Human exploitation of stream and land ecosystems has created the need to preserve, restore and rehabilitate. This book discusses the scientific basis of restoration for ecological improvement and some key issues associated with overall projects. In addition, some of the challenges and opportunities for further research in river restoration science is explored and the associated fields of ecohydraulics and eco-hydromorphology. An analysis of the effects of river side-arm restoration on ecosystem functions is also included, as well as an experimental approach to assessing marsh restoration as compared to a strict monitoring process. The concept of combinatorial biodiversity auction is discussed in this book, showing that the combinatorial biodiversity auction can allow farmers to benefit from cost complementarities and help to maximise biodiversity outcomes within a given budget. Also included is a presentation of the need for restoration and rehabilitation projects developed according to an ecological theory considering species life history, habitat template and spatio-temporal scope, the bi-directional effect of self-renaturalisation processes on the environment and a study on how different river typologies may alter the evaluations of biological quality.