北方土石山区冻融与水力复合作用对土壤侵蚀的影响

Effects of Freeze-thaw and Hydraulic Compound Action on Soil Erosion in Northern Rocky Mountainous Area

[目的]揭示冻融与水力作用在不同条件下对北方土石山区土壤侵蚀的影响。[方法]以北京市鹫峰地区土壤为研究对象,采用室内径流冲刷及冻融设备进行模拟试验,探讨在冻融与水力作用下冻融循环次数、坡度、流量、土壤初始含水率和冻融温差这5个影响因素对土壤产沙量与抗冲性的影响。[结果](1)土壤抗冲系数对各因素敏感程度大小为坡度>流量>冻融温差>冻融循环次数>初始含水率,其中坡度与流量对其具有显著影响(p<0.05);土壤产沙量对各因素敏感程度大小为流量>坡度>冻融温差>土壤含水率>冻融循环次数,其中流量对其具有极显著影响(p<0.01),坡度与冻融温差对土壤产沙量具有显著影响(p<0.05)。(2)冻融循环次数、坡度及流量的大小与土壤抗冲系数呈负相关,冻融温差大小却与其呈正相关,而抗冲系数随土壤初始含水率的增加呈先减小后增大的趋势。(3)土壤产沙量随流量、坡度和冻融循环次数的增大而增大,随着冻融温差整体温度的增大而减小;随着土壤含水率的增加,土壤产沙量呈先增大后减小的趋势;在冻融循环次数为7,10次时,土壤产沙率在径流冲刷中期(3~6 min)有峰值出现(96.7~99.7 g/min),随后趋于平稳。[结论]北方土石山区土壤在冻融与水力复合作用下受多种因素影响密切,研究结果有助对该地区复合侵蚀防治及合理配置水土保持措施提供理论支持。

[Objective]This study aims to elucidate the impact of freeze-thaw cycles and hydraulic action on soil erosion in the northern rocky mountain regions under varying conditions.[Methods]Utilizing soil samples from the Jiufeng area in Beijing,we conducted simulation tests using indoor runoff scouring and freeze-thaw equipment.We examined the effects of five key factors-freeze-thaw cycle frequency,slope gradient,flow rate,initial soil moisture content,and freeze-thaw temperature differential-on soil sediment yield and anti-scourability.[Results](1)The sensitivity of the soil’s anti-scourability coefficient to these factors ranks as follows:slope>flow rate>freeze-thaw temperature difference>freeze-thaw cycles>initial moisture content.Notably,slope and flow rate significantly influence the coefficient(p<0.05).For soil sediment yield,the sensitivity ranking is:flow rate>slope>freeze-thaw temperature difference>soil moisture content>freeze-thaw cycles,with flow rate exhibiting a very significant impact(p<0.01),and both slope and freeze-thaw temperature difference showing significant effects(p<0.05).(2)The number of freeze-thaw cycles,slope,and flow rate negatively correlate with the soil's anti-scour coefficient,whereas the temperature difference during freeze-thaw cycles positively correlates with it.The anti-scour coefficient initially decreases and then increases with rising initial soil moisture content.(3)Soil sediment yield increases with higher discharge rates,steeper slopes,and more frequent freeze-thaw cycles,but decreases with an increase in the overall temperature of the freeze-thaw differential.As soil moisture content rises,sediment yield initially increases and then decreases.When the number of freeze-thaw cycles reaches 7 or 10,sediment yield peaks(96.7~99.7 g/min)during the middle phase of runoff scouring(3~6 min)and then stabilizes.[Conclusion]Soil in the northern rocky mountain areas is significantly impacted by various factors under the combined effects of freeze-thaw and hydraulic pressures.The findings of this study provide valuable theoretical support for the prevention and management of combined erosion and for the strategic allocation of soil and water conservation measures in these regions.