Open channel hydraulics has always been a very interesting domain of
scienti c and engineering activity because of the great importance of
water for human l- ing. The free surface ow, which takes place in the
oceans, seas and rivers, can be still regarded as one of the most
complex physical processes in the environment. The rst source of dif
culties is the proper recognition of physical ow processes and their
mathematical description. The second one is related to the solution of
the derived equations. The equations arising in hydrodynamics are rather
comp- cated and, except some much idealized cases, their solution
requires application of the numerical methods. For this reason the great
progress in open channel ow modeling that took place during last 40
years paralleled the progress in computer technique, informatics and
numerical methods. It is well known that even ty- cal hydraulic
engineering problems need applications of computer codes. Thus, we
witness a rapid development of ready-made packages, which are widely d-
seminated and offered for engineers. However, it seems necessary for
their users to be familiar with some fundamentals of numerical methods
and computational techniques applied for solving the problems of
interest. This is helpful for many r- sons. The ready-made packages can
be effectively and safely applied on condition that the users know their
possibilities and limitations. For instance, such knowledge is
indispensable to distinguish in the obtained solutions the effects
coming from the considered physical processes and those caused by
numerical artifacts.
