Experimental Study on Influence of Infiltration Head on Water and Salt Transportation in Saline-Alkali Soil

The indoor saline-alkali soil vertical infiltration experiment under different water head is conducted to analyze the change characteristic of wetting front distance,accumulated infiltration quantity,soil water content,soil electrical conductivity and Cl-accumulated concentration.The result indicates that there are remarkable powers relationships among wetting front distance,accumulated infiltration quantity and infiltration time under different water head,the sequence is 10 cm5.0 cm2.5 cm.There are little influence of infiltration water head on the distribution of soil water content,electrical conductivity and Cl-concentration in desalted zone.However,in salt accumulated zone,the salt accumulation depth decreases with the increase of infiltration water head whether under infiltration condition or redistribution condition,there is remarkable difference of desalting effect under different infiltration head,the sequence is 2.5 cm5.0 cm10 cm.The desalting depth increases with the increase of infiltration water head,the average ratios between the desalting depth and wetting front distance of the soil bulk,of which the density is 1.35 g/cm3 and 1.45 g/cm3,are 0.682 and 0.690 under infiltration condition,respectively.While under redistribution condition,the ratio was 0.619 and 0.632,respectively.Under different water head,the soil water and salt transportation speed in redistribution process was slowly than that in infiltration process.