scholarly journals Experimental Design of Physical Unconfined Aquifer for Evaluation of Well Abstraction Effects: Laboratory Approach

2021 ◽  
pp. 90-102
Author(s):  
Dak Bahadur Khadka
Keyword(s):  
Hydraulic Conductivity ◽  
Vertical Direction ◽  
Fine Sand ◽  
Unconfined Aquifer ◽  
Effective Porosity ◽  
Specific Yield ◽  
Radius Of Influence ◽  
Time Period ◽  
The Comparative Study ◽  
Porosity Model

In unconfined aquifer water flows in both horizontal and vertical direction when pumping. So its study during pumping action is more complex. Soil type, porosity, hydraulic conductivity and transmissivity are important parameters that control the specific yield, drawdown and radius of influence on aquifer while abstraction. Due to large extraction of water from the aquifer, the water table drops down and may lead to permanent depletion of yield capacity of aquifer. For practical understanding of water being pumped from aquifer and its impacts on water storage the easiest method is experimental approach .So therefore, this study was planned to carry out the well abstraction from unconfined aquifer of homogeneous sandy soil designed as physical model on rainfall simulator at hydraulic laboratory hall of Campus itself. The catchment dimension is 2.2 meter length, 1 meter width and 0.15 meter depth with impermeable base filled with fine sand as per specification. The simulator was adjusted to make horizontal aquifer. The experimental observations were carried out in two conditions, first was well abstraction with no rainfall after saturation and the second is with rainfall even after saturation condition obtained. The two wells were operated for the abstraction of water simultaneously so that the effect of one well to another could be studied. After observation and data collection, for the analysis of hydraulic conductivity Dupit model. Empirical model and relative effective porosity model (REPM) were used for the comparative study. Similarly the radius of influence was estimated by three models (weber,Kusakin and Sichardt).  For the estimation of transmissivity of the aquifer Thien model was used. Also the general equation (product of hydraulic conductivity and depth of aquifer) was used. Study showed the suitability of the available theories and governing equations for unconfined aquifer. The most important part of the study was to establish the correlation of drawdown and radius of influence with the time period of well abstraction. From the results the correlation coefficient for time and drawdown was of 90% and for time and radius of influence was 97%.

scholarly journals Soil water management problems using fuzzy arithmetic

2013 ◽  
Vol 11 (4) ◽  
pp. 556-565
Keyword(s):  
Hydraulic Conductivity ◽  
Uncertain Data ◽  
Triangular Fuzzy Number ◽  
Effective Porosity ◽  
Specific Yield ◽  
Fuzzy Arithmetic ◽  
Two Dimensional ◽  
Fuzzy Analysis ◽  
Management Problems ◽  
Α Level

Drainage management problems are usually very hard to simulate due to the uncertainty of the hydraulic parameters involved. Fuzzy analysis is one of the available tools that can be used for such problems, involving uncertain data. A fuzzy analysis approach usually involves the consideration of several α-level cuts and an analytical approach or an explicit scheme approach for the PDE's discretization. Several application examples of this approach are listed in the literature, including uncertainty in hydraulic conductivity, specific yield, transmissivities, porosities, dispersivities, and deoxygenation rate coefficient. A methodology for the simulation of drainage problem having vague values of hydraulic parameters is introduced in this paper, and an analytical solution for a two-dimensional drainage application is presented. The two-dimensional problem of drainage is handled using fuzzy analysis by defining the hydraulic conductivity K as a triangular fuzzy number (TFN). The method of interval analysis is used in all the α-level cut examples. A solution is obtained using eleven α-level cuts and also solutions for two, three, and five α-level cuts are presented. Trials for different values of effective porosity are also performed. Finally conclusions on the necessary number of α-cuts utilized for drainage problems are drawn.

scholarly journals Automatic calibration of the groundwater simulation model with high parameter dimensionality using sequential uncertainty fitting approach

2020 ◽  
Vol 20 (8) ◽  
pp. 3487-3501
Author(s):  
Fariborz Masoumi ◽  
Saeid Najjar-Ghabel ◽  
Akbar Safarzadeh ◽  
Behnam Sadaghat
Keyword(s):  
Hydraulic Conductivity ◽  
Simulation Model ◽  
Pso Algorithm ◽  
Unconfined Aquifer ◽  
Flow Equation ◽  
Specific Yield ◽  
Automatic Calibration ◽  
Groundwater Model ◽  
Total Uncertainty ◽  
Groundwater Simulation

