Vízügyi Közlemények, 1965 (47. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

'(45) — under conditions prevailing in Hungary — suitable also for retaining storm runoffs. Maps showing specific runoff values were prepared for regions south and west from the Danube on the basis of extensive investigations (Fig. 1 ). From this map, analysing data relating to the 1963 flood — adopted as typical — a specific flood runoff of 35 000 cu. m/sq. km may be regarded critical. According to operation, flood reservoirs may be classified into three categories: 1) without flood spillway (Fig. 2), 2) with gate controlled spillway (Fig. 3 ) and 3) with fixed-crest spillway (Fig. 44). Examples are given for such reservoirs in the paper. Discharges passing a fixed-crest spillway can be estimated from Eq. (7) derived as the solution of the general differential equation (1). In reservoir planning the entire drainage system should be taken into consideration, since the release of stored water may cause even greater damage (when conciding with floods on tributaries). •i. Nagg, L., Eng.: Effect of hydroelectric stations on stability of the downstream bed (for the Hungarian text see pp. 262) Suddenly changing non-steady water movement is produced by peak-load operation fo hydroelectric stations (Fig. 1 ). The relatively sudden level drop following shutdown may be detrimental to the downstream bed. Forces acting on fully water-covered slopes are illustrated in Fig. 2, while changes due to falling level are indicated in Fig. 3. As will be perceived, to each soil — at given grain-size distribution, density and slope inclination — a critical adhesion velocity pertains, at which the slope is just stable, i. e. on the verge of stability. Experiments for determining the critical slope inclination were performed with four soil fractions (Fig. 3). A close relationship was found between the critical rate of stage reduction and the cotangent of the slope (Fig. 5). 5. Hernády, A., Eng.: Use of bottom-dump barges in the construction of hydraulic rock-fill structures (for the Hungarian text see pp. 267) The original purpose of bottom-dump barges was transportation of slurry produced by floating dredges. The barges are 40 m long, 6 m wide, have a capacity of 160 tons at a full draft of 1 35 m (Figs. 1 and 2). The barges were used successfully for constructing river training rock-fill structures on the Danube, since loading can be fully mechanized and construction simple (Fig. 4). Groynes, cross- and parallel dykes were built using these barges (Fig. 5). Slurry produced by dredges was used for the internal core of parallel dykes. Construction work with the bottom-dump barge — with mechanized loading — results in a saving of 75% over that using conventional barges with manual loading and unloading. RE WIE W 1. Dams in Spain. Reviewed after a publication by the Spanish Ministry of Public Works, Hydraulic Division by Mrs. Gy. Ujj (for the Hungarian text see pp. 272) A catalogue containing dams higher than 15 m was published by the Spanish Ministry of Public Works, Hydraulic Division (Ministerio de Obras Publicas, Dirección General de Obras Hidraulicas), while dams and weirs constructed in major river systems are described in a separate bulletin. Data on 250 completed and 73 planned dams are presented in the catalogue together with maps. The publication entitled Reguláción de los Rios Espaoles illustrates in coloured pictures impressive structures, together with data on reservoirs and hydroelectric installations. 2. Stabilization of slopes witb prefabricated lawn carpets. Reviewed after Linkett

r Sell, G. and Triebet, H. by T. Hazslinszky (for the Hungarian text see pp. 278) Prefabricated lawn carpets, capable of service 5 — 6 weeks after placement can be used advantageously. Favourable experiences were gained in the German Democratic Republic with seed mixtures presented in Table I.