WIHA is a simple operative tool that gives daily information to farmers, via SMS, about actual crop irrigation needs for their fields, on the basis of a soil water balance fed by observed weather data.
The information about crop irrigation is provided by a simple water balance that needs as input: crop information, soil data, daily-observed meteorological data from weather stations and 1-week weather forecasts. The integration of the latter into the system is one of the strengths of WIHA because it allows a wise management of water, in terms of natural resources and irrigation scheduling (see the picture). On the basis of these daily updated inputs, the soil water balance computes the actual crop water needs.
As first pilot, we will apply WIHA in an agricultural district to calibrate the system. Local authorities will be consulted to provide basic information about cropping system and soil and a WIHA manager will be appointed to setup the case studies and to carry out a periodical check of the system in a dedicated computing centre. Specific case studies for the staple crops (sorghum, maize, sugarcane, millet, etc.) of the area will be implemented. The WIHA manager and local farmers will work collaboratively to collect information about crop, match them with the FAO database (http://www.fao.org/agriculture/seed/cropcalendar/welcome.do) and set up realistic case studies where the crop information is tuned on the local reality. Once finalized the system has the great advantage to be semi-automatic and will continue operational activity with routine maintenance.
The WIHA irrigation suggestion to farmers will be provided in two formats: 1) printed or electronically accessible from any computer connected to the system or directly at the data centre where the WIHA manager is stationed; 2) via sms.
In order to provide effective and useful data to small holder farmers, the irrigation information will be formatted in a proper and practical unit of measure easy to interpret and apply.
All calculation modules are written in C++ language. Two reasons justify this choice: 1) it is a low level language, so that calculations are much faster and the computing centre will not need too much processing power to run; 2) this language will continue to be supported by many compilers for long time.