On the basis of the results of calibration of current meters at water of varying temperatures, a hypothesis that water temperature influences measured water velocities was formulated. The analysis of our long-term data showed that the water temperature does have an influence on measured water velocity. This influence can be taken into account for practical purposes as a contribution to the uncertainty of measurements. The influence depends on the type of current meter propeller. This paper presents results obtained for the Ott C-2 current meter with propellers of the types 1, 2, 3, 5 and 6. Our analysis showed that the uncertainty is equal or less than 5% for measurements carried out in water with temperatures above 8°C. The differences between measured water velocities for water temperatures 5°C and 20°C reached maximum 6% (depending on the propeller) in a slowly flowing water (rotational frequency n = 1 s-1 ). For rotational velocity n ≥ 2 s-1 the differences between velocities measured at water temperatures 5 and 20°C were mostly under 3%. The less influenced propeller is of type 3 for which the uncertainty of measurement does not reach 5% even for water temperature 1ºC if the rotational frequency is bigger than 0.7 s-1 .
In the paper, authors are concerned with a hydraulic behaviour of bridges at high water stages and especially with the so far almost unregarded case when bridge roadway is overflowing. There are mentioned their own solutions for the estimation of the backwater by the bridge besides assessment of the applicability of some used relations. These new solutions were derived on the basis of research on the physical model at hydraulic laboratory of the Faculty of Civil Engineering of the Czech Technical University in Prague in 2001 and 2002. and Studie se zabývá hydraulickým chováním mostů při vysokých vodních stavech a zejména dosud téměř opomíjeným případem, kdy dochází k přelévání mostovky. Vedle posouzení aplikovatelnosti některých používaných vztahů jsou zde také uvedena vlastní řešení pro stanovení vzdutí mostem. Tato nová řešení byla odvozena na základě výzkumu na fyzikálním modelu prováděného v letech 2001 a 2002 v hydraulické laboratoři Fakulty stavební ČVUT v Praze.