Vízügyi Közlemények, 1969 (51. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(103) 9. Flood control, changes in the regime of the recipient. Besides pollution, changes in the regime of watercourses passing through cities may also result from urbanization. Flood discharges in small watercourses may be increased significantly by gradual urban development in the catchment area, by sewerage, whereas channel improvement entails higher flood stages. On the other hand industrial withdrawal may reduce dry weather flows. 10. The requirements of recreation. For the recreation of urban population open baths are required, the necessary water exchange for which must be envisaged. Motorized tourism anf foreign travel created a new type of seasonal settlements, namely camping sites. Water supply and wastes disposal for these forms an organic part of urban development. Congestion of highways during dense weekend traffic may induce motorists to seek recreation along the rivers as a consequence of which water sport-centers must be supplied by public utilities and even the construction of boat harbours, launching facilities and rowing courses may become necessary. The occurrence of the above social demands is closely related to urbanization. 11. Conclusions. In conclusion it may be established that the grave consequences of urbanization for water resources management form an irreversible process. In the interest of future generations adverse influences should be minimized, and where possible remedied by all means and in every manner. CHARACTERISTICS OF WATER CONSUMPTION BY IRRIGATION SYSTEMS IN THE TISZA VALLEY By Dr. Dávid, L., Civ. Eng. (For the Hungarian text see pp. 471) No development of water resources management is possible unless more reliable information can be made available on the trend of water consumption by agriculture. The rate thereof is influenced from day to day by a wide variety of factors, so that consumption during the growing period may be regarded as a continuously varying unsteady process. For the proper description of this process records extending to several years and even longer periods, and relying on data collected especially for this purpose, are necessary. Records of this type are as yet available for isolated areas only, so that no claim at completeness can be made during the analysis. For a more exact mathematical formulation further data collection and processing is required. Since various factors affecting water consumption can be related to time, the relationship between consumption and time will be analysed subsequently. The unsteady process of water consumption by irrigation systems was found to be characterized by conditions of consumption during several periods. These periods may be classified as: the growing season, the characteristic period, the design period and the peak period. Consumption during individual periods must be considered — in view of the periodical variation of dry and wet years — as the average for several years and for the critical dry year —since with regard to the different functions of operation and water management different periods are representative. Water consumption can be characterized preferably by the duration curves of daily or monthly consumption in different periods, and by the integral curves of water consumption. Consumption of irrigation systems in the Tisza valley can be characterized on the basis of this study by the following conditions: 1. The half of total consumption within the growing season is in general consumed in the design period (July-August), while 85 to 90% in the characteristic period. Total consumption during April and September may be estimated at no more than 10 to 15%. 2. The actual peak period during the year under consideration may occur at any time during July-August, but the "common" peak period has been observed