Groundwater Recharge Assessment Using Multi Component Analysis: Case Study at the NW Edge of the Varaždin Alluvial Aquifer, Croatia

Exploring the interaction between precipitation, surface water, and groundwater has been a key subject of many studies dealing with water quality management. The Varaždin aquifer is an example of an area where high nitrate content in groundwater raised public concern, so it is important to understand the aquifer recharge for proper management and preservation of groundwater quality. The NW part of the Varaždin aquifer has been selected for study area, as precipitation, Drava River, accumulation lake, and groundwater interact in this area. In this study, groundwater and surface water levels, water temperature, water isotopes (2H and 18O), and chloride (Cl−) were monitored in precipitation, surface water, and groundwater during the four-year period to estimate groundwater recharge. Head contour maps were constructed based on the groundwater and surface water levels. The results show that aquifer is recharged from both Drava River and accumulation lake for all hydrological conditions–low, mean, and high groundwater levels. The monitoring results of water temperature, chloride content, and stable water isotopes were used as tracers, i.e. as an input to the mixing model for estimation of the contribution ratio from each recharge source. The calculation of mixing proportions showed that surface water is a key mechanism of groundwater recharge in the study area, with a contribution ratio ranging from 55% to 100% depending on the proximity of the observation well to surface water.

Wood analyses helped to determine the location and approximate construction period of the Roman bridge over the Drava River in ancient Poetovio (Ptuj, Slovenia)

We present the results of a dendrochronological study and radiocarbon dating of the wooden piles of the bridge over the Drava River in Ptuj. The piles, together with stone elements (a fragment of an imperial building inscription and parts of the architectural decoration) were retrieved from the riverbed in 1913 and are now in the Regional Museum Ptuj - Ormož. Using dendrochronology, radiocarbon dating of carefully selected annual rings in the wood and calibration with the wiggle-matching method, the date of the last (outermost) annual ring on the pile was determined to be 161 ± 27 cal AD (1σ) or 160 ± 32 cal AD (2σ). Since the pile contained no sapwood, the dating approximately agrees with the date of the building inscription on the stone slab, which attributes the commission for the reconstruction or construction of the bridge to Emperor Hadrian in the last years of his reign (117-138 AD). The dating of the wood has thus confirmed that the remains examined do indeed belong to a Roman bridge, probably built or renovated during the reconstruction of the road network in the area of the colony of Poetovio under Hadrian or one of his successors.

Tracce dell’organizzazione di una figlina imperiale a Mursa

This article aims at investigating the administration, the economic activities and the evolution of an imperial estate epigraphically attested in ancient Mursa, in Pannonia inferior, along the Drava river. Particularly, there are evidences of imperial slaves engaged in business management as well as many stamped bricks with different inscriptions. By matching these two types of epigraphs, it can be sketched that the property began its activities between the 1st and 2nd century AD, reached its maximum bricks production under Hadrian, in connection with the establishment of the colony, and went on until a sudden stop due to the Marcomannic invasion. Now, we are quite sure that the production resumed under the Severian dynasty, even if we do not know for how long it continued in the 3rd century, as is the case of neighboring provinces.

Construction Of Economical Pavement Structures With Wood Ash

Stabilized mixes that are used in pavement structures are composed of aggregate bound with hydraulic binders (cement, lime) or bitumen. The most commonly used for the construction of base layers are mixes stabilized with cement. A long-standing construction practice for pavement structures was based on the use of quality granular materials for the construction of base layers. However, when designing the pavement structure and selecting materials, economy, sustainability, and environmental impact, in addition to their mechanical properties, should also be considered. Clear requirements and guidelines for sustainable development have imposed the need to explore the possibility of using non-standard materials in construction. Wood ash, which is formed as a residue from the combustion of biomass in the production of electricity and heat, is one of the newer and, in Croatia, less researched alternative materials that can be applied in construction. The paper describes compressive strength tests of mixtures of sand from the Drava River and cyclone wood ash stabilized with various contents of cement. The obtained results showed that with wood fly ash (in a content of 30 % mass.) in the stabilization mixture of sand, values of compressive strengths can be achieved within the required limits necessary for the construction of base layers of the pavement structure stabilized by a hydraulic binder.

Novelties in the vascular flora of Croatia

We report on and discuss records of five species new to the vascular flora of Croatia. Calamagrostis canescens was found near Đurđevac in remnants of fen vegetation, and we consider it a critically endangered species in the flora of Croatia. Agrimonia procera is native or archaeophyte in central Croatia and its discovery is in accordance with its earlier use as a medicinal plant. Amaranthus emarginatus is an exotic newcomer that was previously found in urban habitats on the north Adriatic coast. Carex vulpinoidea and Oenothera suaveolens were shown to be locally established species, in meadows along the Kupa River, and on the bars of the Drava River, respectively. In addition, we present new distributional and ecological data on two neophytes (Cardamine occulta, Humulus scandens) that were only briefly mentioned in earlier sources from Croatia.