Vol.8, No 2, 2010 pp. 187 - 199
UDC 556.1:556.06:519.21(045)=111
DOI: 10.2298/FUACE1002187P
METHODOLOGY FOR ASSESSING PROBABILITY OF EXTREME HYDROLOGIC EVENTS COINCIDENCE
Stevan Prohaska1, Borislava Blagojević2, Aleksandra Ilić1
1Institute for the Development of Water Resources "Jaroslav Cerni" Belgrade, Serbia
2University of Niš, Faculty of Civil Engineering and Architecture, Serbia
The aim of the presented research is improvement of methodology for probability calculation of coinciding occurrence of historic floods and droughts in the same year. The original procedure was developed in order to determine the occurrence probability of such an extreme historic event. There are two phases in calculation procedure for assessment of both extreme drought and flood occurrence probability in the same year. In the first phase outliers are detected as indicators of extreme events, their return periods are calculated and series' statistics adjusted. In the second phase conditional probabilities are calculated: empirical points are plotted, and both extreme drought and flood occurrence probability in the same year is assessed based on the plot. Outlier detection is performed for the territory of Serbia. Results are shown as maps of regions (basins) prone to floods, hydrologic drought, or both. Step-by-step numeric example is given for assessing conditional probability of occurrence of flood and drought for GS Raska on the river Raska. Results of assessment of conditional probability in two more cases are given for combination of extreme flood and 30 day minimum flow.
Key words: Conditional probability, outlier detection, extreme hydrologic events coincidence
METODOLOGIJA ZA ODREĐIVANJE VEROVATNOĆE KOINCIDENCIJE EKSTREMNIH HIDROLOŠKIH DOGAĐAJA
Cilj prikazanog istraživanja je poboljšanje metodologije proračuna koincidencije pojave istorijskih poplava i suša u istoj godini. Razvijen je originalan postupak za određivanje verovatnoće javljanja takvog istorijskog događaja. Postupak proračuna verovatnoće javljanja istorijskog događaja ima dve faze. U prvoj fazi se otkrivaju izuzeci, kao pokazatelji ekstremnih događaja, sračunavaju njihovi povratni periodi i prilagodjaju statistike serija.U drugoj fazi, sračunavaju se uslovne verovatnoće: nanose na dijagram empirijske tačke i procenjuje verovatnoća javljanja ekstremne poplave i suše u istoj godini. Otkrivanje izuzetaka obavljeno je za serije na teritoriji Srbije. Rezultati su prikazani u obliku karata regiona podložnih poplavama, sušama, i oboma. Dat je detaljan numerički primer za određivanje uslovne verovatnće javljanja poplave i suše na profilu Raška na reci Raški. Prikazani su rezultati proračuna za još dva slučaja, kada se u istoj godini javlja ekstremna poplava i suša karakterisana 30 dnevnim minimumom.
Ključne reči: Uslovna verovatnoća, otkrivanje izuzetaka, koincidencija ekstremnih hidroloških pojava