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China Agricultural University (2018)

Remote Sensing Spatial Observations Using Vegetation Temperature Condition Index for Drought Monitoring Over Punjab of Pakistan


Titre : Remote Sensing Spatial Observations Using Vegetation Temperature Condition Index for Drought Monitoring Over Punjab of Pakistan


Grade : Doctoral Dissertation 2018

Université : China Agricultural University

Drought is a complex phenomenon of environmental processes and considered as the stochastic nature of hazards with a prolonged scarcity and dearth character that results from the meager annual precipitation and superficial water contents.Drought is a prolonged event of insufficient rainfall with follow-on extensive damage to crops,resulting in loss of yield.The drought has always impacted the agricultural,meteorological,ecological and socio-economic with potentially significant consequences.The global warming causes the global climate changes,and Pakistan listed in number eight of the most affected ten countries from 1995-2014 in the world.The natural disasters in response to drought and flood are the most common and frequently occurring hazards in Pakistan over a recent couple of century due to environmental,climatic and ecosystem anthropogenic factors.Droughts and floods are the world’s costliest natural disasters due to extreme climate events under global warming conditions.This is obvious to investigate the agricultural drought conditions in the region,as the soil moisture had a significant role in retains of dry and wet spells in both rain-fed and irrigated conditions and the key indicator of drought and flood.This study determines the multi-years drought conditions as well as the warm edges(LSTmax)and cold edges(LSTmin)in response to soil moisture during 2003-2014 over the cropland of Punjab,Pakistan.This learning employed the Spacebome EOS’s Moderate Resolution Imaging Spectroradiometer(MODIS)data products to acquire the land surface conditions during the winter wheat crop season in the cropland of the plain under rain-fed and irrigated conditions.The employed near-real-time drought monitoring approach termed as vegetation temperature condition index(VTCI)integrate the normalized difference vegetation index(NDVI)and land surface temperature(LST)to determine the warm and cold edges as well as to investigate dry and wet conditions vigorously.The VTCI feature plots reside in LST-NDVI space is the most appropriate method for the determination of VTCI imagery as well as warm and cold edges in response to soil moisture.The geospatial near-real-time coupling(NRTC)approach,which utilizes the VTCI time series values and daily precipitation data,was used for the validation of dry and wet spell at five weather-stations in the plain of Punjab.Variations in warm and cold edges expose the drought conditions due to weather extreme’s uneven temperature from winter into summer.The spatial and temporal observations of the VTCI imagery in the specified periods present the dry and wet conditions due to temporal changes of the land surface soil moisture conditions and demonstrate the irregular retreat states of edges for the agricultural practices which depend on the location and season in the region.The VTCI drought monitoring approach is categorized and offers with normality or wetness(1.00-0.57),mild drought(0.56-0.44),moderate drought(0.43-0.38)and severe drought(0.37-0.00).The VTCI time series generalized characteristics of the drought exhibit the plain with respective weather-stations in three climate zones(south,center,and northeast).The south and center of the plain with low accumulative precipitation results insignificant VTCI values,whereas,in the northeast with adequate precipitation results in significant VTCI values.Even though the Plain had the best-irrigated system but the temporal and spatial observations reveal that the south and center of the plain expose to drought in contrast to the northeast with high occurrences of drought,whereas,the northeast indicates most of the normal conditions of drought in the plain.The VTCI spatial and temporal observations in the region during the 12-yr period represent mostly significant drought conditions in the northeast in contrast to centre and south with insignificant drought conditions for the winter wheat crop seasons in the year of 2004,2006,2008,2010 and 2011 during 2003 to 2014 under both rainfed and irrigated conditions in the region.

Mots clés : Drought monitoring; determination; vegetation temperature condition index; warm and cold edges; Punjab of Pakistan;

Présentation (CNKI)

Page publiée le 16 avril 2019