ISWC OpenIR  > 水保所知识产出(1956---)
黄土高原坡面径流养分流失模拟研究
董文财
Subtype博士
Thesis Advisor王全九
2012-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword黄土坡面 土壤侵蚀 溶质迁移 养分流失 模拟模
Abstract

黄土高原是我国乃至世界上土壤侵蚀最严重的地区,在水蚀严重的黄土高原开展
黄土坡地土壤养分迁移机理及模拟模型研究,有利于揭示坡面物质迁移的内在机理,
为调控坡面物质迁移过程提供理论基础。本论文采取理论分析与试验研究相结合的方
法开展深入研究,取得主要结论如下:
(1) 初始土壤含水量通过影响水分入渗来影响养分流失,初始土壤含水量降低,
养分流失将会减少。随着降雨强度的增加,径流含沙量增大,产流时间缩短。进而增
加了产流时刻土壤表层养分含量,增加了径流养分流失量。坡度对径流泥沙和养分流
失有重大影响,在0º到25º之间随坡度增加而增加。研究结果表明PAM 对径流的影
响不显著,但PAM 增加了土壤抗雨滴击溅和径流冲刷的能力,显著减少径流泥沙含
量,进而减少了径流中溶质的流失。对于杨凌塿土而言,PAM 适宜用量为3g/m2。产
流时刻径流溶质浓度和径流平均溶质浓度与产流时刻土壤表层溶质含量呈正的线性
相关关系。
(2) 植被是通过改变径流的水动力学特性,进而影响径流侵蚀能力的。相同盖度
下植被类型不同,其水土保持效果存在差异,对坡面养分流失影响也不同。对试验区
而言,长芒草的水土保持效果优于紫花苜蓿。植被覆盖增加了地面的粗糙度,使汇流
速度减慢,增加了入渗时间,植被覆盖通过影响水流动力特征和土壤粘聚力来影响径
流泥沙含量,平均单宽输沙率与植被盖度之间呈负的线性函数关系。植被通过减少土
壤侵蚀量和径流量,从而减少土壤养分向地表径流的传递而造成的流失。密函数能够
很好的反映平均径流养分流失浓度与植被覆盖度之间的关系。试验区紫花苜蓿覆盖度
在30%-60%之间每增加15%,平均单宽径流输沙率减少36.7%,平均径流溶质含量
减少33.2%。碎石覆盖只是增加了坡面糟率,减小径流流速,增加入渗时间,从而增
加入渗,减小径流量,进而减小径流泥沙含量,减少可溶性溶质随径流流失量。平均
单宽输沙率与碎石盖度之间呈密函数关系。平均径流溶质浓度与碎石覆盖度之间关系
可以用线性函数来表示。试验区碎石覆盖度在10%和30%之间每增加10%,平均单
宽径流输沙率减少27.2%,平均径流溶质含量减少14.3%。(3) 建立了黄土高原超渗产流机制下用径流剪切力来表示的径流平均单宽养分
流失率模型,模型表达式为Drs=a·k·(τ-τ0),式中,Drs 为平均单宽养分流失率,
mg/(min·m);a 为待定参数,对于不同的土壤养分初始含量和不同养分参数a 是变
化的。其他符号意义与单宽输沙率相同。模型简化了坡面养分流失模拟的复杂性,对
于黄土高原水土流失和面源污染的控制有重要意义。
(4) 提出用交换系数er 来代替对流质量传递模型中的传递系数km 的模型改进方
法,使得对流质量传递模型的物理意义更加明确,同时避免了对流质量传递模型传递
系数km 的推求,使其更加实用于黄土高原降雨径流养分流失的模拟。并利用试验进
行了验证,模型模拟结果与试验结果吻合良好。得出当坡面坡度大于等于15º时常参
数ρ等于1,当坡面坡度小于15º时常参数ρ等于2。
(5) 建立了适合黄土高原产流机制的物理意义明确的径流养分流失模拟模型,并
利用壤土和砂壤土室内人工模拟降雨试验对模型进行了验证。模型模拟结果与实验实
测数据吻合良好,模型能够很好的模拟水分和养分在土壤中的运动以及径流量和径流
溶质含量虽时间的变化情况。建立的模型对于土壤侵蚀严重情况下的应用存在一定的
局限性。对于其他土壤类型的适用性需要进一步的验证。
关键词:黄土坡面,土壤侵蚀,溶质迁移,养分流失,模拟模

