نتایج جستجو برای: in 2002 approximately eight million hectares of agricultural land suffered from drought

تعداد نتایج: 24767166  

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 یزد - دانشکده جغرافیا 1392

the west of esfahan province, iran, is one of the most important agricultural areas throughout the country due to the climate variability and life-giving water of zayanderood river. rice is one of the major and economic crops in this area. the most important climatic elements in agricultural activities which should be considered include temperature, relative humidity, precipitation and wind. so...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تبریز - دانشکده کشاورزی 1394

with the increasing population and the need for more food, as well as with the development of science and technology, human approach to unnatural and often chemical inputs to increase agricultural production has been a great expansion and problems such as increased cancers, chronic diseases has created environmental pollution. implementation of organic organic is a solution to these problems . ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تبریز - دانشکده ادبیات و زبانهای خارجی 1393

abstract in written mode of language, metadiscourse markers are used commonly to help writers in general and academic writers in particular to produce coherent and professional texts. the purpose of the present study was to compare introduction sections of applied linguistics and physics articles regarding their use of interactive and interactional metadiscourse markers based on the model pro...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه فردوسی مشهد - دانشکده ادبیات و علوم انسانی 1391

the present dissertation aims to investigate four-word lexical bundles in applied linguistics research articles by iranian and internationally-published writers. the aims of this study are two-fold: first of all, attempts have been made to create a comprehensive list of the most commonly used four-word lexical bundles categorized by their type and token frequency, their structural characteristi...

2007

1. Agriculture is the predominant user (75-80%) of the available freshwater resource in many parts of the world. At present most of the water used to grow crops is derived from rainfed soil moisture, with non-irrigated agriculture accounting for some 60% of production in developing countries. Although irrigation provides only 10% of agricultural water use and covers just around 20% of the cropl...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده علوم انسانی 1389

rivers and runoff have always been of interest to human beings. in order to make use of the proper water resources, human societies, industrial and agricultural centers, etc. have usually been established near rivers. as the time goes on, these societies developed, and therefore water resources were extracted more and more. consequently, conditions of water quality of the rivers experienced rap...

Journal: :محیط شناسی 0
علی سلاجقه دانشکدة منابع طبیعی دانشگاه تهران، دانشیار گروه احیا مناطق خشک و کوهستانی سمانه رضوی زاده دانشکدة منابع طبیعی دانشگاه تهران، کارشناس ارشد آبخیزداری و عضو باشگاه پژوهشگران جوان نعمت الله خراسانی دانشکدة منابع طبیعی دانشگاه تهران، استاد گروه محیط زیست مینا حمیدی فر کارشناس ارشد محیط زیست سوسن سلاجقه دانشکدة منابع طبیعی دانشگاه تهران ، دانشجوی کارشناسی ارشد محیط زیست

in the case of iran with arid and semiarid climate and lack of freshwater, pay attention to water quality and its effective factors is necessary. karkheh watershed is more than 5 million hectares in area and with biggest soil dam in asia, which has widespread land use changes in last decades. the most important factors of water volume and water resources reduction are aridity and improper land ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان - دانشکده مهندسی 1392

flow in natural river bends is a complex and turbulent phenomenon which affects the scour and sedimentations and causes an irregular bed topography on the bed. for the reason, the flow hydralics and the parameters which affect the flow to be studied and understand. in this study the effect of bed and wall roughness using the software fluent discussed in a sharp 90-degree flume bend with 40.3cm ...

Assessment of land use changes in the previous years and prediction of these changes in the following years is an essential tool for different planning and management of natural resources. Therefore, the aim of present study is modeling of land use changes in Mehran Plain using Markov- Cellular automata Model in 2028. In order to detect land use changes in the studied area, TM and ETM+ satellit...

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