A thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology

Irrigation water management is becoming more important, as irrigation competes for limited water supplies and energy, and as the lands, throughout the world degrade and decline in productivity, because of poor water manage ment. Irrigation Scheduling is predicting the time and amount of the next one or more irrigations, taking into account expected precipitation. Practical irrigation scheduling technology considers rainfall and evapotranspiration since the last irrigation, the allowable soil water depletion at the present growth stage and the expected rainfall before the next irrigation. Irrigation s cheduling i s a deci sion making process that irrigation extension worker/farmer encounter daily or weekly. They can make better decisions if more specific information about crop evapotranspiration and the current soil water status are available in a simplified way for extension to the farmers fields. The type of scheduling information desired by the farmers/ extension workers in Punjab of Pakistan, depends on the flexibility to adjust scheduling practices within the existing irrigation system on weekly turn basis. The computer model of irrigation scheduling is designed to compute the irrigation water requirements for selected crops in the Punjab province of Pakistan, based on weekly intervals of planting dates in appropriate season, upon specific Punjab soil moisture characteristics, crop characteristics as rooting depth and ratio of actual to potential evapotranspiration as experi mentally obtained. The methodology, input data requirements, and results of irrigation schedules of eight crops are presented. The irrigation scheduling results (computer outputs) are simplified into a manual for the extension of practical irrigation scheduling to the farmers' fields in Pakistan. The manual presented is based on the actual water requirements estimated using the model and then adjusted to suit the conditions of water supply on weekly turn basis. This manual will provide the base for the extension of new water management technology for increased crop production in the Punjab province of Pakistan.