Numerische Grundwassermodellierung und -analyse im Flussgebiet der Vuka

Numeričke 3D modele strujanja podzemnih voda karakterizira velika složenost, brojnost ulaznih podataka, ali i velika primjena. U ovom se radu vršilo modeliranje podzemnih voda na slivnom području rijeke Vuke u istočnom dijelu Hrvatske. Osnovne karakteristike ovog područja su automorfna i hidromorfna tla, vertikalna i horizontalna heterogenost geoloških slojeva, vegatacijski pokrov, te brojne rijeke i kanali. Nakon uspostavljanja konceptualnog modela, model se pretvorio u numerički uz odgovarajuće matematičke izraze. Nakon kalibracije modela, rađena je parametarska analiza koja je pokazala da najveći utjecaj na strujanje u analiziranim uvjetima ima infiltracija, koja je kalibracijom određena na 17% od ukupnih oborina palih na slivno područje. Ovo predstavlja važan podatak zbog toga što se promatrane vrste tla prihranjuju uglavom oborinama, ali i zbog proračuna vodne bilance. Parametarska je analiza pokazala i da vrlo mali utjecaj na konačan rezultat kod ovakvih modela ima evapotranspiracija unatoč tome što je 70% sliva prekriveno vegetacijom.3D numerical models of groundwater flow are characterised by great complexity and numerous input data but also high applicability. The paper presents groundwater modelling in the Vuka river basin in eastern Croatia. The key features of this area are automorphic and hydromorphic soils, vertical and horizontal heterogeneity of geological strata, vegetation cover and numerous rivers and canals. Following the establishment of the conceptual model, we turned it into a numerical model using appropriate mathematical expressions. After the model calibration, we conducted a parameter analysis that revealed infiltration as having the highest impact on the flow in the analysed conditions, which was determined as 17% of the total precipitation that occurred in the river basin by the calibration. This is important data since the observed soil types are recharged mostly through precipitation, but also for purposes of water balance calculation. The parameter analysis showed that evapotranspiration has very low impact on the final result in such models despite 70 % vegetation cover in the basin.Numerische 3D-Modellierung der Grundwasserströmung ist durch hohe Komplexität und Vielzahl von Eingabedaten, aber auch durch große Änderungen charakterisiert. In dieser Arbeit wurde das Grundwasser im Flussgebiet der Vuka im östlichen Kroatien modelliert. Die Grundmerkmale dieses Gebietes sind automorphe und hydromorphe Böden, vertikale und horizontale Heterogenität geologischer Schichten, Vegetationsdecke und zahlreiche Flüsse und Kanäle. Erstens wurde ein Konzeptmodell erstellt, das in ein numerisches Modell mit entsprechenden mathematischen Ausdrücken umgesetzt wurde. Nach der Modellkalibrierung wurde eine parametrische Analyse durchgeführt, die zeigte, dass Infiltration die größte Auswirkung auf die Strömung unter den analysierten Bedingungen hat. Die Infiltration wurde auf 17 Prozent der Gesamtniederschlagsmenge im Flussgebiet durch Kalibrierung festgestellt. Das ist eine wichtige Angabe, erstens, weil die beobachteten Bodentypen meistens durch Niederschlag gewässert werden, und zweitens, diese Angabe ist für die Wasserbilanzberechnungen erforderlich. Die parametrische Analyse zeigte auch, dass Evapotranspiration eine geringe Auswirkung auf das Endergebnis bei solchen Modellen hat, obwohl 70 Prozent des Flussgebietes mit Vegetation bedeckt ist

Hydrological Drought Assessment in a Small Lowland Catchment in Croatia

Hydrological drought is critical from both water management and ecological perspectives. Depending on its hydrological and physical features, the resilience level of a catchment to groundwater drought can differ from that of meteorological drought. This study presents a comparison of hydrological and meteorological drought indices based on groundwater levels from 1987 to 2018. A small catchment area in Croatia, consisting of two sub-catchments with a continental climate and minimum land-use changes during the observed period, was studied. The first analysis was made on a comparison of standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI). The results showed their very high correlation. The correlation between the standardized precipitation index (SPI) and standardized groundwater index (SGI) of different time scales (1, 3, 6, 12, 24 and 48 months) showed different values, but had the highest value in the longest time scale, 48 months, for all observation wells. Nevertheless, the behavior of the SPI and groundwater levels (GW) correlation showed results more related to physical catchment characteristics. The results showed that groundwater drought indices, such as SGI, should be applied judiciously because of their sensitivity to geographical, geomorphological, and topographical catchment characteristics, even in small catchment areas

