284 research outputs found
Hydrodynamic model of groundwater flow in āBokanjac - PoliÄnikā aquifer - calibration
Za simulaciju toka podzemnih voda u krÅ”u primjenjuju se razni tipovi deterministiÄkih modela,
kao Å”to su model ekvivalentnog poroznog medija (eng. Single-Continuum Porous ā Equivalent -
SCPE), hibridni model (HM), diskretni model s jednom ili viŔe pukotina. Najjednostavniji pristup
od svih je primjena SCPE modela koji se bazira na pretpostavci laminarnog toka te konstantne
temperature, gustoÄe i viskoznosti vode, gdje je tok voÄen potencijalnom energijom, tj. gradijentom
tlaka. Cilj ovog rada je primijeniti SCPE pristup unutar numeriÄkog modela Modflow
kako bi se simuliralo otjecanje podzemnih voda u krÅ”kom vodonosniku āBokanjac ā PoliÄnikā
te dobio uvid u raspodjelu ekvipotencijala i strujnog polja unutar vodonosnika. Sliv āBokanjac
ā PoliÄnikā predstavljen je ortogonalnom mrežom s Äelijama dimenzija 200 m x 200 m u horizontalnoj
ravnini te s dva sloja u vertikalnom smjeru. Kalibracija se odnosi na 29. sijeÄnja do
30. lipnja 1967. godine (153 dana). KoriŔteni su podaci dnevnih oborina s ombrografske stanice
smjeÅ”tene unutar analiziranog podruÄja. Simulacija je pokazala da se definiranjem pukotina na
naÄin da im se pridruže velike vrijednosti koeficijenata propusnosti mogu uspjeÅ”no opisati pojave
unutar vodonosnika, bez upotrebe sofisticiranijih modela kao Å”to je hibridni model (HM).Deterministic models such as Single ā continuum porous ā equivalent (SCPE), the hybrid model
(HM), the discrete single fracture or pipe set model (DSFS), and the discrete multiple fracture
or pipe set model (DMFS) have been used in simulating groundwater flow in karst aquifer.
The simplest one, the SCPE, is based on laminar flow assumtion with constant temperature,
density and viscosity of water where flow can be simulated with the potential flow equation
of fluid mechanics. The goal of this paper is to apply SCPE approach within numerical model
Modflow in order to simulate groundwater flow in karst aquifer āBokanjac ā PoliÄnikā and to
get insight into spatial distribution of equipotentials and flow field. Catchment āBokanjac ā PoliÄnikā
is represented by an orthogonal network with grid spacing of 200x200 m in horizontal
plane and with two layers in vertical direction. Calibration period covers period from 29.1.1967
to 30.6.1967 (153 days). Data from nearby ombrographic station ware used. Simulation shows
that defining of karst fractures with very large hydraulic conductivity cells in an SCPE approach
can successfully describe flow regime within karst aquifer
Comparison of modelled and measured surface wind waves
Prikazana je usporedba rezultata mjerenja i numeriÄkog modeliranja povrÅ”inskih vjetrenih valova na Jadranu. Model za valno generiranje uzima podatke o vjetru iz prognoze Aladin. Rabljene su dvije modelske prostorne domene: regionalna (Jadran) i lokalna (kanalski sustav jugoistoÄnog Jadrana). U lokalnoj domeni upotrijebljena je detaljnija prostorna diskretizacija. Stupanj korelacije izmjerenih i modeliranih vrijednosti primarno ovisi o pouzdanosti ulaznih podataka o vjetru.The comparison between measurement data and numerical modelling results for surface wind waves on the Adriatic is presented. The wave generation model receives wind data from the Aladin forecast. Two spatial model domains are used: regional (Adriatic) and local (south-eastern Adriatic channel system). A detailed spatial discrĆ©tisation is used in the local domain. The degree of correlation between the measured and modelled values is primarily dependent on the reliability of input wind data
The (im)possibility of reducing the meteotsunami amplitude by constructing protective breakwaters
