降雨类型与坡度对棕壤垄沟系统产流产沙的影响

Effects of Rainfall Type and Slope on Runoff and Sediment Yield in Brown Soil Furrow System

为深入理解棕壤垄作坡耕地的土壤侵蚀机理,利用1.60 m×0.53 m的试验土槽,设计2个降雨类型,即增强型(70~70~100~100 mm/h)和减弱型(100~100~70~70 mm/h),以及2个坡度(9°和18°)的人工模拟降雨试验。每个雨型分2个阶段(阶段I、阶段II),每个阶段进行相同雨强的2个场次降雨,每个场次降雨历时20 min。结果表明:(1)雨强对径流量呈显著影响(P<0.05),100 mm/h雨强下的径流量>70 mm/h时的径流量。在减弱型雨型下,坡度对径流量影响显著(P<0.05),而增强型雨型下在不同阶段坡度对径流量的影响不同。(2)雨强对产沙量的影响显著(P<0.05),在阶段Ⅰ降雨中,100 mm/h雨强下9°和18°坡面的平均每分钟产沙量分别为70 mm/h雨强下的23.98,9.07倍。在70 mm/h雨强下,坡度对产沙量的影响显著(P<0.05),而100 mm/h雨强下不同阶段坡度对径流量的影响具有差异性。(3)100 mm/h雨强在不同雨型中出现的时序对产沙量影响不显著(P>0.05);在70 mm/h雨强下,产沙量整体较小,基本在15 g/min以下。同一雨强在不同雨型中的时序对径流量均存在显著影响(P<0.05)。(4)总径流量从大到小依次为:9°减弱型>18°减弱型>9°增强型>18°增强型;总产沙量从大到小依次为:18°增强型>18°减弱型>9°减弱型>9°增强型。不同雨型下,雨强发生改变后,累计径流量和累计产沙量增加速率和雨强的改变具有一致性。

In order to deeply understand the soil erosion mechanism of ridged farmland on brown soil,this paper used a 1.60 m×0.53 m test soil trough and designed two rainfall types,namely,intensive-type(70~70~100~100 mm/h)and reduced-type(100~100~70~70 mm/h),and artificial simulated rainfall tests on 2 slopes(9°and 18°).Each rainfall type is divided into two phases(phase I,phase II),and two sessions of rainfall of the same raininess at each stage,and each session of rainfall lasts 20 minutes.The results show:(1)Raininess has a significant effect on runoff(P<0.05).Runoff at 100 mm/h rain intensity is greater than 70 mm/h.Under the reduced rainfall type,the slope has a significant effect on runoff(P<0.05),while under the intensive rainfall type,the slope at different stages has different effects on runoff.(2)Raininess has a significant effect on sediment yield(P<0.05).During the rainfall of Phase I,the average sediment yield per minute at 9°and 18°slopes at 100 mm/h raininess was 23.98 times and 9.07 times of 70 mm/h raininess.Under 70 mm/h raininess,the slope has a significant effect on sediment yield(P<0.05),while under 100 mm/h raininess,the slope at different stages has different effects on runoff.(3)The time sequences of 100 mm/h raininess in different rainfall types has no significant effect on sediment yield(P>0.05);under 70 mm/h raininess,the overall sediment yield is smaller,basically below 15 g/min.The time sequences of the same raininess in different rainfall types had significant effects on runoff(P<0.05).(4)The total runoff is as follows:9°reduced-type>18°reduced-type>9°intensive-type>18°intensive-type;the total sediment production is in descending order:18°intensive-type>18°reduced-type>9°reduced-type>9°intensive-type.Under different rainfall type,after the change of rain intensity,the cumulative runoff and cumulative sediment yield increase rate and the change of rain intensity are consistent.