نتایج جستجو برای: drought trend
تعداد نتایج: 152148 فیلتر نتایج به سال:
Drought is a concept that is generally understood on a basic level, but is difficult to quantify. Palmer defined a drought as a meteorological phenomenon that is characterized by ‘‘prolonged and abnormal moisture deficiency. A drought can alternatively be broadly defined as a temporary, recurring reduction in the precipitation in an area. Aridity and drought are not synonymous. A...
Introduction Drought is one of the environmental disasters that is very frequent in arid and semi-arid regions of the country. Rainfall defects have different effects on groundwater, soil moisture, and river flow. Meteorological drought indices are calculated directly from meteorological data such as rainfall and will not be useful in monitoring drought if the data are missing. Therefore remot...
Projected changes in the frequency and severity of droughts as a result of increase in greenhouse gases have a significant impact on the role of vegetation in regulating the global carbon cycle. Drought effect on vegetation Gross Primary Production (GPP) is usually modeled as a function of Vapor Pressure Deficit (VPD) and/or soil moisture. Climate projections suggest a strong likelihood of incr...
introduction: drought is a recurrent feature of climate that caused by deficiency of precipitation over time. due to the rise in water demand and alarming climate change, recent year’s observer much focus on drought and drought conditions. a multiple types of deficits and relevant temporal scales can be achieved through the construction of a joint indicator that draws on information from multip...
Land use change in watershed management one of the most important hydrological factors surface runoff change and water management practices. the purpose of this investigation, Impact of Land Use and drought on runoff of Tuyserkan watershed in Hamedan In central zagros In the three time periods of 1991, 2003 and 2015 (25 years) using hydrological modeling is the rainfall-runoff relationship (I...
consecutive droughts in sistan and baloochestan province cause water resources restriction and this isa very significant problem for this region. in this study, in order to forecast the drought cycle in 9climatological stations in the province, we used artificial neural networks. the input data wereaverage of annual rainfall data in all stations and also deciles precipitation index, which the f...
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