發(fā)布時(shí)間：2018-02-10 17:13

  本文關(guān)鍵詞： 黃土高原 坡地 土地利用 環(huán)境示蹤劑 深層滲漏量　出處：《西北農(nóng)林科技大學(xué)》2016年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：黃土高原地處我國(guó)西北內(nèi)陸地區(qū),氣候干旱,降水稀少,土壤水分成為該地區(qū)植物生長(zhǎng)的主要限制因子。1999年退耕還林還草生態(tài)工程的實(shí)施,有效的改善了局部生態(tài)環(huán)境,減少了水土流失,但同時(shí)也引發(fā)了土壤干燥化和地下水位下降等一系列生態(tài)水文問(wèn)題,并直接威脅生態(tài)建設(shè)的可持續(xù)性和穩(wěn)定性。盡管黃土塬區(qū)不同土地利用類(lèi)型下,深剖面土壤水分的研究已經(jīng)取得了很多進(jìn)展,但對(duì)黃土坡面土壤深剖面土壤水分及其對(duì)地下水補(bǔ)給的研究還很少,阻礙了全面回答該區(qū)退耕還林還草生態(tài)工程和地下水資源利用是否可持續(xù)這一重大科學(xué)問(wèn)題。本文利用環(huán)境示蹤劑研究黃土高原分布面積較廣的坡地不同坡位的深層滲漏,以陜西長(zhǎng)武王東溝為例,研究其不同坡位不同土地利用類(lèi)型下土壤水分及水同位素特征,研究黃土坡地不同土地利用類(lèi)型下的耗水情況,估測(cè)不同坡位深層滲漏量及其變化,進(jìn)而探討黃土坡地深層土壤水的補(bǔ)給方式。取得的主要研究結(jié)果如下:(1)黃土塬面和坡面不同土地利用類(lèi)型的耗水特點(diǎn)。通過(guò)對(duì)塬面和坡面不同土地利用深剖面土壤水分對(duì)比分析可知,由于受不同生長(zhǎng)年限、林地管理水平、根系空間分布狀況的影響,相比于淺根植物(荒草、玉米),深根植物均有不同程度的水分虧缺,其中塬面盛果期17年蘋(píng)果,虧缺深度達(dá)15 m;其次上坡位23年蘋(píng)果,由于管理水平低下以及蘋(píng)果齡期較大,產(chǎn)量較低,其虧缺量有限,根系耗水深度可達(dá)22.6 m;最后,中下坡位杏樹(shù),耗水深度達(dá)6-7 m。(2)黃土坡地林-草土壤水分平均入滲速率和深層滲漏量。草地黃土坡地上、中、下三個(gè)剖面有比較清晰完整的鈴形氚峰,說(shuō)明非飽和區(qū)土壤水主要以活塞流的形式運(yùn)移,且存在不同程度的彌散作用。通過(guò)氚峰值示蹤法估算得到草地三個(gè)坡位的深層滲漏量分別為20 mm y-1、22 mm y-1、27 mm y-1,約占多年平均降水量的3%-5%。中、下坡位的深層滲漏量較上坡位分別大10%和35%,這主要由于該地區(qū)6-9月的集中降雨產(chǎn)生的地面徑流導(dǎo)致,中、下坡位上方集水面積較大,能夠接受較多徑流,從而產(chǎn)生較大的深層滲漏量。改進(jìn)的氯質(zhì)量平衡法估算黃土坡面草地深層滲漏量:上坡位為19-23 mm y-1,中坡位為23-29 mm y-1,下坡位為37-45 mm y-1,其深層滲漏量約占多年平均降水的3.3%-7.7%�？傮w來(lái)說(shuō),氯質(zhì)量平衡法較氚峰值示蹤法的估測(cè)量偏大,尤其下坡位兩者的差異較大,這主要是由于下坡位地勢(shì)最低,上方來(lái)水最多,容易產(chǎn)生更多入滲量;其次與降水中氯離子空間變異及土壤孔隙水中氯離子的陰離子排斥效應(yīng)有關(guān)。林地不同坡位也存在清晰的峰值,3H剖面波動(dòng)較大,平均入滲速率為6.0 cm y-1、7.8 cm y-1、10.0 cm y-1;該峰值深度與入滲速率均比草地相同坡位的峰值深度與入滲速率分別偏淺、偏慢,這主要由深根植物的根系不斷向下生長(zhǎng)及耗水,阻滯了土壤水分向下運(yùn)移造成的。(3)應(yīng)用環(huán)境示蹤劑研究深層土壤水補(bǔ)給規(guī)律。通過(guò)分析黃土坡面草地氫氧同位素剖面的變化特征發(fā)現(xiàn),受土壤蒸發(fā)、降水入滲補(bǔ)給的影響,淺層土壤水同位素出現(xiàn)貧化峰值,深層土壤水同位素基本不發(fā)生變化,并結(jié)合相應(yīng)坡位的3H剖面分布,可知草地的深層土壤水主要以活塞流的形式進(jìn)行入滲補(bǔ)給。通過(guò)對(duì)比分析林-草土壤水的氫氧同位素剖面變化特征,可知林地深層土壤水在不同土層出現(xiàn)不同程度的貧化現(xiàn)象,其中上坡位氯離子受到“稀釋”,且氚的波動(dòng)較大,認(rèn)為林地深層根系不斷生長(zhǎng)、衰敗的生理現(xiàn)象,導(dǎo)致土壤根系區(qū)密集孔隙的出現(xiàn),使得降水可以快速均勻流的方式入滲補(bǔ)給到深層土壤。
[Abstract]:The Loess Plateau is located in the northwest inland region, China's dry climate, scarce rainfall, soil moisture has become the main limiting factor of.1999 in the area of plant growth in returning farmland to forest and grass ecological engineering implementation, effectively improve the local ecological environment, reduce soil erosion, but also caused the soil desiccation and underground water level after a series of eco hydrological problems, and a direct threat to the sustainability and stability of ecological construction in Loess Plateau. Despite the different land use types, research on deep soil moisture has been made a lot of progress, but on the loess slope soil deep soil moisture and Study on groundwater recharge is very few, hindered the full answer to this area of returning farmland to forest ecological engineering and sustainable use of groundwater resources