Study of groundwater flow in the coarse gravel unsaturated zone by means of isotope hydrograph separation

Abstract

The paper presents the use of isotope hydrograph separation method in the determination of snowmelt impact on groundwater dynamics and in the investigation of preferential flow in the high permeable coarse gravel unsaturated zone. Preferential flows as well as matrix flow dynamics are important for groundwater storage in the unsaturated zone and for pollution transport to the saturated zone. Data analysis is based on data collected during the time of sudden snowmelt in March 2004 in the Selniška Dobrava lysimeter. The results indicate the piston flow effect phenomenon also in the high permeable coarse gravel aquifer at the time of infiltration of large quantities of water. The preferential flow influence decreases with depth. A larger share of new water was observed up to 1.5 m depth (38 %), while it decreases with depth.