Impact of the shale mine on the River Purtse hydrological regime in north-east Estonia

Abstract

The present paper studies long-term changes in the hydroiogicai regime of the medium (100-1,000 i<m2) river of the Ordovician oil shaie field of north-east Estonia. The changing regime in the heaviiy mined catchments is contrasted with a morphoiogicaiiy simiiar reference catchment (River Keiia) where there has been no mining activity. The Gumbei IVIethod and Rodionov Regime Shifts Algorithm (STARS) were used to study high-and iow-water changes of the mining area. The study shows that mine water has no significant impact on the River Purtse annual run-off; however, it has infiuence on the low water period and minimum flow vaiues, increasing the amount of run-off.Mine water discharge can affect the course of the run-off during the high water period and high water season peal<s. Therefore, in terms of the river maximum fiows return period, there are no major differences between the mining and naturai catchments.