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681.
我国降水的时空变化与暴雨洪涝灾害 总被引:21,自引:2,他引:21
本文论述与降水的时空变化相联系的我国暴雨洪涝灾害的主要特征。我国受东亚季风影响明显,暴雨活动频繁。各地的降水分布极不均匀。暴雨(降水)活动具有明显的年代际变化、年际变化、季节性变化和季节内振荡。与之相对应的暴雨洪涝灾害也具有以上的时空变化特征。我国东南部沿海地区受两种不同性质的降水天气——非台风暴雨和台风暴雨的影响,而各沿海省(区)由两者造成的洪涝灾害程度大小也不同。华南地区后汛期中的暴雨洪涝灾害比前汛期的严重。湖南省的降水一年中具有两个峰值,所造成的洪涝灾害也有两个季节性极大值点。 相似文献
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2012年秦皇岛市夏秋季降水异常偏多,暴雨洪涝、地质灾害严重,给工农业生产及交通航运等带来严重损失。利用统计分析方法对6~11月秦皇岛异常降水进行分析,结果表明:6~11月连续6个月降水偏多,为1955年有气象记录以来唯一年份;11月全市降水偏多5倍以上,创有气象记录以来极值;7下8上区域性暴雨范围大,持续时间长,尤其8月3~4日受台风“达维”影响,出现了近50 a最大洪涝。在分析降水异常基础上,对引起的气象灾害及其影响进行了分析。 相似文献
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ABSTRACT: Catch in standard (unshielded) rain gages exposed 3 feet above the land surface was compared with catch in pit (buried) gages exposed 1 inch above the land surface. These tests confirmed that catch in standard gages under estimates point rainfall in forest openings, as well as in conventional weather stations. Pit gages caught significantly (P=0.05) more rain than did standard gages at each of four locations tested. Catch increases ranged from 2.3 to 3.4 percent. 相似文献
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利用全国多雨、中雨和少雨典型区的自记雨量曲线和 Kinnel 方程:E=29.233·(1-e~(-(0.0477I+0.112)))计算出各点各次降雨的雨能值,并作出各区按月降雨(x)和雨能(y)的关系式:y=15.592x-171.630(多雨区),y=16.257x-280.279(中雨区),y=16.493x-107.676(少雨区)。将全国77个观测点的按月雨量资料计算出全年的雨能值。通过作图得到我国多雨和中雨区的年降雨量 P 和年雨能值 E 的关系:E=11.67p;和少雨区的关系:E=14.95P。从而可用此来估算全国各测点的雨能值。 相似文献
686.
Jantanee Jamsangtong Preeda Parkpian R. D. Delaune Aroon Jugsujinda 《Chemistry and Ecology》2004,20(4):241-256
Adsorption and desorption of 137Cs by acid sulphate soils from the Nakhon Nayok province, South Central Plain of Thailand located near the Ongkarak Nuclear Research Center (ONRC) were investigated using a batch equilibration technique. The influence of added limestone (12 and 18 tons ha-1) on 137Cs adsorption-desorption was studied. Based on Freundlich isotherms, both adsorption and desorption of 137Cs were nonlinear. A large portion (98.26-99.97%) of added 137Cs (3.7 × 103-7.03 × 105 Bq l-1) was sorbed by the soils with or without added lime. The higher lime treatments, however, favoured stronger adsorption of 137Cs as compared with soil with no lime, which was supported by higher Kads values. The addition of lime, the cation exchange capacity and pH of the soil increased and hence favoured the stronger adsorption of 137Cs. Acid sulphate soils with a high clay content, medium to high organic matter, high CEC, and predominant clay types consisting of a mixture of illite, kaolinite, and montmorillonite were the main soil factors contributing to the high 137Cs adsorption capacity. Competing cations such as NH4+, K+, Na+, Ca2+, and Mg2+ had little influence on 137Cs adsorption as compared with liming, where a significant positive correlation between Kads and soil pH was observed. The 137Cs adsorption-desorption characteristics of the acid sulphate soils studied exhibited a very strong irreversible sorption pattern. Only a small portion (0.09-0.58%) of 137Cs adsorbed at the highest added initial 137Cs concentration was desorbed by four successive soil extractions. Results clearly demonstrated that Nakhon Nayok province acid sulphate soils have a high 137Cs adsorption capacity, which limits the 137Cs bioavailability. 相似文献
687.
Coastal environments in Australia are under development pressures. Human settlement encroaches on disease vector salt marsh mosquito breeding areas that are underlain by potential acid sulfate soils (PASS). Altering the hydrology by runneling solves the mosquito problem but may lead to acid sulfate problems. Appropriate analytical tools can assess the risk to the environment. The objective of the research was to compare three methods of assessing PASS. The study area was a low-lying intertidal subtropical salt marsh that was being considered for runneling. The results indicated that using field pH and field peroxide pH (and the relationship between these), and also the peroxide oxidation-combined acidity and sulfate (POCAS) test, appeared to overestimate the potential acidity. This was because the source of acidity in the intertidal salt marsh includes a large organic content, which is not a major environmental concern. The chromium-reducible sulfur test, which is not affected by organic content, was found to provide the most appropriate assessment, and is recommended for use in highly organic salt marshes. 相似文献
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690.
On East Asian Sand and Duststorms and Associated Significant Dustfall Observed from January to May 2001 总被引:4,自引:0,他引:4
Monitoring of dust pollution at the western shore of Tae-ahn Peninsula (TAP) and in the Chongju area of central Korea was carried out from January to May 2001. It was found that in Koreathere were 9 cases of sand and duststorms (DS) and 16 associatedsignificant dustfall (SD) days. Observed maximum concentrations of DS and SD coming from NW China and Mongolia were in the rangeof 300–920 for TSP, 200–690 for PM10 and 100–170 g m-3 for PM2.5.Satellite measurements clearly showed the formation and subsequent movement of DS to the Korean Peninsula and onward to the Korea East Sea, Japan and the Gulf of Alaska. According to satellite image analysis of dust clouds there were abundant coarse particles, measuring in size of 11.0 m. Medium-sizedparticles measuring in the range of 3.5–7.0 were also prevalent,while fine particles of less than 2.0 m were less distinctive in reflectivity. Measured values of PM2.5 were alsorelatively low with SD events.The measured average pH values of dusty precipitation associatedwith DS were 7.24. Alkaline precipitation can play a `temporary'role in the neutralization of acidified soil until the subsequentevent of acidic rain. The new selection criteria of SD days from PM2.5 at 85 g m-3, PM10 190 g m-3 and TSP 250 g m-3 are recommended on dust pollution occurring from the invasion of a DS elsewhere. 相似文献