نتایج جستجو برای: drought trend

تعداد نتایج: 152148  

Journal: :Science 2004
Edward R Cook Connie A Woodhouse C Mark Eakin David M Meko David W Stahle

The western United States is experiencing a severe multiyear drought that is unprecedented in some hydroclimatic records. Using gridded drought reconstructions that cover most of the western United States over the past 1200 years, we show that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900 to 1300, an interval broadly consistent with the Med...

Investigation of changes in groundwater resources is of great importance in planning and sustainable management of water resources. Knowledge on the relationship between groundwater and drought is prerequisite for water resources management. In this study, climatic variables including evaporation, temperature, precipitation as well as hydrological variables i.e. discharge and groundwater depth ...

ژورنال: علوم آب و خاک 2014

The geographical location of Isfahan province has led the province to be at risk of drought. One of the ways to mitigate drought is evaluation and monitoring of drought based on indices that can determine its intensity and permanence in each region. In this research, for drought and trend analysis standard precipitation index and Mann-Kendall test were used, respectively. Also, monthly precipit...

Journal: :Remote Sensing 2017
Shiliang Liu Yueqiu Zhang Fangyan Cheng Xiaoyun Hou Shuang Zhao

Grassland, as the primary vegetation on the Qinghai-Tibet Plateau, has been increasingly influenced by water availability due to climate change in last decades. Therefore, identifying the evolution of drought becomes crucial to the efficient management of grassland. However, it is not yet well understood as to the quantitative relationship between vegetation variations and drought at different ...

2018
Amy E Hessl Kevin J Anchukaitis Casey Jelsema Benjamin Cook Oyunsanaa Byambasuren Caroline Leland Baatarbileg Nachin Neil Pederson Hanqin Tian Laia Andreu Hayles

The severity of recent droughts in semiarid regions is increasingly attributed to anthropogenic climate change, but it is unclear whether these moisture anomalies exceed those of the past and how past variability compares to future projections. On the Mongolian Plateau, a recent decade-long drought that exceeded the variability in the instrumental record was associated with economic, social, an...

Journal: :علوم گیاهان زراعی ایران 0
رضا کشاورز افشار دانشجوی دکتری مسعود کیخواه کارشناس ارشد محمدرضا چائی چی دانشیار، پردیس کشاورزی و منابع طبیعی کرج، دانشکده علوم زراعی و دامی، گروه زراعت و اصلاح نباتات، تخصص: اکولوژی گیاهان زراعی محیا انصاری جوینی دانشجوی دکتری

salinity and drought stress are among the common environmental factors which adversely affect germination and growth of plants. this experiment was conducted to evaluate the effects of salinity and drought stress on turnip seed germination and early growth in seed lab of college of agriculture, university of tehran, during 2010. the experimental design was a complete randomized block with three...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید چمران اهواز - دانشکده مهندسی علوم آب 1393

drought is transient phenomenon , slow , repetitive and integral part of the climate of each region. drought begins with a substantial reduction in precipitation over the long-term average rainfall and over time, reduced soil moisture and surface and ground water resources will continue to decrease. this phenomenon is the most important in bakhtegan basin because of its importance in strategic ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده برق و کامپیوتر 1392

هدف از انجام این پروژه آشکارسازی trend باند آلفا سیگنال الکتروانسفالوگرام با استفاده از پردازش تصویر اسپکتروگرام آن است. به عبارت دیگر تغییرات ایجاد شده در طیف باند آلفا که در طول زمان و به دلیل یک پدیده¬ی فیزیولوژیکی یا شناختی رخ می¬دهد را بتوان با استفاده از پردازش اسپکتروگرام آشکار کرد. در این پروژه خستگی ذهنی به عنوان یک پدیده¬ی شناختی برای ایجاد تغییرات در باند آلفا مورد مطالعه قرار گرفت. ...

2016
Yajing Lu Denghua Yan Tianling Qin Yifan Song Baisha Weng Yong Yuan Guoqiang Dong

Based on the national precipitation dataset in the Huang-Huai-Hai River Basin of China for the 1961–2011 period, the China-Z growing season index was calculated to analyze the characteristics of the evolution of meteorological droughts. Data from statistical droughts (the droughts which are defined and classified by the actual statistic data) were compared with those of meteorological droughts ...

Germination and seedling establishment are sensitive and important stages in the life cycle of plants that are affected by abiotic stresses, especially drought and salinity stresses. This study was conducted to investigate the effects of osmotic potential (due to sodium chloride and polyethylene glycol) on germination and biochemical indices of Salicornia sinus-persica Akhani spec. nov.Akhani s...

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