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排序方式: 共有568条查询结果,搜索用时 46 毫秒
491.
干旱定义及其指标评述 总被引:42,自引:1,他引:42
本文对气象、水文、农业、经济四种干旱类型的概念进行了论述,并对这四种干旱类型之间的并、交和包含关系及其指标进行了探讨。 相似文献
492.
自然灾害对社会的影响:以1920年北方大旱为例 总被引:2,自引:1,他引:2
本文通过1920年我国北方五省大旱对社会影响的分析,提出了自然灾害对社会影响顺序的基本模式,讨论了社会对灾害的放大与缩小等问题。 相似文献
493.
Tiao J. Chang 《Journal of the American Water Resources Association》1989,25(5):1037-1040
ABSTRACT: Records of extreme precipitation were investigated using the Discrete Autoregressive Moving Average (DABMA) process, which can explain long persistences of wet and dry spells that exist in daily precipitation data. The results show that the daily precipitation with strong autocorrelation is inclined to be better fit by a Discrete Autoregressive (DAB) model. On the other hand, those data with weak autocorrelations tend to be best fit by a Discrete Moving Average (DMA) model. It can also be concluded that based on the records from extremely wet and dry regions there is no geographic preference regarding the selection of the best model. 相似文献
494.
James E.T. Moncur 《Journal of the American Water Resources Association》1989,25(3):499-505
ABSTRACT: Municipal water utilities, when faced with drought conditions, typically impose a temporary water use restrictions program to achieve conservation goals. If water is sufficiently price-elastic, however, at least some of the problems associated with restrictions can be avoided by imposing a drought surcharge and allowing users to adjust voluntarily. This paper develops two sources of evidence on price elasticity in Honolulu, Hawaii, with the evidence suggesting that a drought surcharge will induce much of the desired conservation, especially when used with educational publicity. 相似文献
495.
496.
湖北省旱涝灾害的若干统计特征及对农业生产的影响 总被引:3,自引:2,他引:1
着重分析了湖北省40多年来旱涝灾害的若干统计特征及其对农业生产的影响,指出了旱涝灾害的演变趋势,以及人类活动对灾害加剧的主导作用,为防、抗旱涝灾害提供参考。 相似文献
497.
Junfang Zhao Houquan Lu Yijun Li 《Journal of the American Water Resources Association》2019,55(5):1235-1247
This study investigates agricultural adaptation to drought for different cropping systems in southern China. The study area was divided into three regions: South China (SC), South of the Yangtze River (SYR), and Southwest China (SWC). An index of agricultural adaptation to drought (D) was established. Our findings indicated that the average total crop water demand varied greatly among the regions from 1961 to 2010 in southern China. The maximum value was found in the SC region, followed by the SYR and SWC regions. The effects of droughts on different crops were noticeable. Frequent droughts were recorded in late rice than in early rice in the SC and SYR regions. Droughts in the SWC region mainly affected winter wheat. Moreover, the effects of droughts on crops varied during different growth stages. More frequent and serious droughts occurred during the crop critical flowering stage. Particularly, the frequency of moderate and severe droughts for late rice in the SYR region was 62% during the critical flowering stage. For the SC and SYR regions, the D values of early rice (0.29 and 0.29) were lower than that of late rice (0.31 and 0.33), respectively. For the SWC region, the D values of winter wheat and rice were both low, with averages of 0.16 and 0.29, respectively. Our study provides interesting insights for improving the drought defense abilities for different cropping systems by changing crop planting proportion on a regional scale in China. 相似文献
498.
499.
基于AWTP指数的浙江省干旱规律时空分析 总被引:2,自引:0,他引:2
利用浙江省51个气象站1960-2009年的50 a逐日降水资料,基于降水的平均等待时间(AWTP)指数,采用小波分析和克里金空间插值方法对浙江省干旱时空特性进行分析。结果表明,浙江省的干旱随时间增加有加剧趋势。在50 a中,1979年干旱程度最强,相当干期值最大,达到52 d。在趋势变化上还同时叠加着明显的年际和年代际变化。浙江省干旱存在3 a左右的主周期;另外浙江省的干旱具有明显的区域性,干旱程度由南向北递增。嘉兴的平湖市及浙西金华周围内陆丘陵盆地发生干旱比其他地区更明显,其次是杭州市西部、温州市及台州市温岭等东南沿海山地丘陵地区,中东部的宁波市和绍兴市、西北部的湖州市以及浙江西南部等地区发生干旱程度较轻。 相似文献
500.
《Environmental Hazards》2013,12(4):343-357
The effect of drought on crop yield and water resources has been an important socio-economic concern in the Sahel region of Africa. The most severe droughts in the Sahel region occurred during the strong El Niño Southern Oscillation (ENSO) events. There is thus increased need to understand the stochastic relationship between such physical mechanism like ENSO and crop yield. In this paper, such a relationship is investigated using a wavelet approach. Our result shows that a statistically significant relationship exists between ENSO and cereal production in the region. In particular, El Niño events are devastation to millet yield with little or no impact on maize and sorghum production. This can be attributed to the lower length of growing period for maize and sorghum compared to millet. On the other hand La Niña events favor cereal production and mirrored sorghum yield during the La Niña years of 1973–1976. The potential value of ENSO-based rainfall forecast and socio-economic impact on local population in Sahel region are discussed. 相似文献