Zmienność na obszarze Polski postaci funkcji rozkładu prawdopodobieństwa przepływu minimalnego w roku

Identification of probability distributions of minimum discharges at fifty cross-sections on Polish rivers is presented in this paper. Three distributions: log-normal, Pearson type III and Weibul were taken into consideration. Their parameters were estimated by two methods: method of moments and the maximum likelihood method. Initial verification was achieved by the [lambda] Kolmogorov-Smirnov goodness-of-fit test. Selection of the best distribution was made based on the maximum log-likelihood value principle. The results were illustrated on the map of Poland. They showed that certain homogeneous areas of distributions appeared. The area of the upper Vistula river basin, middle and lower Odra basin and middle Warta and Noteć rivers are dominated by the Pearson type III distribution. Log-normal distribution prevails on the Bug river and its tributaries, lower Warta and lower Vistula rivers, while the Weibull distribution can be found both in the south and in the north of Poland. However, it should be stressed that the results obtained do not give basis good enough for more general conclusions and practical applications and further extensive research is required.