Vízügyi Közlemények, 1965 (47. évfolyam)
4. füzet - Rövidebb közlemények és beszámolók
'(13) using bentonite slurry as this may lead to appreciable sealing. Characteristics of layers under different pressure can be determined with sufficient accuracy only by separating them. Stationary watersurface values should preferably be related during the investigation to 760 mm mercury pressure, since changes in atmospheric pressure may cause level differences up to 0.5 m. Well flushing performed without proper knowledge may cause considerable damage. Pump discharges must therefore be increased in strictly predetermined increments only and surfaces must be observed after permanent conditions have been reached. (Fig. 1.) Large, rapid discharge fluctuations must be avoided as waterbearing strata may suffer dynamic effects from violent changes of discharge, which may adversely influence the quality and service life of the well. In accurate investigations the trend of phenomena may be traced clearly by a •differential analysis of discharge-, drawdown- and pressure difference curves plotted against time. Dynamic and other effects may be readily detected by the same method (Figs. 6 and 7 ). Optimum well yields can be determined during the investigation by computing the relative values (F r ) of specific drawdown. A linear relationship between yield and drawdown is encountered in exceptional cases only. A plot of F r values against time results usually in a curve, the culmination point, or range of which defines the optimum yield. The interconnection of waterbearing layers under different pressure in the •same well is as a rule not advantageous and is especially detrimental where an unsealed aquifer is left behind the filtered pipe section. Yield parameters of a well, or well group can in practice be determined reliably after long observation and careful analysis only and an occasional deterioration of production figures is not necessarily due to an exhaustion of available resources but may be the consequence of inadequate well design and consequent alteration as well. In selecting the site for a concentrated artesian water producing installation, in which considerable funds are invested, investigations must be extended beyond a single well to at least a group of wells. In constructing production plants of water works separate wells should preferably be sunk into each aquifer with different pressure conditions. COMPARISON OF INLAND WATERWAYS ON THE BASIS OP UTILIZED CARRYING CAPACITY By Dr. G. Fekete Efforts to create interconnection between navigable inland waterways are gaining increasing significance all over the world. The necessity for classifying and comparing various waterways arose simultaneously with these efforts. Waterways are classified according to selected engineering, nautical, or economic aspects. The classifications show in general separately the characteristic features of waterways and vessels, nautical properties, hydrological conditions, as well as the indices revealing economic results (e. g. the tonnage conveyed on the waterway over a year, or the value of ton-kilometres achieved). In the first part of the paper the main factors, parameters, affecting the "quality" of the waterway from the point of view of navigation capacity are listed. It is pointed out that various inland navigable waterways cannot be compared, or classified unless the interrelations of main parameters are known and the mutual influences between them can be described by a common index. Instead of the actual tonnage, or ton-kilometres actually performed, the study of the potential performance is likely to yield a much clearer picture about a waterway. Actual goods ton-kilometres namely involve a considerable amount of uncertainty, which depends on the availability of commercial goods. The problems mentioned are dealt with in two stages. The vessel and the waterway are first studied statically and for describing a waterway, or any section thereof the introduction of a so-called TN-factor, or ton-factor, Eq. (1), is suggested. The
