The Workshop on Parameter Identification and Inverse Problems in Hydrology, Geology and Ecology, Karlsruhe, April 10-12, 1995, was organized to bring to gether an interdisciplinary group drawn from the areas of science, engineering and mathematics for the following purposes: - to promote, encourage and influence more understanding and cooperation in the community of parameter identifiers from various disciplines, - to forge unity in diversity by bringing together a variety of disciplines that attempt to understand the reconstruction of inner model parameters, un known nonlinear constitutive relations, heterogeneous structures inside of geological objects, sources or sinks from observational data, - to discuss modern regularization tools for handling improperly posed pro blems and strategies of incorporating a priori knowledge from the applied problem into the model and its treatment. These proceedings contain some of the results of the workshop, representing a bal anced selection of contributions from the various groups of participants. The reviewed invited and contributed articles are grouped according to the broad headings of hydrology, non-linear diffusion and soil physics, geophysical methods, mathematical analysis of inverse and ill-posed problems and parallel algorithms for inverse problems. Some of the issues adressed by the articles in these proceedings include the rela tion between least squares and direct formulations of inverse problems for partial differential equations, nonlinear regularization, identification of nonlinear consti tutive relations, fast parallel algorithms for large scale inverse problems, reduction of model structures, geostatistical inversion techniques.

Inhalt
Tutorial on Inverse Problems.- 1. An Introduction to Inverse Problems in Partial Differential Equations for Physicists, Scientists and Engineers.- Hydrology.- 2. Interpretation of Field Tests in Low Permeability Fractured Media. Recent Experiences.- 3. New Front Limitation Algorithm.- 4. Identification and Reduction of Model Structure for Modeling Distributed Parameter Systems.- 5. Results from a Comparison of Geostatistical Inverse Techniques for Groundwater Flow.- Nonlinear Diffusion and Soil Physics.- 6. Identification of the Hydraulic Diffusivity of a Soil by Inverse Method with Dual-Energy Gamma Ray Attenuation Measurements.- 7. Identification of Parameters for Heat Conductivity Equations.- 8. Sensitivity Analysis in Parameter Identification, Test Planning and Test Evaluation Procedures for Two-Phase Flow in Porous Media.- 9. An Inverse Problem for Porous Medium Equation.- 10. Evaluation of Different Boundary Conditions for Independent Determination of Hydraulic Parameters Using Outflow Methods.- Geophysical Methods.- 11. Gravity Data Inversion Using Subspace Method.- 12. A Method to Determine Parameters of a Linear Functional Equations Set and its Application to the Lightning Location Problem.- Mathematical Analysis of Inverse and Ill-Posed Problems.- 13. Stability Estimates for Inverse Problems.- 14. Identifiability of Distributed Physical Parameters.- 15. Inverse Scattering Problem for the Wave Equations and its Applications.- 16. A Descriptive Regularization Approach for a Class of Ill-Posed Nonlinear Integral Equations.- 17. Parameter Estimation in Nonlinear Models by Using Total Least Squares.- 18. Tikhonov Regularization for Identification Problems in Differential Equations.- Parallel Algorithms for Inverse Problems.- 19. Parameter Estimation in MultispeciesTransport Reaction Systems Using Parallel Algorithms.- 20. On Design and Implementation of Parallel Algorithms for Solving Inverse Problems.