Changes and typology of discharge regimes of rivers in Croatia

Čanjevac, Ivan (2012) Changes and typology of discharge regimes of rivers in Croatia. Doctoral thesis, Faculty of Science > Department of Geography.

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Abstract

The object of this research and the key starting point of the thesis are spatial differences of river discharge regime and the changes of the regimes over the period from 1990 to 2009 in Croatia. The main goal is to analyse the changes and to develop the typology of the discharge regimes in Croatia. Methods of quantitative statistics (Wilcoxon test, Seasonal Mann-Kendall test, Kendall-Theil test) have been used as the main tool for the trend analysis, while typology has been used to analyse spatial differences (cluster analysis - Ward method, Manhattan distance). Thematic cartography has been used for analysis and visualization. The analysis has resulted in deeper understanding of the direction and intensity of recent changes of river discharge in Croatia. In addition, typological differentiation of discharge regimes has been made. Data from 53 gauging stations have been used in trend analysisi and typology has been developed for 76 stations on 51 rivers in Croatia. Most of the tests have been done for the period from 1990 to 2009, although for a limited number of stations they have been done for the period from 1960 to 2009. More than half of the 53 analysed stations have the descending trend of the mean annual discharge, in most cases statistically insignificant. More pronounced descending trends have been found in smaller lowland rivers in central and eastern part of Croatia. The main rivers in the continental part of Croatia (Sava, Drava, Mura) have either a small increase or decrease. The only pronounced increase of mean annual discharge hase been found in the Kupa basin. Spring months have shown a very pronounced increase of mean annual discharge, especially in the case of rivers mainly fed by snowmelt. In the summer months there is a pronounced descending trend of discharge in the eastern and western part, as well as the mountainous part of Croatia . The general descending trend of discharge in the eastern and western part, as well as the mountainous part of Croatia. The general descending trend of discharge has beed found for the autumn months. The winter months show increasing trends in the part of croatia with the maritime pluviometric regime (mountains, Istria, Lika and Dalmatia) on the one hand, and descending trends in the part with the continental pluviometric regime on the other (except for the upper part of sava river). The cluster analysis based on the annual discharge curve has resulted in 7 types of discharge regimes: 1) Alpine nival-pluvial regime, 2) Dinaric pluvial-nival regime, 3) Peripannonian pluvial-nival regime, 4) Pannonian pluvial-nival regime, 5) Pannonian pluvial regime, 6) Mediterranean pluvial-nival regime, and 7) Mediterranean pluvial regime.

Item Type: Thesis (Doctoral thesis)
Keywords: hydrogeography, hydrology, river, discharge change, discharge regime, statistical analysis, cluster analysis, Croatia
Supervisor: Orešić, Danijel and Bonacci, Ognjen
Date: 2012
Number of Pages: 106
Subjects: NATURAL SCIENCES > Geography
Divisions: Faculty of Science > Department of Geography
Depositing User: Inja Cahun
Date Deposited: 01 Apr 2014 13:20
Last Modified: 07 Jun 2016 11:22
URI: http://digre.pmf.unizg.hr/id/eprint/751

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