Nenad Buzjak

Influence of submarine groundwater discharge on seawater properties in Rovanjska-Modrič karst region (Croatia)

Coastal karst aquifers are dynamic hydrogeological systems with substantial hydrological, geomorphological and ecological impacts on the marine and coastal karst ecosystems, mostly induced by the submarine groundwater discharge (SGD). This paper presents complex hydrogeological settings of the Rovanjska-Modrič coastal karst region on the eastern Adriatic coast characterized by: (1) high temporal and spatial variations in seawater properties; (2) significantly reshaped coastal bottom morphology, and (3) plethora of associated biocenoses from fresh water, brackish, marine and cave assemblages. With the aim of resolving spatiotemporal interconnections of SGD and marine environment changes, we conducted field prospection and seasonal measurements of different water properties on- and off-shore. Obtained results pointed to: (1) the composite recharge system consisting of numerous sinking rivers in the distant hinterland (with different climate settings) and local precipitation input; (2) specific discharge settings highly governed by a complicated karst conduits network, the hydrological situation in the hinterland and local meteorological conditions, i.e. one system that permanently feeds coastal and probably submarine springs, while the other operates periodically; (3) disturbed winter isothermy and three-layered summer stratification of the seawater column, and (4) slightly changed trophic settings. All of that is the consequence of extreme heterogeneity of the coastal karst aquifer, characteristic for the eastern Adriatic coast.

Recent Landform Evolution in the Dinaric and Pannonian Regions of Croatia

This chapter deals with main geomorphological properties of Croatia. The key elements of the geological predispositions are outlined as well as those of geodynamic evolution which, in conjunction with numerous exogenous processes, result in recent landform development. The main points of all important exogenous processes and landforms are presented: coastal, fluvial and fluvio-denudation, slope, aeolian and polygenetic. The main attention has been paid to karst and fluviokarst which cover almost 44% of the territory (the submerged karst excluded) therefore numerous recent research topics are outlined such as the development of structural geomorphological methods in karst, the research on coastal karst, glaciokarst, karst denudation measurements and cave microclimate. All this made a good basis for a detailed geomorphological regionalisation given in the chapter as well.

Changes in hydrological regime caused by human intervention in karst: the case of the Rumin Springs

ABSTRACT Any human intervention or action in karst terrains can unexpectedly, suddenly, strongly and, generally, dangerously change a local and/or a regional hydrological regime. A characteristic example of the Dinaric karst is given in this paper. The operation of two reservoirs in Livanjsko Polje at an altitude of about 702 m above sea level (m a.s.l.) and hydro-electric development of the Cetina River system started in 1973. This year marked a drastic and instantaneous change in the regional hydrological regime. A significant drop in the minimum, mean and maximum annual discharges of two neighbouring karst springs, Rumin Mali and Rumin Veliki, was caused by this anthropogenic construction. The exits of the two analysed karst springs, Rumin Mali and Veliki, are located at altitudes of about 326.8 m a.s.l. and 307.6 m a.s.l. respectively. The areal distance between them is 640 m. Their hydrological regimes have been altered in different ways. The drop in discharges is stronger for the Rumin Veliki than for the Rumin Mali. The analysis shows that the system development influenced the redistribution of the regional karst aquifer and, in this manner, contributed to the reduction of both karst springs’ recharge areas. Editor D. Koutsoyiannis Associate editor E. Rozos

The changes in beaches surfaces in the Medići and Mimice area from 1960 till today.

U radu se analiziraju promjene žala u uvalama Rascine, Juto i Kutlesa u posljednjih cetrdeset godina. Razmotreni su osnovni prirodni cimbenici njihova oblikovanja, a osobita pozornost posvecena je antropogenim utjecajima koji su taj prirodni razvoj poremetili te nacinu na koji obalni sustav reagira na antropogene modifikacije. Izgradnja dužobalnih konstrukcija, kao i odlaganje materijala u neposrednoj blizini obale i u more zbog naglog sirenja obližnjih naselja i razvoja turizma, uzrokovali su visak sedimenta u moru koji uzrokuje progradaciju i eroziju pojedinih segmenata žala. Kljucne rijeci: obalna geomorfologija, žalo, antropogeni utjecaji (geomorfologija), omisko primorje, Jadransko more, Hrvatska The Changes in Beaches Surfaces in the Medici and Mimice Area from 1960 till Today The paper deals with the changes in beach surfaces during the last 40 years in the bays of Rascine, Juto and Kutlesa. The main natural factors of their formation have been presented, but the focus of attention has been the anthropogenic influences that have disturbed their natural evolution, and the way in which this coastal system has reacted to anthropogenic modifications. The construction of coastal structures, as well as the uncontrolled disposal of material left after construction in the vicinity of the coast and even in the sea, due to the quick expansion of nearby settlements and tourism development, has provoked a surplus of sediments in the sea, causing progradation and erosion of particular beach segments.

Physical geographical analysis and geoecological assessment of potential protected area – the example of the Kupčina river valley, Zagreb County, Croatia

The middle section of the Kupčina river valley is listed as a natural asset that has been registered, and proposed to be designated as a protected area of the significant landscape category, in the spatial plan of Zagreb County. However, professional criteria for declaring such protected areas are not clearly defined. Therefore, the aim of this paper is to prepare a proposal for research methodology of physical geographic and geoecological surveys of the landscape in order to create an expert baseline study for protection status. The study area is a prevalently agricultural landscape in which the only natural zone is a narrow riparian zone along the riverbed of the Kupčina. For this purpose, the data on geomorphological, soil, and climate characteristics, water resources, and land use were analysed in order to carry out the assessment of land for agricultural use and protection. By using the method of relative relief evaluation, the suitability of the land for agricultural use was determined. Based on the results, it can be concluded that the inner part of the riparian zone of the Kupčina is suitable for protection under the significant landscape category.

The Intensity of Increment and of Subcutaneous Karst Corrosion in the Krka River Valley (Croatia)

Na podrucju doline Krke obavljeno je istraživanje intenziteta korozije metodom standardnih vapnenackih plocica. Plocice su postavljene na ukupno pet lokacija u blizini Knina (Krcic) i Skradina. Na svaku lokaciju postavljene su po tri plocice. Za potrebe istraživanja obavljeno je uzorkovanje tla u koje su plocice položene te nacinjena analiza njegovih fizikalno-kemijskih parametara. Mjerenjem mase tj. izracunom intenziteta prirasta ili korozije uocene su velike razlike između plocica. Na podrucju Krcica izmjeren je prirast cije su maksimalne vrijednosti 0, 7797 µm/god., a kod Skradina izmjerena je korozija cije vrijednosti iznose do maksimalno 0, 2436 µm/god. Razlike u uvjetima zbog kojih je doslo do prirasta, odnosno korozije mogu se povezati s klimatskim uvjetima te fizikalno- kemijskim svojstvima tla, posebno njegovim pH te udjelom CaCO3 i humusa.