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131.
干旱是威胁我国及世界农业发展的自然灾害之一,利用遥感技术进行干旱监测与评估已成为一种重要而有效的手段。2008年10月至2009年2月,我国北方地区出现了大面积的持续干旱,给冬小麦的生长造成了严重的影响。基于2000年至2009年Terra卫星MODIS传感器8天合成的地表反射率数据,结合地面实测土壤水分和实地调研数据,利用距平植被指数(AVI)和距平水分指数(AWI)对我国北方冬小麦主产区的干旱程度进行了分级,对干旱的发生、发展和时空变化情况进行了连续监测,得到了该时期的旱情分布结果:2008年10月份以后旱情逐渐加重,2009年1月下旬各地旱情达到了最严重的程度。研究表明,AWI对干旱的反应比AVI敏感而且准确。 相似文献
132.
云南省Palmer旱度模式的建立——2010年干旱灾害特征分析 总被引:1,自引:0,他引:1
2010年春季云南省发生了特大干旱灾害,造成了严重的经济损失。按照Palmer旱度模式的思路,利用云南省的气象和土壤数据,建立了云南省的Palmer旱度模式。通过将计算得到的Palmer指数值与云南省的实际旱涝灾情历史记录进行对比,发现所建立的Palmer旱度模式能够较好地反映云南省的旱涝情况。基于该模式对2010年云南特大干旱灾害进行了特征分析,结果表明,此次干旱灾害是云南省30年来干旱变化过程中的一次突变。而且结果显示,在2010年的云南干旱灾害中,严重干旱地区整体呈现东西走向的空间分布,极端干旱地区主要分布在云南省的东南部。 相似文献
133.
基于标准化降水蒸散指数的华南干旱趋势研究 总被引:11,自引:0,他引:11
最近几年华南地区干旱频发,为探讨该地区的干旱趋势,用标准化降水蒸散指数(SPEI)和1961-2010年华南地区具有代表性的50个站点的月降水及月平均气温资料,分析了该地区近50年来的干旱趋势、干旱空间分布、极端干旱事件发生频次和干旱持续时间。结果表明,华南地区普遍存在干旱事实,最近10年是干旱最严重的10年,Mann-Kendall检验表明该地区平均SPEI指数从1998年开始突变;干旱化最严重的区域是海南岛、广西南部和西部地区,广东的干旱化趋势最轻。20世纪70年代干旱和极端干旱事件较少,其后明显增多,干旱持续时间也有所延长。由于该地区降水呈现弱增加趋势而温度升高显著,因此推测温度升高导致蒸散增加可能是华南地区干旱化的主要原因。另外,降水频次的减少和集中也是导致近来极端干旱事件增多的原因之一。SPEI指数较好地体现了气候变暖导致的干旱化趋势。 相似文献
134.
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136.
Unusual Salinity Conditions in the Yangtze Estuary in 2006: Impacts of an Extreme Drought or of the Three Gorges Dam? 总被引:1,自引:0,他引:1
During the extreme dry year of 2006, abnormal salinity conditions in the Changjiang Estuary of the Yangtze River occurred
in partial coincidence with the second impoundment phase of the TGD (Three Gorges Dam). Analysis of discharge observations
in the upper reaches of the estuary and of salinity observations in the estuary as a whole reveals that in 2006 salinity was
over 100 mg/l during 275 days, over 250 mg/l during 75 days and over 400 mg/l during 48 days. It is well known that this is
due to extreme low discharges from the upper catchment area into the estuary. Moreover, large amounts of water consumed along
the lower reaches of the Yangtze River can also aggravate the low discharges that lead to stronger saltwater intrusion in
the estuary. Of the 75 days that salinity was over 250 mg/l, the low discharge was decreased further by 10 to 20% due to water
consumption. The additional impact of the impoundment phase of the TGD (lasting 37 days in autumn) was noticeable only during
7 days in 2006. During that period, the relative contributions of the TGD and the water consumption in the lower reaches of
the Yangtze River amounted to 70 and 30%, respectively. It may be concluded that the impact of the second impoundment phase
of the TGD on salinity intrusion in the estuary was modest, while the extreme drought of 2006 was the dominant cause. 相似文献
137.
