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Introduction To Well Theory
Published in Ian Watson, Alister D. Burnett, Hydrology, 2017
Ian Watson, Alister D. Burnett
Specific Storage (Ss) may be defined as the volume of water per unit volume, that is released from (or taken into) the elastic storage of an aquifer, per unit change in head. This may be expressed as: () Ss=Ve/Vt(perunitchangeinhead)
Introduction
Published in James Johnson Butler, The Design, Performance, and Analysis of Slug Tests, 2nd Ed, 2019
The slug test is a deceptively simple approach in practice. It essentially consists of measuring the recovery of head (water level) in a well after a near-instantaneous change in head at that well (a nearby observation well can also be used in certain situations). Figure 1.1 is a pair of schematic cross sections that illustrate the major features of a slug test. In the standard configuration, a test begins with a sudden change in water level in a well (Figure 1.1A). This can be done, for example, by rapidly introducing a solid object (hence the term “slug”) or equivalent volume of water into the well (or removing the same), causing an abrupt increase (or decrease) in water level. Following this sudden change, the water level in the well returns to static conditions as water moves out of the well (as in Figure 1.1B) or into it (when change is a decrease in water level) in response to the gradient imposed by the head change. An example record of head changes with time during a slug test is given in Figure 1.2. These head changes, which are termed the response data, can be used to estimate the hydraulic conductivity of the formation through comparisons with theoretical models of the well-formation response to the slug-induced disturbance. In theory, slug tests can often also be used to obtain an estimate of the formation’s ability to release or accept water into storage; this storage capability of the media is characterized in hydrogeology by the specific storage parameter. However, given the realities of the field, one can have little confidence in the estimate of specific storage resulting from a slug test. In contrast to pumping tests, slug tests are rapid and affect a relatively small volume of the formation, so little information about slow-to-develop flow mechanisms (e.g., pore drainage or multiporosity flow) or formation boundaries can be obtained.
Aquifer storage and abstraction impacts
Published in Ian Acworth, Investigating Groundwater, 2019
The specific storage is the volume of water released from a unit cross-sectional area of aquifer for a unit decrease in hydraulic head. The Ss is multiplied by the density to maintain the equation as a mass flux.
Using MODFLOW/MT3DMS and electrical resistivity tomography to characterize organic pollutant migration in clay soil layer with a shallow water table
Published in Environmental Technology, 2021
Chang Gao, Xiujun Guo, Shuai Shao, Jingxin Wu
The governing equation used in our study is a standard transient three-dimensional groundwater flow equation [18]: where h is the groundwater head (m), , , and represent the values of hydraulic conductivity (m/d) along the , , and coordinate axes, respectively, W represents the amount of water in or out of a unit volume of aquifer per unit time (d−1), is the specific storage of the aquifer (m−1), and is time (d).
The impact of rock fracturing and pump intake location on the thermal recovery of a standing column well: model development, experimental validation, and numerical analysis
Published in Science and Technology for the Built Environment, 2019
Gabrielle Beaudry, Philippe Pasquier, Denis Marcotte
A comprehensive experimental program was undertaken in 2017 to acquire detailed information about the site characteristics. Parameters needed for the development and validation of an accurate numerical model were obtained following the tests listed in the following. These parameters include the nature, depth, undisturbed ground temperature, specific storage, and hydraulic and thermal conductivities of the bedrock, as well as groundwater static hydraulic head and potential thermal interaction between the SCW and IW. A dynamic heat extraction test was also conducted to appreciate the SCW’s efficiency through winter operation. A summary of the experimental program conducted and results obtained is presented in Table 2. Note that the confidence intervals were obtained by the usual method of propagation of errors described in Moffat (1988). Both systematic and random errors on the measurements were fully considered. The 95% confidence interval is obtained by assuming a Gaussian distribution for the total combined error.
Groundwater flow modeling for cachar, India using MODFLOW: a case study
Published in ISH Journal of Hydraulic Engineering, 2022
Mrinal Kumar Singh, Susmita Ghosh
Hydraulic conductivity and specific storage, specific yield these are the aquifer parameters that control the groundwater movement. Sandy clay, sandstone, and shale are the main forms of the aquifer which has low hydraulic conductivity and specific storage. Hydraulic conductivity and specific storage were assigned in the model at eight pumping well locations (Figure 5(a)), where aquifer parameters were estimated by CGWB, Guwahati using the pumping test data. Hydraulic conductivity and specific storage were assigned in the model which lies between 0.35 and 3.2 m/day and 0.000136 to 0.00693 respectively. The specific yield value of 0.20 was uniformly assigned for the whole area (Gogoi 2014).