Vízügyi Közlemények, 1932 (14. évfolyam)

2. füzet - XII. Kisebb közlemények

24 investments that do not seem sufficiently remunerative, for our climate renders only a supplemental irrigation necessary ; furthermore, because of the dismemberment by the Peace Treaty of the Tisza basin, the building of storage reservoirs, which would serve also for the purpose of flood control, has become extremely expensive and difficult. Table XIII shows the gradual rising of flood flow line, the main cause of which lies in the fact that especially up to 1895 the levees were weak and low, and breaches often occurred, consequently only a part of the flood water flowed off between the levees. The rising of the flow line is still going on, as a result of new levee constructions of smaller extent. Table XIV contains records of duration of water levels showing that, irrespective of some local exceptions, the level of floods is sinking, or rather the occurrence of exceptional high waters is becoming more infrequent. Finally Fig. 14 proves that between 1890 and 1930 the silting up of flood areas between river banks and levees was not of such an extent as to bring about the rising of flood flow line. C) River improvement. The Tisza as a waterway. Fig. 15 and the Table annexed illustrates the alterations of river bed, and Figs. 16—17 show some characteristic windings of the Tisza River. According to the principles of river improvement of that time, the cutoffs were made in a straight line ; this damaged the river bed, the cutoffs have grown too wide, consequently have not deepened in a suitable manner ; this necessitates special improvement works with respect to low water. These works together with the canalization of the tributaries and the constructing of the Danube-Tisza Canal had already been taken in hand before the world war, but have given up because of the dismemberment of the country. Only the improvement of fords is in progress, this is done cheafly with fascine work, stone being but little used on the Tisza (see Figs. 18—20). The results of ford improvement are shown in Table XVIIT. (Heads : Water levels at Szolnok, Their duration in days expressed as averages of 25 years and of two dry years, Depth available for shipping above and below Szolnok before and after construction of the works). D) Flood-fighting organization. Levee companies and State cooperation. The works of river improvement were done by the State, those of flood control by autonomous levee companies formed of the interested landowners. This system has necessarily involved a gradual development of State supervision, which is of great importance for the maintenance of works, as well as for the flood fighting organization. E) Economic and hygienic successes. By the work done in the Tisza basin by means of investment of 400 million gold crowns, the national wealth has been augmented by 2 milliards of gold crowns. The cadastral net income of the protected lands has increased 2-2 times, the area of arable lands has become 2-22 times as large, the uncultivated areas have been decreased to 6-3 per cent of those existing before flood control. Malaria previously frequent, has been eliminated from the Tisza Valley, and the density of population considerably increased. F) Situation of the Carpathian basin with regard to flood control. Figure 21 shows the map of the Carpathian basin with the frontiers before (white dotted line) and after the world war (black dashed line). Pre-war Hungary had a geographic and economic unity almost unrivalled in the whole world. In this territory the Hungarian hydraulic engineers achieved a real second conquest of the country, by constructing 6380 kilometres (39(54 miles) of levees and protecting against floods