Infiltration models for different textures of water-repellent soils
Song Hongyang1, Li Yi1,2, He Chansheng3
1. College of Water Resources and Architecture Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China; 2. Institute of Water-saving Agriculture in Arid Areas of China, Northwest A&F University, Yangling, Shaanxi 712100, China; 3. Research School of Arid Environment & Climate Change, Lanzhou University, Lanzhou, Gansu 730000, China
In order to study the infiltration characteristics and mechanism in water-repellent soils deeply, one-dimension vertical infiltration experiments were conducted on water repellent soils with four different textures. The accumulation infiltration, infiltration rate and wetting front length were analyzed by using diagram when the infiltration was in progress, the soil moisture profiles were examined as well. The correlation between infiltration rate and time was predicted by means of four different models and compared with the measurements. The relationship between accumulation infiltration and wetting front length was described by a linear function. The results showed that for those hydrophobic soils there is a time instance at which the infiltration characteristic is changed. Thus the infiltration process can be divided into two stages: fore-stage and post-stage. The Kostiakov equation can describe the i-t relationship of hydrophilic soils and that at the fore-stage of hydrophobic soils very well, compared with the other models. Different hydrophobic soils show relatively large difference in infiltration rate during the post-stage of infiltration. The correlation between wetting front depth and accumulation infiltration can be described by a linear model in each of the two stages for hydrophobic soils, respectively. An effect, which the soil moisture in the upper-layer of hydrophobic soil is higher than hydrophilic soil,was observed.