本文選題：模擬降雨 + 放水沖刷��； 參考：《華中農(nóng)業(yè)大學(xué)》2015年碩士論文

【摘要】：南方紅壤丘陵區(qū)氣候溫和,雨量豐富,是我國水熱條件較好、占地面積較大,是我國重要的糧食生產(chǎn)區(qū),對我國農(nóng)業(yè)經(jīng)濟發(fā)展起關(guān)鍵性作用。隨著經(jīng)濟發(fā)展,過度的人為活動使該區(qū)森林和地表植被大面積破壞,加之該區(qū)地形復(fù)雜,降雨強度大且集中,水土流失比較嚴(yán)重,致使該區(qū)土層薄化,巖石裸露,耕地面積銳減,耕地質(zhì)量下降,農(nóng)業(yè)生產(chǎn)全面衰退。同時土壤中大量的農(nóng)藥和養(yǎng)分隨著徑流泥沙流入河流、湖泊、水庫等,使水體受到嚴(yán)重污染。因此,開展南方紅壤區(qū)土壤侵蝕機理及養(yǎng)分遷移機制研究,保護紅壤資源迫在眉睫。本研究結(jié)果可為紅壤區(qū)防治水土流失、改善生態(tài)環(huán)境及發(fā)展農(nóng)業(yè)生產(chǎn)提供依據(jù)。本文基于室內(nèi)模擬降雨試驗和徑流沖刷試驗相結(jié)合的研究方法,選擇非吸附性Br-作為示蹤劑,研究了雨滴打擊、徑流沖刷、降雨-徑流組合作用這三種侵蝕動力下坡面紅壤侵蝕過程和養(yǎng)分遷移規(guī)律,評價了降雨-徑流不同作用機制對坡面產(chǎn)流產(chǎn)沙的影響,揭示了坡面產(chǎn)流產(chǎn)沙的水動力學(xué)機理及坡面徑流溶質(zhì)溴的遷移機制,闡明了坡面土壤侵蝕過程及溶質(zhì)遷移特征。主要結(jié)論如下：(1)雨滴打擊對坡面侵蝕過程及溶質(zhì)流失的影響模擬降雨條件下,雨強對坡面產(chǎn)流產(chǎn)沙速率影響顯著,雨強越大,產(chǎn)流、產(chǎn)沙速率越大。產(chǎn)流、產(chǎn)沙速率和徑流含沙量隨降雨時間的持續(xù)呈現(xiàn)階段性變化趨勢,其中累計徑流量和累計泥沙量均與產(chǎn)流歷時呈較好的線性關(guān)系,累計徑流量與累計泥沙量之間呈現(xiàn)顯著的冪函數(shù)相關(guān)關(guān)系；產(chǎn)流初始6 min是徑流溶質(zhì)流失的主要階段,相同降雨歷時下徑流溶質(zhì)Br-流失量表現(xiàn)為：120 mm/h 90 mm/h 60 mm/h。(2)徑流沖刷對坡面侵蝕過程及溶質(zhì)流失的影響模擬徑流沖刷條件下,不同流量下坡面侵蝕產(chǎn)沙呈現(xiàn)不同的變化趨勢,其中低流量下(10L/min)侵蝕泥沙變化平緩,高流量下(15L/min、20L/min)侵蝕泥沙主要集中在最初5 min。溶質(zhì)流失主要集中在最初5 min,占總量的40%以上。累計徑流量與產(chǎn)流歷時呈現(xiàn)顯著的正線性相關(guān)關(guān)系,累計泥沙量與產(chǎn)流歷時、累計徑流量間均呈現(xiàn)冪函數(shù)關(guān)系；徑流溶質(zhì)Br-濃度隨產(chǎn)流歷時呈現(xiàn)冪函數(shù)遞減規(guī)律。(3)降雨-徑流共同作用對坡面侵蝕過程及溶質(zhì)流失的影響降雨和放水沖刷共同作用下,降雨強度和上方來水流量對產(chǎn)流產(chǎn)沙動態(tài)變化曲線影響較小,產(chǎn)流產(chǎn)沙速率隨產(chǎn)流時間總體呈減小趨勢,產(chǎn)沙速率衰減速度比產(chǎn)流速率快。累計徑流量與產(chǎn)流歷時呈線性關(guān)系,而累計泥沙量與產(chǎn)流歷時、累計徑流量間呈冪函數(shù)關(guān)系。徑流溶質(zhì)Br-濃度與產(chǎn)流時間呈冪函數(shù)關(guān)系。降雨-徑流共同作用下,坡面水流流態(tài)主要以紊流、急流為主,阻力系數(shù)(f)與雷諾數(shù)(Re)之間呈現(xiàn)很好的冪相關(guān)關(guān)系。通過通徑分析與相關(guān)分析得出,雷諾數(shù)是影響土壤坡面侵蝕的主要水力學(xué)參數(shù)。徑流剪切力、水流功率和單位水流功率三個水動力學(xué)參數(shù)均是描述徑流平均輸沙率、徑流溶質(zhì)流失率的良好指標(biāo)。
[Abstract]:The southern red soil hilly region has a mild climate and abundant rainfall, which is the most important grain production area in our country. It plays a key role in the development of our country's agricultural economy. With the economic development, excessive human activities make the forest and surface vegetation in the area damaged in large area, and the terrain is complex and rainfall intensity in this area. Large and concentrated soil erosion is serious, resulting in the thinning of soil layer, bare rock, the sharp decrease of cultivated land area, the decline of cultivated land quality, and the overall decline of agricultural production. At the same time, a large amount of pesticides and nutrients in the soil flow into rivers, lakes and reservoirs, so that the water is seriously polluted. Therefore, the soil erosive machine in the red soil region of the south is carried out. This study can provide a basis for the prevention and control of soil erosion, the improvement of the ecological environment and the development of agricultural production in the red soil region. Based on the study method combined with simulated rainfall experiment and runoff scour test, this paper selected non adsorptive Br- as a tracer and studied the rain drop. The erosion process and the rule of nutrient migration in the