Water movement characteristics in hydrophobic soils between two emitters of trickle irrigation
LI Yi, GUAN Bing-Yi
(1. College of Water Resources and Architecture Engineering, Northwest A＆F University, Yangling, Shaanxi 712100, China; 2.Water Saving Agriculture Academy in China Aridzone, Northwest A＆F University, Yangling, Shaanxi 712100, China; 3. Water Authority of Qidong, Qidong, Jiangsu 226200, China)
Abstract：The variation of wetting front and the characteristics of soil moisture distribution were studied and compared for the hydrophobic and hydrophilic soils by means of indoor water infiltration experiment in which two emitters of trickle irrigation is put 30 cm apart and at 0.41 mL/min flow rate. The experimental results indicated that all the wetting fronts are relatively smooth and take a quarterellipse shape regardless of if these wetting fronts originated from the two emitters meet each other or not for the hydrophilic soil; the horizontal wetting front was longer than the vertical one, and the times for the two wetting fronts to meet each other are 1 270 and 279 min, corresponding to wettable Lou and salinealkaline soils,respectively. For the hydrophobic soil, however, the wetting fronts are not so much smooth, and they move forward faster in some directions than in the others; and the times for the two wetting fronts to meet each other are 40 and 210 min,corresponding to hydrophobic Lou and salinealkaline soils, respectively. The relationship between wetting front position and time at various conditions can be described by a logarithmic or power function, their regression coefficients are over 0.86. All the relations of the horizontal and vertical wetting fronts to time yield a logarithmic function in the interface plane of two wetting fronts, the corresponding regression coefficients are more than 0.98. For the loess soil, soil water content contours in the vertical profile, which was through and beneath the emitter origin, are very uniform and the wetting surfaces are mostly like circles. The water content contours in the interface plane are less uniform than those in the vertical plane, but they are still more regular than those for the salinealkaline soil. The water content distributions in various depths are much stochastic and spatially heterogeneous for both hydrophobic soils. In general, water movement in loess hydrophilic soils are more regular than in salinealkaline hydrophilic soils; and because of the unstable flow in hydrophobic soils, the water movement in hydrophobic soils is less regular than in hydrophilic soils. The obtained results might be useful for applying some saving water irrigation techniques into hydrophobic soils irrigation.
李毅, 关冰艺. 滴灌两点源交汇入渗的斥水土壤水分运动规律[J]. 排灌机械工程学报, 2013, 31(1): 81-86.
LI Yi, GUAN Bing-Yi. Water movement characteristics in hydrophobic soils between two emitters of trickle irrigation. Journal of Drainage and Irrigation Machinery Engin, 2013, 31(1): 81-86.
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