Effect of scaling on hydraulic conductivity in a Karst Aquifer

Hydraulic conductivity was determined for samples from the Biscayne Aquifer in Miami Florida at bench and field scales. Hydraulic conductivity values obtained were examined for increase due to scale and for anisotropy. Bench scale testing was performed on Key Largo Limestone cubes for total porosity, effective porosity, and hydraulic conductivity. Total porosity was determined by drying and weighing, while effective porosity was determined by submersion. Hydraulic conductivity was determined in a permeameter for each axis of each cube. Field scale testing of hydraulic conductivity was performed with slug tests in the Miami Oolite Formation at the Homestead General Airport. Aquifer scale values for hydraulic conductivity were taken from the literature. Hydraulic conductivity was found to increase with scale in the - Biscayne Aquifer. Furthermore, it increased greatly above an effective porosity of 33 percent. Anisotropy was found to vary in cubes with depth and in proximity to a dense laminated layer

Identification of a hydrodynamic threshold in karst rocks from the Biscayne Aquifer, south Florida, USA

A hydrodynamic threshold between Darcian and non-Darcian flow conditions was found to occur in cubes of Key Largo Limestone from Florida, USA (one cube measuring 0.2 m on each side, the other 0.3 m) at an effective porosity of 33% and a hydraulic conductivity of 10 m/day. Below these values, flow was laminar and could be described as Darcian. Above these values, hydraulic conductivity increased greatly and flow was non-laminar. Reynolds numbers (Re) for these experiments ranged fro

Nonlinear Flow in Karst Formations

The variation of effective hydraulic conductivity as a function of specific discharge in several 0.2-m and 0.3-m cubes of Key Largo Limestone was investigated. The experimental results closely match the Forchheimer equation. Defining the pore-size length scale in terms of Forchheimer parameters, it is demonstrated that significant deviations from Darcian flow will occur when the Reynolds number exceeds 0.11. A particular threshold model previously proposed for use in karstic formations does not show strong agreement with the data near the onset of nonlinear flow