Climate change is expected to have a significant impact on changing the flow regime of the lower Drava River. Four flume experiments were run to see how stabilized, increased and decreased flow and ...the occurrence of a series of floods affect channel planform evolution. Constant discharge produced alternate bars that subsequently merged into bigger bedforms, bedform migration, and a higher sinuosity of the channel. While merging and migration of bedforms may happen in the lower reaches of Drava, its sinuosity is unchanged due to river regulation. Reduced flow initiated transition from a braided to incised single-thread planform, with the formation of dormant channels. Drava already has a single-thread planform (because of dikes) and, in cases of flow reduction, will have the remnant of inactive channels. Increased discharge showed greater erosion and reworking of channel banks, a decrease of sinuosity ratio and active high bluff zones. On Drava sinuosity ratio is more difficult to change because of levees, but erosion, reworking of banks, and increased high bluff risks are possible. Floods simulation generated the construction of an anabranching planform alongside the incised main channel with terraces along banks (active during floods), bars, alluvial islands, and side channels (active during low flows). On the lower Drava River, this situation correlates with past floods.
•The groundwater age ranges from 8 to 29 y in the shallow porous aquifer.•In the lower aquifer, at depths greater than 60 m, MRT is over 50 years.•~70–80% of water younger than 8 y is present at the ...monitoring depth of 15 m.•The samples from lower aquifer contains up to 60% of water younger than 50 y.•Agricultural N pressure and NO3 water concentration decrease after recharge year 1990.
The western part of the Drava alluvial aquifer system, located in northern Croatia, contains significant amounts of groundwater, which is primarily used for public water supply and irrigation. The groundwater of this system contains high concentrations of nitrate which is why aquifer system is classified as a groundwater body of poor chemical status under the Water Framework Directive (WFD).
We investigated the groundwater age in this aquifer system and compared the nitrate concentrations in groundwater and the nitrogen pressure from agricultural activity with respect to the estimated mean groundwater age. We used a combination of the environmental tracers: chlorofluorocarbons (CFCs: CFC-12, CFC-11, and CFC-113), sulphur hexafluoride (SF6), tritium (3H) and noble gases. By applying lumped parameter models, we determined the groundwater age in aquifers at different depths. On comparing the recharge year, historical data on nitrate concentrations in groundwater, and nitrogen pressure from agricultural activity, we found that these elements are closely related. Our investigation was also supported by the results of numerical simulation of the evolution of nitrate concentration in the saturated zone of the aquifer. The decrease in agricultural pressure caused a decrease in the nitrate concentrations in the youngest, shallow, and oxic groundwater. However, the trend of increasing nitrate concentrations in the deeper part of the aquifer can last for many years. Our research supports the thesis that groundwater age is an important criterion for assessing the effectiveness of protection measures taken in groundwater management and implementation of the WFD and Nitrate Directive.
The paper presents results of archaeological study of one particular moment in time regionally determined as the middle Neolithic period in Drava river valley (northern Croatia). The main aim is ...reconsidering old periodical and chronological sequences in use for this period. Recent archaeological research carried out on several sites yielded new data about middle Neolithic settlement infrastructures and the remains of material culture. For the first time, remains of Linear Pottery culture (LBK) were recognized south of Transdanubia sheading new light on dispersal of this culture in its early phase. Combined with new interpretation of some old excavation results and new radiocarbon dates from recent excavations, transition from early Neolithic Starčevo culture to middle Neolithic Linear Pottery culture, emergence of Ražište style and its development under the early Vinča influence are outlined. Differences in pottery tempering, decoration and firing are discussed as well as the main types of vessels. New interpretation for 5450–4900 cal BC chronological sequence in this specific micro region is given. Results are compared with data from wider southwestern Carpathian region adding to newly developed discussion about Starčevo–LBK–Ražište–Vinča connections.
The objectives of this study are as follows: (a) an assessment of the geochemical background signature of the Drava Valley before the industrial revolution; (b) an evaluation of anthropogenic ...geochemical influences on the alluvial plains and river terraces in the valley; and (c) a determination of the spatial distribution of trace elements in the alluvial soils of the Drava River downstream of the Austrian–Slovenian border to the confluence of Mura and Drava Rivers.
