Vízügyi Közlemények, 1970 (52. évfolyam)
4. füzet - Rövidebb közlemények és beszámolók
extent on the bed material which may also be a source of suspended sediment. It should be clear therefrom that suspended sediment transportation is controlled mainly by the hydrological, geological and meteorological conditions prevailing in the catchment. Since the suspended sediment transportation of individual watercourses and even the extreme values thereof can be determined with a fair degree of accuracy, provided a sufficient number of observation data is available, the determination of the suspended sediment load, or of sediment concentration is possible in terms of the above characteristics of the watercourse. Relationships of adequate reliability are already available from which the concentration of sediment suspended in the watercourse can be estimated in terms of the shape (average width and average length) of the catchment area, as well as of the precipitation falling on the catchment (specific runoff, peak and lowest discharges). Relationships have been developed successfully in which the effect of geological conditions and the resulting erosional processes have been taken into account. In the knowledge of similar relationships, interference in the catchment and eventually the control of the suspended sediment transportation may become possible. This implies obviously the provision of storage volume on canalized rivers, since by reducing the volume of suspended sediment the sedimentation of the storage volume may be decreased appreciably. Substantially greater difficulties are encountered in the determination of bed-load transportation and we are perhaps justified in stating that still no reliable computation methods are available for estimating or predicting the volume of bed-load transported and that not even suitable devices have been developed for bed-load measurements. From among the great number of bed-load relationships, those developed by Einstein and Meyer —Peter appear to be most suitable in view of their physical background. Both calculation methods have been investigated repeatedly and consequently several modifications have been published. In the method of Einstein and the modified forms thereof, an attempt is made to estimate bed-load transportation from the known hydraulic properties of the watercourse. In the relationship of Meyer — Peter and especially the latest interpretation thereof, the full tractive force of the watercourse is related to a critical value pertaining to a particular bed-load material to determine the volume of bed-load transportation. Although these relationships have been verified repeatedly by field observations, their generalization is prevented by a great number of reservations. It is for this reason that several attempts have been made recently towards the development of new sediment traps and their investigation. Their introduction was accompanied by extensive confidence, but the extreme scatter of observation results caused a certain discouragement. The advantages of direct observation are obvious and recent experiments offer renewed hope in this respect. 12
