本文選題：模擬降雨 + 細(xì)溝發(fā)育��； 參考：《中國科學(xué)院研究生院（教育部水土保持與生態(tài)環(huán)境研究中心）》2015年碩士論文

【摘要】：坡面細(xì)溝侵蝕和細(xì)溝間侵蝕比率問題一直是坡面土壤侵蝕研究的難點問題,由于傳統(tǒng)研究方法的局限性,制約了這一問題的深入研究,因此利用新方法新技術(shù)對這一問題進行深入研究,得到準(zhǔn)確的坡面細(xì)溝侵蝕和細(xì)溝間侵蝕比率并分析其變化規(guī)律,對坡面土壤侵蝕理論的深化、構(gòu)建土壤侵蝕預(yù)報模型及評價土壤侵蝕的環(huán)境效應(yīng)(如農(nóng)田非點源污染物的來源、估算與評價)有著重要科學(xué)意義。本研究分室內(nèi)模擬降雨和室外模擬降雨兩部分,室內(nèi)模擬降雨采用三維激光掃描儀對坡面進行監(jiān)測,研究了黃綿土坡面不同坡度(10°,15°,20°,25°)、降雨強度(90,120 mm.h-1)和坡長(5,7 m)下細(xì)溝發(fā)育過程、形態(tài)特征及細(xì)溝與細(xì)溝間侵蝕比率變化規(guī)律。室外模擬降雨利用7Be示蹤法對坡面進行監(jiān)測,研究了不同坡度(10°,15°,20°,25°,30°)、5 m坡長下細(xì)溝與細(xì)溝間侵蝕比率變化特征,同時較深入的研究了次降雨過程中細(xì)溝與細(xì)溝間侵蝕比率變化規(guī)律及其與徑流、時間等的關(guān)系。主要結(jié)論如下:1.黃綿土坡面細(xì)溝侵蝕特征隨著坡度、降雨強度增大,坡面產(chǎn)流時間、細(xì)溝出現(xiàn)時間有減小趨勢,斷面流速有增大趨勢;隨著降雨強度、坡度、坡長增大,坡面侵蝕率和產(chǎn)流速率明顯增大,隨坡度變化規(guī)律不明顯;總侵蝕量和總徑流量隨降雨強度增大而明顯增大,5 m坡長條件下,總侵蝕量和徑流量隨坡度變化規(guī)律不明顯,而7 m坡長條件下,總侵蝕量隨坡度增大而明顯增大,徑流量隨坡度變化存在臨界坡度;黃綿土坡面細(xì)溝形態(tài)變化受降雨強度影響較小,受坡度影響較大。以7 m坡長為例,在10°,15°坡度條件下,受溯源侵蝕及溝道下切作用較強,形成的細(xì)溝長、窄、深;在20°,25°條件下,受溝壁坍塌作用影響較大,形成的細(xì)溝短、寬、淺。2.次降雨過程中泥沙顆粒組成變化侵蝕泥沙分形維數(shù)與黏粒、粉粒含量呈極顯著正相關(guān),與砂粒含量呈極顯著負(fù)相關(guān);侵蝕泥沙分形維數(shù)隨降雨強度增強有減小趨勢,受坡度、坡長影響變化規(guī)律不明顯,在5 m坡長條件下,侵蝕泥沙分形維數(shù)隨著降雨歷時的延長有先降低后升高趨勢。7 m坡長條件下,10°、15°坡度情況下,侵蝕泥沙分形維數(shù)隨降雨歷時變化規(guī)律不明顯,而在20°、25°坡度情況下,侵蝕泥沙分形維數(shù)有隨降雨歷時增大趨勢;坡度為10°的條件下,細(xì)溝出現(xiàn)后侵蝕泥沙分形維數(shù)明顯小于細(xì)溝出現(xiàn)前,在坡度為15°、20°、25°條件下,細(xì)溝出現(xiàn)后侵蝕泥沙分形維數(shù)明顯高于細(xì)溝出現(xiàn)前。3.細(xì)溝與細(xì)溝間侵蝕比率變化規(guī)律研究對于室內(nèi)模擬降雨,利用稀土元素示蹤法研究坡面細(xì)溝與細(xì)溝間侵蝕比率試驗結(jié)果與預(yù)想相差較大,具體原因還需進一步研究;對于室外模擬降雨,利用7Be示蹤法計算次降雨過程中細(xì)溝間累計侵蝕量,發(fā)現(xiàn)細(xì)溝與細(xì)溝間侵蝕比率隨降雨進行并不是持續(xù)增加,而是先逐漸增加,到達臨界點然后逐漸降低;采用多元回歸方法對細(xì)溝與細(xì)溝間侵蝕比率與坡度、降雨強度、徑流的關(guān)系進行擬合,擬合函數(shù)為冪函數(shù)方程,室內(nèi)模擬降雨和室外模擬降雨擬合方程分別為:,;利用RUSLE模型中計算細(xì)溝與細(xì)溝間侵蝕比率的方程進行計算,得出計算值與實測值差異較大,說明RUSLE模型中計算細(xì)溝與細(xì)溝間侵蝕比率的方程在黃土高原不適用。
[Abstract]:The rate of rill erosion and rill erosion is a difficult problem in the study of slope soil erosion. Because of the limitations of the traditional research methods, it restricts the deep research of this problem. Therefore, the new method and new technology are used to study this problem deeply to get the exact ratio of rill erosion and rill erosion. It has important scientific significance for the deepening of the slope soil erosion theory, the construction of soil erosion prediction model and the evaluation of the environmental effects of soil erosion, such as the source of non point source pollutants in farmland, estimation and evaluation. This study is divided into two parts of indoor simulated rainfall and outdoor simulated rainfall, and three-dimensional laser is used in indoor simulated rainfall. The scanner monitors the slope surface, and studies the development process of the rill under the different slopes (10, 15, 20, 25), the rainfall intensity (90120 mm.h-1) and the slope length (5,7 m), the morphological characteristics and the change law of the erosion ratio between the rill and the rill. The outdoor simulated rainfall is monitored by the 7Be tracer method, and the different slopes (10 degrees, 15) are studied. Degrees, 20 degrees, 25 degrees, 30 degrees), the change of erosion ratio between rill and rill under 5 m slope. At the same time, the relationship between the change of rill and rill erosion ratio and its runoff and time in the process of rainfall is studied. The main conclusions are as follows: 1. the characteristics of the rill erosion on the slope of 1. yellow soil slope, the increase of rainfall intensity, and the flow of the slope In the meantime, the occurrence time of the rill is decreasing and the velocity of the