نتایج جستجو برای: desertification map

تعداد نتایج: 196664  

In order to deal desertification phenomenon it is necessary to identify its producing and increases causes. For this purpose several studies conducted inside and outside the country that have been led to submit regional models.. Each of these models has different pattern and use different indicators which can lead to different results. In this study, Fakhrabad plain of Mehriz region by extent o...

Journal: :Remote Sensing 2011
Doris K. Lam Tarmo K. Remmel Taly D. Drezner

Most remote sensing studies in deserts focus solely on vegetation monitoring to assess the extent of desertification. However, the application of sand dune encroachment into such studies would greatly improve the accuracy in the prediction criteria of risk-prone areas. This study applies the latter methodology for tracking desertification using sand dunes in the Kelso Dunes (in Newberry-Baker, ...

2011
J. F. REYNOLDS D. M. STAFFORD SMITH G. BASTIN L. GARCIA-BARRIOS R. J. FERNÁNDEZ M. A. JANSSEN N. JÜRGENS R. J. SCHOLES A. VELDKAMP M. M. VERSTRAETE G. VON MALTITZ P. ZDRULI

The Global Drylands Observing System proposed in this issue should reduce the huge uncertainty about the extent of desertification and the rate at which it is changing, and provide valuable information to scientists, planners and policy-makers. However, it needs careful design if information outputs are to be scientifically credible and salient to the needs of people living in dry areas. Its de...

1998
S. E. Nicholson

Many assumptions have been made about the nature and character of desertification in West Africa. This paper examines the history of this issue, reviews the current state of our knowledge concerning the meteorological aspects of desertification, and presents the results of a select group of analyses related to this question. The common notion of desertification is of an advancing “desert,” a ge...

2004
Steffen Bauer

Embedded in a larger qualitative research framework on organizational effectiveness, this paper explores the role of small treaty secretariats—conceptualised as a distinct type of intergovernmental organizations—in international politics. Although the relevance of bureaucratic actors in international negotiations and regime implementation has been acknowledged by a number of scholars, IR resear...

2006
MATTHEW A. BOWKER HARLAND GOLDSTEIN

1. Desertification negatively impacts a large proportion of the global human population and > 30% of the terrestrial land surface. Better methods are needed to detect areas that are at risk of desertification and to ameliorate desertified areas. Biological soil crusts are an important soil lichen-moss-microbial community that can be used toward these goals, as (i) bioindicators of desertificati...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه یزد 1388

یکی از مسائلی که در سیستم sar مطرح می شود مسأله نویز speckle می باشد. منبع تولید نویز speckle فاز نسبی پراکنده گرهای مختلف در یک سلول رادار می باشد که نوسانات شدیدی در سیگنال دریافتی به وجود آورده و تصویر حاصل را دانه دانه می نماید. این نویز تفسیر تصاویر را مشکل و اطلاعات زیادی را مخفی می کند و لذا کاهش آن یکی از ملزومات در پردازش سیگنال sar است. الگوریتمهای متعددی جهت کاهش نویز speckle در نوا...

Soil is one of the most important natural resources covering a large area of the land surface. Soil plays a vital role in biosphere processes, such as energy balance, hydrology, biochemistry, and biological productivity. It supports plants that supply foods, fibers, drugs, and some other human needs. Conversely, desert regions include about one third of earth lands and these regions have increa...

2016
Ignacio Bordeu Marcel G. Clerc Piere Couteron René Lefever Mustapha Tlidi

Desertification due to climate change and increasing drought periods is a worldwide problem for both ecology and economy. Our ability to understand how vegetation manages to survive and propagate through arid and semiarid ecosystems may be useful in the development of future strategies to prevent desertification, preserve flora-and fauna within-or even make use of scarce resources soils. In thi...

2010
D. Kaneko N. B. Chang T. Kumakura

This paper aims to present an integrated approach for assessing the desertification processes on one hand and spot possible source locations of dust storm in Eurasian continent across the central Asia and northern China on the other hand. The authors have bu ilt Remote Sensing Environmental Monitor (RSEM) for Desertification Assessment System (DAS). Such an integrated sensing, monitoring and mo...

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