Vízügyi Közlemények, 1969 (51. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(107) inaccessible forest area. Peat in a thickness varying from 3 to 7 m formed the subsoil. The plan of the canal network draining the marsh is decribed (Fig. 2). Drainage is accomplished by 4 principal (30 km long), 164 km long secondary and 330 km third-order canals. At the same time 13 km principal and 35 km secondary canals have been built for irrigation (Fig. 3). Rather than increasing the density of the canal network underground drainage is practiced using burnt clay pipes and mole drains. The hay produced is processed centrally in a plant of 12.000 tons per year capacity (Fig. 6). Undisturbed traffic in the area is ensured by a suitable network of roads ( Fig. 7 ). 5. Barangi, S. Civ. Eng. : Flow measuring structures on small watercourses. (For the Hungarian text see pp. 532.) During the past ten years about 40 flow measuring structures have been constructed for measuring streamflow on small watercourses by the Research Institute for Water Resources Development, Budapest. Depending on engineering and hydrological aspects these structures can be classified into the following groups: 1) measuring weirs, 2) Venturi-type weirs, 3) measuring throats with bottom sills, 4) streamflow measuring structure with bottom sill and broad-crested weir, 5) flow-measuring structure with bottom sill without lateral constriction, 6) flow-measuring structure with bottom sill and constriction for low-water measurement, 7) established measuring section with constriction for low-water measurement. On the basis of experience and observations during several years of operation the advantages and drawbacks of individual types are described. It is concluded that sound hydraulic design is capable of producing structures on which stream-flow measurement can be made with the results showing no more than 5—10% average relative scatter. Structural design problems are also mentioned, together with the conditions warranting the construction of a structure. The requirements to be saisfied by measuring structures are listed. It is pointed out that flow measuring structures must not be designed and constructed unless in coordination with regulation and training projects. From among the types of structure hitherto built types 5, 6 and 7 are recommended for conditions prevailing in Hungary. Besides these also weirs can be successfully applied for measuring stream flow on small watercourses carrying no sediment. 11 Vízügyi Közlemények