Príspevok analyzuje vplyv prelivu hladiny podzemnej vody na odtokové koeficienty v inundačnom území rieky Alzette v hornej časti povodia nad mestom Luxemburg. Na základe hydrologickej bilancie ...(určenia zásoby vody v povodí) v dennom kroku bolo určené prahové nasýtenie povodia, ktoré sa časovo zhoduje s výskytom prelivu podzemnej vody v inundačnom území rieky Alzette. Po vzniku prelivu odtokové koeficienty dosahujú svoju maximálnu hodnotu približne 70 %, bez ohľadu na celkový úhrn jednotlivých zrážkových udalostí. Monitoring hladiny podzemnej vody teda môže byť použitý pri určení celkového nasýtenia povodia aj odtokových koeficientov, ktoré sa v takom prípade pri výskyte zrážok dajú očakávať. Hydrologická bilancia a hladiny podzemnej vody ako indikátory stavu nasýtenia povodia pred udalosťou boli použité na odvodenie empirického spôsobu odhadu kulminačného prietoku v povodí Alzette pre zrážkové udalosti s danou dobou opakovania.
The role of groundwater resurgence on runoff coefficients was investigated in the Alzette river floodplain, upstream of Luxembourg-city (Grand-Duchy of Luxembourg). A threshold in the saturation level was identified through the calculation of a water balance at daily time step. This threshold appeared to coincide with groundwater resurgence in the Alzette river floodplain. Once groundwater resurgence appears, runoff coefficients reach their maximum level of approximately 70%, regardless of individual rainfall event totals. Groundwater level monitoring can thus serve as a tool for evaluating the overall saturation level, as well as the runoff coefficients that are to be expected in case of rainfall. The water balance and groundwater levels having been identified as indicators of the overall soil moisture in the basin prior to a flood, these variables were used to develop an empirical tool for the estimation of peak discharge in the Alzette river basin for rainfall events of a given return period.
The Influence of Roughness on the Discharge Coefficient of a Broad-Crested Weir The use of environmentally-friendly materials in hydraulic engineering (e.g. the stone lining of weirs at levees) calls ...for the more accurate estimation of the discharge coefficient for broad-crested weirs with a rough crest surface. However, in the available literature sources the discharge coefficient of broad-crested weirs is usually expressed for a smooth crest. The authors of this paper have summarized the theoretical knowledge related to the effect of weir crest surface roughness on the discharge coefficient. The method of determination of the head-discharge relation for broad-crested weirs with a rough crest surface is proposed based on known discharge coefficient values for smooth surfaces and on the roughness parameters of the weir. For selected scenarios the theoretical results were compared with experimental research carried out at the Laboratory of Water Management Research, Faculty of Civil Engineering (FCE), Brno University of Technology (BUT).
Článek pojednává o stanovení základních charakteristik proudu na široké koruně pravoúhlého přelivu a detailně o charakteristikách odtržení proudu za návodní hranou koruny přelivu. Charakteristiky ...jsou stanoveny na základě měření úrovně hladiny, tlakové výšky a rychlostního pole metodou Particle Image Velocimetry. Charakteristiky jsou vyjádřeny bezrozměrně ve vztahu k energetické přepadové výšce a kritické hloubce.
The paper deals with the determination of the basic characteristics of flow at the crest of a rectangular broad-crested weir and in detail with the characteristics of flow separation at the upstream ...edge of the weir crest. The determination of the characteristics is made on the basis of measurement of the water surface level, the pressure head and the velocity field using the Particle Image Velocimetry method. The characteristics are expressed dimensionless in relation to the energy overflow head and the critical depth.
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