硬梁包水电站泥石流对沟口建筑物的影响评价

概述了硬梁包水电站左岸磨子沟泥石流的基本特征、泥石流危险性、泥石流发展趋势,泥石流对工程区的影响进行了分析和评价,为解决该泥石流沟治理设计提供了依据。     

大理近地层山谷盆地湖陆风及湍流特征分析

研究湖陆风特征不仅能够为提高天气气候的预测能力奠定基础,而且对风能资源的开发利用等具有重要的实用意义。利用大理国家气候观象台近地面通量观测系统的2007年3月－2008年5月资料,采用涡动相关法等分析了大理近地层中湖陆风、峡谷风特征及形成原因和影响因素。结果表明：大理地区白天以东风和东南风为主,夜间以西风和西南风为主。进一步对湍流和湍流通量特征分析发现,大理地区白天不稳定层结多于夜间;湍流强度白天强于夜间,并且随着风速的增大而减小;湍流通量具有明显的日变化特征,热量交换形式以潜热为主。     

Numerical simulation for the coupling effect of local atmospheric circulations over the area of Beijing,Tianjin and Hebei Province

Using the model system MM5.V3 and multi-layer grid nesting technique, we have done a multi-scale numerical simulation over the area of Beijing, Tianjin and Hebei Province to analyze the temperature and wind field there and study its local circulations. The results show a coupling effect of Urban Heat Island Circulation (UHIC), Mountain Valley Breeze (MVB) and Sea Land Breeze (SLB) occurs in this area when the synoptic system is weak. The SLB can penetrate deep into the mainland for about 200 km when it is blooming. MVB can extend to south and cover almost the whole plain area in Beijing. Both MVB and SLB are diurnal periodical; meanwhile the phase of MVB drops behind that of SLB for about six hours. As a local circulation, the UHIC weakens the two circulations above, and it also has a diurnal period. As a result, the coupling effect of circulations reveals not only different features in spring-summer period and autumn-winter period in a year but also the difference between early morning to noonday and afternoon to night in a day. We noted the diffusion of contamination over the area around Beijing, and found the steady presence of a transport routine of contamination over North-China throughout the year caused by the Coupling Effect mentioned above. This find is important for studying the environment pollution in this area. Supported by Central Public Welfare Special Fund Program for the Institute and Higher Education (Grant No. IUMKY200701), Public Welfare Special Fund Program (Meteorology) of China Scientific and Technological Ministry (Grant Nos. CYHY20080620, CYHY200706004), Spread New Technology Program of China Meteorological Administration (Grant No. CMATG2007M15) and Urban Meteorology Scientific Research Fund Program of the Institute of Beijing Urban Meteorology, China Meteorological Administration (Grant No. UMRF200702)     

Catastrophic middle Pleistocene jökulhlaups in the upper Susquehanna River: Distinctive landforms from breakout floods in the central Appalachians

Widespread till and moraines record excursions of middle-Pleistocene ice that flowed up-slope into several watersheds of the Valley and Ridge Province along the West Branch of the Susquehanna River. A unique landform assemblage was created by ice-damming and jökulhlaups emanating from high gradient mountain watersheds. This combination of topography formed by multiple eastward-plunging anticlinal ridges, and the upvalley advance of glaciers resulted in an ideal geomorphic condition for the formation of temporary ice-dammed lakes. Extensive low gradient (1°–2° slope) gravel surfaces dominate the mountain front geomorphology in this region and defy simple explanation. The geomorphic circumstances that occurred in tributaries to the West Branch Susquehanna River during middle Pleistocene glaciation are extremely rare and may be unique in the world. Failure of ice dams released sediment-rich water from lakes, entraining cobbles and boulders, and depositing them in elongated debris fans extending up to 9 km downstream from their mountain-front breakout points. Poorly developed imbrication is rare, but occasionally present in matrix-supported sediments resembling debris flow deposits. Clast weathering and soils are consistent with a middle Pleistocene age for the most recent flows, circa the 880-ka paleomagnetic date for glacial lake sediments north of the region on the West Branch Susquehanna River. Post-glacial stream incision has focused along the margins of fan surfaces, resulting in topographic inversion, leaving bouldery jökulhlaup surfaces up to 15 m above Holocene channels. Because of their coarse nature and high water tables, jökulhlaup surfaces are generally forested in contrast to agricultural land use in the valleys and, thus, are readily apparent from orbital imagery.     

THE PARLOR IN THE WILDERNESS: DOMESTICATING AN ICONIC AMERICAN LANDSCAPE*

ABSTRACT. Thirty years ago D. W. Meinig argued that certain landscapes “are part of the iconography of nationhood.” From the earliest European settlement, the North American “wilderness” forged the crucible that shaped U.S. culture. By the early nineteenth century romantic aesthetic theories and nationalistic patriotism influenced American perspectives on the emerging cultural landscape. Artists, writers, and travelers sought out places for their healthful and scenic qualities as well as for moral instruction from nature. The locus of this confluence of politics, philosophy, and art was the Hudson River Valley of New York State. Guesthouses and hotels, especially in and around the Catskill Mountains, accommodated these travelers. This article examines the cultural basis of the mountain resort in its appropriation and marketing of a regional landscape and its incorporation as a national icon, with a specific history of the development of Mohonk Mountain House by the Smiley family from 1869 to 2008.     

