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| Titel |
Statistical Analysis of Streamflow Trends in Slovenia |
| VerfasserIn |
M. Jurko, M. Kobold, M. Mikoš  |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250020614
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| Zusammenfassung |
| According to climate change, trends of river discharges were analyzed showing the
hydrological change and future projections of hydrological behaviour in Slovenia. In last
years droughts and floods are becoming more and more frequent. In the statistical analysis of
streamflow trends of 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.
Trend analysis requires long records of observation to distinguish climate change-induced
trends from climate variability. The problems of missing values, seasonal and other
short-term fluctuations or anthropogenic impacts and lack of homogeneity of data due to the
changes in instruments and observation techniques are frequently present in existing
hydrological data sets. Therefore the analysis was carried out for 77 water gauging stations
representatively distributed across Slovenia with sufficiently long and reliable continuous
data sets. The average length of the data sets from the selected water gauging stations
is about 50 years. Different indices were used to assess the temporal variation of
discharges: annual mean daily discharge, annual maximum daily discharge, two
magnitude and 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 a 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.
Reference: Kundzewicz, Z.W. and Robson, A. (2000). Detecting trend and other changes
in hydrological data. WMO Report WMO/TD-No. 1013. Geneva. |
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