SOIL SHEAR STRENGTH: AN INDICATOR FOR ERODIBILITY OF THE LOESS SOILS   总被引：1，自引：0，他引：1  

WANG Guiping  WEI Zhongping  ZHANG Zhiguo 《国际泥沙研究》1994,(1)

ＳＯＩＬＳＨＥＡＲＳＴＲＥＮＧＴＨ：ＡＮＩＮＤＩＣＡＴＯＲＦＯＲＥＲＯＤＩＢＩＬＩＴＹＯＦＴＨＥＬＯＥＳＳＳＯＩＬＳＷＡＮＧＧｕｉｐｉｎｇ；ＷＥＩＺｈｏｎｇｐｉｎｇａｎｄＺＨＡＮＧＺｈｉｇｕｏＡｂｓｔｒａｃｔ：ＦｉｅｌｄｅｘｐｅｒｉｍｅｎｔＳｕｎｄｅ...  相似文献   

Soil hydrophobic effects on infiltration and catchment runoff   总被引：1，自引：0，他引：1  

G. J. Burch  I. D. Moore  J. Burns 《水文研究》1989,3(3):211-222

After dry summers or drought, eucalypt forest soils at two sites in southeastern Australia developed hydrophobic or non-wetting surface characteristics that reduced infiltration, measured using a sprinkling infiltrometer. At one site the development of hydrophobic conditions caused the rainfall to runoff conversion efficiency of a forested catchment to increase from 5 per cent to 15 per cent. Under non-hydrophobic conditions at this site, grassland always generated more runoff than forest. However, one major rainfall-runoff was recorded at a time of highly hydrophobic forest soil conditions and this storm generated greater runoff on the forested catchment than the grassland catchment. At the second site forest soils have naturally highly conductive surface layers because of a dense network of macropores and pathways for preferential flow. Hydrophobic conditions produced by drought caused soil water movement to be confined to only a few of the larger macropores exposed to surface ponded water. Even so, infiltration rates remained relatively high so that the impacts of hydrophobic soils were not translated into increased catchment runoff as at the first site.  相似文献   

On the stable growth of segregated ice in freezing soil under negligible overburden pressure     

Yoshisuke Nakano 《Advances in water resources》1986,9(4)

The stable growth condition of a segregated ice layer is studied by the use of the principle of mass and heat conservation. This condition evidently depends upon the properties of a thin transitional zone, which is believed to exist between the boundary of an ice layer and a 0[°C] isotherm. All probable models of the transitional zone are classified and the conditions for each model is derived. The effect of the small amount of soil minerals contained in an ice layer is also studied.  相似文献   

Time effects on dynamic soil properties under random excitation conditions     

F. Amini 《Soil Dynamics and Earthquake Engineering》1995,14(6):439-443

Two types of clayey soils, a kaolinite and a bentonite, were tested using a resonant column apparatus under random excitation conditions. The concept of root mean square (rms) strain was utilized for the purpose of strain calculations during random loading. The conventional estimator of the transfer function was used for random vibration analysis. The effect of confinement duration (at a constant pressure) on dynamic soil properties, namely damping and shear modulus, was evaluated. The results indicate that for both cohesive soils, the effect of time was less pronounced during random vibration than sinusoidal loading at the same rms strain. This effect is however more pronounced when the peak shearing strain of sinusoidal loading is considered. Furthermore, time effects were more pronounced at low strain levels than at high strain levels.  相似文献   

南海夏季风爆发前后亚洲地区的大尺度环流突变   总被引：9，自引：1，他引：9  

江宁波  罗会邦 《热带气象学报》1995,11(4):289-296

用１９８０—１９８６年的ＥＣＭＷＦ资料分析了南海季风爆发前后大气环流突变的平均特征。结果表明：南海季风的爆发一般发生在５月１０日前后，大气环流出现一次明显突变──高空南亚高压由１０—１５°Ｎ骤然北跳到１５—２０°Ｎ，南海北部西风转为东风；低空南海北部及附近地区西南风迅速加强并向东扩展，而中纬地区的偏北风也相应加强南压，青藏高原东南部到中国长江中下游一带为温度、湿度梯度大值区；中国西南地区出现低压环流。同时，青藏高原东南部及中国东部平原地区对流层大气发生急速增暖，大气热源和水汽汇明显增强。在南海季风爆发后南海北部大气热源亦显著增强，但比风场的突变落后５—１０天，而西沙海温的变化与季风爆发却比较一致。另外，地形对大气热源的分布有一定的影响，青藏高原东南坡的加热对南海季风的爆发可能比较重要。  相似文献   

