Spread Sheet Solutions in Irrigation Canal Modeling Help to Achieve Better Operational Performance in Major Irrigation Schemes

Levels of Operational performance in Major Irrigation Schemes have become a major concern to the scheme operators and scheme managers. To achieve better levels of performance a situation analysis close to reality is needed when they schedule their irrigation deliveries in the canals. Various methods are being practiced by the system operators in their scheduling processes. Most of the methods are not in conformity with the scheme objectives and water rights of the farmers. So there is a vacuum demanding a better solution which can be applied as a tool for planning and monitoring irrigation schedules taking in to account the instantaneous changes in climatic and cropping conditions.

In order to fulfill the above requirements, a mathematical model was developed using spread sheets and Visual Basic Applications. This model creates irrigation schedules for Primary, Secondary and Tertiary canals by considering instantaneous conditions such as cropping data, metrological data, reservoir levels and canal properties.

This model was tried out in the Mahaweli System C during six consecutive cultivation seasons and a better water productivity could be obtained. Mahaweli System C covers cultivated paddy (Rice) land of 24,100 ha and this model covered 16,772 ha of that land area..

ENGINEER, Vol. 48, No.02, pp. 51-64 2015