Comparison of nitrate concentrations, precipitation and groundwater levels observed on the canal test section

Kako bi se definirali odnosi između koncentracije nitrata, oborina i podzemne vode te analiziralo onečišćenje podzemne vode uslijed poljoprivrednih aktivnosti, na bankinama melioracijskog kanala smještenog u blizini Osijeka ugrađeni su piezometri dubine 5 m iz kojih su analizirani uzorci podzemne vode u razdoblju od lipnja 2014. do lipnja 2016. godine. Kako je u melioracijskom kanalu vegetacija, a samo s lijeve strane poljoprivredna parcela, radila se i usporedba koncentracija opaženih na piezometrima koji su smješteni u istoj ravnini, ali na suprotnim bankinama. T je analiza pokazala da je 78,1 % slučajeva, koncentracija nitrata na lijevoj obali kanala, uz poljoprivrednu parcelu bila veća nego zabilježena koncentracija nitrata na desnoj obali u isto vrijeme unatoč maloj udaljenosti između piezometara. U radu su analizirane i korelacije nizova koncentracije nitrata, oborina i razina podzemne vode. Kako provedena analiza nije pokazala značajnu korelaciju, pristupilo se usporedbi distribucija navedenih nizova, a to je rađeno preko kopula. Značajnu korelaciju (koeficijent korelacije 0,706) pokazala je jedino usporedba maksimalnih zabilježenih razina podzemnih voda (gornji kvartil) i koncentracije nitrata na piezometrima smještenim na desnoj bankini kanala.In order to define the relationship between nitrate concentrations, precipitation and groundwater and analyse groundwater pollution caused by agricultural activities, piezometers (of 5 m depth) were installed in the banks of an amelioration drainage canal located near Osijek. Groundwater samples from the piezometers were analysed in the period from June 2014 to June 2016. As there is an agricultural lot only on the left side of the canal and the rest contains vegetation, a comparison of concentrations observed in the piezometers located on the same plane but on the opposite canal banks was also performed. T-analysis showed that the nitrate concentration along the agricultural lot on the canal’s left bank was higher in 78.1 % of the cases than the simultaneously measured nitrate concentration on its right bank despite a short distance between the piezometers. The paper further analysed the correlations of the series of nitrate concentrations, precipitation and groundwater levels. As the performed analysis showed no significant correlation, the distributions of the copula series were also compared. Only the comparison of the maximum recorded groundwater levels (upper quartile) and nitrate concentrations in the piezometers located on the right canal bank showed a significant correlation (correlation coefficient of 0.706)

Hydrological Drought Assessment in a Small Lowland Catchment in Croatia

Hydrological drought is critical from both water management and ecological perspectives. Depending on its hydrological and physical features, the resilience level of a catchment to groundwater drought can differ from that of meteorological drought. This study presents a comparison of hydrological and meteorological drought indices based on groundwater levels from 1987 to 2018. A small catchment area in Croatia, consisting of two sub-catchments with a continental climate and minimum land-use changes during the observed period, was studied. The first analysis was made on a comparison of standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI). The results showed their very high correlation. The correlation between the standardized precipitation index (SPI) and standardized groundwater index (SGI) of different time scales (1, 3, 6, 12, 24 and 48 months) showed different values, but had the highest value in the longest time scale, 48 months, for all observation wells. Nevertheless, the behavior of the SPI and groundwater levels (GW) correlation showed results more related to physical catchment characteristics. The results showed that groundwater drought indices, such as SGI, should be applied judiciously because of their sensitivity to geographical, geomorphological, and topographical catchment characteristics, even in small catchment areas