Other Abstract

The Loess Plateau is the most serious region in soil and water loss in China and even
in the world. By increasingly drier climate and human activities, the region Loess Plateau
where is also one of the important regions requiring ecological restoration for severe
ecological degradation. Soil erosion and solute transport on loess slope is a complicatedly
physicochemical process. It is affected by many factors and mutually intersected with
multi-discipline, such as soil science, ecology, hydrology, hydraulics, environmental
science and so on. The mechanisms and predictions of water and nutrient transport in soils
on a slope during rainfall have played important roles in the research on the degradation of
soil quality and the expansion of non-point source pollutions in recent years, which also
have been an interdisciplinary field focused in soil erosion, hillslope hydrology, dryland
agriculture and related environmental sciences.
Investigating the mechanism and model of soil water and nutrient transport could
predict and prevent effectively soil nutrient loss at intensively-eroded area on the loess
section. And it’s good for understand and master the nature and mechanism of erosion and
internal law of solute transport during the process of erosion on loess slope. This is very
important in ecological environment management of the Loess plateau. The main works
and detailed results of this study are as following:
(1) The initial soil moisture content influences solute loss by virtue of its impact on
infiltration, which suggests that if infiltration could be facilitated, the loss of solutes could
be reduced. Rainfall intensity increases the mass of sediment carried away by the runoff
and decreases the time required for runoff formation; the latter in turn increases the solute
concentration in the surface layer. The slope gradient also has a significant influence on the
masses of solute and sediment in the runoff; both increase as the slope gets steeper between
0 to 25 gradient. Treatment with PAM effectively increased the soil’s resistance to
raindrops and water flow-induced detachment. For the soil examined in this work, the
optimal PAM loading was 3g/m2. Solute concentration in the runoff at the first minute  when runoff take place and the average solute concentration in the runoff were positive
linear correlation with solute concentration in the soil surface when runoff take place.
(2) Plant cover effect the runoff erosion ability by controlling the hydraulic
characteristics of flow. It’s different both the soil and water conservation effects and the
influence of the nutrient loss from slope from different vegetation types under the same
vegetation coverage. For the experimental area, the Stipa bungeana was better than alfalfa
for soil and water conservation. The vegetation coverage increased the soil surface
roughness, slower down the flow velocity and increase the time of water infiltration. The
vegetation coverage influenced the soil sediment in the runoff by controlling the hydraulic
characteristics of flow and the soil cohesion. The relationship between the average
sediments in the unite width of runoff and vegetation coverage could be expressed by
negative linear equations. The relationship between the average solute concentration in the
unite width of runoff and the vegetation coverage could be described by density function.
The average sediments in the unite width of runoff decreased 36.7 percentage and the
average solute concentration in the unite width of runoff decreased with 33.2 percentage
with the coverage of alfalfa increased 15 percentage between 30 and 60 percentage. The
stone cover decreased the runoff volume, soil sediment in the runoff, the solute loss with
runoff by increasing the surface roughness of soil surface, decreasing the flow velocity of
overland flow, increasing the time of water infiltration and the volume of infiltration. The
relationship between the average sediments in the unite width of runoff and the stone
coverage could be expressed by density function. The relationship between the average
solute concentration in the runoff and stone coverage could be expressed by linear equation.
For the experimental area, the average sediments in the unite width of runoff decreased
27.2 percentage and the average solute concentration in the unite width of runoff decreased
with 14.3 percentage with the coverage of stone increased 10 percentage between 10 and
30 percentage.
(3) We developed the average solute concentration in the unite width of runoff model
which expressed by the runoff shear stress under the infiltration excess condition on the
Loess plateau. The model expressed as Drs=a·k·(τ-τ0), where Drs was average solute
concentration in the unite width of runoff; a was empirical parameter and which changed
with solute types and the solute concentrated in the soil. The other parameter the same with  the average sediments in the unite width of runoff. The model made the modeling solute
transport with runoff easier. The developed model to control the soil and water loss,
non-point pollution has a very important role.
(4) The method we used to refine power functions solute transport model developed
by Wang Quanjiu et al was change the exchange rate km with the raindrop-induced water
transfer rate er, which make the model physically-based and without the km calculation.
The refined model was more suitable for modeling the solute loess with runoff on the
Loess plateu. Test the model with experimental date. The model fitted the experimental
data very well. Our results also showed that when the slope gradient was 15° or larger than
15°, the constant parameter, ρ was equal to 2, ρ was equal to 1while when the slope
gradient was less than 15°.
(5) We have developed a physically-based solute transport model for estimating the
solute concentration in runoff originating from the soil surface under the infiltration excess
condition on the Loess plateau. To test the model, we carried out laboratory experiments
that used two soil types (loam and sandy loam) and exposed them to simulated rainfall.
The results simulated by the model were highly correlated with the experimental data. The
simulated data showed a high level of correlation with the measured data for soil water,
solute transport in the soil profile and runoff volume, solute concentration in the runoff.
This demonstrates that the model captured the temporal behavior of the runoff and solute
transport in the runoff. The model could not predict the solute concentrations in the runoff
under severe soil erosion conditions accurately.
KEY WORDS:Loss slope, soil erosion, solute transport, nutrient loss, model

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8933
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
董文财. 黄土高原坡面径流养分流失模拟研究[D]. 北京. 中国科学院研究生院,2012.
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