Conceptual model for groundwater status and risk assessment - case study of the Zagreb aquifer system

Abstract

This paper presents a conceptual model of the Zagreb aquifer system. The conceptual model can be applied to groundwater status risk assesstnent and pollution risk assessment at the local seale, thus satisfying both environmental and preventative/limitation objectives of the Water Framework Directive (WFD) and Groundwater Directive (GWD). Its main purpose is to apply a risk assessment procedure, according to the WFD requirements, and to serve as a foundation for setting up a numerical model of flow in both the saturated and unsaturated zones in order to identify pressure and impact effects on groundwater quality. The model is divided into two parts, taking into account the WFD requirement to assess a risk for a wide range of source-pathway-receptor relationships. The Global Conceptual Model (GCM) provides insight into the processes and pressures at the level of the groundwater system. It contains the geological and hydrogeological characterization of the Zagreb aquifer system and the description of the most significant point and difilise sources and pathways of pollution and processes influencing pollutant behaviour in saturated and unsaturated zone of the groundwater system. The main pollutants of the Zagreb aquifer system are potentially toxic metals, nitrates, pesticides, pharmaceuticals and chlorinated aliphatics. A Local Conceptual Model (LCM) supports parameterization of the whole groundwater system through the description of heterogeneities and flow and solute parameters of the system components at two sites representing local conditions in the saturated (Stara Loza) and unsaturated (Kosniea) zones. This concept can be regarded as an effective tool for groundwater management of the groundwater system and its compartments and for communicating the conditions in complex groundwater systems with experts, policy makers and general public in an understandable way.

Herbicide micropollutants in surface, ground and drinking waters within and near the area of Zagreb, Croatia

“…The geographical position of the city of Zagreb between the south-west slopes of Mount Medvednica and the banks of the Sava River as well as the geological and pedological traits of the Zagreb aquifer system have been described in detail by Nakić et al (2013) who developed a conceptual model for groundwater status and pollution risk assessment at a local scale. The system, which is an alluvial unconfined aquifer, includes the city of Zagreb and its surroundings covering an area of 350 km 2 .…”

Fluvisol permeability estimation using soil water content variability

“…Highly variable lithology, pedological features and land use characterize the broader region. The study area consists of a large alluvial plain that has two marked geomorphological features: the raised sealed terrace of the Sava River (varying in width down the rivers length), and a Holocene terrace (Nakić et al, 2013). Numerous meanders of the Sava River inundated fluvial cones and numerous bowl-shaped depressions abound in the alluvial plain.…”

Estimation of Nitrate Trends in the Groundwater of the Zagreb Aquifer

“…4 based on the operational monitoring data. Previous research has shown that nitrates present one of the main groups of contaminants in the Zagreb aquifer [5]. Furthermore, two areas with elevated nitrate concentrations have been observed, while lower concentrations generally appear in the vicinity of the Sava River and in the eastern part of the aquifer [6,7].…”

“…Due to the expansion of the City of Zagreb and nearby rural areas, anthropogenic influence on groundwater quality has been observed, while nitrates have been recognized as one of the main contaminants [5]. Two main areas with elevated nitrate concentrations have been identified, one on the left bank of the Sava River, in a predominantly urban area, and the other on the right bank of the Sava River, in a predominantly agricultural area.…”

“…High nitrate concentrations have been observed in the groundwater of the Zagreb aquifer [5][6][7]. The Zagreb aquifer presents the only source of potable water for the citizens of the City of Zagreb and part of Zagreb County.…”