Zmienność wskaźnika surowości suszy Palmera i jego wpływ na odpływ ze zlewni nizinnej

The purpose of this study was to evaluate the growing threat of droughts as hydrological extremes. Using the values of the Palmer Drought Severity Index available from Climatic Research Unit, University of East Anglia, Norwich in the United Kingdom, tendencies in the appearance of drought months were analysed for the period from 1901 to 2002. The research was conducted for the lowland catchment located on the Mazovian Lowland within the Kampinos National Park. An increase in frequency of appearance of drought months was detected in 1951-2002, in comparison to the frequencies calculated for the whole analyzed period 1901-2002 as well as for years 1901- 1950. Relationship between the Palmer Drought Severity Index and standardized value of mean monthly discharge was approximated by the linear regression model.