Numerical modeling of groundwater flow to delineate spring protection zones. The case of Krokos aquifer, Greece

Abstract

This study deals with protection of springs, which are fed by aquifers susceptible to contamination by anthropogenic activities. Krokos aquifer, located in Western Macedonia, Greece, whose springs provide water to Krokos town, is used as a case study. In this aquifer, concentrations of nitrates, exceeding the legislation limits, had been occasionally detected. First, some additional water quality measurements have been conducted, covering more than one calendar year, which confirmed rather high concentrations of nitrates, close, but not exceeding the World Health Organization guideline limit of 50 mg/L. Then, numerical simulation of groundwater flow in Krokos aquifer took place. Groundwater modeling system, which allows for construction of a three-dimensional flow model, has been used in this task. First, the boundaries of the aquifer and the respective boundary conditions have been defined, based on available field data. Then, the required hydraulic head and groundwater velocity values have been calculated. Based on them, the spring protection area from pollution sources has been defined, using the particle-tracking package MODPATH. Finally, sensitivity analysis has been conducted to check the influence of some uncertain data to the delineation of the spring protection zone.

Keywords:

• Spring protection
• Hydrochemical analysis
• Groundwater flow modeling
• Particle tracking
• Sensitivity analysis
• Krokos aquifer

Acknowledgments

The authors are grateful to Dr V. Tsiridis and Dr M. Petala for their assistance with the chemical analyses of water samples at the Laboratory of Environmental Engineering and Planning (Civil Engineering Department, Aristotle University of Thessaloniki, Greece). They are also grateful to Mr A. Stamos, senior geologist at I.G.M.E., for additional information on the geology and hydrogeology of the studied area.

Notes

Presented at the 12th International Conference on Protection and Restoration of the Environment (PRE XII) 29 June–3 July 2014, Skiathos Island, Greece