Nieprawidłowości przy ocenie czasu przesączania zanieczyszczeń przez strefę aeracji na podstawie formuł obliczeniowych stosowanych w praktyce hydrogeologicznej

Abstract

Anomalies in the assessment of pollution seepage time through the vadose zone based on formulas used in hydrogeological practice.A b s t r a c t. Polish practitioners of hydrogeology normally use the formulas by either Bindeman, Bindeman as modified by Macioszczyk or by Bachmat and Collin to calculate the time of seepage of conservative pollutants through the vadose zone. These calculations require the knowledge of several hydrogeological parameters (coefficient of vertical permeability, effective porosity, volumetric humidity, intensity of filtration), and the lithology and thickness of the vadose zone. The results obtained depending on the formula used vary considerably, even by more than 1 order of magnitude, which results in differences in technical recommendations for water protection formulated on their basis, and thus has impact on the costs of this protection. Moreover, this variability of results negatively affects the credibility of hydrogeological studies, enhancing the possibility of manipulating the output values. Credibility of calculations dependsessentially on two factors: choice of formula, as each has its drawbacks and restrictions, and correctness of the adopted calculation parameters, which are often only unverified estimates. The paper analyzes the most common mistakes and their impact on the calculated seepage time. The author signals the need for further theoretical and practical studies (including fieldwork and laboratory testing using modeling methods) of this problem. Research on the vadose zone should be one of the primary topics pursued, as risks of pollutionin this zone results in the quality of water occurring below.