人工模拟降雨下高寒区坡面径流水动力特性对砾石覆盖的响应OA

[Objective]The Tibetan Plateau has complex terrain and extensive gravel distribution.This study aims to investigate the relationship between gravel coverage and hydrodynamic parameters of slope runoff in the region,and to reveal its impact on soil erosion and ecological environment protection.[Methods]Laboratory artificial rainfall experiments were conducted to study the hydrodynamic parameters of runoff on bare soil slopes and soil-gravel mixed slopes,using four gravel coverage levels(0,20%,40%,60%)and three gravel size ranges(0.2-2,2-6,6-10 cm).[Results]1)On bare soil slopes,flow velocity initially decreased and then increased with increasing gravel coverage(6.31,3.60,3.59,4.12 cm/s).When the gravel size was 0.2-2 cm,runoff depth increased with gravel coverage(0.42,0.51,0.84,1.03 mm),while the opposite occurs for other particle sizes.On soil-gravel mixed slopes,flow velocity decreased with increasing gravel coverage(5.23,5.07,5.26,3.83 cm/s),and the trend of runoff depth was consistent with that on bare soil slopes.2)The Reynolds numbers for both bare soil slopes and soil-gravel mixed slopes were below 500,indicating laminar flow.The Froude numbers showed complex variation.With gravel coverage of 40%and gravel sizes of 2-6,6-10 cm,the flow was rapid.Under other conditions,it was tranquil.3)On bare soil slopes,when the gravel size was 0.2-2 cm,the resistance coefficient increased with gravel coverage(0.02,0.02,0.03,0.04),while showing inverse trends for other sizes.The Manning roughness coefficient first increased and then decreased with gravel coverage(0.02,0.06,0.07,0.06).On soil-gravel mixed slopes,the variation trend of resistance coefficient remained consistent with that on bare soil slopes.For gravel sizes of 0.2-2 cm,the Manning roughness coefficient increased with gravel coverage(0.03,0.04,0.13,0.17),while the opposite trend was observed for other sizes.4)On bare soil slopes,when the gravel size was 0.2-2 cm,shear stress increased with gravel coverage(1.93,2.34,3.85,4.69 Pa),while exhibiting opposite trend for other sizes.Stream power first decreased then increased with gravel coverage[0.12,0.08,0.07,0.10 N/(m·s)].On soil-gravel mixed slopes,the variation trend of shear stress was consistent with that on bare soil slopes.For gravel sizes of 0.2-2 and 2-6 cm,stream power first increased then decreased with gravel coverage[0.11,0.13,0.10,0.08 N/(m·s)].For gravel sizes of 6-10 cm,stream power first decreased and then increased[0.11,0.09,0.10,0.11 N/(m·s)].[Conclusion]Surface gravel coverage,internal gravel content,and gravel size have different regulatory effects on hydrodynamic parameters.It is recommended that bare soil slopes adopt a configuration of small gravel sizes(0.2-2 cm)with medium cover(40%),and soil-gravel mixed slopes use small gravel sizes with high cover(60%).This study provides support for understanding soil erosion patterns and preventing soil and water loss in the region.