Delineation of wellhead protection zones: the analysis of main geological factors

Abstract

Introduction. Analysis of the projects concerning wellhead protection (WHP) zones delineation shows the majority of the reports to use a simplified calculation. The applied analytical solutions do not refer to the actual geological conditions of the operating water intakes. The lack of distinct guidelines for geological data to be used in the research and the cost increase force the researchers to represent a simplified assessment. Materials and methods. The control of different WHP zone size geological parameters was studied by applying a series of theoretical calculations. Thus, software for analytical modelling of groundwater wells ANSDIMAT developed by the Institute of environmental geoscience, RAS, was used. Delineation of WHP zones is performed by the Particle-Tracking method. Results. Both size and geometry of WHP zones are controlled by several geological and hydrogeological parameters, which entail a synergetic effect. Within the parameters mentioned above, there are such as 1) pumping discharge; 2) aquifer thickness; 3) accessible porosity; 4) flow direction and the hydraulic gradient; 5) hydraulic conductivity; 6) the hydraulic connectivity of an aquitard. Our research shows all six factors perceptibly influence the results. To avoid significant errors each of the factors should be taken into account. Conclusion. Regulations actualization and the Guideline for delineation of wellhead protection zones, in particular, remain to be an area for improvement. Clear requirements for geological and hydrogeological parameter contamination, parameters uncertainty.