Calculating flow rate for ceramic emitters in subsurface infiltration irrigation under various soil types based on fractal capillary bundle model

Accurately calculating the flow rate of the emitters for subsurface infiltration irrigation is essential to match crop water requirements and provide a suitable water amount. However, drip emitters usually have a single flow path and are assumed to have a constant flow rate, which does not apply to subsurface infiltration irrigation represented by ceramic emitters (CEs). Therefore, a flow model was developed to accurately calculate the flow rate of CEs considering ceramic pore flow channels and soil types. Five experiment sites were selected for validation, with the average values of MAE , RMSE , and R 2 being 0.0064, 0.0095 and 0.8138, respectively. Meanwhile, the relationship between different soil types, porosities, and working water heads on the flow rate of CEs was explored using a dataset with 403 points of all soil types. Results show that the flow rate of CEs increased with the sand content, and the average flow rates of CEs in sand, silt, loam, and clay soil were 0.0525, 0.0453, 0.0257, and 0.003 L h −1 , respectively. Furthermore, the flow rate of CEs in more sandy soil was significantly affected by the porosity, which in clay soil was mainly determined by soil type. In addition, the influence of the working water head on the coefficient of variation (CV) for the flow rate of CE diminished significantly beyond approximately 74 cm. The model can accurately calculate the flow rate of CEs in practice, which is conducive to the practical application of subsurface infiltration irrigation systems and the efficient utilization of irrigation water.