Effect of partial penetration on flow in unconfined aquifers considering delayed gravity response

Abstract

Previously, a new analytical model was proposed by the author for the delayed response process characterizing flow to a well in an unconfined aquifer. It was shown that contrary to prevailing belief this process can be simulated by using constant values of specific storage and specific yield without recourse to unsaturated flow theory. In the present work the theory is extended to account for the effect of a well partially penetrating a homogeneous anisotropic unconfined aquifer. Field and laboratory evidence is quoted to suggest that the elastic storage properties of unconfined aquifers may often be much more pronounced than those of deep‐seated confined aquifers composed of similar materials. The need for further research into the mechanical properties of unconfined aquifers and the role of unsaturated flow in the response process is emphasized.

Evaluation of the streambed leakage concept in analytical models using data from three pumping tests

“…Kollet and Zlotnik (2005a,b) showed that re-infiltration and resulting aquifer return flow was likely during the pumping test and studied the effect on parameter estimates. They used three-dimensional analytical (e.g., Neuman 1974) and numerical models in their analysis of PT. Their estimates of the hydraulic conductivity (K≈100 m/day) agree well when compared to results in the section Results of time-drawdown data analysis, despite that simpler two-dimensional models were used in this study.…”

“…3. The measured time-drawdown behavior is characteristic of unconfined aquifers and exhibits the three distinct drawdown phases that are attributed to the interaction of compressible aquifer storage and the vertical movement of the free water-table surface in the unconfined aquifer (Neuman 1972 and1974).…”

Investigation of Hexavalent Chromium Flux to Groundwater at the 100-C-7:1 Excavation Site

“…Hydraulic properties were estimated using a type-curve fitting method according to the analytical solution of Neuman (1972Neuman ( , 1974Neuman ( , 1975 for an unconfined aquifer with delayed gravity response (specific yield). In this analysis, the wells can be either partially or fully penetrating.…”

Field Test Report: Preliminary Aquifer Test Characterization Results for Well 299-W15-225: Supporting Phase I of the 200-ZP-1 Groundwater Operable Unit Remedial Design

“…The analysis approach is based on type-curve matching methods (i.e., Neuman 1972Neuman , 1974Neuman , 1975 that are commonly used to analyze standard pumping test responses. These approaches, however, do not account for wellbore storage effects either at the pumped well or observation well locations.…”