【摘要】：水分在土壤侵蝕過程中扮演著重要的角色。土壤侵蝕過程通常認(rèn)為是水的侵蝕性與土壤可蝕性之間的相互作用,侵蝕性和可蝕性是理解和預(yù)測土壤侵蝕的基石。土壤水分條件有多種表現(xiàn)形式,包括土壤含水量、水分運動、水力梯度等,大量研究指出土壤水分條件影響土壤侵蝕,但多數(shù)土壤侵蝕預(yù)測模型并沒有調(diào)整相關(guān)的土壤侵蝕參數(shù)。因此,進(jìn)一步研究土壤水分條件對土壤侵蝕的影響十分必要,以便改進(jìn)現(xiàn)有的土壤侵蝕模型。本文以湖北南部三種母質(zhì)(第四紀(jì)紅色粘土、花崗巖、泥質(zhì)頁巖)發(fā)育的紅壤為研究對象,基于WEPP模型理論,分別研究土壤水分條件對細(xì)溝侵蝕過程和細(xì)溝間侵蝕過程的影響,所得到的主要結(jié)論如下:(1)對于細(xì)溝可蝕性而言,土壤水分條件是存在影響的,風(fēng)干條件下的細(xì)溝可蝕性值顯著高于飽和和排水條件,而后兩者之間的差異并不顯著。由風(fēng)干到排水再到飽和的過程中,即模擬自然坡面上土壤由干燥而濕潤進(jìn)而出現(xiàn)滲流的過程,前期土壤含水量較低時極細(xì)砂含量、粘粒含量對于細(xì)溝可蝕性的影響力都是顯著的,粘粒含量的影響力雖然在初期較大,但這種影響力逐漸衰減,至滲流出現(xiàn)時已不產(chǎn)生顯著影響;極細(xì)砂含量則自始至終發(fā)揮著重要作用。這也意味著土壤水分條件難以撼動極細(xì)砂含量對細(xì)溝可蝕性的影響。第四紀(jì)粘土母質(zhì)發(fā)育的紅壤在風(fēng)干條件下的值明顯高于公式預(yù)測值,花崗巖母質(zhì)發(fā)育的紅壤則偏低。(2)對于臨界剪切力而言,不同的水分條件下測定的值是不同的,風(fēng)干條件下的最小,顯著低于飽和和排水條件下的均值。風(fēng)干和排水條件下砂粒含量所起的作用高于其它土壤性質(zhì),而飽和條件時粘粒的增加有助于提高臨界剪切力。(3)土壤水分條件對侵蝕過程趨向穩(wěn)定時的產(chǎn)流量和含沙量影響較大,而對于泥沙的粒徑分布則主要在徑流剛產(chǎn)生時發(fā)生影響。(4)對于細(xì)溝間可蝕性而言,在飽和(即滲流)條件下,其值大幅增長;排水和風(fēng)干條件下的細(xì)溝間可蝕性差異不明顯,即使前者略高于后者。當(dāng)土壤水分條件為風(fēng)干時有0.25mm水穩(wěn)性團(tuán)聚體含量(%)一個土壤性質(zhì)與細(xì)溝間可蝕性顯著相關(guān);排水時的有砂粒含量、極細(xì)砂含量和粉粒含量3個;飽和時無一存在相關(guān)性,僅粉粒含量(g/kg)影響徘徊在顯著性邊緣(P=0.053)。實測值普遍大于公式預(yù)測值,特別是在“泥質(zhì)頁巖-飽和”條件下,前者超過后者5倍。(5)土壤水分條件對細(xì)溝間可蝕性的影響顯著大于細(xì)溝可蝕性,尤其是當(dāng)滲流出現(xiàn)時。
[Abstract]:Water plays an important role in soil erosion. The process of soil erosion is generally regarded as the interaction between water erosion and soil erodibility, which is the cornerstone of understanding and predicting soil erosion. Soil moisture conditions have many forms, including soil water content, water movement, hydraulic gradient and so on. A large number of studies have pointed out that soil moisture conditions affect soil erosion. However, most soil erosion prediction models do not adjust the soil erosion parameters. Therefore, it is necessary to further study the influence of soil moisture on soil erosion in order to improve the existing soil erosion models. Based on the theory of WEPP model, the effects of soil moisture conditions on the process of rill erosion and inter-gully erosion were studied based on the red soil developed by three parent materials (Quaternary red clay, granite, shales) in southern Hubei Province, based on the theory of WEPP model. The main conclusions are as follows: (1) for the erodibility of the rill, the soil moisture condition is affected, the erodibility of the soil under the air-dry condition is significantly higher than that of the saturation and drainage conditions, but the difference between the latter two is not significant. The process from air drying to drainage to saturation is to simulate the process of soil wetting and percolation on the natural slope, and the very fine sand content in the early stage when the soil moisture content is low. The influence of the clay content on the erodibility of the rill is significant, although the influence of the clay content is great in the initial stage, but the influence gradually decreases, until the seepage appears, it has no significant effect. The content of very fine sand plays an important role from beginning to end. This also means that the soil moisture condition can not shake the effect of very fine sand content on the erodibility of the rill. The value of red soil developed in Quaternary clay is obviously higher than the predicted value of formula under the condition of air drying, while the red soil developed by granitic material is lower. (2) for critical shear stress, the values measured under different water conditions are different. The minimum value under air drying condition is significantly lower than the average value under saturated and drainage conditions. The effect of sand content on air drying and drainage is higher than other soil properties. But the increase of clay in saturated condition can increase the critical shear stress. (3) soil moisture condition has a great influence on the yield and sediment content when the erosion process tends to be stable. The particle size distribution of sediment is mainly affected when runoff is first produced. (4) for the erodibility of the gully, the value increases greatly under the condition of saturation (i.e. seepage); There was no significant difference in erodibility between drains and drains, even though the former was slightly higher than the latter. The content of 0.25mm water stable aggregates (%) was significantly correlated with the erodibility of the rill when the soil moisture condition was air-dried, the sand content, the ultrafine sand content and the silt content were 3 in drainage. There was no correlation during saturation, but only the effect of powder content (g/kg) hovered at the significant edge (P0. 053). The measured values are generally greater than the predicted values of the formula, especially under the condition of shale-saturation, the former is 5 times greater than the latter. (5) the effect of soil moisture on the erodibility of the rill is significantly greater than that of the erodibility of the rill. Especially when seepage occurs.
【學(xué)位授予單位】：華中農(nóng)業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S157

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相關(guān)期刊論文 前1條

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本文編號：2417932