Procedure for Saving Water Application and Irrigation Scheduling

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There are several factors for water saving irrigation, for example, effective use of rainfalls, continuous use of upward flux from sub-soil and so on.In this research, the investigations were carried on for establishing the suitable irrigation schemes such as irrigation scheduling and irrigation system operation concerning factors of saving water. Finally,the water planning technics were proposed and discussed.Obtained results are as follows.(1) Water requirements were established using daily intake water into irrigation system by a reverse calculation of the TRAM method. The time series of irrigation operation were defined by two variables ie. the amount and the time of water application. An optimized evaluation method of water requirements was achieved with introducing an suitable objective function.(2) The two layer model for simulating the upward moisture flux from sub-soil to root zone. The obtained results were varified by field tests on the Kuroboku soil.(3) It is tried to evaluate individually both evaporation rate and transpiration rate from planted fields.(4) The reasonable irrigation scheduling methods were proposed conbining the developed technics on each factor above mentioned.(5) In addition, new regulation technics of hydraulic pressure and discharge were presented for suitable oparation of sprinkler system and micro irrigation system.