This study investigates changes in channel morphology of the Cetina River over the last 130 years affected by climate changes and various human impacts. A detailed digitalisation and analysis of the ...channel features was performed by using historical maps from the 1880s, archival aerial images from the 1950/60s, and contemporary orthophoto maps from the 2010s. According to these sources, we defined three study periods, and distinguished changes in the pre-dam phase (1880s–1950/60s) and the post-dam phase (1950/60s–2010s). In the pre-dam phase, a partial channel narrowing and drying of marsh zones in the source area were recorded, possibly due to reduced humidity and discharge following the end of the Little Ice Age. A drop in discharge and an increase in sediment supply caused by agricultural intensification most probably affected the expansion of fluvial bars. The increase in sediment supply is particularly evident in considerable river delta progradation of 500 m during this period. In the last 50 years, five hydroelectric power plants were built in the catchment. Consequently, severe reductions in discharge led to channel narrowing by about 50% which occurred in the third of the river length. Apart from the dam construction, a reduction in the area of bars by 85% and an increase in the number of islands by 103% can be related to decreased sediment supply following land abandonment and natural reforestation. This study adds to the knowledge on river morphology and channel adjustments following natural and strong human disturbances in the Mediterranean environment.
Water Framework Directive (WFD) guidance documents from 2019 provide a comprehensive review of methods and guidelines to improve the comparability of heavily modified water bodies (HMWBs) in the ...European Union. However, there is currently no common, single methodology for monitoring HMWBs and artificial water bodies (AWBs) or for determining maximum (MEP) and good ecological potential (GEP). This study presents the first assessment of hydromorphological conditions of HMWBs and AWBs in Croatia based on type-specific indicators. The typology of HMWBs and AWBs was based on distinct hydromorphological characteristics and modifications in order to be easily related to the uses of the water bodies. The classes of hydromorphological potential were graded from the theoretical MEP, which was determined by the score scale as the tolerated deviation from natural reference conditions, considering potential mitigation measures. The use of the water body and/or the effects on the wider environment were considered while determining MEP and choosing indicators included in monitoring and assessment. In the case of AWBs, the parameters dependent on natural reference conditions, which are non-existent, were omitted from the assessment. Only 27% of HMWBs and 2 out of 51 AWBs achieved good potential for all three hydromorphological elements. The most significant hydromorphological modifications include channelization, straightening, deepening and removal of riparian vegetation due to flood-protection management practices. In order to achieve the environmental objectives set out by the WFD, the Croatian water management system has to start implementing mitigation measures, especially related to natural flood management.
Although rivers are inherently dynamic systems that are susceptible to change, human impact on rivers in the last century is considered to have been so significant that it has caused an unprecedented ...intensity of geomorphological change in river channels and floodplains. As these changes often lead to deterioration of ecological conditions as well as increased flood risks, the approach to river management has changed over the past twenty years. There is an increasing emphasis on a holistic approach based on the understanding of river system processes, for which studies of geomorphological change in rivers represent a very important source of information. The aim of this review is to present the basic methods used in studies of geomorphological change in rivers, including the spatio-hierarchical delineation of the river system, data sources, and the most commonly analysed geomorphological characteristics and factors of change. The results of previous research are presented for the period of the last 150 years. The most important geomorphological changes include channel narrowing, incision, and reduction in the complexity of fluvial landforms and processes due to channelization and the construction of numerous barriers that disrupt the connectivity in water flow and sediment transport. Explaining the cumulative impacts and predicting future changes are the major research challenges. These challenges are related to the complexity of the river system, i.e. a large number of causal factors, connections, and interactions in the river system, and to the nonlinearity of the evolutionary trajectory of changes in rivers.
Iako su rijeke prirodno dinamični sustavi skloni promjenama, smatra se da je u posljednjem stoljeću antropogeni utjecaj na rijeke postao toliko snažan da je uzrokovao dosad nezabilježen intenzitet ...geomorfoloških promjena korita i naplavnih ravnica. Budući da te promjene nerijetko rezultiraju degradacijom ekoloških uvjeta, ali i povećanim rizicima od poplava, u posljednjih dvadesetak godina dolazi do promjena u pristupu upravljanju rijekama. Sve veći naglasak daje se holističkom pristupu i razumijevanju procesa u riječnom sustavu, za koji su studije geomorfoloških promjena tekućica vrlo važan izvor informacija. Cilj je ovoga preglednog rada prikazati osnovne metode u istraživanju geomorfoloških promjena tekućica, uključujući prostorno-hijerarhijsku delineaciju riječnoga sustava, izvore podataka te najčešće analizirana geomorfološka obilježja i čimbenike promjena. Rezultati dosadašnjih istraživanja prikazani su za analizirane radove koji se bave razdobljem od posljednjih 150 godina. Najvažnije geomorfološke promjene uključuju sužavanje i usijecanje korita te smanjenje složenosti fluvijalnih oblika i procesa zbog kanaliziranja i izgradnje velikoga broja poprečnih građevina koje sprečavaju slobodan protok vode i prijenos sedimenta. Objašnjavanje složenih, kumulativnih utjecaja i predviđanje budućih promjena glavni su izazovi u istraživanjima, a vezani su uz kompleksnost riječnoga sustava, odnosno velik broj čimbenika promjena, veza i interakcija u riječnom sustavu, te nelinearnost geomorfološkoga razvoja tekućica.
