Geotechnical Hazards Associated with Desert Environment     

Shehata  W.M.  Amin  A.A. 《Natural Hazards》1997,16(1):81-95

The aridity of the Arabian Peninsula's deserts ranges between arid to hyperarid with hot dry climate, scarce precipitation and sparse vegetation. These harsh environmental conditions enhance some geomorphologic processes more than others, cause specific geotechnical problems, and increase desertification.From west to east, the general physiography of Saudi Arabia shows the Red Sea coastal plains and the escarpment foothills called Tihama followed by the Arabian Shield mountains, the Arabian Shelf plateau and finally the Arabian Gulf coastal plains. Sand moves by wind either as drifting sand or migrating dunes in four major sand seas, over the Arabian Shelf, and in the inter-mountain valleys, in the Arabian Shield causing problems of erosion and deposition. Human activities in the deserts may cause more instability to the sand bodies, enlarging the magnitude of the problem. Fine silty soil particles also move by wind, depositing loess mainly in selected areas downwind in the Tihama. These loess deposits subside and may form earth fissures by the process of hydrocompaction upon wetting. The addition of water can be either natural through storms or man-made through human agricultural or civil activities. Extensive sabkhas exist along the coastal plains of both the Red Sea and Arabian Gulf. The sabkha soil may also heave by salt re-crystallization or collapse by wetting. The shallow groundwater brines present in sabkhas also attack and corrode civil structures. Urbanization and excessive groundwater pumping may also deplete the fresh groundwater resources and may cause subsidence, ground fissuring and surface faulting as observed in some locations in the Arabian Shield. Although the average annual precipitation is very low, rain usually falls in the form of torrential storms, collected by dry valley basins and causing floods to unprotected downstream areas on the coastal plains of the Red Sea.The desert environment, being a fragile echo system, needs to be treated with care. Intercommunications between different national and international agencies and education of the layman should help to keep the system balanced and reduce the resulting environmental hazards. In addition, any suggested remedial measures should be planned with nature and engineered with natural materials.  相似文献   

Causes of Land Subsidence in the Kingdom of Saudi Arabia     

Amin  Ammar  Bankher  Khalid 《Natural Hazards》1997,16(1):57-63

The occurrence of land subsidence in the Kingdom Saudi Arabia is either natural or man-made. Natural land subsidence occurs due to the development of subterranean voids by a solution of host rocks in carbonate and evaporite terrains, over many areas of Saudi Arabia. Man-induced land subsidence is either due to the removal of groundwater in the agricultural areas or to wetting of unstable soils. Therefore, earth fissures and a lowering of the ground surface in unconsolidated sediments took place in alluvial plains and volcanic vent terrains. Unstable soils include Sabkha soils and loess sediments. These types of soils occur in coastal plains, desert areas and volcanic terrains. When this soil is wetted either during agricultural activities, waste disposal or even during a rain storm, subsidence takes place due to either the removal of salts from the Sabkha soil or the rearrangement of soil particles in loess sediments.  相似文献   

陕北砂黄土区公路地质灾害及防治对策   总被引：8，自引：0，他引：8  

张永双  曲永新  何锋 《中国地质灾害与防治学报》2004,15(2):35-38

中国西北黄土的颗粒组成具有明显的地带性分布规律，自NW向SE可依次划分为砂黄土带、典型黄土带和粘黄土带。黄土高原北部地质灾害综合调查表明，砂黄土区公路地质灾害的主要类型包括黄土边坡滑塌灾害、路堤裂陷灾害、路桥变形和冲蚀灾害等。根据试验测试分析结果，公路地质灾害的形成主要受黄土本身的物质组成、结构及力学性质控制，人类工程活动的盲目性是诱发地质灾害的重要因素。文章在砂黄土公路地质灾害特征分析的基础上，提出加强边坡防护和冲蚀灾害防治是公路地质灾害防治的两个基本途径，并给出了针对性的防治对策。这不仅对该地区的公路建设具有重要的指导作用，而且对其它生命线工程如铁路、输油气管道、渠道等也具有重要的借鉴意义。  相似文献   

    

