1. Purpose and objectives

CRIWAR 2.0 calculates the crop irrigation water requirements, either per month or per 10-day period, of a cropping pattern in an irrigated area, for various stages of crop development throughout the crops' growing season. Application of the model can assist irrigation engineers to maintain soil water content at a level that will not limit plant growth and crop yield. The crop irrigation water requirement consists of two components: potential evapotranspiration ETp, minus the effective precipitation Pe.

2. Description

To achieve effective irrigation management it is important that the water requirements are known at different management levels within the irrigated area. CRIWAR 2.0 is a useful tool in the design of irrigation systems, because it quickly calculates the summarized irrigation water requirements of a complex cropping pattern for a large area with ready-to- use output tables and graphs. This allows the design engineer to review alternative cropping patterns under various meteorological conditions.
Furthermore, CRIWAR can be helpful in the management of operational irrigation projects with frequently changing cropping patterns and in the studies on performance assessment of irrigation projects.

The model calculates ETp on the basis of two user-selected alternative methods of computing the reference evapotranspiration: the FAO Modified Penman Method ETg, and the Penman-Monteith Method ETh. To determine ETp, these reference values of ET are then multiplied with the crop coefficient kc. Subsequently, the calculated ETp-value is reduced by the effective part of the precipitation Pe.

Following the 'user manual' part of this ILRI publication (Chapters 2 through 4), this publication gives theory and information on evapotranspiration (Chapter 5), effective precipitation (Chapter 6), capillary rise (Chapter 7) and on how to transfer the crop irrigation water requirements into irrigation water requirements of an irrigation command area.

3. Input

The input data of CRIWAR 2.0 are organized through three files: a general data file on the irrigated area, a meteorological data file and a cropping pattern file. The cropping pattern file can be composed of 50
CRIWAR-programmed crops and of any user-defined crop.

4. Output

For a user-selected combination of general data, meteorological data and cropping pattern data, CRIWAR creates tables and graphs giving: the reference evapotranspiration, the crop irrigation water requirement per month or per 10-day period, the cropping intensity, the effective precipitation, etc. All tables and graphs can be imported into commonly used word-processing software.

5. Operational requirements and restrictions

CRIWAR operates in the MS-DOS environment. Version 2.0 requires about 480 kB of memory. A hard disc drive is recommended, as is a 80286 or faster microprocessor. The 3.5 inch distribution disc is protected against illegal copying by a software protection system. The system installs one 'token' on
the disc drive on which the CRIWAR directory is located. Each time that CRIWAR is started, it will check for the presence of that token. If it is not found, CRIWAR will abort and show a warning on the screen. The original distribution disc contains two tokens of CRIWAR.

6. Form of presentation

The complete software package is for sale as ILRI Publication 46 and includes a description of the model, a user's manual, and CRIWAR 2.0 on a 3.5 inch disc, which contains the executable program and the overlay and configuration files required to run CRIWAR. This disc also contains some samples of crop factor files and meteorological files. The latest developments are given in the README.CRW file.

7. Operational experience

The CRIWAR model has been applied in studies on performance assessment of irrigation projects around the world. It is also part of the curriculum of regular and tailor-made ILRI courses on water management.

8. Originator and technical support

Wageningen Agricultural University, Department of Water Resources, International Institute for Land Reclamation and Improvement - ILRI P.O. Box 45, 6700 AA Wageningen, The Netherlands
Tel: (31 317) 490144, Fax: (31 317) 417187

9. Availability

Through the HOMS National Reference Centre for The Netherlands or directly from ILRI.

10. Conditions for use

The program and manual are for sale. Discounts are available for educational purposes.