This paper deals with studying of two topics – measuring of velocity profile deformation behind a over-flooded construction and modelling of this velocity profile deformation by computational fluid dynamics (CFD). Numerical simulations with an unsteady RANS models - Standard k-ε, Realizable k-ε, Standard k-ω and Reynolds stress models (ANSYS Fluent v.18) and experimental measurements in a laboratory flume (using ADV) were performed. Results of both approaches showed and affirmed presence of velocity profile deformation behind the obstacle, but some discrepancies between the measured and simulated values were also observed. With increasing distance from the obstacle, the differences between the simulation and the measured data increase and the results of the numerical models are no longer usable.
The channel network at this region was built up for drainage and also to provide irrigation water. The water level in the whole channel network system affect groundwater level and viceverse. From the view of mutual interaction between channel network and groundwater it has been necessary to assess impact of channel network silting on this interaction. The measurements of thickness of silts along three main channels were carried out in 1993. Then in 2004 there were done measurements in selected profiles along three channels: Aszód, Gabčíkovo-Topoľníky and Komárňanský channel. The paper shows changes in measured thickness and volume of silt in particular channels. It was shown the channel silting up has not been changed significantly during the monitored period. This fact is documented by graphical presentation of silt thicknesses of channels. The differences between silt top and channel bottom levels are presented. and Obsahom príspevku je hodnotenie zmien stavu kanálovej siete Žitného Ostrova z hľadiska zanesenia kanálov dnovými nánosmi v období rokov 1993 až 2004. Kanálová sieť bola vybudovaná v tomto regióne v priebehu 19. storočia jednak na čiastočné odvodnenie územia a zároveň na zabezpečenie závlah. Hladina vody v kanáloch ovplyvňuje výšku hladiny podzemnej vody v ich okolí a naopak. Z hľadiska procesu vzájomnej interakcie kanálovej siete s okolitou podzemnou vodou je nevyhnutné venovať pozornosť vplyvu zanášania kanálov dnovými nánosmi, keďže tieto môžu v značnej miere tento proces ovplyvňovať. V roku 1993 boli merané zanesenia kanálovej siete ŽO na vopred stanovených priečnych profiloch niektorých hlavných kanálov. V priebehu rokov 2004 boli vykonané kontrolné merania zanesenia vo vybraných profiloch kanálov Aszód, Gabčíkovo-Topoľníky a Komárňanského kanála. Tieto kontrolné merania sa robili vždy v úseku na začiatku, v strede a na konci jednotlivých kanálov, pretože sa uvažovalo s predpokladom lineárnych zmien hrúbok nánosov pozdĺž kanálov. Grafickými prílohami príspevok dokumentuje skutočnosť, že v priebehu sledovaného obdobia nedošlo k podstatným zmenám zanesenia kanálovej siete. Keďže pre účely príspevku sú dôležité hrúbky nánosov (teda rozdiely medzi dnom kanála a vrchom nánosovej vrstvy), bolo postačujúce, aby kontrolné merania boli robené od hladiny a neboli vztiahnuté na nadmorské výšky.
The objectives of the study were to: (1) assess the strength of associations of direct CO2 and N2O emissions with the seasonal variations in the relevant soil properties under both tillage systems; 2) evaluate how CT and RT affect magnitudes of seasonal CO2 and N2O fluxes from soil. Field studies were carried out on plots for conventional tillage (up to 0.22–0.25 m) and reduced tillage (up to 0.10–0.12 m) during the growing season and post-harvest period of red clover. The results showed that daily CO2 emissions significantly correlated only with soil temperature during the growing season under conventional and reduced tillage. Soil temperature demonstrated its highest influence on daily N2O emissions only at the beginning of the growing season in both tillage systems. There were no significant inter-system differences in daily CO2 and N2O emissions from soil during the entire period of observations. Over the duration of post-harvest period, water-filled pore space was a better predictor of daily CO2 emissions from soils under CT and RT. The conventional and reduced tillage did not cause significant differences in cumulative N2O and CO2 fluxes from soil.