The projects seems Quiet Interesting? In what aspect are you focusing Irrigation water use efficiency or in terms productivity you are expecting Any enhancement when SRI method reduces Water use by almost 50% and yield enhancement by almost 30 %?
The amount of water to be provided is 'the minimum' according to its originator Fr. Laulanie, just enough to meet the plant's essential needs to and to maintain enough soil moisture for the life in the soil (from microbes to earthworms -- don't forget about these as they are essential for maintaining soil fertility). The question of 'depth' is missing the point. If you email me, I can send some articles: [email protected]
Modeling irrigation for crops determined in timing and amount. This depends on incorporating all of weather, soil, plant and other inputs within one software system to schedule. I recommend you to get Aqua crop 4 Software done by FAO.
I don't have much confidence in modeling exercises, having seen how they can be misused an abused. I prefer to stick to real, not hypothetical, plants.