Vízügyi Közlemények, 1934 (16. évfolyam)
4. szám - XI. Szakirodalom
19 Considering that the dispute between the two writers is of interest only to limited circles in this country, it has not been thought necessary to publish summaries of this article in foreign languages. V. METHODS USED IN ITALY FOR DETERMINING WATER VOLUMES TO BE CARRIED DOWN IN DRAINAGE CANALS. BY E. NÉMETH. Determination of the maximum discharge that comes to downflow in natural watercourses, or is to be carried down in artificial canals, forms one of the most important problems in the practice of hydraulic engineering. The largely empiric methods, still used as the basis of computations, cannot, in view of the importance of the problem, be regarded as affording the engineer a modus operandi upon which he can rely with a clear conscience. The maximum discharge of a watercourse or canal is affected by so many reciprocal factors, that it is simply impracticable to set forth general laws, formulas, or tables. In attempting to solve this problem, we have to seek for a process which will enable us to allow, as far as possible, for the individual particularities of the watercourse, and of its watershed area. The factors required may be divided into three groups, and consequently : 1. as to the rainfall conditions, some regularity expressible in a mathematical form is to be sought for ; 2. the runoff coefficient is to be established, regard being paid to the particularities of the watershed area ; 3. the phenomena of downflow in the river or canal bed are to be analyzed. Former investigations took into consideration only the factors under 1. and 2., while the phenomena under 3. were regarded as simple kinematic circumstances. Recent investigations in Italy pointed to the fact that at the downflow in channels storage, as well as the kinematic process, plays a considerable part. The rainfall conditions were taken into account by means of Montanari's climatic probability function li=at n, and the rate of runoff by using Pasings monthly runoff coefficients. Recently, at the suggestion of Sr. Puppini, the monthly variations of the runoff coefficient was reckoned with in such a way that, when applying Montanari's function to a certain area, in order to determine the parameters n and a, precipitation values reduced by the monthly runoff coefficients were employed. This reduction is necessary for the reason that the amount of precipitation observed in different months are, as to the runoff, of unequal value, just on account of the monthly change of the runoff coefficient. But, after the aforesaid reduction, all amounts of precipitation may be regarded, as if they had fallen in the month of February, when the runoff coefficient is a maximum. For this month Sr. Puppini suggested a runoff coefficient of k = 0-56, which of course is to be controlled and corrected in the different regions on the basis of local observations. Among the procedures recently used in Italy, Puppini' s analytical method and Visentini's graphical method are worthy of special attention. Sr. Puppini 2*