Vízügyi Közlemények, 1932 (14. évfolyam)

2. füzet - XII. Kisebb közlemények

22 In Austria an important sphere of activity is the regulation of torrents and the prevention of erosion. These works are done by special departments created in the individual States for torrent regulation, and subordinated directly to a central bureau in Vienna. Annually on an average 6-5 million shillings is appropriated to this work, of which sum 85 per cent is supplied by the Confederation and the States. Apart from personal and material expenses, as well as from sums employed for construction of water power plants, on an average and in round numbers 50 million shillings is expended on hydraulic structures annually. 80 per cent of this sum is granted by the Confederation and the States, while only the remaining 20 per cent falls to the charge of parties interested. II. THE TISZA VALLEY. Hydrographie Description aud Enumeration of River Improvement Works. By : WOLDEMÁR LÁSZLÓFFY. A) Hydrographie Description. The waters of the eastern part of the Carpathian basin are collected and carried into the Danube by the Tisza River. Its tributary areas comprise 157,135 square kilometres (60,670 sq. miles) and are embraced in a semi-circle by the Carpathian Mountains ranging to elevations between 700 and 2500 metres (2300—8200 feet). From these areas numerous tributaries abounding in water run onto the vast plain, the elevation of which averages from 80 to 100 m (260—330 ft). Of these tributaries the Szamos, Bodrog, Sajó, Körös and the Maros are the most important (Fig. 1). In the Tisza basin semi-permeable and impermeable rocks prevail. (Fig. 2, Black spots indicate permeable, white spots impermeable surface). This fact together with the steepness of bordering hillsides has brought about the torrential character of the Upper Tisza and of its tributaries. The Tisza has a total length of 1000 kilometres (620 miles). In its lower section of 700 kilometres (430 miles) the river has a fall of only 32 metres (105 feet), i. e. on an average 4-5 centimetres per kilometre (0-24 ft per mile). Owing to this slightness of its fall the river cannot carry off the mass of its flood water, which before the controlling works were made, spread over its flood area, covering it with water for months in every year. 26 per cent of the watershed area is under forest. Figure 3 shows the seasonal distribution of rainfall ; Tables I and II and Figure 5 represent the percentage relations of rainfall to runoff. Fig. 4 displays types of the characteristic features of the river showing typical floods of long duration extending into the spring rainfall period ; the other type is represented by summer floods following mild winters poor in precipitation. Table III gives variations of the coefficient of annual runoff and Table IV those of monthly runoff. Table V shows the low, mean, and high waters of the river with discharges and range of fluctuations in water levels, respectively. Table VI gives data as to the alluvial matter carried by the Tisza in suspension, the average amount of which is 345—643 grams per cub. metre (150—280 grains per cu. ft.), that is 10—11 millions of metric tons (11—12 millions of short tons) per annum. B) Flood control of the Tisza Valley. The Tisza basin was long the scene of wars with the Turks, in which Hungary protected Western Europe against Islam, and then was devastated by wars of independence against the Austrian hegemony,