Roberto Torra 《中国地球化学学报》2004,23(3):220-237

Littoral siliciclastic shallow marine horizontal conformable beds (a heterolithic succession), Middle to Late Miocene, outcropping in northeastern Argentina (Ituzaingó Formation) and overlying transitional conformable horizontal regolithic mantle-rock bed derived from them (the Pampean and Post-Pampean Formations), were geochemically analyzed. The focus of this study is placed on the application of geochemical parameter and signature analyses related with the aforementioned geological units, which are of subcontinental extension into South America. The encountered results show an outstandingly similar geochemical behaviour between them. The main conclusion is that regolithic mantle-rock beds were derived from the littoral shallow marine mudstone (silty-argillaceous) beds. This is in oposition to previous aeolian processes proposed early in the 50’s and later. These mudstone beds constitute important sections of the littoral shallow marine sequence beds (outcropping HST parasequence). Such regolitization proposed for the Pampean and Post-Pampean Formations predominantly developed in-situ during the Late Pleistocene and Holocene. The main erosional and mobilized agents were the surface free water (pluvial, fluvial and laminar water sheets) and vadose water. So, the wind flows and/or the immense air flow hurricanes are of insignificant sedimentological influence. Otherwise, there is not a proved appropiate sandy-silty reservoir for a reasonable support of the “aeolian hypothesis”, as well as clear aeolian structures settled in the regolithic mantle-rock bed. In spite of these lines of equality textural-structural evidence, the geochemical values for both major elements and trace elements, demonstrate that the Miocene heterolithic marine succession was the mother rock of the overlying regolithic mantle-rock bed, which was formed as an in-situ mantle-rock bed.  相似文献   

青海湖南岸全新世黄土地球化学特征及气候环境意义   总被引：13，自引：6，他引：13  

周笃珺  马海州  高东林  马万栋  谭红兵  徐黎明 《中国沙漠》2004,24(2):144-148

位于青藏高原东北部的青海湖是我国最大的内陆湖泊，通过湖相沉积进行湖区全新世环境演变研究已取得诸多成果。作者选择青海湖南岸黑马河有绝对年代控制的全新世黄土剖面，利用CaCO2、CaO、MgO和Sr元素组分以及氧、碳同位素等较为可靠的地球化学指标，尝试进行了湖区全新世黄土的分层，探讨了黄土堆积过程中的气候环境演变。结果表明，青海湖南岸的黄土按成土作用强度的不同可分为两层：上部为成土化较弱的黄土层；下部为成土化较高的古土壤层，其仍可进一步分为两个亚层。全新世湖区气候环境的波动在地球化学分布特征中有较强表现。  相似文献   

洛川黄土剖面中矿物固定态铵的分布   总被引：1，自引：2，他引：1  

饶文波  李晓彪  高振敏  罗泰义 《中国沙漠》2004,24(6):685-688

对洛川黄土中的固定铵进行了初步分析。结果表明,在所测定的黄土古土壤层中,固定铵态氮含量在130-1之间变化。黄土中的固定铵态氮含量明显低于古土壤。13万a以来洛川黄土剖面中固定铵的分布呈～210现三次大的低高值的振荡特征,即末次间冰期S1古土壤中固定铵态氮含量最高,其次为冰后期的S0古土壤层,末次冰期形成的马兰黄土中固定铵态氮含量最低;在马兰黄土中同样体现出三次小的低高值的波动特征。黄土与μm组分的分布具有相似性,这些特征反映了洛川黄土中固定铵态氮的含量变化与气互层的古土壤中固定态铵的分布与黄土高原区气候的冷暖变化有较好的一致性,并且13万a以来洛川黄土剖面中固定铵的分布与磁化率和<2候条件有紧密的联系,揭示了黄土中固定铵的变化在一定程度上能指示黄土高原区古气候的演变。  相似文献   

Determining the climatic boundary between the Chinese loess and palaeosol: evidence from aeolian coarse-grained magnetite   总被引：3，自引：0，他引：3  

Qingsong Liu  Subir K. Banerjee  Michael J. Jackson  Fahu Chen  Yongxin Pan  Rixiang Zhu 《Geophysical Journal International》2004,156(2):267-274

  相似文献   

New insights into partial oxidation model of magnetites and thermal alteration of magnetic mineralogy of the Chinese loess in air   总被引：10，自引：0，他引：10  

Qingsong Liu  Subir K. Banerjee  Michael J. Jackson  Chenglong Deng  Yongxin Pan  Zhu Rixiang 《Geophysical Journal International》2004,158(2):506-514

  相似文献   

黄土震陷灾害典型震例的综合研究   总被引：6，自引：0，他引：6       下载免费PDF全文

张振中  张冬丽  刘红玫 《地震工程学报》2005,27(1):36-41,46

阐述了1995年甘肃永登5.8级地震时造成的黄土震陷灾害形成条件、震害形态特征、黄土的基本性质及湿陷性和静、动土力学参数与震陷灾害的成因关系。并用震陷量预测计算方法和三维有限元数值模拟方法检验了黄土震陷灾害预测的理论、方法并解释了永登5.8 级地震黄土震陷现象。  相似文献   

鄂尔多斯盆地南部的黄土塬区地震资料处理与解释,第一部分:地震资料处理     

Jiang Jiayu Fu Shouxian Li Jiuling 《应用地球物理》2005,2(4):241-246

Branching river channels and the coexistence of valleys, ridges, hiils, and slopes＇as the result of long-term weathering and erosion form the unique loess topography. The Changqing Geophysical Company, working in these complex conditions, has established a suite of technologies for high-fidelity processing and fine interpretation of seismic data. This article introduces the processes involved in the data processing and interpretation and illustrates the results.  相似文献