Plitkovodni gravitacijski val uzrokovan gibanjem atmosferskog poremeÄaja poveÄava svoju amplitudu kroz energetski transfer omoguÄen Proudmanovom rezonancijom. Nailaskom na luÄki bazen oblika lijevka deÅ”ava se dodatna amplificija valnog signala. Ukoliko valna grupa koja nailazi sadrži i frekvencije bliske luÄkim vlastitim frekvencijama moguÄa je i pojava rezonancije s daljnjim poveÄenjem valnih amplituda. Cjelokupna pojava naziva se meteocunami, a primjer te pojave desio se i 21.6.1978. u Veloj Luci, pri Äemu su registrirane valne visine od 6 m. U radu je provedena numeriÄka analiza dinamike morskih razi u krajnjoj toÄki Vele Luke uslijed valne pobude s maksimalnim visinama od 0,19 m ispred ulaza u zaljev Vela Luka. Kao odgovor na valnu pobudu u krajnjoj toÄki luke dobivene su valne visine od 5,5 m. Analiziran je utjecaj hipotetskih vertikalnih nepropusnih lukobrana, na valne visine u samoj Veloj luci. KoriÅ”tene su dvije varijante pozicije ispred ulaza u Velu Luku. Modelski rezultati ukazuju na relativno malo smanjenje valnih visina.Shallow water gravity wave caused by motion of atmospheric disturbances increases its amplitude through energy transfer enabled by the Proudman resonance. The waveform signals get further amplified reaching the funnel shaped port basin. If the incoming wave group contains frequencies close to the port\u27s eigen frequencies the resonance with a further increase of wave amplitude is likely to occur. The whole phenomenon is called meteotsunami, and an example of this phenomenon occurred on 21 June 1978 in Vela Luka, where the wave height was registered to be 6 m. The paper deals with carrying out the numerical analysis of the sea level dynamics in the final point brought about due to wave excitation with a maximum height of 0,19 m in front of the entrance to the Vela Luka Bay. In response to the wave excitation in the port\u27s final point, the obtained wave height was 5,5 m. Furthermore, the analysis involving the influence of hypothetical vertical impermeable breakwaters, set on two variant positions outside the entrance to Vela Luka was carried out. The model results indicate that there is a relatively small decrease in wave height
HYDRAULISCH-HYDROLOGISCHE SYNTHESE DES AUSFLUSSES DER KARSTQUELLE GOLUBINKA
Prikazana je hidrauliÄko-hidroloÅ”ka analiza i rezultati hidrograma istjecanja za krÅ”ki
izvor Golubinka, Å”to obuhvaÄa razdoblje 7. rujna 2012. do 1. listopada 2013. Cilj je bio
stjecanje uvida u procese koji se javljaju na slivnom podruÄju izvora Golubinka, u smislu
koliÄine istjecanja, razina podzemne vode i procjeÄivanja unutar krÅ”kog vodonosnika, u
odnosu na koliÄinu oborina izmjerenih tijekom analiziranog razdoblja. Na osnovi dvaju
pristupa odreÄen je odgovarajuÄi koeficijent turbulentnog procjeÄivanja kroz krÅ”ke kanale
analiziranog vodonosnika koji se potom može koristiti u numeriÄkom modeliranju.The hydraulic-hydrology analysis and discharge hydrograph results for the Golubinka
karst spring are presented for the period from 7 September 2012 to 1 October 2013.
The objective was to gain insight into processes occurring in the Golubinka spring
drainage area, in terms of quantities of discharge, groundwater levels, and seepage
within the karst aquifer, as related to the precipitation measured during the analysed
period. An appropriate coefficient of turbulent seepage through karst channels in
the analysed aquifer was determined based on two approaches. This coefficient can
subsequently be used in numerical modelling.Dargestellt werden die hydraulisch-hydrologische Analyse und die Ergebnisse des
Hydrogramms des Ausflusses fĆ¼r die Karstquelle Golubinka, was den Zeitraum vom 7.
