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Impact of Specific Surface Area on Hydrogeological Properties of Loess Deposits and Loess-Derived Soils in Eastern Croatia (ISSAH) - Pedological tasks within the project

Loess is a terrestrial sediment, formed by aeolian transport and deposition of silt-sized particles during Pleistocene glacial periods. Loess, loess-derived or loess-like materials cover significant areas of the Earth, being important for numerous human activities and scientific disciplines. Given that some of the most fertile soils are formed on loess, its importance for agriculture is especially high. Much of continental Croatia - the main agricultural region of the country - is covered by loess(-derived) deposits. These deposits are spread over important regional aquifers, as semi-permeable layers through which atmospheric water infiltrates into groundwater. At the same time, loess deposits protect groundwater from contamination, which can be pronounced in agricultural areas. Croatian loess(-derived) sediments and soils formed on them have not yet been investigated using an interdisciplinary approach that would involve hydrogeology, hydrology, agronomy, soil science and geology/sedimentology. Thus, the 5 year interdisciplinary scientific project ISSAH (lead researcher: Kosta Urumović, Ph.D.) had started in 2018. Main focus is on the specific surface area of mineral particles in loess and loess-derived soils, as it is the property with the key effect on various hydrogeological, geomechanical and pedophysical parameters. Project will yield a numerical model of groundwater-flow through the covering aquitard and water-bearing complex, helping the efficient use and protection of soils/groundwater in the study area. Also, it will establish an interdisciplinary team that should be able to tackle different and complex environmental issues, particularly in relation to the climate change. Study area is eastern continental Croatia, in which all important aquifers are loess-covered. Climate is semi-humid to semi-arid continental. Across the area, three representative locations were chosen for hydrogeological, meteorological and pedological research/monitoring (Figure). Each location is flat, found below 200 m asl, on loess(-derived) deposits. Two locations are grasslands (Kanovci and Livade) and one is a vineyard (Radoš). Performed pedological tasks comprise the following: a) available literature on soils and soil-forming factors of the study area was analyzed, reviewed and synthesized ; b) on the three locations, soil reconnaissance/augering was performed and soil pits were opened (Figure) ; c) soil profiles were described, sampled by genetic horizons (disturbed samples + triplicate 100 cm3 cores) and classified (WRB-2014): Kanovci - Calcic Kastanozem (Loamic, Novic, Transportic), Livade - Calcic Kastanozem (Loamic), Radoš - Hortic Anthrosol (Epiloamic, Endosiltic, Calcic) ; d) three gravitational lysimeters were installed in each soil pit to collect soil water percolating through the rhizosphere ; e) on each location, soil temperature and moisture sensors were installed in topsoil and subsoil layers. Currently, soil analyses are in progress (pH, organic matter and carbonate content, particle size distribution, density and porosity, aggregate stability, Atterberg limits, water retention across 0-15 bar range, hydraulic conductivity) and first results will be presented herein.

Aquitard, Groundwater, Soil permeability, Soil water retention

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