Comparison of Soil Moisture in Different Soil Layers between Three Typical Forests in the Upper Reaches of Lijiang River Basin,Southern China     

LI Haifang  LIU Qinghua  LI Shimei  LI Wei  YANG Jinming 《资源与生态学报(英文版)》2019,10(3):307-314

Throughfall, stemflow, evapotranspiration and infiltration are likely to vary with forest types, and consequently affect soil moisture regimes in different soil layers. In this study, the spatial and temporal characteristics of soil moisture were investigated to understand variations in soil moisture in three typical forests, including Phyllostachys pubescens forest (abbreviated as PPF), Schima superba forest (abbreviated as SSF) and Cunninghamia lanceolata forest (abbreviated as CLF) in the upper reaches of Lijiang River basin in southern China. The results showed that, (1) Litterfall and soil physical properties differed significantly in the three typical forests. Infiltration capacity in SSF was more favorable to soil moisture than in PPF and CLF. (2) Large variations were found in soil moisture at different forest stands and depths. Due to complicated vertical structures, there were obvious differences in soil moisture from the 0-20 cm soil layer to the 50-80 cm soil layer. (3) Average soil moisture in each layer was higher in SSF than in PPF and CLF. (4) Soil moisture in different layers correlated closely with precipitation (P<0.01) and the three typical forests had the same change trends with rainfall during the studying period. (5) In topsoil, soil moisture was influenced by soil properties which were mostly determined by litterfall, while in deep soil, soil moisture was affected by variations of soil characteristics, which were mostly determined by root distribution. This study provides a scientific basis for better understanding the relationships between forest vegetation and its hydrological effects, helping to facilitate water resources conservation and achieving wise forest management in the upper reaches of Lijiang River basin.  相似文献   

土体工程地质层划分及其在城市地下空间开发中的应用     

唐鑫 《地质与勘探》2024,60(1):164-176

城市地下空间包括岩土体本身的密实部分以及天然或人工形成的无岩土体的空间部分,既是重要的自然资源,又是其它地下自然资源的载体。随着城市的不断发展,向地下空间构建立体城市已成为必然选择。城市地下空间开发多在土体中进行,地下工程建设的成本、难度与土体质量息息相关。针对常州市土体工程地质层划分标准不统一的现状,基于城市地质调查项目获取的海量地质钻孔和土体物理力学指标测试结果,综合考虑沉积时代、物质成分、工程特性指标等因素,采用剖面绘制法对常州市100 m以浅土体工程地质层进行划分,建立基本地层结构和层序编码,通过工程地质层物理力学参数离散性和三维模型平滑度验证划分结果合理可行。将土体工程地质层划分结果应用到桩基持力层选择、地下空间竖向分层规划、地下空间开发适宜性评价、多种地下资源协同利用等方面,可为城市地下空间规划、建设、管理提供基础数据和相关借鉴。  相似文献   

Coupling processes at the magnetopause     

D. G. Sibeck 《Surveys in Geophysics》1995,16(3):267-298

This review covers several aspects of magnetopause research during the two-year period from mid-1991 to mid-1993. It focusses upon three topics which received renewed attention: the structure of the steady-state magnetopause, the origin of the transient events which are superimposed upon it, and the cause of transient signatures observed by high-latitude dayside ground magnetometers. Case and statistical studies defined the relatively unknown characteristics of the magnetosheath plasma layers lying outside the magnetopause, while theoretical studies provided alternative explanations for the presence of magnetosheath plasma within the LLBL. Evidence was presented for a steady transition from magnetosheath to magnetospheric plasma parameters. Detailed studies described the plasma, energetic particle, and magnetic field characteristics of transient events in the outer dayside magnetosphere, and multipoint studies provided important new information concerning the ionospheric response to sudden changes in solar wind parameters. This review emphasizes the competing explanations which have been advanced to explain these phenomena.  相似文献   

豫西前寒武纪汝阳群和洛峪群中风暴沉积   总被引：8，自引：0，他引：8       下载免费PDF全文

孟庆任  胡健民 《地质科学》1995,30(3):240-246

豫西前寒式纪汝阳群和洛峪群中广泛发育不同类型的风暴岩,主要包括丘状交错层砂岩、洼状交错层砂岩、浅水浊积岩以及与风暴作用有关的硬底、凝缩层和层间砾岩。不同类型风暴署具有不同的岩相组合及形成过程,并且发育在浅海陆棚的不同沉积带中。由洼伏交错层砂岩为主的相组合代表了滨岸带的下部;丘状交错层砂岩相组合指示风暴浪基面以上的内陆棚;而浅水浊积岩相组合则主要发育在外陆棚沉积区。这种风暴岩的沉积模式可用于详细恢复受风暴影响的古陆棚环境。  相似文献   

