deviation of a stream width ob(B) is used for evaluation of horizontal deformations. To calculate upper limit of the standard deviation, the formula is used: ob² = s²-(N-1) /^1-02, where a-a significance value; N - volume of sample; tf-i-an - a percentage point of distribution s² - an estimation of a dispersion. The significance value should be 5 % taking into account maximum allowed error for defining water discharge with some tools. To prove the technique, channel measurements on the Chulym river in the Asino town (tributary of the Ob river, Western Siberia, Tomsk region) were analyzed. The channel measurements were taken during 2001-2006. It is shown that ratio of ob and the module of the maximum annual erosion velocity at a significance value of 5 % equals 0,97 for horizontal deformations, and 0,82 for vertical deformations in the research area of the Chulym river in Asino (for 29 cross-sections). Using obtained results, values of horizontal and vertical channel deformations have been adjusted or defined for Vasjugan river at Maisk (ob(B) =4,3 m/year; ob(hmax) =0,32 m/year), Erkal-Nadei-Pur river at Khalesovoy (ob(B) =24,4 m/year; ob(hmax) =1,71 m/year), and Chuchja river at Chuchie (ob(B) =96,0 m/year; ob(hmax) =1,96 m/year). The mentioned rivers are generally typical for taiga (Vasjugan river), forest-tundra (Erkal-Nadej-Pur river) and tundra zones (Chuchja river) in Western Siberia. Their characteristics can be used for calculation of channel deformations of hydrologi-cally unexplored rivers in Western Siberia, which belong to a corresponding category, as well as for construction of pipeline and motorway connections (in a similar environment including the same type of channel process) using following formulas: Ziim = Zmin - oj(hmax) - Sn, ABt = T-(ob(B) + SB), where Sb and Sh - errors of measurement of width and depth of a stream; Zmin -the minimum mark of a bottom; Zlim - extremely possible vertical washout of a channel; ABr -greatest possible horizontal channel deformations; T- the projected period.

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