Samples of topsoil (depth of 0–5
cm) and subsoil (depth of 20–30
cm) were collected from 134 sampling sites on alluvial plains and river terraces. Analysis for 41 chemical elements was performed. Based on a comparison of statistical parameters, the spatial distribution of particular elements and the results of factor analysis, one anthropogenic and three natural geochemical associations were identified. The anthropogenic association (As–Ba–Cd–Mo–Pb–Sb–Zn) is mostly a result of historical zinc and lead mining and smelting in the Drava River watershed. The natural geochemical associations (Al–Fe–K–Co–Cr–Cu–Li–Ni–Rb–Sc–Th, Ti–Ce–La–Nb–Ta and Ca–Mg–Sr) were mainly influenced by lithology. The entire assessed area of about 130
km
2 is, according to Slovenian and Croatian legislation, critically polluted with trace elements, especially zinc.
► Mines and smelters contributed to the Drava alluvial sediments. ► One anthropogenic and three natural geochemical associations were identified. ► Al–Fe–K–Co–Cr–Cu–Li–Ni–Rb–Sc–Th, Ti–Ce–La–Nb–Ta and Ca–Mg–Sr are effects of lithology. ► As–Ba–Cd–Mo–Pb–Sb–Zn is influenced by historical zinc and lead mining and smelting.
This paper provides an overview of the physical and chemical landscape changes that have occurred at four reference sites due to historical mining and smelting activities within Slovenia, and their ...comparison with similar sites around the World. Literature review has been made with the intention to identify major pollutant sources, its dispersion control factors, and effects. The four reference sites are Idrija, with more than 500‐year Hg mining and ore smelting history, the Meža Valley, also with a 500‐year PbZn mining and smelting history, the Celje area where Zn was smelted for 100 years and the Drava River alluvial plain, which is contaminated because of historical PbZn mining upstream. Based on the comparison between the four abovementioned reference sites and similar sites around the world that are situated in different landscapes and climates, we identified major sources of contamination, which are the erosion of mine and ore processing wastes, and atmospheric emissions of metal‐containing particles from smelters. In the first case, major control factors are rainfall pattern and river gradient, controlling erosion and sediment deposition patterns. In the second case, the prevailing control factors are topography and the dominant wind directions.
Rivers flowing through sedimentary basins are subjected to a variety of controls. The main goal of our study was to identify the effect of external (e.g. climate changes, tectonics) and internal ...controls (e.g. sediment transport, deposition, vegetation cover) on the evolution of meandering rivers flowing through sedimentary basins using the example of the lower Drava River (Europe, Hungary/Croatia). Field research was conducted along a 50‐km‐long section of the valley. Sedimentary data from boreholes and corings, 35 km of ground‐penetrating radar surveys and analyses of digital maps were conducted to reconstruct channel planform changes. Traces of four meander belts were identified, and 39 AMS radiocarbon dates were used to distinguish the chronology of the fluvial events. The evolution of the lower Drava River comprised alternating periods of deposition (formation of aggrading meander belt) and avulsions. The channel belts were formed owing to upstream sediment delivery and floodplain storage. Changes in climate humidity and the occurrence of high flows influenced the planform of the meanders within particular channel belts. The oldest channel was active at least ~40 000 cal. BP before being reworked by subsequent meanders active between the Late Pleniglacial (30 000–14 700 cal. BP) and Late Glacial (~11 000 cal. BP) periods. The channel belts shifted to the south in the Holocene, between ~11 000 and 250 cal. BP due to the presence of a thrust fault situated diagonally to the Drava Valley. Results show channel width, channel belt width and the surface area of point bar deposits increased in the succeeding generations of meanders and that the style and sedimentary architecture of the channel belts were dominantly dependent on autogenic controls, that is, sediment delivery, aggradation and erosional events (e.g. formation of chute cut‐offs).
We aimed to determine the influence of climate changes, tectonics and floodplain storage on the evolution of the lower Drava River (Hungary/Croatia). Geophysical and geological surveys, sediment dating and digital maps analyses were applied to reconstruct the formation of the Drava meander belts during the last 40 000 years. The channel belts evolved through the floodplain storage, avulsions and preferential shift caused by tectonics. This corresponds to the record of fluvial events in other European rivers evolving in sedimentary basins.
Soils with elevated arsenic contents are common in the Pannonian Basin. However, little is known about their distribution and occurrence. The subject of this study is the distribution of arsenic in ...Gleysol developed on an agricultural field in the Podravina region, Croatia. The main objective was to determine which soil parameter has the greatest influence on the overall distribution of arsenic in the area. Mineralogical, geochemical, and physico-chemical characteristics of 56 topsoil samples in were analyzed with statistical analyses, and the spatial distribution of the most important soil parameters was determined and presented. Mineralogical analysis revealed the presence of quartz, plagioclase, clays and micas, and Fe-oxyhydroxide goethite. Geochemical analysis determined elevated contents of iron (max. 23.37 mass. %) and arsenic (max. 824 mg/kg). The spatial distribution of eight parameters indicates overlap in the distribution of iron and arsenic, influenced by the topography of the area. The hierarchical cluster analysis resulted in two main groups: Fe-rich samples (Group 1) and Si-rich samples (Group 2). The Si-rich group of samples has lower arsenic contents, while the Fe-rich group has elevated arsenic contents. This indicates that iron content is the parameter that has the largest influence on the overall distribution of As. Although Fe-oxides can be dissolved under reductive conditions, the predominant presence of well-crystalized goethite implies that As is not mobilized under reductive conditions and remains adsorbed onto goethite mineral phase.
