Analiza sezonske spremenljivosti pretokov rek v Sloveniji : magistrsko delo

Oblak, Janij (author), Šraj, Mojca (mentor), Kobold, Mira (co-mentor)

V zadnjih desetletjih smo priča vse bolj očitnemu spreminjanju podnebja. Za razumevanje sprememb podnebja je pomembna identifikacija statističnih trendov. V magistrskem delu smo izdelali statistično analizo trendov značilnih pretokov in njihovih indeksov na izbranih vodomernih postajah v Sloveniji na letni ravni, analizo trendov značilnih pretokov in njihovih indeksov na izbranih vodomernih postajah v Sloveniji po letnih časih, analizirali vpliv lokacije vodomerne postaje na spremenljivost pretokov, analizirali vpliv dolžine časovnega niza podatkov na rezultate analiz in izdelali pregled trendov značilnih pretokov in njihovih indeksov po posameznih porečjih RS. V analizo je bilo zajetih 40 vodomernih postaj s časovnim nizom dnevnih srednjih pretokov, dolgim 52 let. Za oceno trenda v nizih podatkov o pretokih je bil uporabljen Mann-Kendallov test. Uporabljeni indeksi pretokov za oceno časovnega spreminjanja pretokov vključujejo analize srednjih letnih/sezonskih pretokov, največjih letnih/sezonskih pretokov, ekstremnih letnih/sezonskih pretokov nad izbranim pragom (POT1 in POT3) ter dveh indeksov nizkih letnih/sezonskih pretokov s trajanjem 7 in 30 dni. Z analizo smo potrdili upad srednjih letnih pretokov po celi Sloveniji, upad najnižjih letnih pretokov v Črnomorskem povodju in upad najnižjih letnih pretokov pri polovici postaj v Jadranskem povodju. V analizi je prikazana razlika med trendi pri posameznem indeksnem kazalniku pretoka glede na sezone in na leto za posamezno vodomerno postajo. Prav tako analiza potrdi pokrajinsko raznolikost Slovenije s primerjavo trendov, saj odstopajo trendi pri vodotokih na vzhodu države, zgornji Savi in v Jadranskem povodju. Pokaže pa tudi vpliv dolžine obravnavanega časovnega obdobja.

• Language: Slovenian
• Keywords: pretoki, podnebne spremembe, hidrologija, trendi, Mann-Kendallov test, statistična analiza, programsko okolje R
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publisher: [J. Oblak]
• Year: 2017
• PID: 20.500.12556/RUL-94355
• UDC: 551.583.1:556.5(282)(497.4)(043.3)
• COBISS.SI-ID: 8116833
• Publication date in RUL: 02.08.2017

Secondary language

• Language: English
• Title: Analysis of the seasonal streamflow variation in Slovenian rivers : Master's thesis

Abstract

In the last few decades global climate is apparently changing. To understand the global climate changes it is important to identify statistical trends. The thesis presents the statistical analysis of streamflow trends and their significant indices for the chosen water gauging stations in Slovenia on a yearly base, the analysis of distinctive streamflow trends and their indices for the chosen water gauging stations in individual seasons, the assessment of the influence of the water gauging station locations on the variation of streamflows, the assessment of the influence of the length of the time data series on the analysis results and the overview of streamflow trends and their indices according to the individual river basins in Slovenia. 40 water gauging stations with a daily mean discharge time series of 52 years was carried out in the analysis. The analysis was carried using R and Hydrospect software. The Mann-Kendall test was applied for the estimation of the trends in the discharge data series and their indices. The used streamflow indices for the estimation of the variation of the streamflows in time were annual/seasonal mean discharge, annual/seasonal maximum daily discharge, extreme annual/seasonal discharge defined by peak-over-threshold method (POT1 and POT3) and two low flow annual/seasonal discharge indices describing the different duration duration of low flows (7 and 30 days). The analysis confirmed decreasing of mean annual discharges all over the country, decreasing of the low discharges in the Black Sea catchment area and decreasing of the low discharges at half of the stations in the Adriatic catchment area. The comparison of the trends confirms the landscape diversity of Slovenia, as they differ for the streams in the Eastern part of the country, the upper Sava River and the Adriatic catchment area. The influence of the length of the time data series on the analysis results was also demonstrated in the research.

• Keywords: streamflow, climate changes, hydrology, trends, Mann-Kendall test, statistical analysis, R software