Field study on the influence of subsurface drainage pipes and envelopes on discharge and salt leaching in arid areas

The selection of suitable drainage materials is crucial for the efficient operation of subsurface drainage systems. Previous studies on drainage material selection have focused on anti-clogging characteristics, and less attention has been given to their effects on the process of soil salt leaching, which is an important consideration in arid and semi-arid areas. To investigate the influence of subsurface drainage pipes and envelopes on salt leaching and discharge, field leaching experiments under flood irrigation and drip irrigation were conducted in Xinjiang region in China. Results show that the amount of drainage water in treatments that use gravel envelopes is higher than that in treatments that use synthetic envelopes. Meanwhile, the amount of drainage water in treatments that use gravel envelopes decreases the most after 1 year of operation. The synthetic envelope, the interaction between the perforation rate of the drainage pipe and the synthetic envelope significantly influence water and salt discharge. The optimal level of the synthetic envelope used in this study is spun-bonded non-woven geotextile, that of the layer number of envelopes is a single layer, and that of the perforation rate of the drainage pipe is 3.0%.