本文選題：環(huán)式入滲儀　切入點：土壤入滲　出處：《中國農(nóng)業(yè)大學》2017年博士論文　論文類型：學位論文

【摘要】：土壤入滲和優(yōu)先流是降水或灌溉水轉化為土壤水或地下水的關鍵環(huán)節(jié),影響著洪水預算、灌溉系統(tǒng)設計與運行、污染物在地表及土壤中的運移過程。準確測量土壤入滲性能與定量區(qū)分土壤基質入滲和優(yōu)先流過程的相關研究與實踐具有重要意義。環(huán)式入滲儀是應用最為廣泛也是最經(jīng)典的土壤入滲性能測量儀器。本文提出了環(huán)式入滲儀測量入滲率的優(yōu)化算法與改進裝置及定量區(qū)分土壤基質與優(yōu)先流過程的方法。主要研究內容如下。本文認為環(huán)式入滲儀的入滲率計算方法及安裝過程會造成其測量結果偏大,進行室內試驗對假設進行驗證。提出了土壤入滲性能曲線最優(yōu)計算方法,即適當長的時間步長和中點賦值方式能夠減小時間步長和水位讀數(shù)誤差對入滲率造成的誤差,準確測量土壤入滲性能曲線。提出了可剖分入滲儀和土槽,可視化環(huán)內部及下部土壤的真實入滲過程。土壤剖切面濕潤特征表明打擊環(huán)式入滲儀入土的過程造成環(huán)壁和土壤之間形成縫隙產(chǎn)生優(yōu)先流,造成初始階段環(huán)內入滲由垂直向下和徑向向內的入滲共同構成,因此環(huán)式入滲儀測量的初始入滲率偏大。側向入滲造成穩(wěn)定入滲階段的入滲率測量結果偏大。根據(jù)Green-Ampt模型和濕潤體特征提出入滲率的校正模型。入滲率校正值與垂直一維入滲率基本一致。在此基礎上提出表置式入滲儀,即將雙環(huán)入滲儀直接放置地表進行測量以避免對地表擾動。室內試驗和數(shù)值模擬均表明表置式入滲儀能準確測量土壤入滲過程(最大誤差18.95%)。提出土壤基質入滲過程的測量方法,進而根據(jù)土壤總入滲為基質入滲與優(yōu)先流入滲之和的事實,發(fā)展了用土壤總入滲扣除基質入滲測量得到土壤大孔隙優(yōu)先流的方法,并進行野外試驗,研究林地土壤基質入滲和優(yōu)先流的定量關系。林地優(yōu)先流的累積入滲量是基質流的2.0～11.8倍,優(yōu)先流入滲率是基質流入滲率的2.3～10.2倍;優(yōu)先流是影響林地水文循環(huán)過程的主要因素。提出根據(jù)兩個初始入滲率計算完整入滲過程的數(shù)學方法。計算值與傳統(tǒng)測量結果的比例系數(shù)為1.001～1.050,R~2＞0.95,表明該方法具有很高的測量精度。該方法能將入滲測量時間縮短到30 min以內,提高了測量效率。本研究對提高土壤入滲性能測量準確性、提高測量效率,為水文循環(huán)過程、土壤侵蝕、面源污染防控及灌溉系統(tǒng)設計管理提供有效的工具和研究手段。
[Abstract]:Soil infiltration and preferential flow are the key links for the conversion of precipitation or irrigation water to soil water or groundwater, which affect flood budget, design and operation of irrigation system. Accurate measurement of soil infiltration performance and quantitative differentiation of soil matrix infiltration and preferential flow process are of great significance. Ring infiltration instrument is the most widely used. It is also the most classical instrument for measuring soil infiltration performance. In this paper, an optimization algorithm and an improved device for measuring infiltration rate with a ring infiltration meter are proposed, and a method for quantitatively distinguishing soil matrix from preferential flow process is proposed. The main contents of this paper are as follows. In this paper, it is considered that the calculation method and installation process of the infiltration rate of the ring infiltration meter will cause the measurement results to be too large. An optimal calculation method of soil infiltration performance curve is put forward, that is, a proper time step and a midpoint assignment method can reduce the error caused by time step and water level reading error to infiltration rate. The curve of soil infiltration performance was measured accurately. A divisible infiltration instrument and soil trough were proposed. The wetting characteristics of soil profile indicate that the penetration process of punching ring infiltration instrument results in the formation of gap between the ring wall and the soil to produce preferential flow. In the initial stage, the infiltration in the ring is composed of vertical downward infiltration and radial infiltration. Therefore, the initial infiltration rate measured by the loop infiltration meter is larger than that measured by the loop infiltration instrument, and the measurement result of the infiltration rate in the stable infiltration stage is larger due to the lateral infiltration. According to the Green-Ampt model and the wetted body characteristics, the correction model of the infiltration rate is proposed. The vertical one-dimensional infiltration rate is basically the same. In order to avoid surface disturbance, the double ring infiltration instrument is placed directly to avoid surface disturbance. Laboratory tests and numerical simulation show that the surface infiltration instrument can accurately measure soil infiltration process (the maximum error is 18.95 50.The method of measuring soil matrix infiltration process is put forward. According to the fact that the total infiltration of soil is the sum of matrix infiltration and preferential infiltration, the method of subtracting matrix infiltration from soil total infiltration to obtain the soil macroporous preferential flow is developed, and the field test is carried out. The quantitative relationship between soil matrix infiltration and preferential flow in forestland was studied. The cumulative infiltration amount of forestland priority flow was 2.0 ~ 11.8 times as much as that of substrate flow, and the preferential inflow infiltration rate was 2.3 ~ 10.2 times as much as that of substrate flow. Priority flow is the main factor affecting the hydrological cycle process of forestland. A mathematical method for calculating complete infiltration process based on two initial infiltration rates is proposed. The proportional coefficient between the calculated value and the traditional measurement result is 1.001 ~ 1.050 / Rn2 > 0.95. it shows that this method has a very good performance. This method can shorten the time of infiltration measurement to less than 30 min. This study can improve the accuracy and efficiency of soil infiltration measurement, and provide effective tools and research means for hydrological cycle, soil erosion, non-point source pollution prevention and control and irrigation system design and management.
【學位授予單位】：中國農(nóng)業(yè)大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：S152.7

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