Model test of concentration variation effect of suspended load in rivers

The main aim of the article is to show (present) the influence of vegetation zone on concentration of suspended load. New standards (principles, rules) of river engineering conducted in harmony with nature assign enormous plant significance. It is treated not only as a natural factor but also as a component of hydraulic reaction which clearly shapes hydraulic and hydrologic conditions. Until recently it was generally believed that vegetation is only the faktor which makes exploatation of water facilities difficult and unfavourably influence on structure working. At present vegetation has begun to be appreciated as a new element in contemporaly water management which may favourably influence on hydraulic conditions. Vegetation may cause riverbed roughness changes, bed configuration changes, water level slope changes increase of riverbed erosion resistance and also may cause retention of considerable amount of suspended load transported by (in) the river. Existing of vegetation zone in rivers and reservoirs influences on fluvial processes. Vegetation degree and its vertical and horisontal dimension influence on longitudinal and transverse transport of suspended load as well as its variation dynamics. The research of the suspended load transoport in vegetation zone was conducted in Institute of Environmental Engineering on model in scale 1:1. The ...

Determination of sediment trap efficiency of small water reservoir at Krempna

The assessment of sediment amount transported by river based on indirect methods may lead to considerable errors. It particularly pertains to the assessment of transported suspended sediment quantity. In the paper methods are presented of determining the amount of load transported by the river and supplied to the water reservoir at Krempna on the WisÅ‚oka river. The quantity of load flowing into the reservoir determined on the basis of field measurements was assumed reliable in the assessment of applied computational methods. On the basis of results of the multi-annual investigations on the silting processes, the authors, set a value of β-parameter using the results of the silting volume measurements and load transport computations during the subsequent years of the reservoir’s operational period. The sediment trap efficiency of the reservoir determined on the basis of transported sediment mass computed according to bathometric measurements and silting surveys ranges between 65% in 1998 and 50% in 2005. The determined sediment trap efficiency on the basis of the results of calculations by the DRUSLE method is on about 30% larger than the sediment trap efficiency value calculated on the basis of bathometric measurements. The amount of sediment transport computed by the MUSLE method is ...