|Coastal and River Engineering Support System|
|A cooperation project of the Netherlands Ministry of Infrastructure (Rijkswaterstaat), Delft University of Technology and Unesco-IHE Delft|
This program is intended as a support for design and planning of coastal and river projects and is not intended to replace the judgement of a qualified engineer on a particular project. The contents of CRESS are not to be used for advertising, publication or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. The issuing partners do not accept liability for interpretations or implementations made by users of this program.
Most recent version
Cress is available as
on-line tool via the internet. It has been tested for use on Windows,
Linux and Apple platforms, using browsers as Internet Explorer,
Firefox, Opera, Chrome, Safari. The online version is available
(this is short for http://cress.tudelft.nl)
For mobile application a mobile version has been developed. The main difference between the normal version and the mobile version is that the mobile version does not have the option to make graphs. The mobile version is at this moment available via http://m.cress.nl. This platform has been tested for Android, Palm OS, Blackberry OS and Apple OS systems .
At this moment Cress is available in English, Dutch, French and Spanish. Some parts are also available in Chinese.
Comments are welcome; we maintain a faq-list.
Cress is not able to compute the shallow water wave parameters Tm-1,0 and H2% from a deepwater spectrum, because then you need to enter depth profile information. These parameters can be calculated with Swan. The full Swan code can be downloaded from the Swan-homepage. However, also a practical Graphical User Interface, SwanOne is available free of charge. With the use of SwanOne you may calculate Tm-1,0 and H2% without detailed knowledge of the Swan computational system.
For more advanced
overtopping calculations is referred to the calculation
of the Overtopping Manual.
The present version of cress is no longer available as stand-alone version. However, the perivous (stand-alone) versions are still available, see below. These versions are not updated any more. In case of problems, you may consult the faq-list.
Cress is not able to compute the shallow water wave parameters Tm-1,0 and H2%, because then you need to enter depth profile information. These parameters can be calculated with Swan. The full Swan code can be downloaded from the Swan-homepage. However, also a practical Graphical User Interface, SwanOne is available free of charge. With the use of SwanOne you may calculate Tm-1,0 and H2% without detailed knowledge of the Swan computational systemPhilosophy of the package
In mathematical modelling of coastal processes there is in general a tendency to make programs more sophisticated and more advanced. The consequence of this modelling is that models become usually more specialized, and also more difficult to handle.
Although much effort is paid to the user friendliness of systems, general systems require much input, which has to be defined in some way. Most programs nowadays can be handled relatively easy only if one is familiar with the program.
On the other hand, 90 % of the problems in engineering are rather standard problems. These problems require only the application of very few formulae. Continuous research is going on to improve the quality of such formulae, although also here is a tendency to concentrate on the more exotic cases. This is very understandable, because for a researcher the challenge of such problems is much more attractive. For the design engineer, this development is not so attractive, because for his daily work he is therefore often condemned to use outdate reference material. Especially engineers working in smaller companies or agencies have difficulties is accessing the latest developments. Often the Shore Protection Manual (and not even the Coastal Engineering Manual) is still their major source of reference information.
Because application of a dedicated program requires familiarity with the input structure, many designers having a minor problem, will not use such dedicated programs. The time they have to invest in learning how to handle the program is too much in comparison with the importance of the problem. So in such cases designers often go back to graphs and design manuals.
To overcome this problem, IHE has developed a very simple package, called CRESS (Coastal and River Engineering Support System). In fact, CRESS is a collection of small routines, each containing a formula, or group of formulae, important in coastal and river engineering. The input and output is highly standardized, and is both available in numerical and graphical form. Working with CRESS is fast and simple, the package is designed in such a way that is works on all types of machines, even on the slow ones, and that it does not require a lot of memory. Uncompressed it still fits on a 720 Kb diskette. However, on modern computers this Dos based program cannot work any more.
For a design several steps have to be taken. CRESS does not automatically transfer data from one step to the next one. In this case the user is forced to think about the input and all the intermediate results. CRESS does not prevent the user to apply a formula outside its range of application. Often in engineering it is useful to do so, however it has to be done with great care. Tendencies and sensitivities are very important. The graphical routines of CRESS are made in such a way, that the sensitivity of a given parameter can be shown easily in the diagram.
The available Help routines allow the user to find some background information on applied formula, but also lists of constants, which can be entered (for example the Manning coefficients).
Simultaneously with IHE the Netherlands Ministry of Public Works developed a package of computational rules to be used by their engineers in a standardised way. This package was called "Rekenregels". In 2000 it was decided to merge both programs, use the basic software of "Rekenregels", but continue to use the name CRESS. The present day CRESS is written in Delphi, and uses separate dll's for the various routines. This makes that the program does not fit any more on a 720 kB diskette, but because these diskettes do not exist anymore, this is not a problem.
For more detailed background information is referred to literature, sometimes to the IHE lecture notes but in most cases internationally standards. For example many rules are based on the Rock Manual.
Being an educational institute, our first aim in developing CRESS both for IHE as well as TU Delft was not to provide a handy tool for designers, but to develop an instrument for the training of our students. In our view a design engineer has to be able to understand the physical background of the formulae used, and has to know the sensitivity of the various input parameters. In most cases it is not necessary that a designer can derive all formulae used, neither it is necessary to know the formulae by heart. However, for training in real design, one has to apply formulae quite often, especially in order to develop a feeling for the ranges of validity and for the sensitivity. Doing this with a (programmable) pocket calculator takes a lot of time (with the risk of many data entry errors) which is in our opinion not well spent time.
In CRESS all these formulae have been placed. Applying CRESS goes very fast, and therefore all the available time can be used for evaluation of the given output. Because of the fast and flexible graphical output, students get develop a feeling for ranges in a relative short time.
It is our intention to keep CRESS on the level of the state-of-the-art in coastal and river engineering. When research results in new approaches to design problems, and in practical application this leads to acceptable results in the design process, such new developments will be implemented as soon as possible in CRESS.
It is not our intention to build out CRESS as a sophisticated tool able to solve all major problems in coastal and river engineering. For example, a very simple routine is available to compute a backwater curve. This routine is fast, and also the input can be generated very fast. However, this routine is not able to compute a backwater curve in a network, with a time dependent flow, etc. For such problems, one has to use a package, specially designed to solve that kind of problems.
Cress is free of charge and may be used by
anyone. Of course none of the initiators will be responsible for misuse
or unqualified use of the package. See also the liability clause in the