On an inverse problem for scalar conservation laws

We study in what sense one can determine the flux functions k = k(x) and f = f(u), k piecewise constant, in the scalar hyperbolic conservation law u(t) + (k(x)f (u))(x) = 0 by observing the solution u(t, center dot) of the Cauchy problem with suitable piecewise constant initial data u vertical bar(t=0) = u(o).