DIE FLÜSSE DRAU UND DONAU UND DIE ÜBERSCHWEMMUNGEN IN OSIJEK IM LAUFE DER GESCHICHTE

Na području grada Osijeka, kao i okolici, poplave se bilježe već od 18. st. Od tada je pretvoren dio okolnog močvarnog područja u naselja i poljoprivredna područja, skraćen je tok rijeke Drave, a smanjeno je i inundacijsko područje. Blizina ušća Drave u Dunav pokazala se izuzetno važnom zbog utjecaja uspora. Provedene hidrološke analize od 1926. do 2014. god. pokazale su da na maksimalne vodostaje Drave kod Osijeka veći utjecaj ima protok Dunava nego Drave, a najveći je zajednički utjecaj protoka obiju rijeka. Izračunate su RAPS vrijednosti maksimalnih mjesečnih i godišnjih protoka. Rezultati pokazuju da protoci rijeke Drave opadaju od kraja 1976. god., dok vode Dunava bilježe porast od 1995. god.Floods in the City of Osijek area and its surroundings have been recorded since the 18th century. From that time period, a part of the surrounding wetland area has been transformed into settlements and agricultural surfaces whereas the Drava course has been shortened and its inundation surfaces reduced. The vicinity of the Drava and Danube confluence proved to be of utmost importance due to the backwater impact. Hydrological analyses performed from 1926 to 2014 showed that maximum Drava water levels at Osijek are under a stronger influence by the Danube than by the Drava, while the joint influence of both river flows exert the strongest influence. The RAPS values of the maximum monthly and annual discharges were calculated, and the results show that the Drava discharges have decreased since the end of 1976, while the Danube records increases since 1995.Auf dem Gebiet der Stadt Osijek und in ihrer Umgebung werden Überschwemmungen seit dem 18. Jahrhundert registriert. Seit dieser Zeit ist ein Teil des Sumpfgebietes in Siedlungen und landwirtschaftliche Nutzfläche umgewandelt, der Flusslauf der Drau verkürzt und das Vorland verkleinert worden. Die Nähe der Mündung der Drau in die Donau ist auch wegen der Auswirkung des Wasserrückstaus besonders wichtig. Die zwischen 1926 und 2014 ausgeführten hydrologischen Analysen zeigen, dass der Durchfluss der Donau einen größeren Einfluss auf maximale Wasserstände der Drau bei Osijek hat als der Durchfluss der Drau, und dass der gemeinsame Durchfluss beider Flüsse den größten Einfluss hat. Mit Hilfe der RAPS-Methode (rescaled adjusted partial sums) sind maximale Monats- und Jahresdurchflüsse errechnet worden. Die Ergebnisse zeigen, dass die Durchflusswerte der Drau seit dem Ende des Jahres 1976 niedriger werden, während die Durchflusswerte der Donau seit dem Jahr 1995 höher werden

