| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 91 === The thesis makes a logical algorithmic model to simulate dynamic ponding depth of each paddy field in the objective system, stands on ordinary rules of water supply and demand in the cropping seasons.
This algorithmic model calculates dynamic ponding depth by the amount of evapotranspiration, percolation, irrigation, drainage, rainfall, lateral seepage and the paddy field’s spatial information. The estimation of the quantity of return flow is accumulating the overflow from weirs and the paddy border’s lateral seepages.
The model simulates different spatial distributions of virtual paddy field by the climatic data of year 2000. In the case that rice paddy interlaced with upland crops contrasting with the disposition of all rice paddy field results in obvious increment of water requirement (WR) and field irrigation requirement (FIR). In the other case that rice paddy interlaced with lotus field contrasting with the disposition of all rice paddy field results in slightly decrement of FIR. And the model also simulates the actual paddy field at Tao-Yuan 11-2 irrigation region 1st unit by the climatic data of year 2000 under the hypothetic conditions. The results indicate that the effective invisible return flow occupies 4.97% ~ 5.67% of the paddy field system’s WR. However, the choice of hydraulic conductivity influences the results seriously.
This model provides one possible way to calculate actuarial FIR under the ideal state, but the spatial meaning should be paid more attention to for the wide gap between the whole system’s and the single plot’s formation and utilization of return flow.
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