Przepływy graniczne niżówek w rzekach Lubelszczyzny

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Przepływy graniczne niżówek w rzekach Lubelszczyzny

Journal Title: Annales Universitatis Mariae Curie-Skłodowska, sectio B - Geographia, Geologia, Mineralogia et Petrographia - Year 2015, Vol 0, Issue 1

Abstract

The most common method to identify periods of streamflow drought is threshold level method (TLM), in which streamflow drought is considered to be a period in which river flows drop below established flow value. In literature there are many ways of determining value of this parameter, however, it still remains a subjective matter of the researcher. This paper summarizes and analyzes most common methods of determining threshold level for flows as well as identifies advantages and disadvantages of their use. The analysis was conducted for hydrological years 1976–2013 in 17 river profiles located in the Lublin region. The results indicate a high resistance to changes of value, due to length of observation periods for flows specified by methods of Q90 and Q87,5 determined from flow duration curves (FDCs). The lowest values of threshold level were obtained by using mean annual low flow and modified Niesułowski method, whose values were also comparable. The highest threshold levels were obtained by using Q70 and highest from low-flows criteria, which led to occurrence of long streamflow droughts even five times during a year. Due to different hydrogeological structure, genetic criterion was not possible to use in rivers located in lowland area. A value of Q90 is recommended as threshold level from all analyzed methods to identify streamflow droughts, and mean annual low flow for analyses of deep periods of droughts.

Authors and Affiliations

Krzysztof Raczyński

Keywords

niżówka przepływy graniczne susza hydrologiczna przepływy niskie krzywa czasu przewyższenia przepływu przepływy charakterystyczne II stopnia Lubelszczyzna

EP ID EP402671
DOI 10.17951/b.2015.70.1.117
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