Vízügyi Közlemények, 1944 (26. évfolyam)

1-4. szám - IV. Szakirodalom

(8) In the past in lieu of the rate of run-off mean yearly discharge or flood discharge was calculated (Table XIII). Later the method of accumulation and of the run-off of rainfall were taken into consideration. Korbély discriminated into three cases — according to whether the duration of the rainfall (T) and the down flow time (г) are equal or different (See Fig. 12, section a, b, c). As a result of his observation the discharges are shown on Tables XI and XII. At present there are quite a number of methods in calculating the rate of water discharge. Turazza, for instance, assumes that the total time of down flow resulting from precipitations is equal to T + r. According to this assumption per unit time in average — quantity of water drains off. Of this we obtain— according to the theory — the T + T maximum discharge by multiplying with an improving coefficient m (1 < m < 2). As a final result the rate of run-off according to Turazza is as follows: g-(ft

3/sec . acre) = 0'001652 m Т + т For the determination of the down flow (accumulation) time r and m in the studies of Pasini, Ventura etc. formulas may be found. (See page 51 in the Hungarian text.) In this study we have determined for each watershed area independently the values of г and min connections with the calculation of the run-off coefficient according to new ideas. (See Fig. 5.) If in the Turazza formula, as cited above, the value of h = a T

n are supplemented, the rate of run-off is expressed in function of T only. On this basis the extreme values of q = / (T), that is the rate of run-off, will be, according to Professor Németh (Budapest)'. q (ft

3/sec . acre) = Г652 m a an Puppini and the more recent Italian scientists take into consideration that the network of canals not only accumulates and drains off water but partially it also stores it. Consequently the rate of run-off according to Puppini is: i q (ft

3/sec . acre) = С ^ a and n are the constants of the Montanari probable climatic function, a is the run-off coefficient, v is the specific storage, that is the ratio of all the space at disposition for the storage (V

m) and the watershed area (

F

); and С — (30 v + 60) n where v is constant depending on the form of channel cross section, while n represents the exponent of the climatic probable function. 4. Run-off of melting snow. The rate of run-off of melting snow cannot be determined with the run-off coefficient since the run-off occurs mostly only after months, at the time of the melting in the spring. In Hungary the rate of run-off of melting snow, on authority of Korbély, is usually calculated on two arbitrary assumptions: 1. Half of the precipitation observed within one month of the winter (November to March) ought to drain off in 30 days, and more recently in 15 days; 2. Third of the precipitation of the winter months (November 1st—March 31st) ought to have been drained off on days with temperatures above the freezing point of the same period. In accepting these assumptions we have naturally no assurance at all that no more drainage water will originate than that calculated on the melting snow and perhaps on the rainfall that took place simultaneously. Neverthless, the two foregoing assumptions have led to satisfactory results in practice. On the basis of the assumptions referred to above we have also calculated the rate of run-off of the melting snow on the watershed areas in question for the years 1912 to 1941 (Table XIX). / пт \