Vízügyi Közlemények, 1958 (40. évfolyam)

4. füzet - VII. Kisebb közleménye

(46) The theoretical power of the rivers should also be classified among the factors affecting hydraulic management. Potential power resources have been compiled in Table 11 and Fig. 7. These data reflect the results of surveys made in 1955 and comprise about 70 per cent of the entire country. However, the rivers to which this survey was extended discharge close to 98 per cent of the total. As to be seen, about 25 per cent of the World's water power resources are in China. Section II gives a brief review of the history of hydraulic construction in China together with the description of plans and construction activities during the past decade. The first aim of the government of the People's Republic of China was in 1949 to restore existing yet neglected hydraulic structures. The building of the first new hydraulic projects was started in the first Five-Year-Plan (from 1953 to 1957). Their building and order of importance was decided upon at the All-Chinese hydraulic conference in 1950. Coordinated multiple-purpose projects have been drawn up for individual river systems, and part of these has already been realized. Of decisive importance in this respect was the scope and magnitude of the problem to be solved. As dictated by conditions and interests of the country, considerations governing the planning work were those of flood control, irrigation, power generation and navigation, in that order. Accordingly, planning and construction work started first on the development of the Iluai basin (Fig. 8). The catchment area of the Huai River comprises 200 000 sq. kilometres of which 189 million mous (= 119 000 sq. kilometres) are cultivated land, and is inhabited by 62,5 million people. Until the middle of the last century the Yellow River discharged into the sea through the bed of the Huai River and deposited a heavy silt load in the formerly sound estuary section. This and the extreme distribution of precipitation results in great floods. The problem was made even more difficult by the heavy sediment load transported by the main river itself. According to the coordinated and inclusive plan prepared in 1954 to overcome these difficulties 7 highland reservoirs and 15 plainland reservoirs were built by 1956 for retaining the peaks of flood waves. Five earth-fill dams and two — the Futzeling and the Meishan dams — multiple-arch dams were constructed for the 7 highland storage reservoirs. The Meishan dam is 88,2 m high and creates a storage volume of 2,2 cu. kilometres. The storage reservoirs alone can provide no satisfactory answer to flood control problems of the lower reaches. Flood levees were therefore built along the rivers. The levees were designed for floods having a frequency of occurence of 1,0 to 0,33 times in 100 years over the upper reaches, of 0,2 times in 100 years over the intermediate reaches and of 0,1 times in 100 years over the lower reaches. Levees along the tributaries offer for the present protection against floods occurring once in 20 years. The discharge capacity of the beds is further increased by dredging. The Hungtze Lake at the lower reach serves as a huge plainland reservoir and floods are routed therefrom by means of numerous large flood gates into the different beds conveying waters of the Huai River into the Sea. Reservoirs serve besides flood control purposes of irrigation and power generation as well. The total capacity of projected power stations is 180 MW. Irrigation of 5,3 million hectares from lhe reservoirs is projected. To be continued. (Author's summary translated by Z. Szilvdssy c. engr.)