Risk Assessment,Emergency Preparedness and Response to Hazards: The Case of the 1997 Red River Valley Flood,Canada

The prevention and/or mitigation offlood disasters requires continual research, numerouscapital investment decisions, and high-qualitymaintenance and modifications of flood-controlstructures. In addition, institutional and privatepreparedness is needed. The experience offlood-control in North America has shown mixedoutcomes: while flood frequency has declined duringthe last few decades, the economic losses havecontinued to rise. Recent catastrophic floods havealso been linked to major structural interventions inthe region. The flood diversions may cause harmfuleffects upon the floodplain inhabitants by influencingflood levels in areas which are not normallyflood-prone. The increasing vulnerability of thefloodplain inhabitants poses new challenges and raisesquestions concerning the existing risk assessmentmethods, institutional preparedness and responses todisaster-related public emergencies, and local-levelpublic involvement in flood mitigation efforts.In the context of the catastrophic 1997 floods of theRed River Valley, Manitoba, Canada, this researchfocuses on two aspects of flood-related emergencygovernance and management: (i) the functions andeffectiveness of control structures, and (ii) theroles, responsibilities and effectiveness oflegislative and other operational measures. The studyconcludes that the flood-loss mitigation measures,both in terms of effects of control structures andinstitutional interventions for emergency evacuation,were not fully effective for ensuring the well-beingand satisfaction of floodplain inhabitants. Althoughorganizational preparedness and mobilization to copewith the 1997 flood emergency was considerable, theirsuccess during the onset of the flood event waslimited. Lack of communication and understandingbetween institutions, a reluctance to implementup-to-date regulations, and minimal publicparticipation in the emergency decision-making processall contributed to the difficulties experienced byfloodplain inhabitants.     

罗布泊东阿奇克谷地雅丹地貌与库姆塔格沙漠形成的关系

阿奇克谷地位于罗布泊洼地之东, 93°E以西, 东西长约150km, 南北宽20~30km。为新生代北山与阿尔金山之间的地堑凹地的一部分, 与东面河西走廊的地堑凹地相通。根据出露的雅丹地层河湖相沉积样品所作的ESR测年(2272~10094kaBP)和本区的地质地貌特征可将阿奇克谷地演化与库姆塔格沙漠的发育史归纳为4个时期。①早更新世至中更新世罗布泊古湖扩大时期, 东部湖湾宽约50~60km, 向东延伸至93°15′E或更东; ②中更新世晚期山地上升与古湖湾退缩消失时期, 距今30万年前左右, 青藏高原强烈隆升, 阻挡了海洋水汽的进入, 亚洲内陆加速变干, 由于阿尔金山的左旋向东滑动, 在北面古湖区地层发生了与阿尔山斜交的羽毛状断裂谷群, 并因东北向的断裂上升与东西向的河西地堑谷地斜交, 阻断了疏勒河水不再向西流入罗布泊, 使东部湖湾向西退缩并逐步消失; ③中更新世晚期至晚更新世初, 暴雨径流与强烈的风蚀作用时期, 阿奇克谷地北部的洪积湖相沉积台地支沟口形成雅丹土丘群, 谷地南面库姆塔格沙漠北面羽毛状断裂谷群形成雅丹垄脊和风蚀谷, 谷地中央呈现出季节性的盐碱沼泽和零星雅丹土丘; ④晚更新世末至全新世库姆塔格沙漠扩大, 向北埋没了羽毛状断裂谷(风蚀谷)和雅丹垄脊, 形成了世界上独特的羽毛状沙丘。     

四川九寨沟地貌与第四纪地质

九寨沟地处青藏高原向四川盆地陡跌的两在地貌单元的过渡地带,经笔者等调查可划分出高山地地貌、高山坡地地貌和高山河谷地貌等三种地貌类型及十种成因类型的第四纪堆积物,并对其分布规律、特征者描述。首次划分了区内第四纪地层,探讨其演化过程。为研究九寨沟自然资源的演化发展以及合理利用和保护提供了基础资料。     

江淮流域大洪水的发生规律探讨

对江淮流域的大洪水进行分析 ,得出如下三点新的认识 :(1)在太阳黑子活动的峰谷年前后 ,江淮流域一般容易出现大洪水 ;(2 )在太阳黑子活动的磁周期转变年前后 ,江淮流域容易出现大洪水 ,甚至是特大洪水 ;(3)在太阳黑子活动磁周期转变年前后的厄尔尼诺同年或次年 ,江淮流域更容易出现大洪水 ,甚至是特大洪水。这些认识可以为长期及超长期的洪水预报提供一定的理论依据。