master thesis no.:81/II. VOI-FRM
Steven Brazda (Author), Mojca Šraj (Mentor), Nejc Bezak (Co-mentor)

Abstract

V okviru raziskave smo analizirali dejavnike, ki vplivajo na nastanek poplav zaradi taljenja snežne odeje in spadajo pod t.i. sestavljene dogodke. Do sestavljenih dogodkov pride ob sočasnem nastopu različnih naravnih pojavov ali nesreč, ko se le-ti pojavijo časovno ali prostorsko sočasno. Posledično je vpliv takih dogodkov večji kot zaradi običajnih dogodkov. V okviru naloge smo analizirali različne vplivne dejavnike kot so temperatura zraka, padavine, debelina snežne odeje, hitrost vetra, vlažnost tal, itd.. Izbrali smo 107 porečij v Evropi in Severni Ameriki, kjer so bili na voljo merjeni podatki o pretokih za obdobje 1979-2019. Največje letne poplave smo klasificirali glede na definirano tipologijo z upoštevanjem naslednjih tipov poplav: poplave zaradi kombinacije padavin in taljenja snežne odeje, poplave zaradi taljenja snežne odeje, poplave zaradi dolgotrajnih padavin in poplave zaradi kratkotrajnih padavin. Omenjene tipe poplav smo nadalje razdelili še glede na mokre in sušne začetne razmere na porečju. Rezultati so pokazali, da se na izbranih porečjih najpogosteje pojavijo poplave zaradi taljenja snežne odeje. Na porečjih, ki so locirana na višjih nadmorskih višinah, se najpogosteje pojavljajo poplave zaradi kratkotrajnih ali dolgotrajnih padavinskih dogodkov. To je mogoče presenetljiv rezultat, saj so na višjih nadmorskih višinah temperature običajno nižje in bi pričakovali večji vpliv snega, vendar so bile poplave v primeru teh porečjih najpogosteje posledica večjih poletnih neviht. Na porečjih, ki so locirana na nižjih nadmorskih višinah, pa so poplave najpogosteje posledica taljenja snežne odeje. Nadalje smo ugotovili, da je predhodna vlažnost (mokri predhodni pogoji) eden izmed pomembnih dejavnikov nastanka poplav. Vlažnost tal je imela tudi največji relativni vpliv na merjene podatke o pretokih. Izvedene so bile tudi analize sezonskosti. Zaznali smo območja, kjer je sezonskost zelo izrazita, kar pomeni, da se poplave skoraj vedno pojavijo v istem obdobju leta, kot je Severna Amerika ter osrednja Norveška in Švedska. To lahko pripelje do sočasnega pojava poplav na večjih območjih, kar še povečuje njihov vpliv in z njimi povezano gmotno škodo.

Keywords

civil engineering;master thesis;snowmelt driven floods;flood typology;soil moisture;compound events;climate zones;flood catchments;

Data

Language: English
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FGG - Faculty of Civil and Geodetic Engineering
Publisher: [S. Brazda]
UDC: 551.579:551.578.46: 504.4:556.166(043.3)
COBISS: 76592643 Link will open in a new window
Views: 311
Downloads: 99
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Other data

Secondary language: Slovenian
Secondary title: Poplave zaradi taljenja snega in sočasnega delovanja več dejavnikov v Severni Ameriki in Evropi
Secondary abstract: This study assessed the drivers of snowmelt floods in relation to compound events. Compound events are when multiple drivers/hazards occur in the same geographic region/time scale, thus amplifying their impacts. The climate drivers considered in this study are temperature, precipitation, snow thickness, snow liquid water equivalent, wind speed, vapour pressure and soil moisture content. 107 different catchments across North America and Europe were investigated, from the years 1979-2019. Each annual maximum flood was sorted into a different flood typology. These typologies were rain-on-snow floods, snowmelt floods, long precipitation floods, and short precipitation floods. These four flood typologies are all split into another two categories, with a wet initial condition and a dry initial condition. The results indicate that the considered catchments have snowmelt floods being the dominant flood type. The high elevation catchments had the dominant typologies being short precipitation floods and long precipitation floods. This initially surprised us, as higher elevations have colder weather and thus are expected to be more influenced by snowfall. However, these mountainous regions often experience large summer rainstorms, thus creating the maximum annual flood. Lower elevation catchments had snowmelt driven floods as the dominant typology. The wet initial conditions were also much more prevalent than the dry initial conditions, proving the importance of the soil moisture condition. This was confirmed through an investigation of the relative influence of the climate factors on the determination of the river discharge. Here, soil moisture had the largest relative influence. Results were determined for the seasonality of the floods as the average day of the year the floods occur on. Based on the results of this, there are geographic regions, such as northeastern North America and central Sweden and Norway, which have a strong seasonality and the floods occur at roughly the same time every year. This can lead to spatially compounding events, where many hazards occur in one geographic region at the same time, thus amplifying their impacts.
Secondary keywords: gradbeništvo;magistrska dela;VOI;poplave zaradi taljenja snežne odeje;tipologija poplav;vlažnost tal;sestavljeni dogodki;podnebni tipi;porečja;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za gradbeništvo in geodezijo
Pages: X, 70 str., [2] str. pril.
ID: 13328279