SEEPAGE FLOW DYNAMICS IN A NEGATIVE PRESSURE DIFFERENCE IRRIGATION SYSTEM

This study proposes a theoretical model to predict soil wetting pattern and water balance in a negative pressure difference irrigation (NPDI) system and describes laboratory experimental results from which this model was derived. The experiments were conducted by using a porous pipe, a water reservoir and a soil column filled with Kawanishi sand. The temporal variations in volumetric water content profile, supplied water, soil water storage and evaporation were calculated by the proposed model. The calculated results were in good agreement with the experimental results. The margin of error of the water balance was in the range of 3 to 7 %. It is concluded that the proposed model is valid for an optimal design of the NPDI system.