Interpretation of Transmissivity Estimates from Single‐Well Pumping Aquifer Tests

Abstract

Interpretation of single-well tests with the Cooper-Jacob method remains more reasonable than most alternatives. Drawdowns from 628 simulated single-well tests where transmissivity was specified were interpreted with the Cooper-Jacob straight-line method to estimate transmissivity. Error and bias as a function of vertical anisotropy, partial penetration, specific yield, and interpretive technique were investigated for transmissivities that ranged from 10 to 10,000 m(2)/d. Cooper-Jacob transmissivity estimates in confined aquifers were affected minimally by partial penetration, vertical anisotropy, or analyst. Cooper-Jacob transmissivity estimates of simulated unconfined aquifers averaged twice the known values. Transmissivity estimates of unconfined aquifers were not improved by interpreting results with an unconfined aquifer solution. Judicious interpretation of late-time data consistently improved estimates where transmissivity exceeded 250 m(2)/d in unconfined aquifers.

Borehole packer tests at multiple depths resolve distinct hydrologic intervals in 3.5‐Ma upper oceanic crust on the eastern flank of Juan de Fuca Ridge

“…We have insufficient information to resolve the potential influence of the first of these parameters, but variations in apparent formation transmissivity and permeability with depth, shown later, suggest that there is heterogeneous layering of the crust around Hole 1301B. Particularly within highly transmissive formations, partial penetration generally has a modest influence on transmissivity values inferred from single‐hole tests [ Halford et al , 2006]. The issue of aquifer anisotropy is addressed in a related study [ Fisher et al , 2008].…”

Estimating Hydraulic Properties of Volcanic Aquifers Using Constant‐Rate and Variable‐Rate Aquifer Tests1

“…Williams and Soroos (1973) assessed the suitability of a few aquifer tests with observation wells using traditional methods on Hawaii volcanic aquifers. Halford et al (2006) found that hydraulic conductivity is better estimated with aquifer thickness rather than screen length in the case of partially penetrating wells in unconfined aquifers. Halford et al (2006) found that hydraulic conductivity is better estimated with aquifer thickness rather than screen length in the case of partially penetrating wells in unconfined aquifers.…”

Hydrogeology of the Basin Granitoids in the Sekyere South District of Ashanti Region, Ghana

“…Also, the drawdown was low indicating that pumping can be sustained and that aquifers can recuperate as reported by [18]. The maximum and minimum sustainable yields recorded are 380 m 3 /day and 50 m 3 /day (Table 3).…”