Hydrodynamic model of groundwater flow in “Bokanjac - Poličnik” aquifer - calibration

Za simulaciju toka podzemnih voda u kršu primjenjuju se razni tipovi determinističkih modela, kao što su model ekvivalentnog poroznog medija (eng. Single-Continuum Porous – Equivalent - SCPE), hibridni model (HM), diskretni model s jednom ili više pukotina. Najjednostavniji pristup od svih je primjena SCPE modela koji se bazira na pretpostavci laminarnog toka te konstantne temperature, gustoće i viskoznosti vode, gdje je tok vođen potencijalnom energijom, tj. gradijentom tlaka. Cilj ovog rada je primijeniti SCPE pristup unutar numeričkog modela Modflow kako bi se simuliralo otjecanje podzemnih voda u krškom vodonosniku “Bokanjac – Poličnik“ te dobio uvid u raspodjelu ekvipotencijala i strujnog polja unutar vodonosnika. Sliv “Bokanjac – Poličnik“ predstavljen je ortogonalnom mrežom s ćelijama dimenzija 200 m x 200 m u horizontalnoj ravnini te s dva sloja u vertikalnom smjeru. Kalibracija se odnosi na 29. siječnja do 30. lipnja 1967. godine (153 dana). Korišteni su podaci dnevnih oborina s ombrografske stanice smještene unutar analiziranog područja. Simulacija je pokazala da se definiranjem pukotina na način da im se pridruže velike vrijednosti koeficijenata propusnosti mogu uspješno opisati pojave unutar vodonosnika, bez upotrebe sofisticiranijih modela kao što je hibridni model (HM).Deterministic models such as Single – continuum porous – 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 “Bokanjac – Poličnik“ and to get insight into spatial distribution of equipotentials and flow field. Catchment “Bokanjac – Poličnik“ 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

CONSTRUCTED WETLANDS FOR WASTEWATER TREATMENT

Otpadne vode se moraju pročistiti prije ispuštanja u recipijent. Jedan od načina pročišćavanja otpadnih voda je pročišćavanje biljnim uređajima. Biljni uređaji su kompleksni biološki sustavi koji oponašaju procese u prirodi. Jednostavan su, prihvatljiv i ekonomski opravdan način zaštite voda. U radu su opisani biljni uređaji (umjetne močvare) kroz vrste uređaja, njihove prednosti i nedostatke, osnove projektiranja i hidraulički proračun. Posebno je analiziran biljni uređaj Vinogradci.Waste water must be treated prior to discharge into the recipient. One way of treating waste water is constructed wetland for wastewater treatment. Constructed wetlands are complex biological systems that mimic the processes in nature. These systems are simple, acceptable and economically feasible way of water protection. This paper describes the constructed wetlands through device types, their advantages and disadvantages, the basics of design and hydraulics. Especially analyzed constructed wetland Vinogradci

HYDRAULISCH-HYDROLOGISCHE SYNTHESE DES AUSFLUSSES DER KARSTQUELLE GOLUBINKA

Prikazana je hidrauličko-hidrološka analiza i rezultati hidrograma istjecanja za krški izvor Golubinka, što obuhvaća razdoblje 7. rujna 2012. do 1. listopada 2013. Cilj je bio stjecanje uvida u procese koji se javljaju na slivnom području izvora Golubinka, u smislu količine istjecanja, razina podzemne vode i procjeđivanja unutar krškog vodonosnika, u odnosu na količinu oborina izmjerenih tijekom analiziranog razdoblja. Na osnovi dvaju pristupa određen je odgovarajući koeficijent turbulentnog procjeđivanja kroz krške kanale analiziranog vodonosnika koji se potom može koristiti u numeričkom 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 für 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 während des analysierten Zeitraums gemessen wurde. Aufgrund zweier Ansätze wurde ein entsprechender Koeffizient der turbulenten Filterung durch die Karstkanäle des analysierten Grundwasserleiters festgelegt, der dann bei der nummerischen Modellierung angewendet werden kann