This study presents methodologically consistent length measurements of rivers with a total length of 40 kilometres or more in the Republic of Croatia. These measurements were performed by vectorising ...river channels from a topographic map at a scale of 1:25,000. Contemporary orthophoto maps were used as additional cartographic sources for verification. The approaches used to determine the starting and ending points of rivers, i.e. sources and mouths or confluences, have been explained and their spatial coordinates were listed. The results showed that in terms of total river length, the 21 rivers in this study differed from the available official data by less than 5%. Considerable differences were found for rivers where significant river engineering works had been carried out to channelize and divert flow, as well as for rivers in the Adriatic Basin where there have been methodological differences in determining the river mouth, and for large lowland rivers where changes in channel planform are common due to natural dynamics and engineering interventions. Moreover, this research revealed that the longest Croatian river, with its source, confluence, and both river banks situated entirely within the territory of Croatia, is the Karašica River, with a total length of 148 km.
Promjene zemljišnog pokrova vidljiv su odraz promjena u društvu, a važno ih je proučavati zbog njihovih potencijalno negativnih posljedica na okoliš i stanovništvo. Predmet su ovoga istraživanja ...promjene zemljišnog pokrova na području sjeverne Hrvatske (Međimurska, Varaždinska i Koprivničko-križevačka županija) u razdoblju između 1981. i 2011. godine, tijekom kojega je došlo do velike promjene u društvenogospodarskom sustavu. Metode daljinskih istraživanja temeljene na digitalnim snimkama satelitskog sustava Landsat omogućile su nadziranu klasifikaciju zemljišnog pokrova u četiri klase: izgrađeno, poljoprivredno zemljište, prirodna vegetacija i voda. Najvažnijim procesima promjena pokazali su se porast udjela prirodne vegetacije i izgrađenog zemljišta te smanjenje udjela poljoprivrednih površina. Rezultati istraživanja pokazali su da se intenzitet promjena zemljišnog pokrova mijenjao ovisno o reljefnim obilježjima područja. Porast prirodne vegetacije bio je najintenzivniji u brežuljkastim područjima blagog i srednjeg nagiba te u polojima rijeka Drave i Mure. U gusto naseljenim ravničarskim područjima najčešći je bio porast izgrađenog zemljišta zbog utjecaja (sub)urbanizacije.
Wildfires are an important factor of landscape dynamics in fire-prone environments of the world. In the Mediterranean, one of the most fire-susceptible environments globally, between 45,000 and ...50,000 wildfires are recorded every year, causing disturbances in forest and grassland ecosystems. As a Mediterranean country, Croatia faces these problems, averaging over 1000 registered wildfires annually, with the coastal areas dominated by forest fires and continental Croatia by fires on agricultural lands. This research combines various landscape and socio-economic factors in the analysis of fire occurrence in Croatia's southernmost region of Dalmatia. Around 275 of the largest fires (encompassing 98% of the total burnt area) registered in 2013 were investigated using OLS, and different spatial indices were employed to analyse regional variability in fire distribution. The results revealed that areas more prone to fires are the northern inland areas of Dalmatia and its entire coastal zone. Altitude and vegetation type demonstrated a correlation with fire occurrence, but an increase in population in the study area was also correlated with wildfire occurrence. Regarding vegetation, the grasslands and Mediterranean shrubland (maquis) were found to be the most fire-prone vegetation types in the study region, the distribution of which can be linked to different socio-economic and demographic processes occurring in the Eastern Adriatic.
U ovome je radu prikazano metodološki konzistentno mjerenje duljina tekućica ukupne duljine 40 ili više kilometara na prostoru Republike Hrvatske. Mjerenje je obavljeno vektorizacijom toka na temelju ...topografske karte u mjerilu 1 : 25 000. Suvremene ortofoto-karte korištene su kao dodatni kartografski izvor za provjeru. U radu su objašnjeni pristupi određivanja početne i završne točke tekućica, odnosno izvora i ušća, te su navedene njihove prostorne koordinate. U slučaju ukupne duljine toka rezultati su pokazali da se 21 duljina izmjerena u radu razlikuje do 5 % od dostupnih službenih podataka. Značajne razlike zabilježene su na rijekama na kojima su provedeni opsežniji hidrotehnički zahvati kanaliziranja i promjene pružanja toka, na rijekama jadranskoga slijeva na kojima postoje metodološke razlike u određivanju točke ušća te na velikim nizinskim rijekama na kojima su česte promjene u tlocrtu korita zbog prirodne dinamike i hidrotehničkih zahvata. Ovim je istraživanjem također utvrđeno da je najdulja hrvatska tekućica, s izvorom, ušćem i objema obalama na prostoru Hrvatske, rijeka Karašica, s ukupnom duljinom od 148 km.
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