Ocena magnitud drobirskih tokov v izbranih hudourniških območjih v Sloveniji

Sodnik, Jošt (author), Mikoš, Matjaž (author)

V prispevku je opisana uporaba različnih metod za oceno magnitud drobirskih tokov, sproženih ob padavinah, na 18 hudournikih v Zgornjesavski dolini in na dveh na Pohorju (Lobnica, Lobničica). Dodatno preverjanje metod je bilo opravljeno na hudourniških območjih z aktivnimi drobirskimi tokovi v bližnji preteklosti (Predelica, Brusnik). Za nekatere metode zadošča poznavanje morfometričnih lastnosti hudourniškega območja, hudourniške struge in hudourniškega vršaja. Za druge metode je bilo treba uporabiti matematično orodje (HEC-HMS) in izdelati hidrološki model odtoka izbranih padavin, ki lahko sprožijo drobirske tokove. Izračunane magnitude drobirskih tokov se gibljejo v območju od 6500 m3 do 340.000 m3. Vrednosti so odvisne od parametrov hudourniškega območja; najpomembnejši parametri so: površina prispevnega območja, Meltonovo število, naklon vršaja in strmec hudourniške struge. Obravnavane vršaje smo razdelili v tri skupine glede na nevarnost delovanja drobirskih tokov: drobirski vršaji (nevarnost obstaja), hudourniški vršaji (ni nevarnosti) in prehodni vršaji (drobirski tokovi so možni, a malo verjetni). Predlagali smo mejni vrednosti Meltonovega števila (0,3) in naklona hudourniškega vršaja (4° oziroma 7 %) za razdelitev med drobirskimi in hudourniškimi vršaji. Od obravnavanih 24 hudourniških vršajev smo med drobirske vršajev razvrstili 13 vršajev, v hudourniške vršaje pet, ostalih šest vršajev pa smo uvrstili med prehodne vršaje.

• Language: Unknown
• Keywords: erozija, masna gibanja, drobirski tokovi, empirični modeli, ocena nevarnosti, vršaji, Zgornjesavska dolina, Pohorje, Slovenija
• Work type: Not categorized
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publisher: Anton Melik Geographical Institute
• Year: 2006
• Number of pages: 93-110
• Numbering: 46
• PID: 20.500.12556/RUL-68424
• ISSN: 1581-6613
• DOI: 10.3986/AGS46104
• Publication date in RUL: 10.07.2015

Secondary language

• Language: Unknown
• Title: Estimation of magnitudes of debris flows in selected torrential watersheds in Slovenia

Abstract

In this paper the application of different methods for estimation of magnitudes of rainfall-induced debris flows in 18 torrents in the Upper Sava River valley, NW Slovenia, and in 2 torrents in Pohorje, N Slovenia is described. Additional verification of the methods was performed in the torrential watersheds with active debris flows in the recent past (Predelica and Brusnik in the Soca River basin, W Slovenia). For some of the methods, the knowledge of morphometric characteristics of a torrential watershed, torrential channel and torrential fan is enough. For other methods, a mathematical tool (HEC-HMS) had to be applied in order to develop a hydrologic run-off model of precipitation that can trigger debris flows. Computed debris-flow magnitudes were of the order between 6,500 m(3) and 340,000 m(3). Their values are a function of torrential watershed parameters, such as: watershed area, Melton number, fan gradient, and torrential channel gradient. The investigated fans were classified into 3 groups with regard to the debris-flow hazard: debris-flow fans (hazard exists), torrential fans (no hazard), and transitional fans (debris flows are possible, but with low possibility). A limit between debris-flow fans and torrential fans is proposed: Melton number 0.3 and torrential fan gradient 4 degrees, that is, 7%. Out of 24 investigated torrential fans, 13 fans were classified into the group of debris-flow fans, 5 fans were classified into the group of torrential fans, and the rest 6 fans were classified into the group of transitional fans.

• Keywords: erosion, mass movements, debris flows, empirical models, hazard estimation, fans, Upper Sava River valley, Pohorje, Slovenia