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Proshlyakov I.V., Ismaiylov G. KH. - Concerning the Theory of Formation of the Maximal Rain Slope Runoff |
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Written by Erkin Turdibaev
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Thursday, 12 October 2017 |
The purpose of the work is the improvement of theoretical ideas about the formation of rain runoff from slopes and development on this basis of engineering methods for the determination of design characteristics of the maximum runoff when creating anti-erosion hydro technical structures on the slopes and in the primary channel network. Formation of slope runoff is considered as a result of deterministic-stochastic processes of rain events, infiltration of a part of the rainfall into the soil and runoff of the non-absorbed water along the slope. The technique of determining the statistical characteristics of potentially forming a drain of the rains (with a layer of more than 10 mm) such as the total layer, duration of falling, the intensity for various time periods. The method is based on the simulation of a non-stationary random process of the intensity of rainfall. It is implemented using actual realizations of dimensionless realizations of the layer increase of precipitation fallen during rain precipitation obtained from the data of the nearby weather stations. There is formulated a very probable qualitative picture of water absorption in the soil and process of water yield of slopes under surface runoff formation. The analytical expression of the slope infiltration capacity is given during the period of rain falling taking into account the initial (before the rain) moistening of the upper 10-cm soil layer. For the probabilistic assessment of the initial soil moisture content there is proposed a bilateral limited normal distribution. The upper and lower limits of fluctuations of a random variable of the initial moistening and other parameters of the distribution (mean and RMS) are defined by water-physical properties of the soil or according to the observations of humidity at the regional meteorological stations. On the basis of the model of the kinematic waves and curves of the distributions of the characteristics of the water yield there is proposed a technique of determination of sufficiency of maximum discharges of slope flow taking into account the assessment of the probability of the "current" slope length in the formation of the considered maximum. Comparison of modules maximum discharges obtained by the proposed scheme of their determination with the normative maxima showed that the latter are overrated by 20...40 % under provision of 5 % and 40 % respectively. At the provision of 1% they are practically the same.
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