共查询到20条相似文献，搜索用时 15 毫秒
1.
《Gondwana Research》2000,3(1):3-5
The tectonic history of Sri Lanka - India can be traced from the Precambrian to the present. On the basis of the geological record, plate tectonic processes have operated for example, the Highland Group of Sri Lanka may have represented a Precambrian plate tectonic suture. Tectonic models of these Precambrian events may be presented by spreading, collision, subduction, shearing or in situ jostling. The recent tectonic history of Sri Lanka and India relates to the evolution of the Indian Ocean since at least the Cretaceous. Although Sri Lanka is considered to be a part of the larger Indo - Australian plate, it may have had a local independent history as a block within the larger crustal unit of India. There is evidence that the separation of Sri Lanka from India was in part controlled by Precambrian structures and a history of translational, rotational and vertical adjustments to the Indian Ocean developmental plate tectonic stresses still operating. 相似文献
2.
The prediction of high extremes in sustained water level is very important for coastal engineering design and planning. The recorded historical water level datasets in Colombo, Sri Lanka, are not long enough for the traditional frequency analysis in predicting extreme water levels, such as 50-, 100- and 200-year extreme water levels. In this study, the integrated ADCIRC + SWAN hydrodynamic model and Monte Carlo model have been applied to predict extreme water level in Colombo station of Sri Lanka. The meteorological driving forces of cyclone storm surge are simulated by Monte Carlo stochastic model. The calibrated ADCIRC model with SWAN wave model is used to simulate the potential surge setups with the driving forces generated by Monte Carlo model. By ranking the maximum high water levels in each storm surge procedure, the estimation on extreme high water levels for the desired return period is proposed in this study. The estimated extreme high water levels with return period of 50, 100 and 200 years are 1.28, 1.40 and 1.50 m correspondingly. The estimated extreme high water levels are recommended for engineering design and planning. 相似文献
3.
清道光二十九年（1849年）长江中下游地区的大水灾,对民生造成了严重的影响。作者系统收集了档案、方志、日记和文集资料中关于该年份水灾的记载,以县级成灾分数资料为基础,重建了此次水灾的时空分布,并分析了形成这次水灾的天气气候特征。研究认为,该年度水灾基本在N28°～N33°间呈条状东西向分布,而以N31°一线的灾情最为严重;连续性的降水开始于5月18日左右,到7月18日才结束,中间还有3次持续各达10余天的强降雨过程;这次大水灾是全流域性的,涝灾大于洪灾,降水最集中区域为东部的太湖流域,这和有器测记录的几次长江全流域大洪水并不一致;本次大水灾的直接天气成因是梅雨期提前并超长,雨量明显偏大,持续时间长达62天左右,比有器测记录的更早、更长;当年夏季风应偏弱,副热带高压脊线位置异常偏南,且西风分支明显,经向环流发展,西风南支位置应该也异常偏南;夏季冷空气异常活跃可能是雨带长期在长江沿岸徘徊的真正原因。 相似文献
4.
Margo Kleinfeld 《GeoJournal》2005,64(4):287-295
This paper describes the changing discourses of territory in Sri Lanka and their utility in conflict relations. The primordial
homeland has been at the center of Sri Lanka’s armed struggle, in which both Sinhalese and Tamil nationalisms have used claims
of ancient and ethnically determined territories to justify their right to self-determination, territorial sovereignty, and
armed struggle. This identity–territory nexus based on historical argument has been destabilized in Sri Lanka, however. Scholarly
findings suggest that historical linkages between ethnicity and territory in Sri Lanka are highly problematic and are no longer
effectual means for adjudicating territorial desires in Sri Lanka and producing stable homelands. I argue that rights-based
territorial discourses have emerged to enhance the old historical justifications for territorial authority. New narratives
based upon fulfilling or denying human rights have been put to work linking authority to territory based upon moral fitness
and unfitness, political legitimacy and illegitimacy, and ultimately, upon which political actor deserves to rule the territorially
bound population under its control. The first part of the paper examines historical narratives linking national homelands
to identity as well as scholarly work that deconstructs this linkage. In part two, external sovereignty and political legitimacy
are discussed as the starting point for understanding how rights-based discourses justify territorial claims. In part three,
accusations related to human rights violations are described as an important vehicle for shaming political adversaries, undermining
their legitimacy, and making and unmaking territorial claims in Sri Lanka. 相似文献
5.
