稀土元素定量監(jiān)測坡面淺溝產(chǎn)生及發(fā)育過程
發(fā)布時間：2018-08-01 08:00
【摘要】：針對目前坡面淺溝侵蝕的產(chǎn)生及發(fā)育過程研究不足的現(xiàn)狀,本論文以黃土為研究對象,在室內(nèi)模擬降雨條件下采用稀土元素示蹤技術(shù),主要研究了坡面產(chǎn)流產(chǎn)沙過程,量化了坡面侵蝕形式的變化過程,分析了土壤類型和降雨動能對坡面侵蝕形式變化的影響以及瓦背型地貌淺溝侵蝕過程。所得的研究結(jié)果為淺溝侵蝕發(fā)生地區(qū)尤其是黃土高原地區(qū)坡耕地土壤侵蝕治理提供科學(xué)參考。主要研究結(jié)論如下:(1)研究了不同降雨強(qiáng)度、不同土壤類型和不同降雨動能條件下坡面產(chǎn)流和產(chǎn)沙過程。坡面產(chǎn)流率和產(chǎn)沙率均隨著累積降雨量的增加呈現(xiàn)先增加后平穩(wěn)波動的變化規(guī)律,部分實(shí)驗(yàn)最后階段出現(xiàn)逐漸減小的趨勢。降雨強(qiáng)度、土壤類型和降雨動能對坡面產(chǎn)流和產(chǎn)沙均具有較大影響。(2)量化了坡面侵蝕形式的變化過程。位于溝坡表面的Eu示蹤層降雨初期開始出現(xiàn)產(chǎn)沙,隨后在雨滴打擊和徑流共同作用下逐漸下切至其他各層。安塞黃綿土在405 mm降雨過程中十個示蹤層(共50 cm)均先后出現(xiàn)明顯產(chǎn)沙,而楊凌X土和長武黑壚土坡面最下面三層(每層各6 cm,共18 cm)一直未出現(xiàn)明顯產(chǎn)沙。片蝕產(chǎn)沙量隨著累積降雨量的增加呈現(xiàn)先增加再波動減小的變化趨勢。其貢獻(xiàn)率則呈現(xiàn)復(fù)雜變化,在降雨初期提供主要泥沙貢獻(xiàn),隨后在細(xì)溝發(fā)育過程中逐漸減小至平穩(wěn)階段,并在淺溝出現(xiàn)后呈現(xiàn)進(jìn)一步減小的變化趨勢。細(xì)溝侵蝕產(chǎn)沙量隨著累積降雨量的增加呈現(xiàn)先快速增加后波動穩(wěn)定至淺溝侵蝕發(fā)生后略有減小,隨后細(xì)溝產(chǎn)沙量持續(xù)增加至最大值后處于波動穩(wěn)定后再減小的變化趨勢。細(xì)溝在降雨初期貢獻(xiàn)率較小,隨后快速增加到較大值并處于穩(wěn)定波動至淺溝出現(xiàn)后再逐漸減小至平穩(wěn)波動。淺溝產(chǎn)沙量隨著累積降雨量的增加呈現(xiàn)先增加后波動穩(wěn)定至降雨結(jié)束,或先增加后波動穩(wěn)定再減小的變化趨勢。淺溝貢獻(xiàn)率自出現(xiàn)后逐漸增加至穩(wěn)定波動狀態(tài)。根據(jù)三種侵蝕類型產(chǎn)沙貢獻(xiàn)率的變化規(guī)律,將坡面侵蝕過程分為以下五個階段:片蝕階段(片蝕貢獻(xiàn)率大于80%)、細(xì)溝發(fā)育階段、細(xì)溝侵蝕穩(wěn)定階段(細(xì)溝貢獻(xiàn)率大于70%、片蝕貢獻(xiàn)率小于20%)、淺溝侵蝕發(fā)育階段和淺溝侵蝕穩(wěn)定階段(淺溝貢獻(xiàn)率50%-70%,細(xì)溝貢獻(xiàn)率20%-40%,片蝕貢獻(xiàn)率小于5%)。(3)分析了土壤類型和降雨動能對坡面侵蝕形式變化的影響。土壤類型和降雨動能對坡面侵蝕形式變化具有重要影響。不同土壤類型的團(tuán)聚體穩(wěn)定性差異較大,隨著土壤團(tuán)聚體穩(wěn)定性的增加,除細(xì)溝發(fā)育階段外,其他各階段持續(xù)時間均隨著團(tuán)聚體穩(wěn)定性的增加而增加。隨著降雨動能的增加,對細(xì)溝發(fā)育階段及細(xì)溝穩(wěn)定階段的溝道發(fā)育起促進(jìn)作用,對淺溝發(fā)育階段的影響較為復(fù)雜,在整體上促進(jìn)溝道發(fā)育。侵蝕過程中0.002mm粒級和0.002-0.02 mm粒級富集明顯。隨著土壤團(tuán)聚體穩(wěn)定性增加,更多的0.002 mm粒級和0.002-0.02 mm粒級以0.05 mm粒級團(tuán)聚體的形式搬運(yùn)出坡面。降雨動能主要對片蝕階段泥沙分選具有較大影響,而對其他侵蝕階段泥沙分選影響不大。土壤類型和降雨動能均對溝寬具有影響較大,黃綿土坡面溝深最大,X土和黑壚土坡面溝深差別不大。整個降雨過程中,降雨動能對溝深的影響較小。(4)研究了瓦背型地貌淺溝侵蝕過程。瓦背型淺溝徑流率均隨著累積降雨量的增加存在著先快速增加后慢速增加再趨于波動穩(wěn)定的變化趨勢,而產(chǎn)沙率則呈現(xiàn)先增加后平穩(wěn)波動再減小的趨勢。溝坡部位產(chǎn)沙量隨著累積降雨量的增加呈現(xiàn)先慢速增加后快速增加至最大值再波動減小的變化規(guī)律。溝坡部位產(chǎn)沙貢獻(xiàn)率先處于穩(wěn)定波動變化,隨后逐漸增加至最大值再減小到較小值,隨后穩(wěn)定波動且略有減小。溝底部位產(chǎn)沙量隨著累積降雨量的增加呈現(xiàn)先快速增加后慢速增加至最大值,之后出現(xiàn)穩(wěn)定波動再逐漸減小的變化現(xiàn)象。溝底部位產(chǎn)沙貢獻(xiàn)率先處于穩(wěn)定波動變化,隨后逐漸減小至最小值再增加達(dá)到較大值,而后穩(wěn)定波動且略有增加。瓦背型地貌的在整個降雨過程中溝底部位產(chǎn)沙貢獻(xiàn)率均大于溝坡部位產(chǎn)沙貢獻(xiàn)率。隨著累積降雨量的增加,溝坡部位和溝底部位產(chǎn)沙貢獻(xiàn)率共出現(xiàn)了三個明顯拐點(diǎn),根據(jù)這三個拐點(diǎn)可以將瓦背型地貌淺溝侵蝕過程大致分為四個階段:溝底溝道下切階段;溝坡快速坍塌階段;溝坡坍塌減緩階段;溝道穩(wěn)定階段。
[Abstract]:In view of the present situation of insufficient research on the production and development process of shallow gully erosion on the slope, this paper takes loess as the research object. The process of runoff and sediment production on slope surface is mainly studied by using rare earth element tracing technique under indoor simulated rainfall conditions, and the change process of slope erosion form is quantified, and soil types and rainfall kinetic energy are analyzed on the slope surface. The influence of erosion form changes and the shallow gully erosion process of tile back landform. The results of the study provide scientific reference for soil erosion control in shallow gully erosion area, especially in the Loess Plateau area. The main conclusions are as follows: (1) the slope surface of different rainfall intensity, different soil type and different rainfall kinetic energy conditions are studied. The runoff yield and sediment yield in the process of runoff and sediment yield increase first and then the steady fluctuation with the increase