Streamflow drought is a period of continuing low flows in river. Depending on the time of year streamflow drought are caused by long-term shortage of preci-pitation or long-lasting temperatures below zero. Streamflow droughts are one of the current problems in the management of water, especially in the light seen in recent years, frequent occurrence of droughts. The goal of this work consists in analysis of long-term changes in selected characteristics of streamflow droughts (duration, deficit) in the Zagożdżonka river at the Płachty Stare gauging station. The Zagożdżonka catchment is situated in the strip of the Central Polish Lowlands, in the region where droughts are the most frequent. The Zagożdżonka small river catchment is one of a few in Poland with long-term records on rainfall and runoff. To identify droughts in daily discharge hydrograms, truncation levels SNQ and Q90% were used. The study did not show a tendency to pre-existing low flow periods in the catchment Zagożdżonka. Analysis of the statistical significance of trends in the course of aggregation of the individual years of deficits of droughts and duration of droughts in the Zagożdżonka river at the Płachty Stare showed a positive trend on the level of significance 0,1. In ...
This work concentrates on the analysis of monthly trends of extremes daily temperatures, both minimum and maximum. Analysis was done for the period 2000-2013, based on freely available hourly temperature measurements from 60 Polish stations. Percentiles Tmin10 for minimum and Tmax90 for maximum daily temperature within each month were used as thresholds for selection of extreme temperature values. Count of days with extreme temperatures below/above threshold described every month. Significance of days count trend was analyzed with Mann-Kendall test at the significance level 0.05. For maximum temperatures, significant decreasing trend was found only for 3 station-months. For minimum temperature, 26 significant trends were found and presented in the form of map. ...
