黄土区土壤结皮和垄高对坡面产流产沙的影响

Effect of soil crust and ridge height on runoff producting and sediment yield in loess area

通过室内人工模拟降雨方法,研究不同坡面处理(有结皮、无结皮)和垄高(7、10和13 cm)产流产沙情况,为黄土区等高耕作水土流失治理提供理论依据。结果表明,同一垄高下,土壤结皮使坡面初始产流时间提前,径流强度增大,径流总量增加;同一坡面处理下,随垄高增加,坡面径流总量和泥沙总量减少。垄高通过蓄积雨水能力影响土壤结皮对坡面泥沙总量作用。垄高7 cm时,蓄积雨水能力较小,坡面径流量较大,土壤结皮增大坡面产沙量,相比无结皮坡面增加38.70%;垄高为10 cm和13 cm时,蓄积雨水能力较强,坡面径流量较小,土壤结皮减少坡面产沙量,相比无结皮坡面分别减少21.10%和65.70%。坡面土壤侵蚀过程中,土壤结皮首先抑制坡面产沙,但随着降雨历时增加,土壤结皮促进坡面产沙。因此,在黄土区等高耕作中,应合理设置垄高,抑制结皮,以降低土壤侵蚀程度。

Indoor simulated rainfall experiments were conducted to study the effects of two slope treatments(soil crust and non-crust)and three ridge heights(7,10and 13 cm)on slop runoff and sediment yield and provide a theoretical basis for soil and water loss control of contour tillage in loess area.Results showed that for the same ridge height,the initial slope runoff producting time was brought forward,slope runoff producting intensity and the total slope runoff producting increased under soil crust treatment.For the same slope treatment,the total slop runoff producting and sediment yield decreased with the increase of ridge height.Ridge height influenced the effect of soil crust on the total sediment yield by rainwater storage capacity.At the ridge height of 7 cm,the total sediment yield of soil crust increased by 38.70%compared to non-crust,because its rainwater storage capacity was smaller and slop runoff producting was bigger.At the ridge height of 10 and 13 cm,the total sediment yieldof soil crust decreased by 21.10%and 65.70%,respectively compared to non-crust,because its rainwater storage capacity was bigger and slop runoff producting was smaller.During soil erosion process,soil crust first inhibited slope sediment yield and then promoted slope sediment yield as rainfall time.Therefore,ridge height would be set up reasonably and soil crust would be destroyed to decrease soil erosion in contour tillage in loess area.