Vietnam is a coastal country projected to be heavily affected by climate change.Binh Thuan Province is part of the driest region of Vietnam and is prone to desertification.An expert panel participated in developing a Leopold matrix which allowed for identification of desertification impact factors on the province's socioeconomic activities and assessment of the strength of cause-effect relationships in terms of magnitude and importance.Land use planning,surface water,and the length of the dry season are considered the most important causes,with the overall highest scores for both magnitude and importance in the cause-effect relationship.The largest effects of the different factors are perceived on water supply for agriculture and household use.Water availability and land use planning are important remedial action domains,while drought and land cover require monitoring to assess impacts.The indicators of cause and effect can be used in a longer-term general monitoring and assessment framework to combat desertification in the area. 相似文献
138.
Modeling Summer Month Hydrological Drought Probabilities in the United States Using Antecedent Flow Conditions 下载免费PDF全文
Samuel H. Austin David L. Nelms 《Journal of the American Water Resources Association》2017,53(5):1133-1146
Climate change raises concern that risks of hydrological drought may be increasing. We estimate hydrological drought probabilities for rivers and streams in the United States (U.S.) using maximum likelihood logistic regression (MLLR). Streamflow data from winter months are used to estimate the chance of hydrological drought during summer months. Daily streamflow data collected from 9,144 stream gages from January 1, 1884 through January 9, 2014 provide hydrological drought streamflow probabilities for July, August, and September as functions of streamflows during October, November, December, January, and February, estimating outcomes 5‐11 months ahead of their occurrence. Few drought prediction methods exploit temporal links among streamflows. We find MLLR modeling of drought streamflow probabilities exploits the explanatory power of temporally linked water flows. MLLR models with strong correct classification rates were produced for streams throughout the U.S. One ad hoc test of correct prediction rates of September 2013 hydrological droughts exceeded 90% correct classification. Some of the best‐performing models coincide with areas of high concern including the West, the Midwest, Texas, the Southeast, and the Mid‐Atlantic. Using hydrological drought MLLR probability estimates in a water management context can inform understanding of drought streamflow conditions, provide warning of future drought conditions, and aid water management decision making. 相似文献
139.
气候变化对鄱阳湖流域干旱灾害影响及其对策 总被引:6,自引:0,他引:6
以我国历史气候变化的事实与过程重建的成果为基础,以历史文献为依据,分析了两宋以来鄱阳湖流域气候变化与洪水干旱灾害发生的关系,结果表明,不管气候处于温湿期还是冷干期,发生洪水灾害的频率没有显著区别;但是当气候处于冷干时期,发生干旱灾害的频率增大,特大干旱年和连续干旱年组频频出现。利用气象、水文资料统计分析表明,最近60 a来,气温呈现增高趋势,逐年的日降水强度明显增加,洪水干旱等极端事件发生更加频繁。为了更好地应对干旱灾害,必须加强水需求管理、坚持节约用水为先;加强病险水库的治理,使其充分发挥作用;对现有水利工程进行再评估,实施适应性管理,充分挖掘工程潜力;加大力度,新建与自然和谐相处的水利工程 相似文献
140.
Enhancing the Ability of a Soil Moisture‐based Index for Agricultural Drought Monitoring by Incorporating Root Distribution 下载免费PDF全文
Hongkui Zhou Jianjun Wu Guangpo Geng Xiaohan Li Qianfeng Wang Tianjie Lei Xinyu Mo Leizhen Liu 《Journal of the American Water Resources Association》2017,53(6):1409-1423
Agricultural drought differs from meteorological, hydrological, and socioeconomic drought, being closely related to soil water availability in the root zone, specifically for crop and crop growth stage. In previous studies, several soil moisture indices (e.g., the soil moisture index, soil water deficit index) based on soil water availability have been developed for agricultural drought monitoring. However, when developing these indices, it was generally assumed that soil water availability to crops was equal throughout the root zone, and the effects of root distribution and crop growth stage on soil water uptake were ignored. This article aims to incorporate root distribution into a soil moisture‐based index and to evaluate the performance of the improved soil moisture index for agricultural drought monitoring. The Huang‐Huai‐Hai Plain of China was used as the study area. Overall, soil moisture indices were significantly correlated with the crop moisture index (CMI), and the improved root‐weighted soil moisture index (RSMI) was more closely related to the CMI than averaged soil moisture indices. The RSMI correctly identified most of the observed drought events and performed well in the detection of drought levels. Furthermore, the RSMI had a better performance than averaged soil moisture indices when compared to crop yield. In conclusion, soil moisture indices could improve agricultural drought monitoring by incorporating root distribution. 相似文献