Determination of transmissivity and storage of a large water table aquifer from long-term pumping test data

1977 ◽  
Vol 14 (4) ◽  
pp. 61
Keyword(s):  
Water Table ◽  
Test Data ◽  
Pumping Test ◽  
Large Water ◽  
And Storage

Drawdowns at the Free Water Table During Pumping Tests in Artesian and Semiartesian Aquifers

1980 ◽  
Vol 11 (3-4) ◽  
pp. 159-168 ◽  
Author(s):  
Henrik Kærgaard
Keyword(s):  
Water Table ◽  
Free Water ◽  
Pumping Test ◽  
Water Withdrawal ◽  
Specific Yield ◽  
Minor Role ◽  
Long Term Effects ◽  
Long Term Storage ◽  
Term Storage

In an earlier paper I have shown an example of how long term drawdowns can be used for the computation of long term storage in artesian and semiartesian areas. In most cases the long term storage is more or less equivalent to the specific yield at the water table; the storage mechanisms of consolidation playing a minor role in long term situations. The specific yield in artesian areas is a very important parameter in the prediction of long term effects of ground water withdrawal. Especially the stream depletion will often mainly be governed by draw-downs in upper nonpumped aquifers near the water table, and these drawdowns depend to a great extent on the specific yield at the water table. A determination of long term storage will often necessitate long term draw-down data, however, under certain circumstances a determination can be made on the basis of a pumping test of limited duration (3-5 weeks) provided drawdown observations at the water table can be made. In this paper some formulas dealing with water table drawdowns in different geohydrologic systems are reviewed, and two cases in which these formulas have been used in practice are presented.

scholarly journals A Straight-Line Method for Analyzing Residual Drawdowns at an Observation Well

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Mesut Çimen
Keyword(s):  
Groundwater Resources ◽  
Dimensionless Time ◽  
Observation Well ◽  
Recovery Method ◽  
Straight Line ◽  
Well Function ◽  
And Storage ◽  
Straight Line Method

Determination of the hydraulic parameters (transmissivity and storage coefficients) of a confined aquifer is important for effective groundwater resources. For this purpose, the residual drawdowns have been in use to estimate the aquifer parameters by the classical Theis recovery method. The proposed method of this paper depends on a straight-line through the field data and it helps to calculate the parameters quickly without any need for long-term pumping data. It is based on the expansion series of the Theis well function by consideration of three terms, and this approach is valid for the dimensionless time factoru′=S′r2/4Tt′≤0.2. The method can be applied reliably to extensive and homogeneous confined aquifers resulting in different storage coefficients during the pumping and recovery periodsS≠S′. It presents a strength methodology for the parameters decision making from the residual data in the groundwater field of civil engineering.

Geoelectric sounding for the determination of aquifer characteristics in parts of the Umuahia area of Nigeria

Geophysics ◽  
1991 ◽  
Vol 56 (2) ◽  
pp. 284-291 ◽  
Author(s):  
P. D. C. Mbonu ◽  
J. O. Ebeniro ◽  
C. O. Ofoegbu ◽  
A. S. Ekine
Keyword(s):  
Hydraulic Conductivity ◽  
Test Data ◽  
Pumping Test ◽  
Model Parameters ◽  
Current Electrode ◽  
Entire Area ◽  
Maximum Current ◽  
Electrical Soundings ◽  
Aquifer Characteristics

Seventeen Schlumberger vertical electrical soundings (VES) were carried out in parts of the Umuahia area of Nigeria, using a maximum current electrode separation of 1 km. The data were interpreted using a conventional partial curve‐matching method to obtain initial model parameters, which were used in a computer program to obtain final parameters. Three soundings were made at existing boreholes for comparison. Aquifer parameters of hydraulic conductivity and transmissivity were obtained by analyzing pumping test data from existing boreholes. The results of the interpretation revealed three distinct geoelectric layers overlying a conductive geoelectric basement. Based on the model obtained, aquifer hydraulic conductivity and transmissivity were calculated. The hydraulic conductivity calculated agreed closely with that determined from pumping test data. The results of the present study also indicate that the entire area is divided into two zones, each of which is homogeneous in hydraulic properties and water quality, but distinct from the other zone. A local groundwater divide between the Imo and Kwa‐Ibo drainage systems was also defined.

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