Factors controlling fluoride contents of groundwater in north-central and northwestern Sri Lanka 总被引：1，自引：0，他引：1
Chemical characterization has been made of groundwater bodies at 294 locations in four village districts in north-central
and northwestern Sri Lanka, with special focus on fluorine contamination. High fluoride contents in groundwater are becoming
a major problem in the dry zone of Sri Lanka, and dental fluorosis and renal failures are widespread. Field measurements of
temperature, pH, and electrical conductivity were made during sampling. Chemical analyses of the water samples were later
made using atomic absorption spectroscopy, spectrophotometry, and titration. Fluoride concentrations in the study area vary
from 0.01 to 4.34 mg/l, and depend on pH and the concentrations of Na, Ca, and HCO3
−. Basement rocks including hornblende biotite gneiss, biotite gneiss, and granitic gneiss seem to have contributed to the
anomalous concentrations of fluoride in the groundwater. Longer residence time in aquifers within fractured crystalline bedrocks
may enhance fluoride levels in the groundwater in these areas. In addition, elevated fluoride concentrations in shallow groundwater
in intensive agricultural areas appear to be related to the leaching of fluoride from soils due to successive irrigation. 相似文献
6.
Kasun Gayantha Joyanto Routh Krishnamurthy Anupama Jean Lazar Srinivasan Prasad Rohana Chandrajith Patrick Roberts Gerd Gleixner 《第四纪科学杂志》2020,35(4):514-525
The catastrophic impact and unpredictability of the Indian Ocean Monsoon (IOM) over South Asia are evident from devastating floods, mudslides and droughts in one of the most densely populated regions of the globe. However, our understanding as to how the IOM has varied in the past, as well as its impact on local environments, remains limited. This is particularly the case for Sri Lanka, where erosional landscapes have limited the availability of well-stratified, high-resolution terrestrial archives. Here, we present novel data from an undisturbed sediment core retrieved from the coastal Bolgoda Lake. This includes the presentation of a revised Late Holocene age model as well as an innovative combination of pollen, source-specific biomarkers, and compound-specific stable carbon isotopes of n-alkanes to reconstruct the shifts in precipitation, salinity and vegetation cover. Our record documents variable climate between 3000 years and the present, with arid conditions c. 2334 and 2067 cal a bp. This extreme dry period was preceded and followed by more wet conditions. The high-resolution palaeoenvironmental reconstruction fills a major gap in our knowledge on the ramifications of IOM shifts across South Asia and provides insights during a time of major redistribution of dense human settlements across Sri Lanka. 相似文献
7.
R. Suppiah 《GeoJournal》1985,10(1):109-118
Due to the absence of marked thermal differences in Sri Lanka, the paddy-climate relationship has been confined to rainfall alone in this study. Increase in total paddy production is highly attributed by the increase in paddy lands rather than yields, particularly in the drier parts, called Dry Zone. The effective rainfall period for the two principal cropping seasons in Sri Lanka, Maha and Yala, were determined according to the crop calendar of the Districts. The deviation values from the trend lines of 20 years (1961–1980) observations in sown, harvest and yield were well correlated with the deviations from the mean rainfall. The effects of rainfall on paddy production are well pronounced in the Dry Zone during the Maha season and in the Wet Zone during the Yala season. From the statictical analyses, four types of relationship, were observed: (1) Type I is the positive relationship, (2) Type II is the negative relationship, (3) Type III is the no realtionship and (4) Type IV a complex one which has a positive relationship below certain critical rainfall value and no or negative relationship above the critical rainfall value. The combination of Types I and IV shows the areas which need irrigation facilities with proper water management while the combination of the Types II and III indicates the areas which are prone to frequent floods and waterloggings. 相似文献
8.
S. R. Kalsi 《Journal of Earth System Science》2000,109(2):211-220
BOBMEX-Pilot was organised from 23rd October–11th November, 1998 when the seasonal trough had already shifted to south Bay
of Bengal. The activity during this period was marked by the development of a monsoon depression from 26th–29th October that
weakened over the sea; onset of northeast monsoon along the east coast of India on 29th October; a low pressure area that
formed on 2nd November over southwest Bay off Sri Lanka — southTamilnadu coast; and another cyclonic circulation that formed
towards the end of the BOBMEX-Pilot period. This paper describes the development of these synoptic systems through synoptic
charts and satellite data. 相似文献
9.
浙江宁波市地质灾害的雨量阈值及预报分析 总被引：1，自引：0，他引：1
山体滑坡、崩塌、泥石流等地质灾害主要由强降水或连续性降水引发产生,根据最近七年来宁波市国土资源局和宁波市气象台联合制作的地质灾害气象预报预警和地质灾害实况资料分析,结果发现:在最近七年里出现的159处地质灾害中,由热带气旋强降水引发的地质灾害有142处,约占89%;宁波市绝大多数地质灾害是由强降水引发,而强降水中又以热带气旋强降水为主要诱因,引发宁波市地质灾害的有效雨量大多数在100mm以上,因此,100mm有效雨量可作为预报引发宁波市地质灾害的雨量阈值,而200mm有效雨量可引发多处地质灾害产生。统计结果为以后地质灾害气象预报预警及强降水的临近监测提供参考依据。 相似文献
10.
