The influence of neogene lithology on the Lithuanian river hydrologic regime

Abstract

Due to the recently increasing frequency of extreme changes in river runoff regime, scientific literature deals with the characteristics of runoff formation. Works are carried out in analyzing climate changes and a lot of attention falls on land–use structures. Following thorough analysis of the lithological structure of river basins in separate costal zones, this article aims at evaluating river runoff formation characteristics. The basin lithological factor was calculated based on Quaternary map of Lithuania M 1:200000 and Lithuanian river map M 1:50000 using ArcGis software. In order to carry out more thorough analysis of the influence of lithology in given territories, sections of 0–20 m, 50–200 m, 200–500 m, 500–800 m, 800–1000 m and is greater than 1000 m were established, calculating the distance in meters from the riverbank. Eight river basins of typical lithological structure (sandy, loamy, argillaceous) were selected and examined. The period of the years 1960–2007 was analyzed as this period saw the greatest amount of precipitation (up to 33% probability), and relation between the runoff and precipitation was established as well as that with the lithological structure, established following the derivation of a hydromodule.