is an important scientific problem. In this paper, using environmental tracers to study the distribution area of Loess Plateau Wide slope slope seepage in Shaanxi Changwu Wang Donggou as an example to study the different slope under different land use types of water and water isotope characteristics of soil, water consumption under different land use types on loess slope, estimation of different slope deep percolation and its changes, and to explore the deep soil of loess slope the water supply mode. The main results are as follows: (1) the water consumption characteristics of different land use types in Loess Plateau and the slope. The slope Tableland and different land use of deep soil moisture analysis can know, due to different growth years, the management level of forest land, influence spatial distribution of root system. Compared to shallow rooted plants (grass, corn), deep root plants have different degree of water deficit, the tableland full fruit period 17 years Apple deficit depth of 15 m; the second top 23 years due to apple. The management level is low and the apple age bigger, lower yield, the deficit is limited, water consumption depth of up to 22.6 m; finally, the lower slope position apricot, water consumption depth of 6-7 M. (2) loess slope forest grass average soil moisture infiltration rate and deep percolation. Grassland on the loess slope. In the three section has clear bell shaped tritium peak, non saturated soil water is the main form of transport to the piston flow, and there are different degrees of dispersion. The tritium peak tracer estimated by deep percolation three grassland slopes were 20 mm y-1,22 mm y-1,27 mm Y-1. About the average annual precipitation of 3%-5%. in deep percolation is a downhill uphill respectively 10% and 35%, this is mainly due to the surface runoff in the region concentrated rainfall caused by the 6-9 month, in the downhill, above the catchment area is larger, can receive a multipath flow from Due to a large amount of deep percolation. Estimation of grassland on Loess Slope deep percolation chloride mass balance method improved: upper slope is 19-23 mm Y-1, middle slope is 23-29 mm Y-1, the downhill is 37-45 mm Y-1, the deep leakage accounted for annual precipitation 3.3%-7.7%. overall, quantitative estimation of the chloride mass balance method a tritium peak tracer method is too large, especially a large difference between the downhill, this is mainly due to the downhill is the lowest, the most easy to produce more upslope runoff and infiltration; secondly and chloride ions in precipitation and soil spatial variability in pore water of chloride anion exclusion effect. There are also clear forest in different slope positions the peak of 3H profile fluctuations, average infiltration rate of 6 cm y-1,7.8 cm y-1,10.0 cm Y-1; the peak depth and infiltration rate of grassland with same peak slope and depth of infiltration rate was low, slow, 榪欎富瑕佺敱娣辨牴妞嶇墿鐨勬牴緋諱笉鏂悜涓嬬敓闀垮強(qiáng)鑰楁按,闃繪粸浜?jiǎn)鍦熷￥姘村垎鍚戜笅杩惪U婚，

本文編號(hào)：1501026