Comparative Study of Step Drawdown and Constant Discharge Tests to Determine the Aquifer Transmissivity: the Kangavar Aquifer Case Study, Iran

T.A. Tizro; K.S. Voudouris; M. Kamali
Evaluation of the hydraulic parameters of aquifers is essential for estimating and developing groundwater resources. Constant discharge pumping tests, monitoring the groundwater level variations in observation wells, can be expensive and time consuming. This paper introduces an approach that is efficient and economical and probably can replace the full pumping test. Well-choosing through field survey, constant discharge pumping tests and step drawdown tests are used in this study to determine the transmissivity (T) of the Kangavar aquifer, located in western Iran. To describe the geological characteristics of the subsurface formations, 16 vertical electrical soundings were performed and interpreted using Schlumberger array. To estimate the transmissivity by a step drawdown test, the aquifer coefficient (n) in well was computed by solving the Miller and Weber equation, through Fixed Point Iteration numerical method by using Visual Basic 6.5 programming. Contours of transmissivity attained through constant discharge and step drawdown tests were plotted for the study area, using kriging method. The results obtained were analyzed applying statistical comparisons, through which no significant difference was observed. Finally, it is concluded that step drawdown test can be used as an alternative to the expensive and time consuming constant discharge tests.
Groundwater; Aquifer; Pumping Test; Step Drawdown Pumping Test; Transmissivity; Statistical Analysis
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