Plausible Variable-head Tests Initiated with Continuous Pumping in Monitoring Wells

ABSTRACT: The variable-head (VH) test is initiated by suddenly injecting or withdrawing a volume of water and recording the water level recovery in the monitoring well (MW). A slug or solid rod is added to displace water, which yields a falling recovery of water level. For a rising-head test, a slug of water is removed by extracting the sunk rod or a bailer. A pump can also be used to either inject or remove water, but it is more difficult to practise because it must be conducted very quickly. Seven real and numerical tests in aquifers were considered to be variable-head tests. However, the water recovery in the MW occurred after 15- to 40-min pumping, which are actually constant-head (CH) tests. The paper proves that the interpretation methods for the VH test are applicable to the recovery data of CH test. Five tests have different KCH and KVH values, and present curved or scattered velocity plots instead of straight lines, which is indicative of poorly installed MWs.