本文選題：雙面蒸發(fā)　切入點：溝岸地　出處：《西北農(nóng)林科技大學》2015年碩士論文

【摘要】：黃土高原是我國水土流失最嚴重的地區(qū),也是水資源最為缺乏的地區(qū)之一,因而水資源成為該區(qū)生態(tài)恢復的關鍵因子。由于溝壑密度較大,切溝溝壁的側面蒸發(fā)和土壤表面蒸發(fā)使得土壤水分蒸發(fā)強烈,該區(qū)的土壤水分條件進一步惡化。本文在野外調(diào)查和定位監(jiān)測的基礎上,研究了受到雙面蒸發(fā)影響強烈的溝岸地土壤水分時空分布規(guī)律,得到如下結論：(1)溝岸地四個試驗小區(qū)中的土壤水分含量整體較差,其大小順序為檸條林地除去檸條后的裸地草地除去長芒草的裸地。雙側面蒸發(fā)條件下且東側水分虧損比西側更嚴重。溝壁的側面蒸發(fā)作用致使溝岸地土壤水分整體較低,大部分接近萎蔫含水量,側面蒸發(fā)作用對距溝壁距離為20 cm處土壤水分的影響最為顯著,致使其含水量達到萎蔫含水量以下,其作用強度隨距離增加而減弱。在雙側面蒸發(fā)條件下,水分橫向分布與單側面蒸發(fā)條件下土壤水分分布規(guī)律一致,東側水分比西側虧缺更嚴重。溝岸地各土層土壤儲水量與距溝壁距離呈二次函數(shù)關系,二次多項式可以用于描述溝岸地土壤儲水量的分布特征。由于溝岸地土壤水分情況較差,土壤含水量整體較低,各土層土壤含水量的均為弱變異,并且與其方差的線性相關性不顯著。(2)溝岸地土壤在各深度的儲水量變化趨勢與降雨的變化趨勢大體一致,即降雨量的增加的月份土壤儲水量也較高。0-2 m土層土壤儲水量的變化較劇烈,隨著土層深度的增加受到降雨的影響減小,土壤儲水量隨時間的變化隨之減小。橫向來看,在受到降雨影響較大的0-2 m土層中,變化最強烈的的為除去長芒草的裸地,在該土層中各小區(qū)變異系數(shù)的大小順序為：檸條林地除去檸條后的裸地草地除去長芒草的裸地,在3-4 m土層,各小區(qū)的變異系數(shù)大小順序也滿足這個關系。從圖中也可以看出土壤溝岸地土壤在3m以下土層的變化較表層小,但也表現(xiàn)出隨降雨量的變化而變化的趨勢。各小區(qū)土壤水分的變異系數(shù)最小的土層為0-1 m,變異系數(shù)均小于20%,屬于弱變異。而變異系數(shù)最大的土層為3-4 m,從時間上來看,雨季的土壤水分分布的變異系數(shù)較大,而旱季的較小。(3)距離溝壁2m范圍內(nèi),土壤水分干濕交替強烈,土壤粘粒含量與土壤水分時間穩(wěn)定性的相關性不顯著。對于溝岸地土壤水分的時間穩(wěn)定性,本文運用相對差分法發(fā)現(xiàn)則MRD的大小順序為草地檸條裸地,分別為12.43%18.84%10.79%,同樣的,SDRD的極差大小則為檸條草地裸地,分別為8.82%8.58%7.96%。KL和GL中0-1m和3-4 m土層中的極干點出現(xiàn)在距離溝壁較遠的測點,而4m以上土層的極濕點則出現(xiàn)在距離溝壁較近處,但極干點不一定總是出現(xiàn)在距離溝壁較近的位置,這說明距離溝壁較近處不一定是測定范圍內(nèi)土壤水分最低的點,而是干濕交替最強烈的的點。SDRD和MRD與土壤粘粒含量的相關性不顯著。(4)距溝壁距離的增加,20-80 cm土層土壤有機質(zhì)呈降低趨勢,而在表層則呈先減小后增加趨勢。在雙側面蒸發(fā)條件下水分狀況較好的溝岸地西側有機質(zhì)含量大于水分含量相對較差的東側。雙側面蒸發(fā)條件下土壤速效鉀的含量分布無顯著差異,在單側面蒸發(fā)條件下,距溝壁2m處0-20 cm土層土壤速效鉀含量較高,其他土層無顯著差異。(5)通過蒸發(fā)槽對三種邊界條件下蒸發(fā)過程的模擬試驗可以發(fā)現(xiàn),側面蒸發(fā)的蒸發(fā)量低于表面蒸發(fā),雙面蒸發(fā)的蒸發(fā)量高于表面蒸發(fā)。如果考慮降雨因素,雙面蒸發(fā)對土壤水分的影響變得尤為顯著。側面蒸發(fā)的蒸發(fā)速率略小于表面蒸發(fā),而雙面蒸發(fā)的蒸發(fā)速率則明顯大于表面蒸發(fā)。雙面蒸發(fā)和側面蒸發(fā)的蒸發(fā)量與表面蒸發(fā)的蒸發(fā)量的比值有先增加后降低,而后又出現(xiàn)增加的趨勢。表面蒸發(fā)和側面蒸發(fā)的蒸發(fā)量與雙面蒸發(fā)存在顯著的線性關系,可表示為：EA3=0.556EA1+0.489Ea2,.,在本實驗中,溫度對三種界面下的蒸發(fā)的蒸發(fā)量有顯著相關性,降雨量和空氣濕度對土壤儲水量的變化量相關性顯著；土壤儲水量的值與溫度和平均濕度相關性顯著。
[Abstract]:The Loess Plateau is the most serious area of soil erosion in China, is also one of the regions most lack of water resources, and water resources become the key factor of ecological restoration in the area. Because of gully density, gully wall surface evaporation and soil evaporation makes the soil water evaporation, soil water conditions in the region further deterioration. Based on field investigation and monitoring on the studied by double evaporation strong gully land soil moisture distribution, we get the following conclusions: (1) the overall poor soil moisture content in the four experimental plots in the gully land, the size of the order for the removal of Caragana forest after bare grassland removal of Caragana long grass vegetation. Double side evaporation conditions and the water loss is more serious than west side. Evaporation trench wall soil water ditch bank is low, most close to Wilting moisture, evaporation from the side of the trench wall distance effect at 20 cm soil moisture is the most significant, the water content reached below the wilting point, its intensity decreases with increasing distance. In double side evaporation conditions, consistent distribution of soil moisture distribution and one side water evaporation conditions on the eastern side, water is more serious than the deficit. Gully land soil water storage with the distance from the trench wall distance is quadratic function relationship, two polynomial can be used to describe the distribution characteristics of gully land soil water storage. Due to poor gully land soil moisture, soil moisture content is low, the soil moisture of soil the water was weak and variation, linear correlation and variance is not significant. (2) the ditch bank soil roughly the same trend in the change trend of the water storage depth and rainfall, the rainfall increased month The change of soil water