HYDROLOGISCHE ASPEKTE DER SCHNEEFÄLLE IN KROATIEN

Cilj rada je bio da se karakteristike snijega u Hrvatskoj povežu s hidrološkim procesima. Jedno je poglavlje posvećeno ulozi snijega u hidrologiji. Detaljno su analizirane sljedeće karakteristike snijega: 1.) Broj dana godišnje sa snježnim pokrivačem višim ili jednakim od 1 cm; 2.) Maksimalna godišnja visina snježnog pokrivača; 3.) Datumi početka i kraja pojave snježnog pokrivača. Analizirani su podatci izmjereni na sljedeće tri stanice (u zagradama su navedena razdoblja obuhvaćena analizom): 1.) Zagreb-Grič (1895./1896.-2009./2010.); 2.) Osijek (1899./1900.-2009./2010.); 3.) Zavižan (1954./1955.-2009./2010.). Analiziran je odnos temperature zraka tijekom hladnog dijela godine i broja dana sa snježnim pokrivačem višim ili jednakim od 1 cm. Definiran je odnos prosječnog broja dana sa snježnim pokrivačem godišnje višim ili jednakim od 1 cm i nadmorske visine u Hrvatskoj. Na osnovi podataka o karakteristikama snijega izmjerenih na 21 stanici u ravničarskom djelu sjeverne Hrvatske u razdoblju 2000.-2009. utvrđeno je da je snježni režim sličan na cijelom ravničarskom području sjeverne Hrvatske. Analize izvršene u ovom radu ukazale su da ne postoji statistički značajno smanjenje niti jedne od ispitivanih karakteristika snijega. Određeni trend snižavanja broja dana godišnje sa snježnim pokrivačem višim ili jednakim od 1 cm je uočen, ali on nije statistički značajan.The aim of this paper was to identify the connection between snow characteristics and hydrological processes in Croatia. One chapter is dedicated to the role of snow in hydrology. The following snow characteristics were analyzed in detail: 1) Number of days per year with snow cover deeper than or equal to 1 cm; 2) maximum annual depth of snow cover; 3) dates of start and end of snow cover occurrence. The analyzed data were measured at the following three stations (periods covered by analysis are in brackets): 1) Zagreb-Grič (1895/1896-2009/2010); 2) Osijek (1899/1900-2009/2010); 3) Zavižan (1954/1955-2009/2010). The relation between air temperature during the cold part of the year and the number of days with snow cover deeper than or equal to 1 cm was analyzed. The relation between annual average number of days with snow cover deeper than or equal to 1 cm and altitude in Croatia was defined. Based snow characteristics data measured at 21 stations in the lowland part of northern Croatia in the period between 2000-2009, it was determined that snow regime is similar in the whole lowland part of northern Croatia. Analyses conducted in this paper showed no statistically significant reduction in any investigated snow characteristic. A trend of reduction in annual days with snow cover deeper than or equal to 1 cm has been observed, but is not statistically significant.Das Ziel der Untersuchung war die Schneeeigenschaften in Kroatien mit hydrologischen Prozessen zu verbinden. Ein Kapitel ist der Rolle von Schnee in der Hydrologie gewidmet. Die folgenden Schneeeigenschaften sind detailliert analysiert worden: 1) Anzahl von Tagen pro Jahr mit Schneedecke mit einer Höhe von ≥ 1cm; 2) maximale jährliche Höhe der Schneedecke; 3) Zeitangaben über Beginn und Ende der Schneebedeckung. Die analysierten Angaben wurden auf drei Stationen gemessen: Zagreb-Grič (im Zeitraum zwischen 1895/1896 und 2009/2010), Osijek (1899/1900-2009/2010) und Zavižan (1954/1955-2009/2010). Das Verhältnis der Lufttemperatur in der kalten Jahreszeit zur Anzahl von Tagen mit Schneedecke mit einer Höhe von ≥ 1cm wurde analysiert. Das Verhältnis der durchschnittlichen jährlichen Anzahl von Tagen mit Schneedecke mit einer Höhe von ≥ 1cm zur Meereshöhe ist definiert worden. Auf Grund der Angaben über die Schneeeigenschaften, die auf 12 Stationen im Flachland im Norden Kroatiens im Zeitraum 2000-2009 gemessen wurden, konnte festgestellt werden, dass das Schneeregime im ganzen Flachland auf dem Gebiet Nordkroatiens ähnlich ist. Die Analysen zeigten keine statistisch signifikante Verminderung einzelner untersuchten Schneeeigenschaften. Obwohl ein gewisser Trend zur Verminderung von Anzahl der Tage mit Schneedecke mit einer Höhe von ≥ 1cm zwar wahrzunehmen ist, ist diese Verminderung nicht statistisch signifikant

Analysis of the Inhomogeneous Effect of Different Meteorological Trends on Drought: An Example from Continental Croatia

The majority of central Europe has a transitional climate type as a result of interactions between maritime and continental climates. This study focuses on the appearance and severity of drought in continental Croatia, which is part of the transitional climate area. It is situated between 15° E and 19° E. The altitude declines from west (167 m a.s.l) to east (88 m a.s.l.). The time period analysed is 1981–2018. Air temperature and precipitation data series from 13 meteorological stations were analysed. The analysis was done on an annual basis to define the spatio-temporal variability in air temperature and precipitation and their impact on drought episodes using the standardised evapotranspiration precipitation index. Different statistical methods (e.g., the nonparametric Mann–Kendall test and agglomerative hierarchical clustering) were used to examine the trend homogeneity of the analysed region. The analysis indicated inhomogeneity across the study area in terms of what significantly impacted the occurrence and severity of droughts. Drought occurrence is influenced more strongly by increasing trends in air temperature as compared with increasing or decreasing precipitation trends. The probability of severe drought occurrence was estimated using a copula function, and the results demonstrated that areas with higher precipitation could be more exposed to drought. Furthermore, the results demonstrated the impacts of specific regional characteristics on drought occurrence, severity, and duration, which indicates that small-scale research on droughts is more reliable

