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三峡库区紫色土侵蚀特征及作物覆盖与管理因子的季节性变化研究
Alternative TitleResearch on the seasonal variation of crop cover and management factor and the purple soil erosion characteristics in the Three Gorges Reservoir Area
Language中文
王丰
Thesis Advisor徐佩
2014
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name硕士
Degree Discipline土壤学
Keyword三峡库区 土壤侵蚀 产流产沙
Abstract三峡库区的紫色土是我国土壤重要的组成部分,紫色土不仅维系着库区粮食生产质量,而且在一定程度上是解决三峡库区生态和环境等问题的基础。植被覆盖与管理因子C值是USLE方程中的一个重要参数,作物在整个生长周期中C因子并不是一成不变的,本文通过人工模拟降雨试验的方法,分析了三峡库区试验产流产沙及土壤侵蚀的特征,计算不同作物生长期的土壤流失比率值的大小,丰富了紫色土区域土壤侵蚀预报的相关研究,为库区农作物生产及科学管理种植提供了一定参考,具体结论如下: ⑴随着降雨强度的增加,试验初始产流时间呈现逐渐缩短的趋势,试验平均产流速率则呈现逐渐增加的趋势。试验降雨强度增大到80-110mm/h,作物覆盖对土壤的保护作用显著降低,在这种极端雨强下,作物的水土保持功能是非常脆弱的,极易造成作物对坡地土壤保护作用的全面丧失。 ⑵随着作物的生长,试验初始产流时间和入渗量的大小均不相同。同样降雨强度下,试验小区的农作物对降雨的阻隔作用越显著,雨滴降落至地表能量越低,径流入渗量越大,初始产流时间自然会延长,入渗量和产流时间总是呈现此消彼长的关系。 ⑶不同的作物生长期所对应的试验产流产沙速率,试验径流模数、侵蚀模数,土壤流失比率(C值)均呈现如下规律,春玉米:播种期>出苗期>拔节期>衰亡期>开花期>成熟期;红薯:移栽期>秧苗期>分枝结薯期>薯块盛长期>收获期;冬小麦:播种期>收获期>成熟期;油菜:移栽期>收获期>成熟期。 ⑷随着降雨历时的延长,作物种植小区的试验产流速率、产沙速率均呈现先增大后逐渐趋于稳定的趋势,两者呈对数函数的关系y=alnt-b,并且作物不同,生长期不同对数项系数也不同。作物对坡耕地土壤的保护作用是随着它生长期的变化而变化的,作物根系的存在可以大大提高紫色土壤的抗侵蚀性能。 ⑸通过对几种典型区域农作物进行的试验研究,计算了作物不同生长期内的植被覆盖与管理因子C值,即春玉米:0.748,0.272,0.051,0.045和0.177,生长季平均值为0.258;红薯:0.863,0346,0.120和0.218,生长季平均值为0.387;冬小麦:0.391和0.664,平均值为0.528;油菜:0.347和0.542,平均值为0.444。 ⑹研究中产流产沙速率、侵蚀土壤量以及土壤流失比率(C值)均与植被覆盖度大小(X)呈现负相关的关系,即春玉米:C=-0.065-0.295InX,X∈[0.06,0.69],拟合结果发现春玉米最优状况下Cmin=0.003,减水减沙效果显著;红薯:C=0.03-0.287InX,X∈[0.05,0.74],拟合结果中Cmin=0.121。 ⑺作物秸秆覆盖在减少坡耕地水土流失、改善土壤质量方面具有重要作用。作物秸秆在试验小区中覆盖位置的差异会对土壤流失造成很大影响,研究中坡底覆盖比同等情况的坡顶覆盖SLR值平均小25.4%;秸秆覆盖度越高,秸秆保护土壤的作用越明显,全覆盖(100%)下计算所得的SLR值约占坡底覆盖(50%)的14.2%。
Other AbstractThe purple soil in Three Gorges Reservoir Area plays an important role in our country, which not only maintains food quality, but to some extent it is the foundation solving the problems involve ecology and environment in the Three Gorges Reservoir Area. The vegetation cover and management factor (C value) is an important parameter in USLE equation and C factor is not a fixed value in the whole growth period of crops. By means of artificial rainfall simulation experiment, this paper analyzes runoff and sediment yields and features of soil erosion in the slope farmland, calculates the soil loss ratio(SLR) values in different crop growing seasons, enrichs the soil erosion prediction in purple soil areas, which all help to develop agricultural production and guide scientific management, the specific results are as follows: ⑴With the increase of rainfall intensity, the initial runoff-yielding time shows a trendency of gradually reducing, the average rate of runoff producing shows a trendency of increasing. When the rainfall intensity increases to 80-110mm/h, the protective capacity of crops significantly reduces. Under the extreme rainfall intensity, the soil and water conservation function of crops is very fragile, which even results in completely lost. ⑵With the growth of crops, the initial runoff-yielding time and infiltration capacity are all different. Under the same rainfall intensity, the more the raindrops are intercepted by crops, the lower energy of the raindrops when they arrive to the surface, and the larger infiltration capacity of the runoff plots, which make the initial runoff-yielding time turn to be longer. ⑶The runoff and sediment yield, runoff modulus and erosion modulus, soil erosion ratio(C value) of different crop growing seasons all show the following rules, spring maize: bare land>seeding time> elongation stage>decline phase > flowering period > mature period; sweet potato: transplanting stage(bare land) > seedling stage > branching stage> mature stage > earthnut formation stage; winter wheat:bare land > harvest time > mature period; rape: bare land > harvest time > mature period. ⑷With the extension of rainfall time, the rate of the runoff and sediment yield in crop planting plots show a trendency of increase at first and gradually turn to be stable, the logarithmic function is y = alnt - b, and the coefficient(a) changes with crop types and growing periods. As the crop growing seasons change, the protective effect to sloping farmland changes with the crop growing seasons, the root system of crops can greatly improve erosion resistance of the purple soil. ⑸Through the study on several typical crops, we calculate the vegetation cover and management factor C in different crop growing seasons, spring maize: 0.748, 0.272, 0.051, 0.045 and 0.177(average:0.258); sweet potato: 0.863, 0346,0.120 and 0.218(average 0.387); winter wheat: 0.391 and 0.664(average:0.528); rape: 0.347 and 0.542(average:0.444). ⑹The rate of the runoff and sediment yield , the amount of soil erosion and the soil loss ratio (C value) in the experiments all have the negative correlations with vegetation coverage (X), spring maize: C= -0.065-0.295InX, X∈[0.06, 0.69], Cmin = 0.003 in the optimal conditions through equation fitting, and the soil and water conservation effect is obvious; sweet potato: C = 0.03-0.287InX, X ∈ [0.05, 0.74], Cmin = 0.121 by equation fitting. ⑺Crop straw mulching plays an important role in reducing water and soil loss and improving soil quality of sloping farmland. The position of straw mulching in experimental plots can lead to great difference to soil erosion, compare the soil loss ratios(SLR) in two kinds of opposite cases, the plots which is covered at the bottom and at the top, while the former is much smaller(25.4%) than the latter. The higher vegetation coverage of straw, the more obvious the soil is protected by straw, compare the SLRs that one is full coverage (100%) an
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/8017
Collection山区发展研究中心
Recommended Citation
GB/T 7714
王丰. 三峡库区紫色土侵蚀特征及作物覆盖与管理因子的季节性变化研究[D]. 北京. 中国科学院研究生院,2014.
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