cross section increases. With the intensity of rainfall, the slope and the length of the slope increase, the erosion rate and flow rate of the slope increase obviously, and the law of the slope change is not obvious. The total erosion and total runoff increase obviously with the increase of rainfall intensity. Under the condition of 5 m slope length, the total erosion and runoff change with the slope. Under the condition of 7 m slope length, the total erosion amount increased obviously with the increase of slope and the critical slope of the runoff with the slope. The change of the rill shape of the yellow soil slope was less influenced by the rainfall intensity and influenced by the slope. The 7 m slope length was taken as an example, under the condition of 10 degrees and 15 degrees, the source erosion and the ditch cutting action was stronger. The formation of the trench is long, narrow and deep; under the condition of 20 degrees and 25 degrees, the effect of the collapse of the ditch wall is great, and the formation of the rill in short, wide and shallow.2. precipitation process, the fractal dimension of the sediment particles is very significant positive correlation with the content of the clay particles and the particle content, and has a very significant negative correlation with the content of the sand particles; the fractal dimension of the eroded sediment is with the rainfall intensity. In the condition of 5 m slope length, the fractal dimension of erosion sediment is not obvious under the condition of 10 degrees and 15 degrees under the condition of 10 degrees and 15 degrees, but the fractal dimension of the erosion sediment is not obvious, but at 20 degrees and 25 degrees, the fractal dimension of the sediment is not obvious under the condition of the slope length of rainfall. Under the condition of 10 degrees, the fractal dimension of the erosion sediment is obviously smaller than that before the emergence of the rill. Under the condition of the gradient of 15, 20, 25, the fractal dimension of the erosion sediment is obviously higher than that of the.3. rill and the rill erosion ratio before the appearance of the rill. In the study of indoor simulated rainfall, the results of the study on the ratio of erosion rate between rill and rill by rare-earth element tracing method are quite different from those in anticipation. The specific reasons are still needed to be further studied. For outdoor simulated rainfall, the 7Be tracing method is used to calculate the erosion amount of the rill among the rill in the secondary rainfall process, and the ratio of the erosion between the rill and the rill is found with the ratio of the rill and the rill. Rainfall does not continue to increase, but first gradually increase, reach the critical point and gradually reduce; using multiple regression method to fit the relationship between rill and rill erosion ratio and slope, rainfall intensity and runoff, fitting function is power function equation, indoor simulated rainfall and outdoor simulated rainfall fitting equation are respectively: using R The equation for calculating the erosion rate between rill and rill is calculated in the USLE model, and the difference between the calculated value and the measured value is obtained. It shows that the equation for calculating the erosion rate between the rill and the rill in the RUSLE model is not suitable for the Loess Plateau.
【學(xué)位授予單位】：中國科學(xué)院研究生院（教育部水土保持與生態(tài)環(huán)境研究中心）
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S157

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