Hydraulic Parameter Identification de Luc C. Lebbe

Hydraulic Parameter Identification: Generalized Interpretation Method for Single and Multiple Pumping Tests

Luc C. Lebbe

Hydraulic parameter identification is a crucial step in hydrogeological investigations. The book proposes a unique and generalized interpretation method for single and multiple pumping tests made in groundwater reservoirs with layered heterogeneity and with or without lateral anisotropy. This method eliminates the drawbacks of the numerous and frequently applied interpretation methods. The book also presents an introduction to inverse modeling, resulting in optimal parameter values with their joint confidence region and the corresponding residuals. Cross sections through this multidimensional region elucidate the relation between the shape of this region and some statistical parameters describing the reliability of the identified parameters. This method is demonstrated by means of five pumping or recharge tests.

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Cuprins

1 / Introduction.- 1.1 Previous literature on pumping test interpretation.- 1.2 Proposed generalized interpretation method.- 1.3 Additional aims of the book.- 1.4 Arrangement of subject matter.- 2 / Hydraulic Parameters.- 2.1 Hydraulic parameters describing water conducting properties.- 2.2 Hydraulic parameters describing water storing properties.- 3 / Evolution of analytical models of pumping tests and their interpretation methods.- 3.1 Model of Thiem.- 3.2 Model of Theis.- 3.3 Model of Jacob-Hantush.- 3.4 Model of Hantush.- 3.5 Model of Hantush-Weeks.- 3.6 Model of Boulton-Cooley.- 3.7 Model of Neuman and Witherspoon.- 3.8 Retrospective view on analytical models and their derived interpretation methods.- 4 / Numerical model of pumping tests in a layered groundwater reservoir.- 4.1 Finite-difference grid.- 4.2 Mean drawdowns.- 4.3 Continuity equation in numerical model.- 4.4 Initial and boundary conditions.- 4.5 Solution of the numerical equations.- 4.6 Verification of numerical model.- 4.7 Program package for numerical simulation of pumping tests.- 5 / Further developments of pumping test model.- 5.1 Drawdown of pumping tests with variable discharge rate.- 5.2 Drawdown in a laterally anisotropic aquifer.- 5.3 Drawdown in pumping wells.- 5.4 Drawdown due to a multiple well field.- 5.5 Drawdown in groundwater reservoir with lateral bounds.- 5.6 Drawdown in groundwater reservoir with lateral discontinuous conductivity change.- 5.7 Land subsidence due to groundwater withdrawal.- 6 / Inverse model as tool for pumping test interpretation.- 6.1 Residual vector.- 6.2 Sensitivity matrix —.- 6.3 Numerical nonlinear regression.- 6.4 Validation of inverse numerical model.- 6.5 Factors influencing accuracy of results.- 6.6 Program package for the nonlinear regression.- 6.7Confidence interval for optimal estimated drawdown.- 6.8 Hypothetical example to demonstrate nonlinear regression and approximation of drawdown confidence intervals.- 7 / Example of performance and interpretation of pumping tests.- 7.1 Double pumping test in layered groundwater reservoir formed by Quaternary sediments.- 7.2 Double pumping test in a laterally anisotropic aquifer formed by fractured rocks of Palaeozoic and Mesozoic age.- 7.3 Triple pumping test in layered groundwater reservoir formed by Tertiary sediments.- 7.4 Single pumping test to determine the conductivity of Tertiary silty clay.