APPLICATION OF PRINCIPAL COMPONENT ANALYSIS TO DROUGHT INDICATORS OF THREE REPRESENTATIVE CROATIAN REGIONS

Drought has become a very frequent hydrological event globally, including in Croatia. It can generally be explained by air temperature and precipitation changes on an annual and seasonal basis, owing to climate change. To contribute to the knowledge on drought phenomena in Croatia, the changes in air temperature and precipitation over a relatively long period between 1951 and 2018 were analyzed. The meteorological stations included in the research were Osijek, Zagreb, and Split, which represented the climate of the entire country. Drought was estimated using the standardized precipitation evapotranspiration index, which is one of the most comprehensive drought indices. Furthermore, the drought severity and duration were calculated using run theory. These parameters were tested for homogeneity using the standard normal homogeneity test. Only the air temperature exhibited inhomogeneity, with a break year in 1991 (Zagreb and Split) and 1998 (Osijek). The existence of significant temporal trends was tested using the non-parametric Mann–Kendall trend test. The probability of drought occurrence with a certain duration and severity was calculated using the copula function. Finally, principal component analysis was applied to the computed standardized Mann–Kendall test statistic (ZMK ) to define the relevance of each parameter change and their combination in drought occurrence on a seasonal basis. Drought occurrence was less recognizable from 1951 to 1991 (1998). In the second sub-period, the impact of an increasing air temperature was the most significant variable, particularly in Zagreb

Monitoring of the lateral canal Zmajevac - Kneževi Vinogradi

Lateralni kanal Zmajevac-Kneževi Vinogradi duljine oko 12,3 kilometara izgrađen je 2015. godine i ima dvojaku funkciju. Njime se rješava se pitanje odvodnje brdskog dijela sliva ukupne površine oko 56 km2 kao i opskrba vodom za navodnjavanje dijela Baranje tijekom sušnog razdoblja ukupne površine oko 5.000 ha. Na cjelokupnoj dužini lateralnog kanala razlikuju se 3 karakteristična poprečna presjeka širine dna 2,0-3,0 m, jednostavnog ili složenog trapeznog presjeka, nagiba pokosa 1:1,5 - 1:2 - 1:3 i oblogom od glinovitog materijala u debljini 0,5 do 1,66 m. Za potrebe projekta „Monitoring i analiza učinkovitosti dovoda vode lateralnim kanalom za potrebe navodnjavanja“ tijekom 12 mjeseci (2017. – 2018.) provodilo se opažanje vodostaja i razina podzemne vode u zaobalju Lateralnog kanala u 3 karakteristična presjeka (Kneževi Vinogradi, Suza i Zmajevac). Cilj monitoringa bio je utvrditi učinkovitost glinene obloge koja je ugrađena na pojedinim dionicama gdje je tlo s većim sadržajem pijeska. Monitoring je pokazao pozitivan učinak glinene obloge, ali i dominantan utjecaj Dunava na razinu podzemne vode u ovom dijelu Baranje. Nadalje, opažanja količina crpljene vode u/iz lateralnog kanala crpljenja omogućila su bilanciranje vode u sustavu navodnjavanja SN Baranja u ovoj fazi izgrađenosti.The lateral canal Zmajevac-Kneževi Vinogradi, completed in 2015, is about 12.3 km long and has two purposes. It resolves the drainage of the mountainous part of the basin with a total surface of approximately 56 km2 and supplies water for irrigation of about 5,000 ha in Baranja during drought periods. Along the entire canal length, there are 3 characteristic cross-sections ranging from 2.0 m - 3.0 m, depending on the bottom width. They are single or double trapezoidal cross sections, with side slopes of 1:1.5, 1:2 and 1:3, and a clay lining in the thickness of 0.5 m - 1.66 m. The implementation of the project “Monitoring and water conveyance efficiency analysis of the lateral irrigation canal” consisted of surface water level and groundwater level monitoring in 3 characteristic cross sections (Kneževi Vinogradi, Suza and Zmajevac) in the period of 12 months. The purpose of monitoring was to evaluate the efficiency of the clay lining constructed in the canal sections passing through predominantly sandy soil. Although the monitoring confirmed the positive effect of the clay lining, it also showed the dominant influence of the Danube River on groundwater levels. In addition, monitoring of water quantities abstracted from the lateral canal facilitated the water balancing in the Baranja irrigation system at this stage of its development

Special-Purpose River-Port Sediment Valorization as Road Construction Material Emphasising Environmental Aspects

Special-purpose river port sediment was investigated for its potential use as a road construction material. Sediment samples were extracted from three locations in three small river ports, and detailed laboratory research was conducted to determine its basic mechanical properties and characteristics that can potentially have an adverse influence in a roadside environment. The results of the research conducted indicate that there is a need for systematic monitoring of the quality and quantity of sediment in special-purpose river ports of the Danube River Basin to maintain its mobility and prevent flooding. The basic engineering characteristics (Proctor elements, Atterberg limits, California bearing ratio, and unconfined compressive strength) determined represent the good potential of the sediment samples tested herein for use in road construction. In addition, the chemical characteristics tested indicate the need for detailed analyses of the potential environmental risk before application in civil engineering structure