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

VISUALIZATION AND ANALYSIS OF SEEPAGE BELOW THE DAM FOUNDATION

The analysis of water seepage below the model’s foundation of hydrotechnical object is conducted in the paper. A physical model of gravitational dam is made with the aim to visualize seepage through the ground below the dam. The model is made at the laboratory of the Faculty of Civil Engineering and Architecture in Osijek. The aim of the paper is to analyze the influence of the hydraulic gradient on seepage domain deformation, as well as to study the effect of different engineering measures on the decrease of hydraulic gradient. Four measurements were conducted which were mutually distinguished by the shape of the dam model, i.e. the foundation sheet. The first part of the paper is based on the assessment of measurement variants, i.e. engineering solutions used for the reduction of the seepage part of the buoyancy and seepage flow. The second part of the paper is dedicated to adoption of different models in the analysis of groundwater seepage below the object. Values related to seepage flow as well as buoyancy and pressure distribution below the foundation sheet were analyzed. Graphical, numerical, and approximate methods of analysis were used

INCREASE OF WAVE HEIGHT DUE TO TRANSITION IN WIND DIRECTION – EXAMPLE: RIJEKA BAY

Surface wind wave dynamics were analyzed during wind transition from the third to the fourth quadrant, with the transition from Sirocco to Libeccio used as an example. This research is focused on the deep-water area in front of the Rijeka port. The analyses utilized a numerical model for wave generation, covering the entire Adriatic basin. Numerical simulations were conducted for relevant situations during the period 1998-2001. The numerical model was forced by the wind field obtained from the Aladin-HR atmospheric model. Numerical simulations were conducted in two steps, initially using hypothetical scenarios with homogenous and stationary wind fields, followed by simulations based on nonstationary wind fields from the Aladin-HR atmospheric model. The first step was used to confirm the hypothesis that significant wave heights rise during the transition of wind direction in the analyzed area. Model simulations in step two verified the assumption that the observed phenomenon can also occur in real atmospheric conditions.The results of the model simulations indicate the onset of a significant wave height increase during the transition of wind direction from the SSE to SW in a wider area that includes Kvarner and Rijeka bay. The increase in wind velocity results in a more noticeable significant wave height maximum

INCREASE OF WAVE HEIGHT DUE TO TRANSITION IN WIND DIRECTION – EXAMPLE: RIJEKA BAY

Surface wind wave dynamics were analyzed during wind transition from the third to the fourth quadrant, with the transition from Sirocco to Libeccio used as an example. This research is focused on the deep-water area in front of the Rijeka port. The analyses utilized a numerical model for wave generation, covering the entire Adriatic basin. Numerical simulations were conducted for relevant situations during the period 1998-2001. The numerical model was forced by the wind field obtained from the Aladin-HR atmospheric model. Numerical simulations were conducted in two steps, initially using hypothetical scenarios with homogenous and stationary wind fields, followed by simulations based on nonstationary wind fields from the Aladin-HR atmospheric model. The first step was used to confirm the hypothesis that significant wave heights rise during the transition of wind direction in the analyzed area. Model simulations in step two verified the assumption that the observed phenomenon can also occur in real atmospheric conditions.The results of the model simulations indicate the onset of a significant wave height increase during the transition of wind direction from the SSE to SW in a wider area that includes Kvarner and Rijeka bay. The increase in wind velocity results in a more noticeable significant wave height maximum

Stress Analysis of Reinforced Concrete Dam under Basic Loads and Earthquakes

U ovom radu izvršeno je dimenzioniranje visoke masivne armiranobetonske brane prema uvjetima opće stabilnosti konstrukcije. Analitičkim postupkom su proračunate vrijednosti normalnih naprezanja u tijelu brane. Provedena je usporedba s rezultatima vrijednosti naprezanja dobivenih numeričkom analizom u programu SAP2000. Provjerene su tri kombinacije opterećenja za dva tipa temeljne stijene. Bolje poklapanje rezultata analitičkog i numeričkog proračuna uočeno je u slučaju temeljenja brane na krućoj stijeni.In this paper, the dimensioning of a high massive reinforced concrete dam according to the conditions of general structural stability was performed. The values of normal stresses in the dam body were calculated by an analytical procedure. A comparison was performed with the results of stress values obtained by numerical analysis in the SAP2000 software. Three load combinations for two foundation rock types were tested. A stronger correlation of numerical and analytical results was observed in the case of the foundation on harder rock