富钆镝易解石的发现   总被引：1，自引：0，他引：1  

蔡根庆 《矿物学报》1987,(1)

该矿物产于铀钍混合矿化的中粗粒黑云母花岗岩中。本文研究了产状、共生矿物、结晶特性、物理及化学性质并与易解石、钍易解石、铀易解石、钇易解石等作了对比。该矿物铀、钍、铅等含量均较高,在稀土含量中,钆、镝含量高达稀土总量的27％,故定名富钆镝易解石。  相似文献   

Relationship between pedogenetic manifestations in some arid soil and age of the landforms     

J. S. Choudhari 《Journal of Earth System Science》1987,96(3):203-210

Arid soils with slight variations in parent material, vegetation and climate were studied for their morphological, chemical and mineralogical characteristics. Results show that the soils are at different stages of profile development. Varying degrees of pedogenic features have been tied up with data on palaeoenvironment to develop a relationship between the soil and age of the landform. Studies reveal that Dune and Shergarh sandy soils with least degree of manifestation belong to early Holocene to latest Pleistocene, whereas Chirai sandy soil with weakly developed B horizon belongs to the upper Holocene. Soils (Khajwana and Gajsinghpura) with well-developed B horizon and a calcic layer with lime segregations belong to mid-Pleistocene whereas Pali and Pipar soils with illuvial clay in B horizon belong to early Pleistocene.  相似文献   

与西太平洋暖池上空对流年际变化相关联的大气环流和海温   总被引：6，自引：0，他引：6  

Lu Riyu 《大气科学进展》2001,18(2):270-282

诊断分析了热带西太平洋暖池上空对流弱和强的情况下,大气环流和海温所表现出来的差异。本文中西太平洋暖池是指（１１０－１６０°Ｅ,１０－２０°Ｎ）地区,向外射出长波辐射（ＯＬＲ）在该地区具有明显的年际变率。对西太平洋暖池对流弱和强之间大气环流和海温的差别进行了合成分析。首先,利用 ＮＣＥＰ／ ＮＣＡＰ再分析资料和卫星观测的 ＯＬＲ资料进行了分析。之后,利用欧洲中期天气预报中心再分析资料和再分析计算而得的ＯＬＲ资料重复进行了合成分析。合成结果表明由这两套资料所分析得到的结果非常相象。与西太平洋暖池上空弱（强）对流显著对应的大气环流表现为北太平洋副热带高压的西伸（东退）,以及副高西北侧更强（弱）的西风。此外,在局地（即暖池）上空,还显著对应着东（西）风异常和下沉（上升）气流异常。对应于西太平洋暖池对流强弱,最为显著的海温差别（对流弱减去对流强）为印度洋、孟加拉湾和南海的正海温异常。也就是说,西太洋暖池上空的对流与局地海温异常只有微弱的联系,而与其西部的海温异常密切相关。  相似文献   

Magnetic properties as indicators of heavy metals pollution in urban topsoils: a case study from the city of Luoyang, China   总被引：8，自引：0，他引：8  

S. G. Lu  S. Q. Bai  Q. F. Xue 《Geophysical Journal International》2007,171(2):568-580

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地下水超采对农业灌溉的影响及对策研究   总被引：1，自引：0，他引：1  

周万亩  齐全  徐敏  付晓刚 《地下水》2007,29(4):17-19,29

在北方一些灌区,由于地下水的过量开采,出现了水位持续下降、地下水矿化度增加、土壤盐渍化等一系列环境问题.一些灌区对地下水的可采资源量估计过高,造成目前超采仍有进一步发展的趋势.因此必须采取有效措施控制地下水超采,实现灌区农业的可持续发展、保护环境.讨论灌区地下水超采的判别方法、超采对灌区的影响、以及应采取的对策.  相似文献