New data on the dolines of Velebit Mountain: An evaluation of their sedimentary archive potential in the reconstruction of landscape evolution

The first approach to the relationships between societies and physical environments on Velebit Mountain shows narrow correlations between spatial distribution of dolines, soil formation, hydric resources, vegetation and land occupation. In 2002, sediment cores have been obtained from different dolines of Velebit Mountain to evaluate the potential of their sedimentary archives in order to reconstruct the landscape history. On the littoral slopes and on the top parts of the mountain, the dolines were difficult to dig due to the presence of rocks in depth. Nevertheless, the cores have been sampled and soil analyses have been made (physical and chemical analyses: colour, grain size, pH, CaCO3, C, N, P, K, Mg, CEC). No dating materials were found. The first results attest to rather homogeneous pedologic processes in each area studied (Kamenica, Stinica, Baške Oštarije and Bilensko Mirevo), but they also indicate colluvial contributions. These contributions differ from one doline to another according to their location and morphology. Dolines reveal themselves to be not very good traps, as the representative nature of their sedimentary archives could be very local. However, the best profile has been obtained at Bilensko Mirevo, which shows a change in the soil nutrient content from an impoverishment in its middle part toward an increase of the soil nutrients in recent parts. Those environmental changes could not be precisely dated, but could be correlated with the 17th to 20th century phase of strong human impact on the Velebit environment and with the rural depopulation observed since the second half of the 20th century.Keywords: karst, dolines, Mediterranean soils, Velebit Mountain,Dinarides, Croatia

From Doline Distribution to Tectonics Movements Example of the Velebit Mountain Range, Croatia

Članek obravnava povezavo med tektonskimi silami in kraškimi površinskimi oblikami. Smer deformacij in napetosti v Velebitskem masivu smo izračunali na osnovi razporeditve vrtač z uporabo metode “center-center” (Ramsay, 1967; Fry 1979). 623 rezultatov lokalnih meritev smo vnesli v 2D model končnih elementov, ki deluje v programskem okolju Castem 2000. Ta na osnovi deformacij izračuna tektonske pogoje, ki tem deformacijam ustrazajo. Rezultati se v veliki meri ujemajo z GPS meritvami in rezultati geološkega kartiranja.The influence of tectonic forces on karst relief development has been studied using dolines as geomorphological markers. The strain and stress orientations have been calculated from the doline distribution, applying the centre to centre method (Ramsay, 1967; Fry, 1979). 623 local results have been obtained which were later injected into a 2D finite element model created in Castem 2 000 software. As the observed deformations are the consequence of the tectonic displacements, the numerical model tends to simulate the tectonic conditions, which are closely related to the observed deformations. The results were correlated with the GPS measurements as well as with the geological field mapping results and great coincidence was observed

THE ANALYSIS OF THE DOLINES DENSITY ON THE NORTH VELEBIT AND SENJSKO BILO

Prikazana je analiza gustoće ponikava na Sjevernom Velebitu i Senjskom bilu. Zabilježeno je 18.059 ponikava na 947 km2.The analysis of the dolines density on the North Velebit and Senjsko Bilo is shown. On 947 km2 has been registrated 18 059 dolines. One of the basic characteristic is the regular ranges of dolines, principally in direction NW-SE, and the regular change of the zones of bigger and smaller density. This indicate that the influence of the fault zones is essencial. The disposition of the ranges of dolines density has an exceptional morphostructural importance. There are three main fault zones: 1. Melnice-Kuterevo NW-SE, 2. Krasno-Lipovo polje WNW-ESE, 3. Bakovac fault zone E-W. The highest intensity of the dolines density is related to a wider area of convergention of three mentioned fault zones i.e. to the SE edge of Senjsko bilo, weider area of Lipovo polje and Bakovac

The gully of Potovošća on the island of Krk – The effects of a short-term rainfall event

The rainfall event during the night of 10th–11th September 2007 caused strong erosion in the gully of Potovošća on the Island of Krk. In the main fan, two new gullies and two fans were formed. Those morphological changes have been mapped, measured and explained, across the drainage basin in terms of topography and precipitation intensity. The drainage basin morphology was studied using GIS that allowed comparison of morphological and dynamic relationships within the study area. In order to obtain the relative potential erosion intensity between different points in the basin, as well as to differentiate areas with areal (diffuse) erosion from those with dominant linear erosion, the Stream Power Index (SPI) was calculated. The drainage basin specific properties were further related to the event specific properties, precipitation intensity and hydrologic estimations. The rainfall intensities obtained, allow the calculation of discharge at the gully mouth and the definition of recurrent periods using the rational method. The rainfall-runoff event studied was also influenced by the relatively high Antecedent Precipitation Index (API). This allows explanation of the morphological consequences of the short-term event. Consequently the interrelationship between short-term and long-term events has been discussed. In addition, the physiography of the gully has been recently modified by human interference, which has also influenced the morphological consequences of the aforementioned short-term rainfall event.</p

Analyses of the Velebit Mountain Ridge Crests

Generally the ridge crests spread in the dinaridic direction that is NW-SE what is mainly the characteristic of the older tectonic phase. The turn point in morphogenesis of the External Dinarides and thus of the Velebit Mt. occurs with the change in the shift of the Adriatic microplate toward N and NNW what is reflected on the orientation and morphology of the ridge crests as well as on the other relief form. The analyses of ridge crests are based on three main criteria: the analysis of orientation, length and the analysis of relatively homogeneous zones

Geomorphological Traces of the Younger Pleistocene Glaciation in the Central Part of the Velebit Mt.

On the central part of the Velebit Mountain the traces of the Pleistocene glaciation have been found. The domination of the dissected relief, characterized by numerous elevations and depressions, in the conditions of low temperatures and richess of snow precipitation during the Pleistocene were a very good predisposition for glaciation development on the central part of the Velebit M