Abstract Calibration of the groundwater simulation model is one of the main challenges in the modeling process. In addition, hydrogeological complexities and the lack of field data in terms of time and space lead to uncertainty in the model. Therefore, the present study linked the groundwater simulation model (MODFLOW) and sequential uncertainty fitting approach (SUFI-2) to the uncertainty-based automatic calibration of the Ardabil groundwater model located in northwestern Iran. Hydraulic conductivity, specific yield, recharge rate, the hydraulic conductivity of the riverbed material, and the boundary conductance of the aquifer were considered as the uncertain parameters. Furthermore, the Newton solution method for the unconfined aquifer was used for solving the groundwater flow equation. A Normalized Total Uncertainty Index was defined to evaluate the performance of the SUFI-2 algorithm. According to the MODFLOW-SUFI-2 calibration findings, 60% of observational data was bracketed by a 95% confidence interval, on average. The Ardabil groundwater model was also calibrated with the PSO algorithm. In comparison with SUFI-2, although this method resulted in good coverage of the solution, it obtained irrational values for most parameters since they only aimed to match observational and computational values. Eventually, SUFI-2 showed a small number of simulation runs compared with the PSO algorithm.

Using groundwater levels and Specific Yield to Estimate the Recharge, South of Erbil, Kurdistan Region, Iraq

2018 ◽  
Vol 7 (4) ◽  
pp. 191
Author(s):  
Sherwan Sh. Qurtas
Keyword(s):  
Unconfined Aquifer ◽  
Middle Part ◽  
Water Levels ◽  
Specific Yield ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Water Table Fluctuation Method ◽  
Recharge Estimation ◽  
Fluctuation Method

Recharge estimation accurately is crucial to proper groundwater resource management, for the groundwater is dynamic and replenished natural resource. Usually recharge estimation depends on the; the water balance, water levels, and precipitation. This paper is studying the south-middle part of Erbil basin, with the majority of Quaternary sediments, the unconfined aquifer system is dominant, and the unsaturated zone is ranging from 15 to 50 meters, which groundwater levels response is moderate. The purpose of this study is quantification the natural recharge from precipitation. The water table fluctuation method is applied; using groundwater levels data of selected monitoring wells, neighboring meteorological station of the wells, and the specific yield of the aquifers. This method is widely used for its simplicity, scientific, realistic, and direct measurement. The accuracy depends on the how much the determination of specific yield is accurate, accuracy of the data, and the extrapolations of recession of groundwater levels curves of no rain periods. The normal annual precipitation there is 420 mm, the average recharge is 89 mm, and the average specific yield is around 0.03. The data of one water year of 2009 and 2010 has taken for some technical and accuracy reasons.

Model Tests on Additional Stress Transmission between Different Granular Materials in Foundation Soils

2014 ◽  
Vol 919-921 ◽  
pp. 828-834
Author(s):  
Chang Dan Wang ◽  
Shun Hua Zhou ◽  
Hui Su
Keyword(s):  
Granular Materials ◽  
Boundary Surface ◽  
Vertical Direction ◽  
Stress Transfer ◽  
Fine Sand ◽  
Compression Modulus ◽  
Model Tests ◽  
Additional Stress ◽  
Stress Transmission ◽  
Different Soils

To research and analyze the additional stress distribution and change of granular materials, the model tests are used to observe vertical additional stress in different position and depth in different foundations. And the comparison between observed values both in different soils and single soils is conducted to analyze the transmission and attenuation of additional stress in granular materials. The research results show that the existing of boundary surface can lead to different vertical additional stress transmit obviously. And with the increasing of loading, the vertical additional stress differences between that of different soils get larger, meanwhile, the ratio of stress differences to smaller additional stress increases slightly. With the increasing of depth, the attenuation rate of vertical additional stress of silty soil changes much fast than that of fine sand. Wherever in horizontal direction or vertical direction, the vertical additional stress of fine sand which has higher compression modulus in different soils is slightly larger than that in single soil and transfers additional stress (loading) more under the same loading. To granular materials, inner friction structure effect is evident influence to additional stress transfer.

scholarly journals Uncertainty in geological and hydrogeological data

2006 ◽  
Vol 3 (4) ◽  
pp. 2675-2706 ◽  
Author(s):  
B. Nilsson ◽  
A. L. Højberg ◽  
J. C. Refsgaard ◽  
L. Troldborg
Keyword(s):  
Water Resources ◽  
Water Resources Management ◽  
Numerical Models ◽  
Effective Porosity ◽  
Environmental Data ◽  
Specific Yield ◽  
Model Structure ◽  
Specific Storage ◽  
Resources Management ◽  
Hydrogeological Data

