本文選題：沙壤土　切入點：濕潤比　出處：《西北農(nóng)林科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：為解決西北地區(qū)水資源分布不均的現(xiàn)狀,更好的保證作物節(jié)水高效,適應(yīng)不同作物各個生育期根系的生長,采用不同的滴灌系統(tǒng)布置技術(shù),形成不同的濕潤體分布形式。以沙壤土(渭河陜西省楊凌段河灘砂壤土)滴灌為研究對象,采用室內(nèi)試驗和模型模擬試驗相結(jié)合的研究方法,開展了基于HYDRUS模型不同土壤有效水邊界對沙壤土滴灌濕潤體特性影響研究,分析了滴灌水技術(shù)參數(shù)(滴頭布置、灌水量、灌水流量)對濕潤鋒在水平、垂直方向的運移距離及不同邊界界定條件下土壤有效濕潤體形狀、水分分布及隨時間變化規(guī)律的影響規(guī)律,取得以下主要結(jié)果:(1)當(dāng)灌水量相同時,大流量滴頭濕潤鋒擴(kuò)散迅速,小流量滴頭擴(kuò)散緩慢;灌水量相同時,不同流量滴頭在滴灌結(jié)束后濕潤體體積差異不大,但在土壤水分再分布過程中,小流量滴頭相比大流量滴頭擴(kuò)散的范圍更大,體積增大主要是垂直方向上水分運移的結(jié)果。當(dāng)采用suffer軟件和Auto-CAD軟件對有效濕潤體體積進(jìn)行計算時,降低了有效濕潤體計算的工作量,提高了計算精度;當(dāng)有效濕潤體邊界層為田間持水量的60%~80%時,有利于植物吸收;按照60%田持為邊界,滴頭流量越小,經(jīng)過再分布后土壤有效濕潤體體積越大。(2)回歸分析顯示飽和區(qū)半徑與流量關(guān)系呈指數(shù)關(guān)系,且隨滴頭流量增大而增大,可用于確定模型模擬的邊界條件;利用實測數(shù)據(jù)對HYDRUS模型進(jìn)行參數(shù)設(shè)定,對比分析濕潤鋒運移和含水率空間分布模擬值和實測值,其結(jié)果誤差較小,具有較高精度。(3)采用HYDRUS軟件模擬單點源和雙點源滴灌不同設(shè)計工況下沙壤土入滲過程,對滴頭流量、田持百分比(有效濕潤體邊界含水率值)、計劃濕潤比和滴灌結(jié)束后持續(xù)時間與實際有效濕潤比進(jìn)行相關(guān)性分析,均呈顯著影響水平,其中田持百分比影響最大,計劃濕潤比和再分布時間次之,滴頭流量影響最小;逐項因素梯度分析獲得了滴頭流量、計劃濕潤比、田持百分?jǐn)?shù)邊界以及再分布時間4種參數(shù)指標(biāo)對實際有效濕潤比的影響函數(shù)關(guān)系式;對于沙質(zhì)土壤,以60%~80%田持含水率作為有效濕潤邊界,有效濕潤體體積小于設(shè)計濕潤體體積,而且有效濕潤比還小于設(shè)計濕潤比,對于合理確定沙壤土滴灌設(shè)計參數(shù)具有指導(dǎo)意義。
[Abstract]:In order to solve the present situation of uneven distribution of water resources in the northwest region, better ensure crop water saving and high efficiency, adapt to the roots of different crops in various growth stages of growth, the layout of different drip irrigation system, the formation of wetting body distribution in different forms. In sandy loam (Weihe Shaanxi section of Yangling river sand loam) using drip irrigation as the research object. Study on the method of laboratory test and simulation test was carried out by combining the HYDRUS model based on different soil water boundary effects on sandy soil wetting characteristics of drip irrigation, drip irrigation technical parameters (drip irrigation, irrigation layout, flow) of the wetting front in the horizontal, vertical migration distance and different boundary the soil moist body shape conditions, effects of water distribution and variation with time. The main results are as follows: (1) when the same irrigation amount, large flow drip wet Front rapid diffusion of small flow drip irrigation by slow diffusion; at the same time, different flow emitters in drip irrigation after the wetted volume had little difference, but the distribution of soil moisture in the process, the small flow range compared to large flow drip drip diffusion greater volume increase is mainly a result of vertical water movement. When the effective wetted volume was calculated using suffer software and Auto-CAD software, reduces the effective wetting calculation workload, the calculation accuracy is improved; when the effective wetted boundary layer for 60%~80% of field capacity, favorable for plant uptake; according to the 60% field capacity as the boundary, the emitter flow is small, after the distribution of soil wetted volume larger. (2) regression analysis showed an exponential relationship between saturated zone radius and flow, and it increases with the increase of dripper discharge, can be used to determine the model boundary conditions; and The HYDRUS model parameters by using the measured data set, comparative analysis of wetting front and water content spatial distribution simulation and measured values, the error is smaller, and has a high precision. (3) simulation of single and double point sources irrigation in different design conditions of soil soil infiltration in Xiasha by using HYDRUS software, the dripper discharge Tian, holding percentage (effective wetted boundary moisture content values), duration of wetting ratio and drip irrigation after wet ratio and the real effective correlation analysis showed a significant effect, which influences the percentage of maximum field capacity, wetting time and distribution, the emitter flow affect the minimum; one by one factor gradient the analysis of the emitter flow, wetting ratio, percentage of field capacity boundary and distribution time of the 4 parameters influence on the real effective wet ratio formula; for the sandy soil, the 60%~80% field to contain As the effective wetting boundary, the effective wetting volume is smaller than the designed wetting volume, and the effective wetting ratio is also less than the design wetting ratio. It has guiding significance for determining the design parameters of sandy loam soil drip irrigation.

【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S275.6;S152.7

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