Trend Detection in Hydrological Series of Main Lithuanian Rivers

Abstract

Runoff being as a main element of the hydrologic cycle and resulting from the climatic processes at the same time can be as an indicator of global climate change. In reality, river runoff mostly characterized by visible extreme values – floods and draughts, therefore the hydrological time series of extreme values for trend detection where chosen. There were selected annual maximum (spring flood), average and minimum (summer time low flow) runoff values of the main Lithuanian rivers (with lowest human impact) over the last 50 years from the major hydrologic regions. The objective of the paper is to determine the trends of selected hydrological series evaluating possible impact of climate change factors employing different statistical tests. The results obtained indicate the substantial difference in runoff fluctuation tendencies among the investigated maximum, average and minimum runoff rates.