Vízügyi Közlemények, 1936 (18. évfolyam)

Kivonatok, mellékletek - Kivonat a 2. számhoz

VIII. canal to be absolutely necessary, and only the outbreak of the world-war prevented its construction within undivided Hungary. For the mutilated country its importance has increased all the more, because it will be a natural continuation of the Rhine

—Main

—Danube waterway. Furthermore we have to make the Sió river navigable and develop the harbours in the Balaton Lake. In order to cheapen our export goods, we have to improve the navigation conditions of our large rivers, and to canalize the smaller ones (Kőrös, Sajó, Bodrog). II. HAS FLOOD CONTROL CHANGED OUR CLIMATE? By Prof. Dr. A. RÉTHLY. (Pages 134—165.) For a long time it has been the fashion in Hungary, whenever there is an unusually dry year, to begin a press-campaign with the phrase : ,,Flood control and drainage have made the climate of the Great Plains arid." But it is nonsensical to assert that the climate of the Great Plains could have been altered by human interference, such as hydraulic engineering. It is incontestable that the carryingaway of harmful waters induced a new form of climate in the local areas affected, especially as regards microclimatologic relations ; but the abolition of evaporating water surfaces, such as swamps and flood areas, has not changed the climate of the country or even that of the Great Plains. Records in chronicles reaching back about a thousand years prove that at all times there have been droughts, which brought the greatest misfortunes and famines upon this country, and dryness has been the cause of 80% of crop failures both in the past and in the present ; whereas flood control has been in action for scarcely a century. The author analyses the elements of the weather on the basis of observations made in this country during several decades ; he points out that dew, air moisture, evaporation, rainfall and temperature were abundant in some years and summers, and practically wanting in others, and in general that they show large fluctuations. The most frequent allegations are as follows : 1. there is no longer any dew on the Great Plains ; 2. the air has lost its moisture content ; 3. evaporation is continually increasing, and has attained extremely large values ; 4. in summer there is no rainfall, and so we are faced with complete aridity, and the lands are becoming a desert ; 5. the temperature is constantly increasing, the summers have become very hot and the winters extremely cold. These allegations are by no means acceptable and are without any scientific basis. 1. Dew. Observations in Szerep reaching back for 30 years (1906—35), show great variations in the number of dewy days (Table I, page 136). The annual average is 107 days and the summer average 35 days ; we find summer with 63 (1915), and again with only 7 dewy days (1931). Similar extremes can be found in the annual numbers of dewy days, such as 184 in 1916 and 33 in 1907. In the neighbourhood of Fegyvernek the annual average is 177 days and the summer average 59. At Kompolt in the months of April

—October, dew has been observed on 29 days on an average (Table II). 2. Air moisture. In order to prove that we cannot speak of a gradually developing aridity, the author has compiled, from the observations made every day