•Three different bog iron ore types (soils, nodules, fragments) were recognized.•Bog iron ore types exhibit comparable REE and microelemental signature.•Geochemical link exists between primary and ...experimentally roasted bog iron ore.•Clustering is recommended tool in iron ore provenance studies.
Throughout the Podravina region, NE Croatia, over one hundred locations with signs of iron production, dating to the late Antique period and the Middle Ages, have been discovered in the last 30 years. Recently, signs of various bog iron ore types and formations were discovered throughout the area. This study investigates the mineralogical and geochemical characteristics of local bog iron and roasted iron ores. Furthermore, statistical clustering of different geochemical components in the ores is presented, while the abundance and distribution of macro-, micro- and rare earth elements (REE) and how they correlate within the bog iron ores and roasted iron ores is considered. A total of 15 samples acquired from geological investigations and 13 samples found during archaeological excavations were analysed using geochemical and mineralogical methods. In bog iron ores, X-ray diffraction (XRD) confirmed goethite and quartz as the primary mineral phases, while roasted iron ores contained several Fe minerals and had variable quartz and clay mineral contents. Chemical analyses confirmed high Fe contents in both bog iron ores (up to 70.89 mass. %) and roasted iron ores (up to 84.97 mass. %), with a distinct differentiation of Fe and Si between the different bog iron ore types. Scanning electron microscopy with attached EDS detector (SEM-EDS) showed features of laminar Fe and Mn mineralization, confirming the theory that bog iron ore forms as seasonal precipitation from groundwater. Using the hierarchical clustering analysis, a geochemical correlation of the iron component in bog iron ores and roasted iron ores was compared to other major oxides, micro- and REEs. It was established that the iron component has very little influence on REE and microelements behaviour. Therefore, microelements and REEs were used as a tracer for establishing a geographical connection between the bog iron ores and roasted iron ores in the Podravina region.
Magnitude frequency analysis of suspended sediment transport provides important information on the sediment transport characteristics of a river. Understanding the sediment transport characteristics ...of rivers plays a vital role in the management of water resource projects. The lower Drava River basin is one of the most extensively hydroelectrically exploited river basins in the world. In this regard, analysis of the sediment transport characteristics in the region is critical. In the present study, magnitude frequency analysis was performed for the Botovo and Donji Miholjac gauging stations on the lower Drava River. It was observed that discharges close to the average daily discharge are responsible for transporting a major fraction of suspended sediment at both stations. The effective discharge was found to be less than half of Q
1.5
and Q
2
. It was also observed that data aggregation affects the effective discharge. Estimation of factor load discharge reveals that discharge with a return interval of around 1 year in the annual maximum discharge time series transports 90% of the total sediment load in the lower Drava River.
Massive construction on the Drava River basin and on the river itself during the last centuries, as well as recent climate change and/or variability, has caused many different and possibly dangerous ...changes to its hydrological and ecological regime. Since 1975, numerous hydrotechnical works have been carried out on the 60-km long section of the Drava River from the Slovenian–Croatian border to the River Mura mouth. Three hydrotechnical power plants with three reservoirs and three long inlet and outlet canals have been built. Changes in water level, discharge and suspended sediment yield along the Drava River measured in Croatia, downstream of the three Croatian reservoirs, during the last 30–130 years are presented. The investigation focuses on changes that have occurred during the last thirty-odd years, caused by the anthropogenic influences on the Drava River watercourse and its catchment in Croatia and Hungary, and probably by climate change or variability. Methods of rescaled adjusted partial sums, statistical tests, as well as regression and correlation analyses are used to explain changes in water level, discharge and suspended sediment yield. There is evidence in the time series of decreases in the minimum, mean and maximum annual water levels, and minimum and mean discharges on the lower part of the Drava River. One of the main objectives of this study was to examine the effect of dams and reservoirs operation on the changes in the downstream suspended sediment regime. The amount of suspended sediment has been greatly reduced, which can cause serious consequences.
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