Gradient-based estimation of Manning's friction coefficient from noisy   data
  We study the numerical recovery of Manning's roughness coefficient for the diffusive wave approximation of the shallow water equation. We describe a conjugate gradient method for the numerical inversion. Numerical results for one-dimensional model are presented to illustrate the feasibility of the approach. Also we provide a proof of the differentiability of the weak form with respect to the coefficient as well as the continuity and boundedness of the linearized operator under reasonable assumptions using the maximal parabolic regularity theory. 
Victor M. Calo, Nathan Collier, Matthias Gehre, Bangti Jin, Hany   Radwan
math.NA math.OC