of accumulated rainfall, and the trend of gradual decrease in the final stage of some experiments. The rainfall intensity, soil type and rainfall kinetic energy have great influence on the runoff yield and sediment yield on the slope. (2) the form of slope erosion is quantified. The Eu tracer layer on the surface of the ditch began to produce sediment, and then gradually cut down to the other layers under the joint action of raindrop and runoff. In the 405 mm rainfall process of Ansai yellow soil, ten tracer layers (a total of 50 cm) all had obvious sediment yield, while Yangling X soil and Changwu black soil slope surface at the bottom of the slope. There has been no obvious sediment yield in the 6 cm layer of each layer, and a total of 18 cm). The amount of sands yield increases first and then decreases with the increase of accumulated rainfall. Its contribution rate presents a complex change, which provides the main sediment contribution at the early stage of rainfall, and then decreases gradually to the smooth stage in the process of the development of the trench, and appears after the appearance of the shallow gully. As the cumulative rainfall increased, the sediment yield of the rill erosion first rapidly increased and then fluctuated to a slight decrease after the shallow gully erosion, and then the sediment yield increased to the maximum value and then decreased after the fluctuation. The contribution rate of the fine ditch at the early stage of the rainfall was smaller, and then fast. The variation trend of shallow gully yield increases first and then fluctuates to the end of rainfall, or increases first and then decreases. The contribution rate of shallow gully increases gradually to stable fluctuation state. The variation of the contribution rate of the three types of erosion is divided into five stages: the erosive stage (the slice erosion contribution rate is more than 80%), the rill development stage, the rill erosion stable stage (the rill contribution rate is greater than 70%, the slice erosion contribution rate is less than 20%), the shallow gully erosion development stage and the shallow gully erosion stable stage (the shallow ditch contribution rate 50%). -70%, the contribution rate of rill is 20%-40%, the contribution rate of sheet erosion is less than 5%). (3) the influence of soil type and rainfall kinetic energy on the change of slope erosion form is analyzed. Soil type and rainfall kinetic energy have an important influence on the change of slope erosion form. The duration of the other stages increased with the increase of the stability of the aggregate. With the increase of rainfall kinetic energy, the growth stage of the trench and the channel development of the rill stable stage were promoted, and the influence on the development stage of the shallow gully was more complex, and the channel development was promoted on the whole body. The 0.002mm grain level in the erosion process was improved. And 0.002-0.02 mm grain level enrichment is obvious. With the increase of soil aggregate stability, more 0.002 mm grain grade and 0.002-0.02 mm grain grade are transported out of slope surface with 0.05 mm particle aggregate. The rain kinetic energy has great influence on the furrow width, and the depth of the slope in the slope of the yellow cotton soil is the largest. The influence of the rainfall kinetic energy on the depth of the ditch is small in the whole rainfall process. (4) the shallow gully erosion process of the tile back topography is studied. The shallow gully flow rate of the