Hrvatske vode
 
Geomorfološke promjene minijaturnog žala na kršu
Geomorphological changes in a miniature beach in the karst

Igor Ružić1, Čedomir Benac1, Suzana Ilić2, Nino Krvavica1, Josip Rubinić1

Sažetak/Abstract: 

Žalo duljine oko 70 m nalazi se u uvali Uboka, na zapadnoj obali Riječkog zaljeva. Od 2. siječnja do 12. travnja 2012. godine provedeno je 11 mjerenja topografije žala. Korištena je Structure-from-Motion (SfM) fotogrametrija pomoću koje su generirani trodimenzionalni oblaci točaka visoke preciznosti i razlučivosti. Korištena metodologija je omogućila povoljno i brzo snimanje geomorfoloških promjena. Zabilježene su značajne promjene tijela žala prouzročene uzajamnim djelovanjem valova i istjecanjem površinskih i podzemnih voda kada dolazi do erozije žala oblikovanjem kanala kroz njegovo tijelo. Nakon prestanka istjecanja žalo se brzo oporavlja, odnosno poprima prvotni oblik djelovanjem vjetrovnih valova. Na mjestu kanala brzo se formira berma žala, najprije ona uža, a nakon toga stabilna široka i visoka berma. U slučaju kanaliziranja bujičnih vodotoka na ušću žala dolazi do znatnog povećanja brzina toka u odnosu na prirodan način otjecanja, koji je opisan u ovom radu, zbog čega može doći do trajne erozije žala.

 

A 70 m long beach is located in the Uboka cove on the western cost of the Rijeka bay. From 2 January to 12 April 2012, 11 measurements of the beach topography were performed by applying the-from-Motion (SfM) photogrammetry which generated 3-D point clouds of high precision and resolution. The applied methodology facilitated an inexpensive and fast survey of geomorphological changes. Significant changes in the beach body were recorded, caused by the interaction of wave action and surface water and groundwater discharges and leading to the beach erosion through a formation of channels within its body. After water discharges the beach quickly recovered and resumed its original form through the wind wave action. The cahnnel position was quickly replaced by the beach berm, followed by a stable, high berm. In the case of channelled torrential watercourses on the beach, a significant increase in the velocities occurs in comparison to the natural runoff, as described in this paper, and leading up to potential permanent beach erosion.

Kategorija: 
Prethodno priopćenje / Preliminary Report
Ključne riječi/Key words: 

minijaturno žalo, SfM fotogrametrija, bujica, priobalni izvor, krš, Riječki zaljev

miniature beach, SfM photogrammetry, torrent, coastal spring, karst, Rijeka Bay

Podaci o autorima/Authors affiliations: 

1Građevinski fakultet Sveučilišta u Rijeci, Radmile Matejčić 3, 51000 Rijeka, iruzic@uniri.hr

 

2Lancaster University, Lancaster Environment Centre, Farrer Avenue, Lancaster, LA1 4YQ, UK

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