|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components|| K70.3.01
|Explanation of the dates on the component's description|
BASCAD: DESIGN AND EVALUATION OF LEVEL BASIN IRRIGATION
1. Purpose and objectives
Basin irrigation is the most widespread method of surface irrigation. Global-wise, the overall efficiency in level basin irrigation is rather poor. Basins can certainly be made bigger and can be irrigated more efficiently than is presently the case. The direct benefits of using the program for design and evaluation purposes will be considerable water
savings. The indirect benefits will be that less water is being lost to the
underlying aquifer resulting in less salinization hazards for both the shallow groundwater and the top soil.
The program BASCAD simulates the flow of irrigation water over the land surface and concurrent infiltration. This surface flow is based on the Saint-Venant equations (zero-inertia approach). The equations are solved in the program by the Newton-Raphson iterative method.
The program offers the possibility to guide the user in the design and evaluation of level basins. To this end, the program presents four so-
called main calculation modes. Modes 1, 2, and 3 are to be used in typical design matters, i.e. how to achieve a certain minimum infiltrated depth and
how to realize a certain minimum application efficiency. Modes 1 and 2 can
be used to obtain first estimates on either the basin dimensions or flow
rate. Mode 3 can then be used to refine these results; it can also be used
directly by more experienced users. Mode 4 can be used to analyze an
existing situation, i.e. to determine the actual irrigation performance in
terms of minimum infiltrated depth, under-irrigation and/or over- irrigation.
The program is fully interactive and user-friendly with pull-down menus and help screens to guide the user through the data entry. In all
modes, data are required on the infiltration characteristics of the soil,
flow resistance of the land surface, and depth of water to be applied to the soil. Depending on the calculation mode, data are also required on the
available flow rate, basin dimensions, or both.
The results of the simulations are advance time, cut-off time,
recession time, and actual irrigation performance in terms of minimum infiltrated depth, under-irrigation, over-irrigation, application and
5. Operational requirements and restrictions
Minimum requirements are a personal computer with 80286 micro- processor, 640 kB RAM, 20 MB hard disc, EGA graphics, MS-DOS operating system; co-processor is recommended.
The flow over the land surface is evenly distributed over the width of the basin (1D horizontally); the flow resistance and infiltration
characteristics are assumed to be homogeneous within the basin.
6. Form of presentation
The program is available on diskette and supported by a manual, giving more background information on basin irrigation, the input and output parameters involved, program features, error messages, guidelines and sample problems.
7. Operational experience
More than 500 copies of the program have been distributed all over the world. The program has been used successfully both in national and
international training courses on irrigation.
8. Originator and technical support
International Institute for Land Reclamation and Improvement ILRI
Through the HOMS National Reference Centre for The Netherlands or
directly from ILRI.
10. Conditions on use
The program and manual are for sale. Discounts are available for educational purposes.
|(First entered: 31 JULY 01||
Last updated: 19 JAN 98)