# Identifiability of the Transmissivity Coefficient in an Elliptic Boundary Value Problem

### Gennadi Vainikko

Tartu University, Estonia### Karl Kunisch

Karl-Franzens-Universität Graz, Austria

## Abstract

We deal with a coefficient inverse problem describing the filtration of ground water in a region $Ω⊂R_{n},n≥2$. Introducing a weak formulation of the problem, discretization and regularization methods can be constructed in a natural way. These methods converge to the normal solution of the problem, i.e. to a transmissivity coefficient of a minimal $L_{2}(Ω)$-norm. Thus a question about $L_{2}$-identifiability (identifiability among functions of the class $L_{2}(Ω)$ of the transmissivity coefficient arises. Our purpose is to describe subregions of $Ω$ where the transmissivity coefficient is really $L_{2}$-identifiable or even $L_{1}$-identifiable. Thereby we succeed introducing physically realistic conditions on the data of the problem, e.g. piecewise smooth surfaces in $Ω$ are allowed where the data of the inverse problem may have discontinuities. With some natural changes, our results about the $L_{1}$-identifiability extend known results about the identifiability among more smooth functions given by G. R. Richter [4], C. Chicone and J. Gerlach [1], and K. Kunisch [3].

## Cite this article

Gennadi Vainikko, Karl Kunisch, Identifiability of the Transmissivity Coefficient in an Elliptic Boundary Value Problem. Z. Anal. Anwend. 12 (1993), no. 2, pp. 327–341

DOI 10.4171/ZAA/562