Tamás TELBISZ¹, Fatima EISAM ELDEEN¹, Zoltán IMECS² & László MARI^1
1Eötvös Loránd University, Department of Physical Geography, H-1114 Budapest, Pázmány sétány 1/C., Hungary, telbisztom@caesar.elte.hu, e.e.fati@gmail.com, mari.laci@gmail.com
²Babeş-Bolyai University, Department of Hungarian Geography, 400006, Cluj-Napoca, Str. Clinicilor 5-7 Romania, zimecs@yahoo.com

GEOMORPHOMETRIC ANALYSIS AND THE EVOLUTION OF DRAINAGE NETWORK IN TRASCĂU MOUNTAINS (ROMANIA)

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Drainage network evolution of the Trascău Mts, including the formation of the famous gorges (e.g. Cheile Turzii) is constrained by the transitional position between the high central Apuseni Mts and the Mureş Valley, further on by the ~N-S oriented geologic settings. The aim of this study is to use digital terrain analysis tools in order to better understand this evolution. Elevation, slope and aspect distributions, topographic swath profiles, stream profiles and doline morphometry were analyzed based on the SRTM dataset, topographic maps, and partially on field GPS measurements. Elevation and slope histograms according to rock groups quantitavely supported differences in rock resistance. It is demonstrated that Cenozoic rocks can be well distinguished from Mesozoic and older rocks based solely on morphometric parameters (slope and standard deviation). Swath analysis highlighted a characteristic W-E change in the slope of the envelope surface that is attributed to tectonic movements. Swaths profiles also helped the recognition of water gaps and wind gaps, which are very important remnant landforms of the post-Cretaceous drainage network. Stream profiles of the study area can be modelled mostly by exponential and linear functions, and a large number of identified knickpoints are in relation with rock boundaries. The denudation blocking effect of the main limestone ridge is clearly seen on stream profiles. It is demonstrated how the original Post-Cretaceous radial drainage pattern evolved to a trellis pattern. It is argued that superposition (with antecedence) played the most important role in the formation of water and wind gaps. All analysis highlighted the differences between the areas north and south of Arieş river. These areas had similar landform evolution, but are at different stages. The Post-Sarmatian evolution of the northern part copies the Post-Cretaceous evolution of the southern part. Differences in doline density between the northern and southern parts are attributed to different duration of subaerial karstification.