發(fā)布時間：2018-05-08 09:25

  本文選題：土壤侵蝕 + 地表糙度　； 參考：《西北農林科技大學》2015年博士論文

【摘要】：在坡耕地上,地表糙度是由耕作及日常管理活動形成的地表起伏,由于它對土壤入滲、坡面產流與產沙具有一定的影響,故它是當前坡地水文學和土壤侵蝕學研究的熱點問題之一。本研究在總結前人研究成果的基礎上,選擇人們在農業(yè)生產中普遍采用的掏挖(又稱點種)、等高耕作等主要耕作措施在坡耕地上形成的地表糙度為研究對象,通過室內人工模擬降雨試驗的研究方法,綜合應用土壤侵蝕學、數(shù)學、土壤學、水文學和三維激光掃描技術、GIS技術等理論知識、技術和方法對地表糙度特征及其在水蝕過程中的作用進行了研究。研究內容包括:地表糙度的特征,地表糙度對坡面入滲過程的影響、地表糙度對坡面產流和產沙的影響、粗糙坡面產流曲線模擬等。主要結果如下:1.與整平坡面相比,耕作措施改變了地表土壤的空間結構,增加了地表糙度的空間異質性。鋤耕、掏挖和等高耕作措施下地表糙度具有多分形特征,分形維數(shù)D分別為2.79、2.72和2.87,渡越長度L分別為1.09、1.03和1.01。地表糙度越大的坡面,分形維數(shù)和空間變異性也越大,渡越長度卻越小。2.初始地表糙度特征對降雨侵蝕作用下地表糙度的變化方向(增大或減小)和變化幅度具有影響。在粗糙坡面,地表糙度隨著累計降雨量的增加而降低,二者呈顯著的冪函數(shù)關系(P0.05)。地表糙度在前20 mm累計降雨量內的累計變化量最大,約占總變化量的20%-40%。隨著降雨歷時的延長,后續(xù)降雨侵蝕作用對地表糙度大小的影響能力降低,但是對空間特征的影響仍然較大;其次,地表糙度具有空間變異性,故它的變化與其所在坡位密切相關。在不同坡位上,地表糙度的形態(tài)特征具有一定差異,這種差異會造成地表糙度對降雨和徑流侵蝕作用的響應不同,從而導致它具有不同的變化特征和規(guī)律。3.地表糙度對入滲鋒面變化的影響較大。在粗糙坡面上,垂直于坡面的方向上入滲呈現(xiàn)從非均勻到均勻過渡的變化特征。但是,隨著入滲鋒面深度的增加,影響減小,故與整平坡面相比,在粗糙坡面上入滲率隨著深度的增加降低較明顯。總體而言,粗糙坡面上降雨入滲率較整平坡面平均提高10%以上。4.地表糙度對坡面產流、產沙過程具有影響。與整平坡面相比,粗糙坡面上徑流產生時間平均晚10 min左右。在產流初始階段,粗糙坡面上徑流量較整平坡面低。但是,隨著降雨歷時的延長,粗糙坡面與整平坡面之間、粗糙坡面之間徑流量差異降低。對于坡面侵蝕產沙也具有與徑流量相似的特征�？梢�,糙度大小對徑流產沙的影響與降雨歷時有關。此外,坡度和降雨強度對地表糙度影響坡面產流、產沙的能力具有消減作用。5.來自粗糙坡面上泥沙中粗顆粒(50μm)含量較整平坡面低。隨著降雨歷時的延長,粗糙坡面與整平坡面泥沙中粗顆粒含量都降低,細顆粒的含量增加。對比整平坡面與粗糙坡面泥沙顆粒分布的變化發(fā)現(xiàn),在降雨過程中粗糙坡面泥沙中細顆粒的含量變化較整平坡面明顯。此外,降雨強度,上方來水與來沙會降低地表糙度對泥沙顆粒分布的影響能力。6.在耕作條件下,凸地和洼地是地表糙度的基本構成元素。在產流過程中,洼地積水造成徑流延緩,凸地通過分散徑流,延長徑流路徑的方式延緩徑流。本研究以洼地和凸地為例,建立了以降雨強度I,平均流速vm和洼地積水時間TPi等為主要參數(shù)建立坡面產流計算模型。對模擬結果與實測結果進行比較分析表明,該模型能夠較好的反映糙度對坡面產流的影響,為人們深入理解地表糙度影響坡面產流機理提供了新的方法。
[Abstract]:On sloping land, surface roughness is a surface fluctuation formed by farming and daily management activities. Because it has a certain influence on soil infiltration, runoff production and sediment yield, it is one of the hot issues in the study of slope land hydrology and soil erosion. The surface roughness formed by high tillage and other major tillage measures, such as high tillage, is widely used in the production, and the research method of the surface roughness formed on the sloping land is the research method of soil erosion, mathematics, soil science, hydrology and three-dimensional laser scanning, GIS technology and other theoretical knowledge, technology and technology. The characteristics of surface roughness and its role in the process of water erosion are studied. The research contents include the characteristics of surface roughness, the influence of surface roughness on the infiltration process of slope surface, the influence of surface roughness on runoff yield and sediment yield, and the simulation of runoff yield curve of rough slope. The main results are as follows: 1. the improvement of tillage measures compared with the leveling slope surface The spatial structure of the surface soil has been changed, and the spatial heterogeneity of the surface roughness is increased. The surface roughness has multi fractal characteristics under the hoeing, excavating and high tillage measures. The fractal dimension D is 2.79,2.72 and 2.87 respectively, and the crossing length L is the greater the surface roughness of the surface roughness of 1.09,1.03 and 1.01., the larger the fractal dimension and the spatial variability, the crossing over. The smaller the.2. initial surface roughness has an effect on the change direction (increase or decrease) and the change amplitude of the surface roughness under rainfall erosion. In the rough slope, the surface roughness decreases with the increase of accumulated rainfall, and the two has a significant power function relationship (P0.05). The surface roughness is accumulated in the cumulative rainfall of the previous 20 mm. The amount of change is the largest, and the 20%-40%. of the total variation is decreased with the duration of rainfall. The influence of subsequent rainfall erosion on the roughness of the surface roughness is reduced, but the influence on the spatial characteristics is still larger. Secondly, the surface roughness has spatial variability, so its change is closely related to its slope position. The morphological characteristics of the degree are different. This difference will cause the response of the surface roughness to rainfall and runoff erosion, which leads to the different change characteristics and the regularity of the surface roughness of.3.. On the rough slope, the infiltration in the direction perpendicular to the slope is from the non uniform to the uniform. However, with the increase of the depth of the infiltration front, the influence decreases, so compared with the leveling slope, the infiltration rate on the rough slope decreases obviously with the increase of depth. In general, the rainfall infiltration rate on the rough slope is higher than that of the leveling slope by more than 10%.4. surface roughness on the slope surface production and sediment production process. Compared with the leveling slope surface, the average runoff generation time on the rough slope is about 10 min late. In the initial stage of the runoff production, the runoff on the rough slope is lower than that of the leveling slope. However, with the extension of the rainfall duration, the difference of runoff between rough slope and the leveling slope decreases. The influence of roughness on runoff and sediment is related to the duration of rainfall. In addition, the slope and rainfall intensity affect the surface roughness on the surface roughness, and the ability to produce sand is reduced by.5. from rough slopes (50 mu m), which is lower than that of the leveling slope. The content of coarse particles in the sediment in the slope is reduced and the content of fine particles is increased. The change of sediment particles in the surface and rough slope of the leveling slope shows that the content of fine particles in the sediment in the rough slope is more obvious than that in the leveling slope. The impact capacity of the cloth.6. is the basic element of the surface roughness under the condition of cultivation. During the process of production, the water accumulation in the depressions is delayed, and the runoff is delayed by dispersing runoff and prolonging the runoff path. In this study, the rainfall intensity, the average velocity of VM and the water accumulation in the depression were built in the case of depression and convex land. The flow calculation model of slope surface is established as the main parameter of TPi. The comparison and analysis of the simulation results and the measured results shows that the model can better reflect the influence of roughness on the runoff yield. It provides a new method for people to understand the influence of surface roughness on the mechanism of slope runoff.

