Hidrológiai Közlöny 1962 (42. évfolyam)

3. szám - Egyesületi és műszaki hírek

200 Hidrológiai Közlöny 1962. 3. sz. Lászlóffy W..- A hidrológiai előrejelzések jelentősége The Sienifieance and Possibilities of the Development of Hydrological Foreeastina; By Dr. W. Lászlóffy Doctor of Technical Sciences The increasing number of large-scale hydraulic projects is a proof of the increasing world-wide significance of water management. A planned economy of water resources is impossible without reliable forecasts eovering (he longest possible period. The reliabilit.y of these forecasts, on the other hand, depends on the extent to which hydrology can be stripped from its more-or-less empirical character, and be raised to the level of natural sciences. Forecasting has been one of the most important tasks of the Hungárián Hydrographio Service established as the first in 1880 in the ÍDanube basin, and the hydrographio maps issued daily contain data on the Danube catchment even from beyond the Hungárián borders, which serve as the basis of forecasting. The International Danube Hydrographio Service had been called to life in 1920, liaving been helped in 1929 by wireless, and has recently been governed by the Danube Commission. For discussing the scientific problems relating to forecasting the first conference on hydrological forecasting of the Danube countries has been organized in spring 1961, the material of which is available in print. Hydrological forecasts may be prepared on the basis of 1. hydrological and 2. meteorological reports, 3. meteorological forecasts, or 4. cosmic observations, and may be founded on a) the causat ive rélationships of events, b) on their development history. The various methods are in practiee frequently used in combination. I. The forecasts founded on hydrological observations (stage-, or discharge data) involve essentially the determination of inulti-variablo rélationships. The problem should be solved with the least possible data and in a manner that the routine work of forecasting should be simple and rapid, and potential mistakes should be reduced to a minimum. The advantage of graphical work is to roveal at first glancé whether or not the inclusion of a variable is worthwhile, whether additional work is involved in relations of higher order, and the number of variables is unlimited just as in the numerical methods. A further advantage is that when used in a /orm resolved to threevariable rélationships, their usefulness is unimpaired even if one-, or two data are omitted. An important requirement in any forecasting work is the rapid and reliable communication of observation data to forecasting headquarters, and even their automated processing is practicable. The exploitation of possibilites offered by communication and instrument techniques is of primary significance. If the forecasts are not limited to individual isolated events (e. g., a flood peak), but are prepared continuously, the first approximating reports can be successively refined from day to day. 2. The forecasts founded on meteorological data (previous precipitation, snow cover) extend to longer advance period, but their aceuracy is necessarily inferior to those of the first group. On smaller watercourses. owing to the rapid passage'of flood waves, these may still represent. the only practically possible method. Automatic recording installations for minimizing time losses are here of particular significance. A further important consideration is that forecasting should be performed by the local authorities, responsible alsó for the necessary preventive measures. A disadvantage is that the continuous observation of meteorological conditions is a prerequisite for estimát ing the'actual water absorbing capacity of the catchment area. without which the potential runoff cannot be predicted. Over an extended period such observations may be felt superfluous. 3. Forecasting on the basis of meteorological prodictions is in the initial stages at present. The systematicstudy of meteorological conditions preceding exceptional hydrological events, the study of causative rélationships appears to be most promising. If the forecast is based on the periodicity in the trend of meteorological phenomena, it will be no more than an indication of the possibility of the hydrological event. but neither such forecasts are insignificant for the practice. 4. The hasis of forecasts founded on cosmic obserrations is the periodicity observable in the occurrence of these events. Similar forecasts relate to an extended period but are usually of an informativé character only. The observation rocords available are, unfortunately, short in most instances, and consist of waves of different — but not constant — length and amplitude. Consequent ly an analysis of the periods cannot lead to a correct restilt, unless the stock of information is representative, homogeneous and sufficiently copious in every respect. The analytical method used must not be based on arbitrary assumptions, and the work involved should be itt proportion with the anticipated result. Finally : the forecast must not be issued, unless its propability is at least 90 per cent, and it should even then not be extrapolated for an excessive period of time (Kresser). In spite of these difficulties remarkably good results have been reported in the literature (V. Frolow). Since any forecast should rely on a very thorough and comprehénsive hydrological knowledge utilizing the results of a variety of related sciences as well, the collective work of several experts is required for any development. In the Danube basin, owing to the geographical situation, this collective work calls further for international cooperation. Starting from these considerations, an organized, regular exchange of opinion is urged among the experts engaged in forecasting work in the Danube countries. * Office copies of this paper have been prepared in Russian and Germán, and can be made available on request. A Limnológiai Szakosztály február 23-i ülésén a következő előadások kerültek sorra : Dr. Woynarorich Elek : Haltáplálék vizsgálatok termésbióló giai jelentősé ge. Kárpáti Árpád : A nemesponty-ivadék táplálkozásbiológiájának néhány kérdése. Antalfi Antal : A harcsa tógazdasági tenyésztésének néhány kérdése. Tőig István : A balatoni berkek, mint árterületek bekapcsolódásának hatása a halállomány táplálékellátottságára. A Szakosztály március 29-i ülésén dr. Boros Ádám „A hazai hévizek felsőbbrendű növényzete" c. előadása hangzott el. A Vízkémiai és Víztechnológiai Szakosztály február 9-i előadóülésén dr. Bolberitz Károly ós Csanády Mihály együttes előadást tartott „Gijors közvetett eljárás a szulfáttartalom meghatározására természetes vizekben" címmel. Az előadók több, különféle eljárást mutattak be a szulfáttartalom gyors meghatározására és ismertették a hazai viszonyoknak legjobban megfelelő, sorozatvizsgálatra alkalmas eljárást is. Az ülés második előadója Gaál Lászlóné volt. Előadásának címe : „Vízvezetéki vizek alapsugárzása." Az előadó az ásott kutak ós foglalt források vizét hasznosító vízművek radiológiai vizsgálatának eredményeit közölte.