Defining the methodology for the determination of the die-off coefficient for fecal indicator bacteria in the conditions of transport through the karst aquifer

Ovim radom predstavljena je metodologija za određivanje koeficijenta odumiranja pokazatelja fekalnog onečišćenja (Escherichia Coli i enterokoki) uslijed pronosa podzemnom vodom kroz analiziranu kršku sredinu. Jedan od ciljeva istraživanja bio je razlučiti procese odumiranja i retardacije te odrediti dominantni proces uklanjanja pokazatelja fekalnog onečišćenja u promatranom krškom slivu. Metodologija pretpostavlja sukcesivnu primjenu statističkog, analitičkog i numeričkog modeliranja u svrhu definiranja kapaciteta samopročišćavanja analiziranog vodonosnika (efekti sorpcije i odumiranja iskazani pripadnim koeficijentima). Analizirani vodonosnik Bokanjac-Poličnik smješten je u zaleđu grada Zadra. Metodologija se sastoji od tri osnovna koraka; preliminarne analize (prikupljanje podataka, statistička obrada podataka), analitičkog i numeričkog modela pronosa onečišćenja. Preliminarne analize kao početni korak metodologije poslužile su u konkretiziranju određenih pretpostavki vezanih uz detektiranje pokretača povećanih koncentracija Escherichie Coli i enterokoka na analiziranim zdencima kao i u određivanju mjesta potencijalnog izvora onečišćenja. Na temelju analize vremenskih serija utvrđeno je kako je kiša dominanti pokretač povećane koncentracije onečišćenja na zdencima. Provedeni Integral Pumping Test poslužio je u određivanju potencijalnog mjesta izvora onečišćenja. Informacije iz preliminarnih analiza koristile su se u izradi analitičkog modela, okosnice predložene metodologije. Model je podijeljen na dva dijela, vertikalnu i horizontalnu dionicu toka. Prvi dio (vertikalni tok) odnosi se na perkolaciju od septičke jame do saturirane zone i kao rezultat je dobivena koncentracija onečišćenja na kraju vertikalnog toka CVAD. Drugi dio analitičkog modela odnosi se na horizontalno strujanje i pronos unutar saturirane zone, a kao rezultat je dobivena koncentracija onečišćenja na početku toka CSAT (inverzni postupak). Proračunom su definirane vrijednosti ukupnog koeficijenta odumiranja ktot za obje faze toka. Višestruko veća vrijednost koeficijenta ukupnog odumiranja dobivena je za vertikalnu dionicu toka (srednja vrijednost iznosi ktot = 8.25), uslijed utjecaja sorpcije na uklanjanje onečišćenja. Unutar saturirane zone koeficijent ukupnog odumiranja ktot se kreće u granicama između 0.1 i 0.5. Definirani koeficijenti odumiranja pokazatelja fekalnog onečišćenja, zajedno s izračunatim koncentracijama onečišćenja CVAD/CSAT korišteni su kao ulazni podatak u numerički model pronosa onečišćenja. Numeričkim modelom dobio se uvid u napredovanje oblaka onečišćenja, ali i provjerila točnost primijenjene metodologije usporedbom modelskih i izmjerenih koncentracija onečišćenja.This thesis presents the methodology for determining die-off coefficient of faecal indicator bacteria (Escherichia coli and enterococci) in terms of seepage through the karst environment. The main problem in exploring karst environment, which this methodology strives to cope with, is lack of field measurements, poor data on karst rock formation, and fractures and channels within it, and groundwater level dynamics. The analysed karst catchment Bokanjac-Poličnik is situated in the hinterland of the city of Zadar and extends to 235.07 km2. In water supply wells within analysed catchment a frequent occurrence of faecal indicator bacteria was observed. The appearance of Escherichia coli and enterococci at the water supply wells of the karst aquifers Bokanjac-Poličnik is an indicator of the existence of faecal pollution that is very dangerous for the environment and people living in this area. During the period from 1/1/2012 to 19/10/2016 the EC/ENT monitoring was carried out in the supply wells. Besides concentration, in the implementation of the methodology the data of groundwater levels at the wells, the pumping rates and precipitation were used. The proposed methodology consists of three basic steps. Preliminary analyses as the initial step were use in concretisation of the certain assumptions related to the detection of increased concentrations of EC/ENT as well as in determination of the potential source of contamination. Time series analysis, Integral Pumping Test and quantification of flow (KarstMod model) were elementary parts of the preliminary analysis. Information from preliminary analysis were used in the development of the analytical model, the main part of the proposed methodology. The analytical model was constructed with the aim of resolving processes of sorption and die-off and determining the dominant factor in the process of natural removal of faecal indicator bacteria in terms of seepage through the karst environment. Within the model, two parts of the pollutant transport are integrated. The first part refers to percolation from septic tank to the saturated zone, and the second part refers to the horizontal flow and transport within the saturated zone (inverse procedure). Initial concentration at the septic tank C0 and final concentration in the water supply wells CB4,JEZ were the input dana in the model. The calculation yields pollutant concentration at the contact of vertical and horizontal part of the flow (CVAD and CSAT). The aim of the calculation was to obtain a set of optimization parameters-coefficients of the model that achieve a minimum difference in the concentrations ΔC = CVAD - CSAT. Reduction of pollutant concentration in the vertical section was associated with the process of natural die-off (ki) and sorption (k), while in the horizontal phase, due to the more pronounced rate of seepage, the effect of sorption was eliminated. The calculation was carried out for each of the suspicious sources of contamination and assumed seepage directions, with variation of the parameter-coefficient values in the transport model (percolation velocity vSAT, total die-off coefficient ktot = ki + k, hydraulic conductivity K and retardation coefficient R). Estimated die-off coefficient for both seepage phases were later used as an input in the numerical flow and transport model (MODFLOW). The numerical model gained insight into the progress of the pollution cloud, but also checked the accuracy of the applied methodology by comparing the measured and model pollutant concentration. The strategy used for creating the numerical flow and transport model was Single Continuum Porous Equivalent model