【學位授予單位】：西北農林科技大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：S157.1

【參考文獻】

相關期刊論文 前8條

1 吳發(fā)啟,范文波;土壤結皮對降雨入滲和產流產沙的影響[J];中國水土保持科學;2005年02期

2 鄭粉莉,趙軍;人工模擬降雨大廳及模擬降雨設備簡介[J];水土保持研究;2004年04期

3 吳發(fā)啟,鄭子成;坡耕地地表糙度的量測與計算[J];水土保持通報;2005年05期

4 吳發(fā)啟,范文波;土壤結皮與降雨濺蝕的關系研究[J];水土保持學報;2001年03期

5 吳發(fā)啟,趙西寧,崔衛(wèi)芳;坡耕地耕作管理措施對降雨入滲的影響[J];水土保持學報;2003年03期

6 劉俊娥;王占禮;高素娟;;黃土坡面片蝕過程試驗研究[J];水土保持學報;2011年03期

7 吳普特，，周佩華;黃土坡面薄層水流侵蝕試驗研究[J];土壤侵蝕與水土保持學報;1996年01期

8 趙西寧,王萬忠,吳發(fā)啟;不同耕作管理措施對坡耕地降雨入滲的影響[J];西北農林科技大學學報(自然科學版);2004年02期

本文編號：1860850