Abstract. Uncertainty in conceptual model structure and in environmental data is of essential interest when dealing with uncertainty in water resources management. To make quantification of uncertainty possible it is necessary to identify and characterise the uncertainty in geological and hydrogeological data. This paper discusses a range of available techniques to describe the uncertainty related to geological model structure and scale of support. Literature examples on uncertainty in hydrogeological variables such as saturated hydraulic conductivity, specific yield, specific storage, effective porosity and dispersivity are given. Field data usually have a spatial and temporal scale of support that is different from the one on which numerical models for water resources management operate. Uncertainty in hydrogeological data variables is characterised and assessed within the methodological framework of the HarmoniRiB classification.

scholarly journals Caracterização de parâmetros hidráulicos em depósitos fluviais paleogênicos na Bacia de Volta Redonda, RJ

2007 ◽  
Vol 30 (2) ◽  
pp. 118-132
Author(s):  
Ana Carolina Lisbôa Barboza ◽  
Gerson Cardoso da Silva Jr ◽  
Claudio Limeira Mello
Keyword(s):  
Hydraulic Conductivity ◽  
Sedimentary Facies ◽  
Fine Sand ◽  
Sedimentary Deposits ◽  
Hydrogeological Parameters ◽  
Variable Head ◽  
Medium Reservoir ◽  
Maximum Permeability

The present study aims for the characterization of the hydrogeological parameters of the Paleogenic fluvial deposits of Volta Redonda Geological Basin, through hydraulic conductivity determinations and grain sized analyses. The overall goal was to produce a hydrogeological data base applicable to the characterization of hydrofacies (interconnected sedimentary bodies with distinct hydraulic properties) and the modeling groundwater flow. The used methods used consisted of in situ permeability determinations (Guelph permeameters) and laboratory tests (variable head permeameter), besides grain size analyses carried out in each sedimentary facies in the study area. These sedimentary facies were characterized by Marques (2006) and belong to the Resende and Pinheiral formations. The permeameter results were coherent to the sedimentological characteristics. The Resende Formation sedimentary deposits are constituted by medium to fine sand with presence of argillaceous matrix and present moderate to very low hydraulic conductivity, varying between 10-4 to 10-8 cm/s, which indicates a poor reservoir. The Pinheiral Formation presents sandy layers with conglomeratic lenses, limited by small thickness pelitic intervals, with a very low permeability, with a hydraulic conductivity varying between 10-5 to 10-7 cm/s. The upper layer has the maximum permeability, around 10-3 cm/s. This formation presents a medium reservoir characteristics and it must be taken into consideration that the upper layer has as role in recharge to the aquifer. From the results of hydraulic conductivity, that varies from 10-8 to 10-3 cm/s for the Resende and Pinheiral formations, it is concluded that these deposits a low to medium hydraulic conductivity, explaining the low productivity of the water-bearing multilayered aquifer of Volta Redonda Basin.

scholarly journals The referential grain size and effective porosity in the Kozeny–Carman model

2016 ◽  
Author(s):  
K. Urumović ◽  
K. Urumović Sr.
Keyword(s):  
Grain Size ◽  
Hydraulic Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Effective Porosity ◽  
Critical Conditions ◽  
Saturated Porous Media ◽  
New Developments ◽  
Mean Grain Size

Abstract. In this paper, the results of permeability and specific surface area analyses as functions of granulometric composition of various sediments (from silty clays to very well-graded gravels) are presented. The effective porosity and the referential grain size are presented as fundamental granulometric parameters expressing an effect of the forces operating on fluid movement through the saturated porous media. This paper suggests procedures for calculating referential grain size and determining effective (flow) porosity, which result in parameters that reliably determine the specific surface area and permeability. These procedures ensure the successful application of the Kozeny–Carman model up to the limits of validity of Darcy’s law. The value of effective porosity in the referential mean grain size function was calibrated within the range of 1.5 μm to 6.0 mm. The reliability of the parameters applied in the KC model was confirmed by a very high correlation between the predicted and tested hydraulic conductivity values (R2=0.99 for sandy and gravelly materials; R2=0.70 for clayey-silty materials). The group representation of hydraulic conductivity (ranging from 10–12 m/s up to 10–2 m/s) presents a coefficient of correlation of R2=0.97 for a total of 175 samples of various deposits. These results present new developments in the research of the effective porosity, the permeability and the specific surface area distributions of porous materials. This is important because these three parameters are critical conditions for successful groundwater flow modeling and contaminant transport. Additionally, from a practical viewpoint, it is very important to identify these parameters swiftly and very accurately.

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