September 2012 bis zum 1. Oktober 2013 umfasst. Das Ziel war es, Einblick in die Prozesse
zu erlangen, die im Wassersammelgebiet der Quelle Golubinka im Sinne der Ausflussmenge,
des Grundwasserniveaus und der Filterung innerhalb des Karstgrundwasserleiters
auftreten, im Vergleich zur Niederschlagsmenge, die wƤhrend des analysierten Zeitraums
gemessen wurde. Aufgrund zweier AnsƤtze wurde ein entsprechender Koeffizient
der turbulenten Filterung durch die KarstkanƤle des analysierten Grundwasserleiters
festgelegt, der dann bei der nummerischen Modellierung angewendet werden kann
Hydraulic properties of U-shaped stormwater overflows
Opisuju se hidrauliÄke karakteristike kiÅ”nog preljeva U oblika, alternativnog rjeÅ”enja kojim se omoguÄuje smanjenje ukupne duljine preljevne graÄevine. Prikazani su rezultati hidrauliÄkih ispitivanja koja su provedena zbog toga Å”to su nedostajali podaci o svojstvima preljeva toga oblika. Ispitivanje na fizikalnom modelu poslužilo je i za optimizaciju preljeva koja je provedena u dva koraka. Opisane su i odgovarajuÄe numeriÄke analize radi usporedbe s rezultatima na modelu.Authors describe hydraulic properties of the U-shaped stormwater overflows, which constitute an alternative solution for reducing an overall length of traditional stormwater overflow facilities. Results of hydraulic tests conducted to obtain additional data about properties of such overflows are presented. Physical model tests were also conducted to optimise overflow facilities using a two-step process. Appropriate numerical analyses are also given to enable comparison with scale model results
Near-bottom pollution transport modelling
Opisano je modeliranje pronosa pridneno ispuÅ”tenog oneÄiÅ”Äenja pri stacionarnom teÄenju u kanalu jednolikog pravokutnog presjeka s primjenom dvodimenzionalnih i trodimenzionalnih modela. Osim usporedbe rezultata ravninskog i prostornog numeriÄkog modeliranja raspodjele koncentracije pridneno ispuÅ”tenog oneÄiÅ”Äenja u kanalu idealiziranih geometrijskih obilježja, dana je i usporedba reprezentativne veliÄine tzv. brzine mijeÅ”anja s rezultatima dobivenim fizikalnim modeliranjem.The near-bottom transport of pollution, discharged during stationary flow into a channel of uniform rectangular cross section, is modelled by means of two-dimensional and three-dimensional models. Comparison between in-plane and three-dimensional numerical modelling results, defining distribution of near-bottom pollution in a channel of idealized geometrical properties, is provided. A comparison between the representative value of the so called mixing velocity, and the results obtained by physical modelling, is also presented
Hydraulic-Hydrology Analysis of the Turbulent Seepage Flow within Karst Aquifer of the Golubinka Spring Catchment
This paper shows the results of the hydraulic-hydrologic calculations of karst spring discharges and the groundwater level in the
aquifer of spring catchment. The calculations were performed for the Golubinka spring in Zadar area for the 4-year period. The
chosen approach was a model using relatively scarce data set, including limnigraphic data on the difference between the sea water
level and the freshwater level on the spring itself and the precipitation data fromthemeteorological station Zadar.The determination
of discharge hydrographs, based on inherent assumptions and available data, yields the proportionality coefficients between the
discharge and the limnigraphic data on the Golubinka spring itself. Further, based on the discharge hydrograph, groundwater
level oscillation was determined.The resulting spring discharge hydrograph and groundwater levels, along with the assumption of
Golubinka spring as the only spring on the catchment, were used in creating turbulent seepagemodel of the fractured system within
the aquifer, which evidently extends along the axis of theGolubinka spring catchment.Themodel yielded suitable turbulent seepage
coefficients of the fracture system. By using the numericalmodel KarstMod it was estimated that, on average, concentrated fracture
flow drains around 85% of infiltrated volumes and the remaining 15% accounts for diffuse matrix flow. Finally, theModflow model
was used in order to get insight into the flow field and the distribution of equipotentials in the aquifer of the Golubinka catchment
Comparison of results obtained by physical and numerical in-plane flow models
Prikazana je usporedba rezultata proraÄuna i mjerenja polja brzine strujanja na dionici umirivanja toka i ulijevanja u more za projektno rjeÅ”enje HE Ombla u podruÄje izvoriÅ”ne Å”pilje i jezerca. U istraživanjima su usporeÄeni rezultati brzina dobiveni mjerenjem na fizikalnom modelu i proraÄunom ravninskih modela. Rabljena su dva numeriÄka modela temeljeni na metodama konaÄnih diferencija i volumena. NumeriÄki rezultati usporeÄeni su s rezultatima mjerenja na fizikalnom modelu.The comparison of calculated and measured field flow velocities at the flow steadying and sea discharge section, for the zone of the source cave and lake, is presented in the scope of design solution development for the Ombla hydropower plant. Velocity results obtained by physical model measurements and in-plane model analyses are compared. Two numerical models, based on the finite difference and volume methods, are used. Numerical results are compared with results obtained by physical model measurements
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