In this study, an analysis of century scale climate trends in the central highlands of Sri Lanka is presented. Monthly rainfall and temperature records of the period 1869–2006 from five climatological stations were analyzed. The trend is calculated by the least square regression analysis and the significance of the observed trend is estimated using the Mann–Kendall statistic. The results clearly show that there is a statistically significant decrease in annual rainfall in the western slopes of the central highlands. Throughout the last century, the annual reduction of rainfall in Nuwara Eliya which is at an altitude of 1895 m was 5.2 mm/year. The decrease is largely due to the reduction in southwest monsoon rainfall which contributes to 75% of the total reduction. No significant change was observed on the eastern side of the central highlands which receives rainfall predominantly from the northeast monsoons. The mean annual temperature in the mountainous region shows a uniform increasing trend which is in line with the 100-year global temperature increase of 0.8 ± 0.2°C. Kandy, which is at an altitude of 477 m and closely linked with the rainfall climatology of Nuwara Eliya, showed no significant change in the mean annual temperature. If the current trend continues, in another 100 years, western and eastern slopes of central highlands will receive the same amount of rainfall from the southwest monsoon and the northeast monsoon which will have far reaching consequences for Sri Lanka’s economy and the ecology of the hill country. 相似文献
11.
Heavy off-season rains in the tropics pose significant natural hazards largely because they are unexpected and the popular
infrastructure is ill-prepared. One such event was observed from January 9 to 11, 2002 in Senegal (14.00° N, 14.00°␣W), West
Africa. This tropical country is characterized by a long dry season from November to April or May. During this period, although
the rain-bearing monsoonal flow does not reach Senegal, the region can occasionally experience off-season rains. We conducted
a numerical simulation of the January 9–11, 2002 heavy off-season rain using the Fifth-Generation NCAR/Pennsylvania State
University Mesoscale Model (MM5) and the Weather Research and Forecasting (WRF) model. The objective was to delineate the
meteorological set-up that led to the heavy rains and flooding. A secondary objective was to test the model’s performance
in Senegal using relatively simpler (default) model configurations and local/regional observations. The model simulations
for both MM5 and WRF agree satisfactorily with the observations, particularly as regards the wind patterns, the intensification
of the rainfall, and the associated drop in temperatures. This situation provided the environment for heavy rainfall accompanied
by a cold wave. The results suggest that off-the-shelf weather forecast models can be applied with relatively simple physical
options and modest computational resources to simulate local impacts of severe weather episodes. In addition, these models
could become part of regional hazard mitigation planning and infrastructure. 相似文献
12.
LiWenxing 《中国地质大学学报(英文版)》2003,14(1):79-84
The karst inunersion and waterlogging is one of the typical and the nmst harmful natural disasters in southern karst areas of China. It is threat to the local production and life for a long time. In recent years, due to the construction of more reservoirs, the disaster became serious. This article takes immersion and waterlogging of BanweUs subterranean rivers in Yantan reservoir area as an example, re-searches the daily rainfalls reflection to the water level of reservoir depression, discusses characteristics of immersion and waterlogging of the valley, analyzes the disaster index in detail, such as water level process, the highest water level, sensitive rainfall, original waterlogged rainfall and delayed day numbers etc., and umvides the reference as a basis to the disaster analysis. 相似文献
13.
1939年为海河流域20世纪特大洪涝灾害年之一。根据历史文献记载及观测资料,从降水过程、洪水过程及受灾情况等方面对1939年海河流域洪涝灾害过程作了梳理,得出以下结论: (1)1939年的洪涝灾害是7—8月份3次大范围集中暴雨导致的,集中降水出现于7月9—15日、7月23—29日和8月11—13日。3次暴雨中心均集中在昌平—紫荆关—中唐梅一带,其7、8两个月份总降雨量最高达到1000 mm以上,向东向西逐渐减小。(2)1939年海河流域诸河径流随着7—8月份集中降雨而出现涨落变化,稍滞后于降水变化1~2天,各河流最大流量和水位出现在7月23—29日集中降水后,并开始涨溢、决口,各河水位至8月底各河上游降雨中止而渐渐回落,9月中旬天津市区各河水位骤落,10月份以后洪水才迟缓退去,而洪水泛滥引发的涝灾一直延续到1940年。(3)1939年洪涝灾害在海河南系和北系都有发生,共造成150多个县市受灾,大部分受灾县市农业减产甚至绝收,被灾耕地面积成数超过8成的县市主要分布在大清河下游沿线、永定河下游沿线和南运河下游沿线靠近天津市的地区。 相似文献
14.
