典型黑土区坡面上方汇流和土壤管道崩塌对坡面水蚀的影响

Impacts of upslope inflow and soil pipe collapse on slope water erosion in the typical Chinese Mollisol region

分析坡面上方汇流和土壤管道崩塌对黑土坡面水蚀过程的影响,可为黑土侵蚀退化防治提供重要科学依据。本研究基于坡面汇流模拟试验,设计3个上方汇流强度和3种近地表土壤水文条件(无土壤管道、有土壤管道无管道流、有土壤管道流),研究坡面上方汇流和土壤管道崩塌对黑土坡面水蚀过程的影响,量化土壤管道侵蚀对黑土坡面侵蚀的贡献。结果表明:1)坡面侵蚀量随上方汇流强度的增加而增加,当上方汇流强度从30 L·min^(-1)增加到40和50 L·min^(-1)时,坡面侵蚀量分别增加100.0%~111.5%和214.8%~289.2%。2)土壤管道发生和管道流形成加剧了坡面水蚀过程,30、40和50 L·min^(-1)上方汇流强度下有土壤管道无管道流和有土壤管道流处理的坡面侵蚀量分别是无土壤管道处理的1.4~1.6倍和1.7~2.1倍。此外,3种上方汇流强度下有土壤管道无管道流和有土壤管道流处理的土壤管道侵蚀对坡面土壤侵蚀的贡献分别为26.7%~37.6%和40.5%~51.9%。3)土壤管道崩塌加剧了细沟侵蚀过程,30、40和50 L·min^(-1)上方汇流强度下有土壤管道无管道流和有土壤管道流处理的细沟侵蚀量较无土壤管道处理增加38.1%~66.0%和93.7%~128.4%。因此,上方汇流强度增加使坡面水流流速增大,导致坡面径流侵蚀能力和搬运能力增强,从而增加了坡面侵蚀量;土壤管道崩塌也加剧了细沟侵蚀过程,尤其是土壤管道崩塌瞬间地表径流全部转化为土壤管道流,极大增加了坡面水流流速,加剧了坡面侵蚀过程,进而增加了坡面侵蚀量。

Understanding the effects of upslope runoff and soil pipe collapse on slope water erosion can provide scien-tific basis for preventing Mollisol degradation caused by soil erosion.We conducted an experiment to investigate the effects of upslope inflow rate and soil pipe collapse on slope water erosion and to quantify the contribution of soil pipe erosion to slope soil erosion.The experiment included three inflow rates(30,40,and 50 L·min^(-1))and three near-surface soil hydrological conditions(without soil pipe:NP;with soil pipe but no pipe flow:PF0;with pipe flow:PF1).The results showed that:1)Slope soil erosion increased with increasing inflow rates;when the inflow rate increased from 30 L·min^(-1)to 40 and 50 L·min^(-1),slope soil erosion increased by 100.0%-111.5%and 214.8%-289.2%,respectively.2)The soil pipe occurrence and pipe flow formation aggravated the slope water erosion process.At inflow rates of 30,40,and 50 L·min^(-1),slope soil loss under the PF0 and PF1 treatments were 1.4-1.6 times and 1.7-2.1 times of that under the NP treatment.The contribution of soil pipe erosion to slope soil loss was 26.7%-37.6%under the PF0 treatment and 40.5%-51.9%under the PF1 treatment.3)Soil pipe collapse intensified the rill erosion process.Compared with the NP treatment at 30,40,and 50 L·min^(-1)inflow rate,rill erosion amounts under the PF0 and PF1 treatments increased by 38.1%-66.0%and by 93.7%-128.4%,respectively.Our results suggested that increasing upslope inflow rate resulted in higher surface runoff velocity,which promoted runoff detachment and transport capacity,and then aggrandized the amount of slope soil erosion.Moreover,soil pipe collapse exacerbated rill erosion process.When the soil pipe collapsed,all surface runoff was converted to soil pipe flow,which accelerated flow velocity and slope soil erosion process,and then increased the amount of slope soil erosion.