The study of the interactions between Sava River and Zagreb aquifer system (Croatia) using water stable isotopes

Jelena Parlov,Zoran Kovač,Jadranka Barešić,O Chudaev,O Shouakar-Stash,Y Kharaka,R Harmon,R Millot

doi:10.1051/e3sconf/20199812017

Jelena Parlov, Zoran Kovač + Show 6 more

Open Access

https://doi.org/10.1051/e3sconf/20199812017

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Abstract

Water stable isotopes were used to investigate hydrological pathways and interactions between surface water and groundwater in the Zagreb aquifer system (Croatia). δ2H and δ18O values indicate a spatial variability of the influence of individual groundwater sources inside the aquifer – local precipitation and the Sava River water. Fractions of surface water in groundwater strongly depend on fluctuations of the river water level and less on the distance from the Sava River. These data extend our understanding of groundwater flow in the Zagreb aquifer system, interactions between Sava River water, local precipitation and groundwater. The results of the research allow more precise monitoring plans and definition of the sanitary protection zones of the well fields in the future.

Highlights

The Zagreb aquifer presents the main source of potable water for the City of Zagreb and part of Zagreb County, and is protected by Croatian state government
Groundwater for water supply is pumped from five different well fields but due to constant decrease of groundwater levels and possible groundwater quantity issues, especially in dry periods, construction of a new regional well-field Kosnica is in progress
In precipitation δ18O values ranged from -14.64‰ to -3.34‰ with mean of -9.44‰, but since the seasonal variation (Fig. 2) is normal for the Northern Hemisphere [3] for calculation of isotope mass balance long term means of δ18O (-8.04‰) from Global Network of Isotopes in Precipitation (GNIP database) were used

Summary

Introduction

The Zagreb aquifer presents the main source of potable water for the City of Zagreb and part of Zagreb County, and is protected by Croatian state government. Groundwater for water supply is pumped from five different well fields but due to constant decrease of groundwater levels and possible groundwater quantity issues, especially in dry periods, construction of a new regional well-field Kosnica is in progress. Kosnica well-field is considered in the future as a main well-field supplier and the location of recharge areas is of prime concern, as such areas have to be protected in order to preserve good groundwater quality and quantity. Groundwater often consists of a mixture of recharge from surface water (lakes or rivers) and local precipitation. It is important to know the proportions of these recharge components in order to increase the sustainable supply of drinking water through bank infiltration, and to prevent drinking water pollution by infiltration of water from a contaminated surface water source

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