In August 2001, the worst flash flooding event of the Caspian Sea regions in over two centuries claimed over 300 lives after
a weekend of heavy rainfall and brought about a devastating disaster in the Mother-Soo catchment, province of Golestan, Iran.
As a result of this event, a series of site investigation were carried out to identify the pertinent factors that led to a
flood of this magnitude. This paper identifies the fundamental causes of the frequent floods and debris flow occurrence in
the area prone to flooding and analyzes the main runoff mechanism of these events. The maximum observed 24-h rainfall depths
and maximum peak discharges at the existing gauges were compared with the depths of rainfall and the peak values corresponding
to the August 2001 flood respectively. For the majority of the rain gauges, the rainfall depth exceeded those of historical
recorded events. In Golestan dam, an increase of 7.5 times the maximum value observed in the past 20 years was noted. The
flood height was 10–15 m while passing through the middle subcatchment area of Golestan National Park. The preliminary evaluation
indicates the existence of bare soil in the catchment, movable material, steep slopes, high rainfall intensity, deterioration
of pasture and forest land, and inappropriate agriculture and development practices as well as climate change were the main
factors for the occurrence and the extent of the August 2001 disaster. Finally, due to the likelihood of flooding and debris
flow events in future, some countermeasures are proposed. 相似文献
15.
The assessment of drought relief by typhoon Saomai based on MODIS remote sensing data in Shanghai,China 总被引：1，自引：1，他引：0
Typhoons are one of the major natural hazards occurring frequently in Shanghai. The comprehensive assessment of drought relief by typhoon has become a major concern of scientists and government agencies in Shanghai, China. In this article, with the support of remote sensing data and the available data from local meteorological stations, the regional drought relief was investigated and the change of drought intensity was quantified by the typhoon “Saomai” between 5 and 8 August 2005. The precipitation anomaly calculated on the basis of recorded rainfall was adopted to analyze drought condition changes before and after the typhoon. Then, vegetation supply water index (VSWI) and normalized difference vegetation index (NDVI) were used to monitor the drought relief due to the consecutive shortage of summer rainfall. Impact of typhoon on drought was compared by VSWI before and after typhoon Saomei. The results showed that the typhoon alleviated the drought of the vegetation by more than 70 %, based on the spatial and temporal distribution of precipitation, the ground temperature, relative humidity, high temperature, NDVI from Shanghai area. The result shows that MODIS remote sensing data are a useful quantitative monitoring tool in drought relief by local typhoons. More strategies are necessary to be adopted for prevention and mitigation of meteorological disaster in Shanghai in recent years. 相似文献
16.
Organic constituents present in the Muthurajawela peat deposit of Sri Lanka, have been investigated. Here, we report the variations with depth of sitosterol and sitostane (stigmastane), which were found to be major constituents of extracts and, hence, were selected to study the process of diagenesis.These two compounds were present in anomalous concentrations in the middle horizon of the depth profile.Considering the stratigraphy and sterol concentrations, it can be concluded that the middle horizon resulted from a sudden terrestrial input, which could have been due to a Pleistocene or Quaternary environmental change. 相似文献
17.
2013年青海北部春季旱涝急转的特征及其成因分析 总被引：2，自引：1，他引：1
利用1961-2013年3-5月的逐日降水、气温和高度环流场资料, 计算了月季降水、气温序列、气象干旱指数序列、高原地面加热场强度指数序列, 研究了春季旱涝急转的主要特征及其规律, 解释了2013年青海省春季降水前期偏少、后期偏多和旱涝急转的成因. 结果表明: 2013年3月1日-4月27日青海大部分地区降水偏少、气温偏高, 出现了大范围不同程度的气象干旱, 海北大部分地区出现50 a一遇的特大气象干旱, 西宁大部分地区出现25 a一遇的严重气象干旱; 4月28日-5月20日青海大部分地区降水偏多, 气温偏高幅度开始逐步减小, 前期的干旱得到缓解, 并出现了大范围不同程度的渍涝, 旱涝急转的台站达21个. 通过对比分析发现, 若极涡面积偏小、中亚和西亚低压槽维持时间长、冷空气主要在欧洲东部和亚洲西部地区堆积、进入中国的冷空气路径偏西、高原位势高度场偏低、东亚槽位置偏东、西太平洋副热带高压北界位置偏北时, 青海降水偏多, 容易出现渍涝. 在相反的环流形势下, 青海降水偏少, 容易发生干旱. 4月干旱和5月渍涝处在青海高原降水长期变化的大气候背景之下, 前期1-3月青藏高原地面加热场强度偏强、春夏季过渡时间提前也有助于青海5月异常降水的形成. 相似文献
18.
