This book addresses computational hydraulics (or computational fluid dynamics). The purpose is to give non-specialist readers sufficient insight to handle real-life problems. It is not directed to specialist developers of computer software for such problems, although it will be a good starting point for them. It describes numerical methods for solving flow and transport problems to a sufficient level to understand other methods as well. In contrast with most other books in this field, a great deal of attention is given to judging and predicting the performance of the methods. The material is not new, but organized in a new way to provide simple but realistic examples from hydraulic, environmental, river and coastal engineering. This will enable the reader to recognize the numerical effects in more complicated applications in his own practice. The benefit is not that one can write (or even copy) ready-made computer programs, but that one knows how to work reliably with existing software.