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Assessment of Methods and Conditions to Locate Boundaries: II. One Straight Recharge Boundary
Author(s) -
Chapuis Robert P.
Publication year - 1994
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1994.tb00894.x
Subject(s) - impervious surface , groundwater recharge , inflection point , boundary (topology) , graph , mathematics , point (geometry) , geometry , value (mathematics) , aquifer , mathematical analysis , geology , statistics , geotechnical engineering , groundwater , combinatorics , ecology , biology
Abstract A straight recharge boundary in an ideal aquifer is easily detected in the drawdown graph of an observation well. Two known and one proposed methods can be used to find the location and orientation of the recharge boundary. This paper assesses their performance. Both the law of times and the method of inflection point overestimate the distance r i to the imaginary well when the ratio β= r i / r r is smaller than 20. In this case, known methods also give incorrect estimates of aquifer parameters. The proposed method gives directly the β‐value when it is higher than 20. For lower β‐values, a correction factor transforms the apparent β‐value into the correct β‐value. Two examples illustrate the quality of predictions by the known and proposed methods. Two known and one proposed methods relative to impervious boundaries are assessed in a companion paper.