J. Birkmann P. Buckle J. Jaeger M. Pelling N. Setiadi M. Garschagen N. Fernando J. Kropp 《Natural Hazards》2010,55(3):637-655
Disaster associated with natural hazards can lead to important changes—positive or negative—in socio-ecological systems. When
disasters occur, much attention is given to the direct disaster impacts as well as relief and recovery operations. Although
this focus is important, it is noteworthy that there has been little research on the characteristics and progress of change
induced by disasters. Change, as distinct from impacts, encompasses formal and informal responses to disaster events and their
direct and indirect impacts. While smaller disasters do not often lead to significant changes in societies and organizational
structures, major disasters have the potential to change dominant ways of thinking and acting. Against this background, the
article presents an analytical framework for distinguishing change from disaster impacts. Drawing from research in Sri Lanka
and Indonesia, formal and informal changes after the Indian Ocean Tsunami of 2004 are examined and discussed against the background
of the conceptual framework. The changes examined range from the commencement of the peace process in Aceh, Indonesia, to
organizational and legal reforms in Sri Lanka. The article concludes that change-making processes after disasters need to
be understood more in depth in order to derive important strategic policy and methodological lessons learned for the future,
particularly in view of the increasing complexity and uncertainty in decision making due to climate change. 相似文献
19.
C. S. Murthy J. Singh P. Kumar M. V. R. Sesha Sai 《International Journal of Environmental Science and Technology》2017,14(9):1981-1988
Hazard analysis is the first step in any disaster management activity. Drought is a serious environmental hazard strongly limiting the agricultural production in the tropical countries like India. A comprehensive drought hazard map is useful for multiple perspectives such as agriculture, environment and hydrology. In this study, daily rainfall data of the Climate Prediction Centre during the south-west monsoon season (June–September) of 12 years, over India was analysed. Based on rainfall and rainy days, six indicators of drought were generated which were then synthesized into a composite index of drought hazard for every 10 × 10 km pixel. The weights for the composite index were generated through variance approach. The index has effectively captured the spatial variations in meteorological drought across India by showing a typical pattern with increasing hazardous area from east to west. The drought hazard map also shows considerable agreement with the climate classification map and the drought proneness map reported by other studies. Thus, the current study presents a simple and novel approach for drought hazard analysis, using the routinely available geospatial rainfall data products. The methodology can be extended to other geographies and disasters too. Use of time series data of longer period would improve the reliability of the composite drought hazard index. 相似文献
20.
Meso-scale characteristics of disturbances that bring about atmospheric disasters in pre- and mature monsoon seasons in Bangladesh
are analyzed. Several types of meteorological instruments capable of observations with high temporal and spatial resolutions
were introduced for the first time in this area to capture the meso-scale structure of rainfall systems. We installed an automatic
weather station (AWS) and several automatic raingauges (ARGs) and utilized the weather radar of Bangladesh Meteorological
Department (BMD). From the radar image in the summer of 2001 (16–18 July), a striking feature of the systematic diurnal variation
in this area was elucidated. In these 3 days, the diurnal evolutions of convective activity were remarkably similar to each
other, implying that this pattern can be understood as a typical response of local cloud systems to the diurnal variation
of insolation under some summer monsoon situations. The ARG data show the difference in characteristics of rainfall between
pre- and mature monsoon seasons. The short intense downpour tends to occur more frequently in the pre-monsoon season than
in the mature monsoon season. The pre-monsoon rainfall also has clear diurnal variation with a peak that is more strongly
concentrated in time. In the northern part the rainfall peak is found in between midnight and early morning, while it is observed
in the daytime in central to western parts of the country. Two disaster cases caused by meso-scale disturbances are analyzed.
Although they occurred in the same season, the structures of the cloud systems were largely different from each other. The
disturbance brought about tornadoes on 14 April 2004, consisting of many spherical cloud systems of approximately 20 km size.
On the other hand, another one that caused the tragic river water transport accident on 23 May 2004 had meso-scale rain band
structure. The latter case was captured by the AWS located at Dhaka. Sudden changes in temperature, wind and pressure were
observed clearly, showing the typical structure of convective rain bands. 相似文献