Statistična analiza trendov značilnih pretokov slovenskih rek

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Language:	Slovenian
Year of publishing:	2009
Source:	Ljubljana
Typology:	2.11 - Undergraduate Thesis
Organization:	UL FGG - Faculty of Civil and Geodetic Engineering
Publisher:	[M. Jurko]
UDC:	519.22:556.535(043.2)
COBISS:	4641121
Views:	2309
Downloads:	551
Average score:	0 (0 votes)
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Secondary language:	English
Secondary title:	Statistical analysis of trends of significant streamflows in Slovenia
Secondary abstract:	Analyzing streamflow trends is of great importance to the understanding and perception of climate changes as well as effective water management. In the statistical analysis of streamflow trends in Slovenian rivers, available data on the low, mean and high discharges were examined using mean daily discharges and the Hydrospect software, which was developed under the auspices of WMO for detecting changes in hydrological data (Kundzewicz and Robson, 2000). The Mann-Kendall test was applied for the estimation of trends in the river flow index series. The analysis was carried out for 77 water gauging stations representatively distributed across Slovenia with sufficiently long and reliable continuous data sets. Different indices were used to assess the temporal variation of discharges: annual mean daily discharge, annual maximum daily discharge, two frequency series by peak-over-threshold (POT) approach (POT1 and POT3) and two low flow indices describing the different duration of low flows (7 and 30 days). The clustering method was used to classify the results of trends into groups. The assumption of general decrease of water quantities in Slovenian rivers was confirmed. The annual mean daily discharges of the analyzed water gauging stations show a significant negative trend for the majority of the stations. Similar results with lower statistical significance show annual minimum 7-day and 30-day mean discharge. For the flood indices, there are generally slightly more stations showing a significant negative trend than a significant positive trend. Significant negative trends were seen for gauging stations with predominantly high-mountain and karstic catchment areas.
Secondary keywords:	streamflow;climate changes;hydrology;trends;Mann-Kendall test;statistical analysis;
File type:	application/pdf
Type (COBISS):	Undergraduate thesis
Thesis comment:	Univ. Ljubljana, Fakulteta za gradbeništvo in geodezijo, Univerzitetni študij Vodarstva in komunalnega inženirstva
Pages:	X f., 99 str., pril.
Type (ePrints):	thesis
Title (ePrints):	Statistical analysis of streamflow trends in Slovenia
Keywords (ePrints):	pretoki;podnebne spremembe;hidrologija;trendi;Mann- Kendallov test;statistična analiza
Keywords (ePrints, secondary language):	streamflow;climate changes;hydrology;trends;Mann- Kendall test;statistical analysis
Abstract (ePrints):	Trendi v pretokih so pomembni z vidika zaznavanja podnebnih sprememb in upravljanja z vodami. Diplomsko delo obsega statistično analizo trendov pretokov slovenskih rek z uporabo povprečnih letnih nizkih, srednjih in visokih indeksov pretokov, izračunanih iz časovne vrste srednjih dnevnih pretokov z uporabo programskega orodja Hydrospect, ki je bil razvit pod okriljem WMO za potrebe zaznavanja sprememb v hidroloških podatkih (Kundzewicz in Robson, 2000). Za oceno trenda v nizih podatkov o pretokih je bil uporabljen Mann- Kendallov test. Uporabljeni indeksi pretokov za oceno spreminjanja pretokov v času vključujejo analize srednjih letnih pretokov, največjih letnih srednjih dnevnih pretokov, velikih pretokov nad pragom (v povprečju ena oz. tri vrednosti letno – POT1 in POT3) ter dveh indeksov nizkih pretokov z različnim trajanjem nizkih pretokov (najmanjši letni 7- in 30-dnevni pretoki). V analizo so zajeti pretoki s 77 vodomernih postaj, reprezentativno razporejenih po vsej Sloveniji. Podobnost med obnašanjem vodotokov v zadnjih 30 letih je izračunana na podlagi razdalje Manhattan in Wardove metode razvrščanja v skupine. Potrjena je hipoteza o splošnem zmanjševanju vodnih količin slovenskih rek. Srednji dnevni pretoki večine analiziranih postaj kažejo na statistično značilen padajoči trend. Podobne rezultate z manjšo statistično značilnostjo kažejo najmanjši letni 7- in 30-dnevni pretoki. Analiza poplavni indeksov kaže na nekoliko več postaj s statistično značilnim trendom upadanja pretokov kot s trendom naraščanja pretokov. Statistično značilne padajoče trende izkazujejo predvsem postaje z visokogorskim in kraškim zaledjem.
Abstract (ePrints, secondary language):	Analyzing streamflow trends is of great importance to the understanding and perception of climate changes as well as effective water management. In the statistical analysis of streamflow trends in Slovenian rivers, available data on the low, mean and high discharges were examined using mean daily discharges and the Hydrospect software, which was developed under the auspices of WMO for detecting changes in hydrological data (Kundzewicz and Robson, 2000). The Mann-Kendall test was applied for the estimation of trends in the river flow index series. The analysis was carried out for 77 water gauging stations representatively distributed across Slovenia with sufficiently long and reliable continuous data sets. Different indices were used to assess the temporal variation of discharges: annual mean daily discharge, annual maximum daily discharge, two frequency series by peak-over-threshold (POT) approach (POT1 and POT3) and two low flow indices describing the different duration of low flows (7 and 30 days). The clustering method was used to classify the results of trends into groups. The assumption of general decrease of water quantities in Slovenian rivers was confirmed. The annual mean daily discharges of the analyzed water gauging stations show a significant negative trend for the majority of the stations. Similar results with lower statistical significance show annual minimum 7-day and 30-day mean discharge. For the flood indices, there are generally slightly more stations showing a significant negative trend than a significant positive trend. Significant negative trends were seen for gauging stations with predominantly high-mountain and karstic catchment areas.
Keywords (ePrints, secondary language):	streamflow;climate changes;hydrology;trends;Mann- Kendall test;statistical analysis
ID:	8308190