red soil of the slope surface of the three kinds of erosion power, such as strike, runoff scouring and rainfall runoff combination, were used to evaluate the effect of rainfall runoff different mechanism on runoff and sediment yield on slope surface. The main conclusions are as follows: (1) the influence of raindrop on the process of slope erosion and the loss of solute in the simulated rainfall conditions, the rainfall intensity has a significant effect on the rate of runoff and sediment yield on the slope, the greater the intensity of rain, the greater the runoff yield, the greater the rate of sediment yield. There is a good linear relationship between cumulative runoff and accumulated sediment volume, which shows a significant power function relationship between cumulative runoff and accumulated sediment; the initial 6 min of runoff is the main stage of runoff solute loss, and the loss of solute Br- in the same rainfall duration is 120 mm/h 90 mm/h 6. The effect of 0 mm/h. (2) runoff erosion on the erosion process and solute loss of the slope surface under simulated runoff erosion conditions, the erosion and sediment yield of the slope surface under different flow rates showed a different trend, of which the erosion sediment was slow under low flow rate (10L/min), and the high flow (15L/min, 20L/min) erosion sediment mainly concentrated on the initial 5 min. solute loss. The initial 5 min, accounting for more than 40% of the total amount, has a significant positive linear correlation between the cumulative runoff and the duration of runoff. The cumulative sediment volume and the runoff time, the cumulative runoff has a power function relationship, and the concentration of the runoff solute Br- presents a power function decreasing rule with the runoff. (3) the rainfall runoff joint action on the slope erosion process and The effect of rainfall and water discharge scour on the loss of solute is less affected by rainfall intensity and water flow rate on the dynamic change curve of runoff and sediment yield. The rate of runoff and sediment yield decreases with the flow time, and the rate of sediment yield is faster than the rate of flow rate. The cumulative runoff is linear with the duration of runoff, and the accumulated sediment is accumulated. The relationship between cumulative runoff and runoff is a power function relationship. The relationship between the concentration of Br- and the time of runoff is a power function relationship. Under the joint action of rainfall runoff, the flow patterns in the slope are mainly turbulent and jet flow, and the resistance coefficient (f) and Reynolds number (Re) show a good power correlation. Renault through path analysis and correlation analysis Number is the main hydraulic parameter that affects soil slope erosion. The runoff shear force, water power and unit flow power are three hydrodynamic parameters which are good indexes to describe runoff average sediment transport rate and runoff solute loss rate.
【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

1 陳利頂,傅伯杰;農(nóng)田生態(tài)系統(tǒng)管理與非點源污染控制[J];環(huán)境科學(xué);2000年02期

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