Calculation of the maximum water discharges of ood in Azerbaijan rivers
The article is devoted to the calculation of the maximum water discharges of rain floods in the rivers of Azerbaijan, according to the formula of maximum intensity, which has been used by the country’s design institutes for many years. It is noted that, as in all mountainous countries, the conditions for the formation of the maximum flow of river in Azerbaijan change depending on the altitudinal position of the river catchment. The maximum water discharges of rivers originating in the middle and high mountains (2000 m and more) are formed as a result of snow melting. With a decrease in the height of the catchment area, the role of rainwater increases, and the maxima of rain origin predominate in the regime of rivers. The article uses information on the maximum instantaneous water discharges of 19 rivers, the basins of which are located in different regions of Azerbaijan, morphometric indicators of these rivers and their watersheds, daily precipitation maxima, as well as a soil map at a scale of 1:500,000. All the main parameters of the maximum intensity formula have been refined: the values of the daily maximum precipitation of 1 % exceedance probability, the runoff coefficient and the relative maximum runoff modulus of 1 % exceedance probability. Using data from 75 meteorological stations, a new map of maximum daily precipitation with 1 % exceedance probability was built. It has been established that the slope travel time for the considered small rivers varies within 52-200 minutes. The value of the runoff coefficient is 0.20-0.40. It is shown that by refining the main parameters of the maximum intensity formula, it was possible to improve the accuracy of calculations of the maximum water discharges of rain floods in the rivers of Azerbaijan. For the considered rivers, the calculation errors vary within 1-238 %. The median value of these errors is 38 %. For comparison, according to earlier calculations, these figures were 4-128 % and 47 %, respectively. Thus, as a result of refinement of the parameters of the maximum intensity formula, the median value of the calculation errors decreased by 9 %