The impact of land drainage on Nevezis river flow

Abstract

The paper overviews the research material related to occurrence of sinkholes and change of their water quality in the conditions of increasingly natural environment and minimal anthropogenic impact. Sinkholes create favourable conditions for interaction of surface and groundwater. Identification of possible sources of sinkholes pollution is ver. important in solution of groundwater safety problems. Water quality investigations are carried out in 4 sinkholes, which are of different age and have differently overgrown slopes. Sinkhole water quality may worsen due to accumulaticr of organic materials (increasing peat content) or natural changes of environment (abrasion of slopes, overgrov. th. etc.), while anthropogenic impact is minimal. Water quality in peat-filled sinkholes and young sinkholes with miner;! slopes is different. Water of peat-filled sinkholes has bigger amounts of N-N03, PTotal, S04 and BOD. than water m young sinkholes. The highest N-N03 and S04 concentration is observed in the sinkhole that is overgrown with trees and shrubs