Comparison of the results of pumping and tracer tests in a karst terrain

• Published in: Journal of caves and karst studies 2016-08, Vol.78 (2), p.110-118
• Main Authors: Nassimi, Alireza, Mohammadi, Zargham
• Format: Article
• Language: English
• ISSN: 1090-6924; 2331-3714
• DOI: 10.4311/2015ES0119

Pumping and tracer tests are commonly used to measure aquifer parameters such as hydraulic conductivity. Hydraulic conductivity is, however, difficult to characterize; especially in heterogeneous karst terrain. In this research, results of pumping and tracer tests are combined to determine hydraulic conductivities of the karst terrain at the Salman Farsi Dam Site. Pumping test data were analyzed by dual-porosity analytical models. The tracer tests were used to determine seepage velocities based on the assumption of Darcy's law, with calculated Reynolds numbers consistent with laminar flow. Geometric means of the hydraulic conductivities calculated from tracer tests were consistently higher than results derived from pumping tests. Movement of injected dye in a natural groundwater flow system is strongly controlled by preferential flow paths; therefore the estimated hydraulic conductivity is mainly affected by major dissolution openings. However, estimated hydraulic conductivity based on the pumping-test data is representative of the average hydraulic conductivity. In addition, Lugeon (or packer) tests were used to delineate the distribution of hydraulic conductivity within three boreholes.