ISWC OpenIR  > 水保所知识产出(1956---)
长武塬区不同土地利用类型土壤大孔隙流研究
赵娇娜
Subtype硕士
Thesis Advisor徐学选
2012-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword土地利用类型 染色示踪 图像处理 大孔隙流 染色百分比 水分入渗 长武塬区
Abstract

以长武塬区王东沟小流域不同土地利用类型下的土壤为对象,采用染色示踪与图
像处理技术对农地、林地和草地土壤进行了灌水入渗染色示踪试验,同时测定了三种
土壤剖面的根系分布、容重和含水率变化,利用图像处理技术得出了剖面染色百分比,
对比分析了不同土地利用类型染色百分比的分布特征及其与土壤物理性质和根系指
标的关系;同时结合降雨入渗下大型土柱不同深度土壤含水率动态变化和降雨在不同
深度渗出量的观测,分析了降雨在大孔隙土壤中的入渗特征、以及降水补给土壤水的
滞后特征,取得如下研究结果:
(1)在0-30cm 土层深度内,林地和草地的容重要高于农地,在40cm 以下深度
农地容重普遍高于林地和草地;农地、林地和草地根系生物量范围分别为:
0.84-38.50g/m2、2.51-150.70g/m2 和0.88-217.61g/m2,在0-20cm 土层内根系生物量、
根长密度和根表面积指数分布表现为:草地>林地>农地,但在20cm 以下土层内这
三个指标的分布均为:林地>草地>农地,反映了同为黄绵土的三类土壤剖面孔隙度
存在着林地﹥草地﹥农地的分布特征;农地、林地和草地根系平均直径均>0.5mm,
具备为水分入渗提供大孔隙通道的潜力。
(2)农地、林地和草地土壤中均存在大孔隙流现象。在有限补给情况下,农地、
林地和草地土壤剖面中染色剂的分布深度不同,分别可达到80cm、100cm 和95cm,
农地和林地平均染色深度主要在60cm 以上,草地在40cm 以上;土壤根系生物量、
根长密度和根表面积指数是影响染色剂分布的主要因子;根系平均直径和比根长对染
色剂分布的影响不显著,与根系连通性有关。相当于100mm 灌水量对农地、林地和
草地土壤水的补给深度不同,分别为200cm、100cm 和140cm。研究区土壤中普遍存
在水分再分布现象,农地、林地和草地水分再分布的范围分别为0-140cm、0-60cm 和
0-120cm。(3)大孔隙土壤中降雨对土壤含水率的影响主要集中在160cm深度以上,随着
入渗路径的增大,降雨的峰值信息被不断削弱;降雨量和雨强越大,土壤含水率对降
雨的响应越显著。降雨入渗湿润锋运移速率随雨强的增大而增大,随表层土壤初始含
水率的升高而下降;湿润锋运移深度同降雨量和雨强呈正相关关系,降雨量和雨强越
大,越有利于湿润锋向下运移。降雨对300cm深度土壤水的补给行为是普遍是存在的,
土层厚度愈大,降雨的入渗路径愈长,降雨入渗补给滞后时间越长。降雨入渗对
100-200 cm土壤水的补给滞后时间约为15-18d左右,对300cm深度土壤水的补给滞后
时间约为30-45d左右。
关键词:土地利用类型;染色示踪;图像处理;大孔隙流;染色百分比;水分入渗;
长武塬区

Other Abstract

Macropore flow is common in soil and plays an important role in soil water infiltration
process. Study on soil macropore flow under different land use types were conducted on
Wangdong small watershed of Changwu Tableland. Farmland, forestland and grassland
were selected as the sample plots. The dye infiltration experiments and image processing
technology were used in this study. Soil water content, soil bulk density, root biomass, root
length density, root area index, average root diameter and specific root length were also
measured in this study. Characteristic of percentage of stained area with soil depth was
compared between different land use types. The relationship between percentage of stained
area and soil water content, soil bulk density and parameters of root distribution was
analyzed. In order to understand the mechanism of water infiltration well, experiment on
characteristic of rainfall infiltration in macroporous soil was also carried out in soil
columns on Changwu tableland. Results show as follows:
(1) Soil bulk density of different land use types was small at surface soil. Soil bulk
density of farmland was lower than forestland and grassland at 0 to 30cm soil layer. But it
was higher than forestland and grassland under 40cm soil layer. Root biomass of farmland,
forestland and grassland distributed at 0.84-38.50g/m2, 2.51-150.70g/m2 and
0.88-217.61g/m2 respectively. Root biomass, root length density and root area index of
grassland soil at 0-20cm soil layer were the highest, the next was forestland, and then was
farmland. But Root biomass, root length density and root area index of forestland was the
highest below 20cm soil layer, the next was grassland, and then was farmland. The average
root diameters of different land use types measured at the sample plots were all more than
0.5mm, which can be the macropore flow channel.
(2) Macropore flow occurred in all the soils under the three land use types. The
formation of soil macropore flow was relevant with soil heterogeneity and soil porosity.
The infiltration depths of macropore flow under different land use types were significant  different. Infiltration depth of forestland was the highest, which can reach to 100cm. The
next was grassland which was about 95cm. Infiltration depth of farmland were less than
the others, which can reach to 80cm. The stained area in soil profile of farmland and
forestland was mainly distributed at 0 to 60cm soil layer. And the stained area of grassland
was mainly distributed at 0 to 40cm soil layer. Soil root biomass, root length density and
root area index were the main factors which effected the distribution of soil macropore
flow. Soil water content and soil bulk density could influence the formation of macropore
flow, but the mechanism was complicated and could not be described as the linear
relationship. Root diameter and root connectivity could joint influence the transport of soil
macropore flow. Depths of interaction of 100mm irrigation quotas to the soil water under
different land use types were different. They were 200cm, 100cm and 140cm for farmland,
forestland and grassland separately. Phenomenon of water redistribution existed in soils of
all the three land use types. Range of soil water redistribution in farmland, forestland and
grassland were 0-140cm, 0-60cm and 0-120cm respectively.
(3) Impact of rainfall on soil water content was mainly concentrated above the depth of
160cm. The extent of impact decreased with depth. Down to the depth of 240cm, the
rainfall peak information carried by soil water content almost disappeared. The wetting
front velocity was correlated positively with rain intensity, and negatively with initial soil
water content. The depth of wetting front transportation was positively correlated with the
rainfall and rainfall intensity. Soil water at the depth of 300cm could be supplied by rainfall.
Piston flow was the mainly mechanism of groundwater recharge in loess. The lag time of
rainfall infiltration recharge to the soil water of 100-200cm soil layer was about 15-18d,
and the lag time to the soil water of 300cm soil layer was about 30-45d.
Key Words:Land use type; dye tracer; image processing; macropore flow; percentage
of the stained area;water infiltration;Changwu tableland

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8929
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
赵娇娜. 长武塬区不同土地利用类型土壤大孔隙流研究[D]. 北京. 中国科学院研究生院,2012.
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