storage was also higher in.0-2 m soil water storage of soil is high, with the increase of soil depth under the influence of rainfall decreases, changes of soil water storage decreased with time. The lateral view, under the influence of rainfall of 0-2 m soil layer, the most change for the removal of grass of the bare land. In the soil in the area of coefficient of variation of the order of Caragana forest and grass vegetation removal remove bare grassland after Caragana, in order of size 3-4 m soil layer, the coefficient of variation of each district also meet this relationship. It also can change soil gully land in the soil layer below 3M the surface, but also exhibit changes with changes in rainfall and trend. The soil moisture variation coefficient of minimum soil was 0-1 m, the coefficient of variation was less than 20%, the variation is weak. The soil maximum coefficient of variation was 3 -4 m, from the time point of view, the rainy season variation coefficient of soil water distribution is larger, while the dry season is small. (3) from the trench wall in the range of 2m, soil moisture wetting strong, no significant correlation between soil clay content and soil moisture time stability. For the time stability of soil moisture to ditch the shore, the relative difference is found in the order of MRD grassland of Caragana bare land, respectively 12.43%18.84%10.79%, SDRD of the same size range, Caragana grass bare land, respectively 0-1m 8.82%8.58%7.96%.KL and GL in very dry and 3-4 m soil layer appeared in the distance measuring point of trench wall far above 4m, and the soil the wet point appears in the distance from the trench wall near, but do not always appear in the distance from the trench wall near the position, the distance is not necessarily the trench wall near the measuring range of soil moisture in the lowest point, but dry Wet alternate the strongest point between.SDRD and MRD and soil clay content was not significant. (4) increased from the trench wall distance, 20-80 cm soil organic matter decreased, and the surface was first decreased and then increased trend. In the double side evaporation conditions better water status in the West Bank the content of organic matter is greater than the moisture content is relatively poor on the east side. The double side soil available potassium evaporation under the condition of no significant difference in the distribution, single side evaporation conditions, away from the trench wall 2m 0-20 cm soil available potassium content is high, the other soil had no significant difference. (5) through the simulation test of three evaporation process the boundary conditions of the evaporation tank can be found, the evaporation side evaporation below the surface evaporation, evaporation double evaporation than the surface evaporation. If considering rainfall factors, effects of double evaporation on soil moisture became more and more obvious side. The evaporation rate of evaporation is slightly less than the surface evaporation, and evaporation rate of evaporation is significantly greater than the double surface evaporation. The ratio of evaporation and surface evaporation evaporation and evaporation of the double side evaporation is first increased and then decreased, and then increased. There is a significant linear relationship between evaporation and double surface evaporation and evaporation the side surface evaporation, can be expressed as: EA3=0.556EA1+0.489Ea2. In this experiment, there was a significant correlation between the three kinds of interface of the evaporation temperature of evaporation, precipitation and air humidity on the soil water content significantly; significant correlation between soil water and temperature and humidity value.

【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：S152.7

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