Methodology for Determining the Die-Off Coefficient of Enterococci in the Conditions of Transport through the Karst Aquifer—Case Study: Bokanjac–Poličnik Catchment

This paper presents the methodology for determining the die-off coefficient of faecal indicator bacteria (enterococci) when transported in a karst environment. The main problem in exploring karst environments, which this methodology strives to cope with, is lack of field measurements, poor data on karst rock formation, fractures and channels within it, and groundwater level dynamics. The analysed karst catchment (Bokanjac–Poličnik) is situated in the hinterland of the city of Zadar (Republic of Croatia) and covers an area of 235.07 km2. In the water supply wells within the analysed catchment, a frequent occurrence of enterococci was observed. The proposed methodology consists of two basic steps. Preliminary analyses as the initial step were used in the accumulation of certain assumptions related to the detection of increased concentrations of enterococci as well as in determination of the potential source of pollution. In the second step, the analytical model was constructed with the aim of resolving processes of sorption and die-off and determining the dominant factor in the process of natural removal of enterococci when transported in karst environment. Within the model, two parts of the pollutant transport are integrated: vertical percolation and horizontal seepage flow and transport. The mean value of the total die-off coefficient by transport through the unsaturated zone in the analysed case is k t o t = 8.25. Within the saturated zone the total die-off coefficient k t o t is within the limits of 0.1 and 0.5