tile back has a rapid increase with the increase of accumulated rainfall. The slow increase then tends to fluctuate and stable, while the sediment yield increases first and then decreases. Then gradually increase to the maximum value and then decrease to the smaller value, and then steady fluctuation and slightly decrease. The sediment yield at the bottom of the ditch shows a rapid increase and then slowly increase to the maximum value with the increase of cumulative rainfall, then the steady fluctuation then gradually decreases. In the whole rainfall process, the contribution rate of sediment yield in the bottom of the ditch is greater than that in the ditch. With the increase of accumulated rainfall, the contribution rate of sediment yield in the slope and the bottom of the ditch has three obvious inflection points. According to these three inflection points, the shallow gully erosion process of the tile back landform can be roughly divided into four stages: the undercut stage of the ditch bottom channel, the rapid collapse stage of the gully slope, the slow collapse stage of the gully slope and the stable stage of the channel.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：S157.1
，
本文編號：2156833
[Abstract]:In view of the present situation of insufficient research on the production and development process of shallow gully erosion on the slope, this paper takes loess as the research object. The process of runoff and sediment production on slope surface is mainly studied by using rare earth element tracing technique under indoor simulated rainfall conditions, and the change process of slope erosion form is quantified, and soil types and rainfall kinetic energy are analyzed on the slope surface. The influence of erosion form changes and the shallow gully erosion process of tile back landform. The results of the study provide scientific reference for soil erosion control in shallow gully erosion area, especially in the Loess Plateau area. The main conclusions are as follows: (1) the slope surface of different rainfall intensity, different soil type and different rainfall kinetic energy conditions are studied. The runoff yield and sediment yield in the process of runoff and sediment yield increase first and then the steady fluctuation with the increase of accumulated rainfall, and the trend of gradual decrease in the final stage of some experiments. The rainfall intensity, soil type and rainfall kinetic energy have great influence on the runoff yield and sediment yield on the slope. (2) the form of slope erosion is quantified. The Eu tracer layer on the surface of the ditch began to produce sediment, and then gradually cut down to the other layers under the joint action of raindrop and runoff. In the 405 mm rainfall process of Ansai yellow soil, ten tracer layers (a total of 50 cm) all had obvious sediment yield, while Yangling X soil and Changwu black soil slope surface at the bottom of the slope. There has been no obvious sediment yield in the 6 cm layer of each layer, and a total of 18 cm). The amount of sands yield increases first and then decreases with the increase of accumulated rainfall. Its contribution rate presents a complex change, which provides the main sediment contribution at the early stage of rainfall, and then decreases gradually to the smooth stage in the process of the development of the trench, and appears after the appearance of the shallow gully. As the cumulative rainfall increased, the sediment yield of the rill erosion first rapidly increased and then fluctuated to a slight