Effects of preferential flow on soil-water and surface runoff in a forested watershed in China |
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Authors: | Jinhua Cheng Hongjiang Zhang Youyan Zhang Yuhu Shi Yun Cheng |
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Institution: | (1) School of Soil and Water Conservation, Beijing Forestry University, Beijing, 10083, China;(2) Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China;(3) Forestry Science Institute of Hubei Province, Wuhan, 430079, China |
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Abstract: | Preferential flow is a runoff mechanism intermediate between matrix flow and surface flow, transmitting water at high velocity
through the subsurface zone. To assess the effect of preferential flow on soil-water flow and surface runoff in a forested
watershed, precipitation and volumes of preferential flow, matrix flow and surface runoff were measured over a period of four
years in a forested watershed in the Three Gorges area of southern China. Results show that preferential-flow hydrographs
have gentler rises and steeper recessions than those for matrix flow and surface runoff. Preferential flow as a percentage
of soil-water flow ranged from 2.40% to 8.72% and the maximum preferential-flow velocity exceeded as much as 5600 times that
of matrix flow. This shows that preferential flow plays an important role in the movement of soil water. Preferential flow
has a significant effect on peak surface runoff by increasing the surface runoff rate and accelerating the appearance of peak
surface runoff. Preferential flow can also prolong the duration of surface runoff. Surface runoff was observed to be positively
correlated with preferential flow. The greater the sum of rainfall amount and antecedent precipitation is, the greater the
effect of preferential flow on surface runoff is. |
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Keywords: | forest hydrology Three Gorges of Yangtze River preferential flow matrix flow surface runoff |
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