This is an open access book. The aim of this book is to provide a thorough grounding in rainfall-induced landslides from three aspects: the coupling effect of hydraulic and mechanic; the analytical, numerical, and physical simulation methods, and the controlling factors underlying the problem of rainfall-induced landslides. The improved numerical methods, nonlinear, and linear iterative methods which can be used to address the related unsaturated infiltration problems are also presented. This book is an essential reading for researchers and graduate students who are interested in rainfall...