decrease after the shallow gully erosion, and then the sediment yield increased to the maximum value and then decreased after the fluctuation. The contribution rate of the fine ditch at the early stage of the rainfall was smaller, and then fast. The variation trend of shallow gully yield increases first and then fluctuates to the end of rainfall, or increases first and then decreases. The contribution rate of shallow gully increases gradually to stable fluctuation state. The variation of the contribution rate of the three types of erosion is divided into five stages: the erosive stage (the slice erosion contribution rate is more than 80%), the rill development stage, the rill erosion stable stage (the rill contribution rate is greater than 70%, the slice erosion contribution rate is less than 20%), the shallow gully erosion development stage and the shallow gully erosion stable stage (the shallow ditch contribution rate 50%). -70%, the contribution rate of rill is 20%-40%, the contribution rate of sheet erosion is less than 5%). (3) the influence of soil type and rainfall kinetic energy on the change of slope erosion form is analyzed. Soil type and rainfall kinetic energy have an important influence on the change of slope erosion form. The duration of the other stages increased with the increase of the stability of the aggregate. With the increase of rainfall kinetic energy, the growth stage of the trench and the channel development of the rill stable stage were promoted, and the influence on the development stage of the shallow gully was more complex, and the channel development was promoted on the whole body. The 0.002mm grain level in the erosion process was improved. And 0.002-0.02 mm grain level enrichment is obvious. With the increase of soil aggregate stability, more 0.002 mm grain grade and 0.002-0.02 mm grain grade are transported out of slope surface with 0.05 mm particle aggregate. The rain kinetic energy has great influence on the furrow width, and the depth of the slope in the slope of the yellow cotton soil is the largest. The influence of the rainfall kinetic energy on the depth of the ditch is small in the whole rainfall process. (4) the shallow gully erosion process of the tile back topography is studied. The shallow gully flow rate of the tile back has a rapid increase with the increase of accumulated rainfall. The slow increase then tends to fluctuate and stable, while the sediment yield increases first and then decreases. Then gradually increase to the maximum value and then decrease to the smaller value, and then steady fluctuation and slightly decrease. The sediment yield at the bottom of the ditch shows a rapid increase and then slowly increase to the maximum value with the increase of cumulative rainfall, then the steady fluctuation then gradually decreases. In the whole rainfall process, the contribution rate of sediment yield in the bottom of the ditch is greater than that in the ditch. With the increase of accumulated rainfall, the contribution rate of sediment yield in the slope and the bottom of the ditch has three obvious inflection points. According to these three inflection points, the shallow gully erosion process of the tile back landform can be roughly divided into four stages: the undercut stage of the ditch bottom channel, the rapid collapse stage of the gully slope, the slow collapse stage of the gully slope and the stable stage of the channel.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：S157.1
，
本文編號：2156833
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