GNGTS 2013 - Atti del 32° Convegno Nazionale

The basin of the Petrace Fiumara is 258.29 km 2 wide, drainage flows on the metamorphic terrains (A class) in the upper part, on marine and continental deposits (Lower/Upper Pleistocene) and partially on clay sediments (Lower/Middle Pleistocene) (C class). Trunk channel runs towards N, in the final tract it changes flowing NW-ward. Fluvial network reaches the VII order and it shows a parallel pattern as it regards high order branches (from IV to VII) (Fig. 2). For both the Petrace Fiumara and Catona Fiumara basins we observed several geomor- phological elements interpreted as markers of perturbation due to active tectonics. Numerous fluvial branches are straight and aligned along the Santa Eufemia Fault as it regards the Catona Fiumara and along the Cittanova Fault for the Petrace Fiumara. Fluvial channels character- ized by anomalous stretch and meandering branches are observed on the Santa Eufemia Fault and Cittanova Fault footwall. Deflected streams and alignments of branch deflections, fluvial captures and suspended valleys are evidence of recent modification of the analyzed fluvial networks (Fig. 2). For both the studied rivers, hierarchical parameters indicate a poor organization of the fluvial network and the presence of uplifted and rejuvenated sectors. Indeed, the bifurcation index, R , reaches high values (Tab. 1) as it regards the segments with low order, I and II, that are the youngest fluvial segments more susceptible to active tectonics. Similarly, the anomaly parameter, A , indicates that there are numerous anomalous branches of I and II orders, particularly high value is detected for the first order of the Petrace Fiumara. Finally, D1 parameter highlights a high density of I order segments with respect to the flowed area due to differential uplift of specific sectors. Tab. 1 – Hierarchical parameters and morphometric indexes of the Catona Fiumara and Petrace Fiumara: see the text for the description. AF index for the Catona Fiumara was also calculated for its 10 sub-basins. Catona Fiumara Petrace Fiumara R1 1,3 A1 271 Sub-basin AF T1 0,46 R1 1,5 A1 536 T1 0,15 R2 2,7 A2 102 1 49,94 T2 0,14 R2 1,4 A2 94 T2 0,04 R3 0,8 A3 7 2 21,18 T3 0,03 R3 0,5 A3 9 Δa 1,69 T3 0,01 R4 0 A4 0 3 33,10 T4 0,12 R4 0,4 A4 2 T4 0,08 Re 0,40 4 73,53 T5 0,14 R5 0 A5 0 D1 6,26 T5 0,18 5 73,53 T6 0,12 R6 0 A6 0 T6 0,32 Δa 0,96 6 52,90 T7 0,35 Re 0,69 T7 0,47 7 79,54 T8 0,10 T8 0,64 8 78,58 T9 0,35 T9 0,69 D1 12,77 9 62,24 T10 0,21 AF 70,78 T10 0,77 10 74,26 Catona F. 56,06 106 GNGTS 2013 S essione 1.1