Die Bodenkultur - Journal for Land Management, Food and Environment
M. Matoušková, Z. Kliment, O. Ledvinka and V. Královec:
Application of selected statistical tests to detect changes in the rainfall and runoff regime
The research discusses the analysis of trends of essential hydrometeorological elements using selected statistical methods. The main aim of our research project was to compare the time series of flows with an adequate series of rainfall values; air temperatures and snow cover depths, and thereby try to determine what kind of changes occur in low mountains areas (study areas: Bohemian Forest, Ore Mountains, Jeseniky Mt.). We verified the absolute and relative homogeneity of the data series, as well as the presence of a trend in the data series. The following statistical tests, in particular, were used for this purpose: Pettitt test; Standard Normal Homogeneity test; two Wilcoxon tests; and a Mann-Kendall test. Simple-mass and double-mass curves of monthly and annual values were also applied in the case of flow and rainfall values; furthermore, quarter-year as well as cold and warm half-year periods were studied. Trends in flow development do not highly correspond to rainfall tendencies. Since the end of the 70s and especially in the 80s (Bohemian Forest and Jeseniky Mt. and later in 90s Ore Mt.), a substantial increase in runoff occurred during the winter months. Starting in 1980, average annual temperatures have been rising, which corresponds very well to a reduction in snow cover.
Key words: Trend, rainfall-runoff regime, statistical test, low mountain areas, Bohemian Forest, Ore Mt., Jeseniky Mt.