The Impact of Water Wells Efficiency on Hydrogeological Parameters Assessment and Defect Identification

This article presents an analysis of the changes in hydrogeological parameters considering borehole efficiency. The first part presents the initial assumptions and methodology for determining hydraulic and hydrogeological parameters. Then, the results of parameter changes analysis are presented for 40 cases of water wells which have been occurring over several decades of their operation. The tested wells were drilled in porous aquifers—Quaternary and Neogene sands—as well as fissured aquifers—Cretaceous marls, Jurassic limestones and marls, and Triassic limestones and dolomites. They were divided into groups depending on the type of aquifer medium and the nature of the damage. Group 1 includes wells where water contamination occurred and where changes in hydraulic parameters suggested damage of a critical nature. Group 2 includes wells with a marked increase inflow resistance where advanced clogging was proposed. In Group 3, the changes were similar, but the extent was not as advanced. The efficiency curves analysis and step-drawdown test results made it possible to determine parameters such as hydraulic conductivity, penetration ratio, well-screen transmissivity and current critical well-yield. The calculation methodology used indicates the types and causes of damage and allows a preliminary assessment of the chance of rehabilitating the object in accordance with the principle of sustainable management of environmental resources and technical assets. Alternatively, it allows for the selection of more detailed or invasive diagnostic tests.