The Pumping Test Data Analyses of Andesite Rock Blocks Aquifer with Varied Hydraulic Boundaries by Generalized Radial Flow Model

The aquifer which includes abundant groundwater resources usually exists at toe of foothill where soil profile at the study area consists of soft silty clay, andesite rock blocks with gravelly sand, and bedrock. A series of constant-rate pumping tests were conducted in the aquifer between two impermeable layers to understand its hydrogeology characteristics. Pumping well is located inside of diaphragm wall, and observation wells are scattered inside and outside of it which was completed before these field experiments. In analytical analyses, diaphragm wall is modeled as impermeable boundary and hillside is assumed as constant recharge boundary. The problem that naturally arises when analyzing data from pumping tests is how to select an appropriate geometry for the particular aquifer system into which flow occurs. This study employs the generalized radial flow (GRF) model to analyze constant-rate pumping test data of the andesite rock blocks-based aquifer and to identify its fractional-flow dimensions further assessing aquifer parameters. This study concludes that the GRF model cannot analyzes the drawdown response if pumping encountered perpendicular boundaries, and the fractional-flow dimension is not unique while other boundaries applied.