Mode coupling due to scattering by weak random inhomogeneities leads to the loss of coherence in the wave field measured a long distances of propagation. This in turn leads to the deterioration of coherent source localization methods such as matched-field. In this dissertation, we study with analysis and numerical simulations how such deterioration occurs and we introduce an original incoherent source localization approach for random waveguides. This approach is based on a special form of transport theory for the incoherent fluctuations of the wave field. The statistical stability of the method is analyzed and its performance is illustrated with numerical simulations. In addition, this method is used to estimate the correlation function of the random fluctuations of the wave speed.