Jelena Parlov

Fully automated objective-based method for master recession curve separation.

The fully automated objective-based method for master recession curve (MRC) separation was developed by using Microsoft Excel spreadsheet and Visual Basic for Applications (VBA) code. The core of the program code is used to construct an MRC by using the adapted matching strip method (Posavec et al. 2006). Criteria for separating the MRC into two or three segments are determined from the flow-duration curve and are represented as the probable range of percent of flow rate duration. Successive separations are performed automatically on two and three MRCs using sets of percent of flow rate duration from selected ranges and an optimal separation model scenario, having the highest average coefficient of determination R(2), is selected as the most appropriate one. The resulting separated master recession curves are presented graphically, whereas the statistics are presented numerically, all in separate sheets. Examples of field data obtained from two springs in Istria, Croatia, are used to illustrate its application. The freely available Excel spreadsheet and VBA program ensures the ease of use and applicability for larger data sets.

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

This paper presents a conceptual model of the Zagreb aquifer system. The conceptual model can be applied to groundwater status risk assessment and pollution risk assessment at the local scale, 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 diffuse 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 (Kosnica) 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.

Gaussian simulation of nitrate concentration distribution in the Zagreb aquifer

ABSTRACT Nitrates present one of the most common groundwater contaminants in the world and one of the five major groups of contaminants in the study area. Gaussian simulation (GS) algorithm was used for determining the spatial distribution of average nitrate concentrations from 2010 to 2015 on 95 sampling points. Results indicate two main focus areas of nitrate contamination, located on the left and right bank of the Sava River. Those areas generally extend according to groundwater flow, while areas near Sava River have much smaller concentrations. GS showed that they can be useful for this kind of mapping because they favor abrupt changes in data values which are in this case a result of heterogeneous lithological composition of the aquifer.

Hydrogeological characteristics of south hills, Ivanščica Mountain

ABSTRACT This article presents results of hydrogeological and hydrogeochemical research conducted at south hills, Ivanščica Mountain, situated in the northwestern part of the Republic of Croatia. Research was carried out in the summer 2013, between July and September. Hydrogeological mapping was undertaken on approximately 20 km2 (at a scale of 1:25000), with water samples taken from 10 springs. Rocks and deposits were classified into three hydrogeological units with respect to permeability. Two main aquifers were identified – the Triassic carbonate aquifer and the Badenian carbonate aquifer. The overall capacity of 41 registered springs (permanent and periodic) was estimated. According to their basic chemical composition, water from springs belong to Ca-HCO3 (calcium-hydrogen carbonate), CaMg-HCO3 (calcium magnesium-hydrogen carbonate) and to MgCa-HCO3 (magnesium calcium-hydrogen carbonate) types.