淮南市区东部地面沉降机制研究     

桂和荣  陈兆炎  任守义  钱谋始 《安徽地质》1995,(4)

根据１９９０年７月－１９９２年１０月在淮南市东部取得的工程地质勘探成果，结合前人资料，分析研究了该区地面沉降的主要原因─—抽汲地下水及粘性土层的工程地质特性，为区内地面沉降防治研究提供了依据。  相似文献   

Evolution of salinity field in the upper layers of the east central Arabian Sea and northern Bay of Bengal during summer monsoon experiments     

R. R. Rao  K. V. Sanil Kumar 《Journal of Earth System Science》1991,100(1):69-78

The intra-seasonal variability observed in the salinity field of the upper layers at a few locations in the east central Arabian Sea and the northern Bay of Bengal during the summer monsoon seasons of 1977 and 1979 is documented with the aid of short time series (1–2 weeks) of salinity measurements made from USSR and Indian ships deployed during MONSOON-77 (1977) and MONEX-79 (1979) field experiments. In the Arabian Sea a typical subsurface maxima observed beneath the mixed layer base either disappeared or considerably weakened due to strong vertical mixing caused by the monsoonal forcing. In the northern Bay of Bengal the salinity variability in the top 30 m water column was rapid and appeared to be influenced by large amounts of fresh water from rain and probably from the major adjoining rivers. Some simple diagnostic calculations are presented to assess the relative importance of various processes which control the observed salinity variability.  相似文献   

CRITICAL CONDITION FOR THE INITIATION OF SUSPENSION     

CHENG Niansheng  ZHU Lijun Senior engineer  Nanjing Hydraulic Research Institute  China Engineer  Nanjing Hydraulic Research Institute  China 《国际泥沙研究》1993,(3)

L INTRODUCTIONSediment particles move either as bed load or as suspended load, depending on thecharacteristics of flow condition and on the properties of the sediment particlethemselves. Exchange between bed load and bed material takes place directly, while thesuspended load, under general conditions, can hardly interact with the stationary bedwithout the bed load as a medium. It is necessary to take into full account theinteractions of suspended load, bed load and bed material when bed d…  相似文献   

辐射通量密度和加热率的计算结果对垂直分层的敏感性     

魏丽  钟强 《高原气象》1994,13(1):84-93

本文利用一个一维辐射传输模式，分析了模式垂直分层对辐射通量密度和加热率计算结果的影响，以示在辐计算方案的应用中选择合理的垂直分层的必要性，结果表明：长波辐射通量和加热率对垂直分层的改变反映敏感；辐射通量最大偏差出现在对流层中层，以中纬度模式大气为例，其值为１４Ｋ／ｍ＾２（相对偏差６％）；长波冷却率的偏差在低层比较明显，最大可达１．０℃／ｄａｙ；在高原地区，垂直分层对近地层加热率的影响更为明显，偏差  相似文献   

第四纪气候变化的旋回和周期   总被引：7，自引：0，他引：7  

赵景波 《冰川冻土》1988,(2)

在西安附近黄土剖面中发现40层古土壤,分别出现在中、早更新世,可将西安黄土沉积以来的气候变化划为25个旋回。在陕西洛川和河北平原也有相似的气候变化。根据古地磁年代,得出第四纪气候变化的基本周期为10万年左右。全球气候变化基本是统一的,研究结果的不同只是由于研究地区、剖面和气候标志对气候变化的反应不同造成的。  相似文献   

一种提取城市多种不透水层的垂直不透水层指数   总被引：1，自引：0，他引：1  

田玉刚  徐韵  杨晓楠 《测绘学报》2017,46(4):468-477

针对中低分辨率影像中不透水层的异质性及其与裸土光谱的易混性两类问题,选用蓝、近红外波段进行线性组合,构建了一种新的不透水层提取指数——垂直不透水层指数(PII)。该指数考虑了不透水层和其他地物在光谱空间的差异与不透水层的内部异质性,并以"不透水层线"与"土壤线"夹角的角平分线作为PII的参照线,实现了自适应的不透水层提取。本文将PII指数应用于武汉和北京不同场景中,并对比归一化建筑物指数(NDBI)、比值居民地指数(RRI)以及生物物理组份指数(BCI)的提取结果。试验表明:1在裸土较少、地形平坦的武汉市区域和裸土较多、地形起伏的北京市区域,PII指数均能有效减弱裸土的混淆影响,不透水层提取精度分别达到96.05%和96.76%,优于其他3种指数;2PII指数不仅增强了不透水层与其他地物的可区分性,还保持了不透水层类内的相似性,在城市不同场景中的不透水层提取精度均能达到90%以上。由于PII指数是一种线性组合形式的指数,能够根据研究区的地物光谱自适应调整指数的方程系数,从而能适用于不同研究区,在裸地较多的地区优势尤为明显。  相似文献