Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(90) runoff, or pedological questions. The studies and study tours were conducted in the areas of Wageningen, South-Netherlands and Zeeland, the Zuider-Lake and NorthHolland. Brief visits were organised to places of professional interest. The lectures on the course were delivered by the competent Dutch experts and the professional level was very high. Experiences gained during the course and of interest to experts engaged at home in agricultural water management are recounted in Chapter 3. a

) Special mention is made of the waterhousehold studies made in connection with land drainage and irrigation, together with the methods used. Studies on water losses in irrigation, the rising of the groundwater table, land drainage and the attendant problems and their effects are described. b

) Potential measures are listed for the drainage and melioration of alkaline soils, the depression of salts below the root zone, the removal of water therefrom, the determination of the quantities controlling the extent of drainage, namely the specific volume of water and the critical groundwater level. c

) The methods used in the application of automation, telereporting and computers in the field of agricultural water management are described and an example is presented for the estimation of future changes in the groundwater level, the relevant computation method of Thiessen by resolving into polygons, the automatic control of groundwater level, automated irrigation in hothouses, etc. d) In connection with the mechanization of maintenance work on small canals and mole drains, the maintenance of small canals ( Figs. 2 and 3), further the mechanical cleaning of mole drains (Fig. 4 and 5 ) are described. A list containing the lecture notes with the subject of the course is attached. BRIEF PUBLICATIONS AND REPORTS 1. Muszkalay, L., Civ. Engr. : Characteristics of wave motion in Lake Balaton (For the Hungarian text see pp. 489) Lake Balaton is the largest lake not only in Hungary, but also in Central Europe. The Research Institute for Water Resources Development established an observing station at the shore, the round 10 years of work there offered opportunity, among others, for studying wave motion in the shallow lake. Wave measurement data obtained at the Balatonszemes shore station and the observing station in mid-lake were processed and relationships established between the velocity u, direction and height H of the wave, its frequency n and period T. W

Tave height was taken into consideration on the one hand with the maximum height during the period of observation, on the other as the squared mean of a series of hundred including the highest wave. Wind velocity was determined as the average for the one hour period preceding the highest ware. The symbols used in the relationships given below are as follows: H

n = height of the wave (m), H

s = arithmetic mean of wave heights (m), H

m = maximum wave height of short-period observation (m), i/

ma

x = maximum wave height of long-period observation (m), U

s =wind velocity (m/sec), a = constant depending on wind direction (values are given in Table I), n =wave frequency (period/min). The relationships are as follows: a) From data of the shore station: H

n =a(U

a — 2)°>'

2

6. for winds from N and NW for other wind directions 168 _ 192 n = —- + 15 л = т +15 Г73/2 [73/2 L'a a Я„ = 1.100Я

а; #

m=2.220tf

a; #

та

х=2.890Я

а