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Northeast Normal University (2017)

Research on Rapid Evaluation Ofthe Grassland Drought Disaster Loss

马齐云;

Titre : Research on Rapid Evaluation Ofthe Grassland Drought Disaster Loss

Auteur : 马齐云;

Grade : Master’s Theses 2017

Université : Northeast Normal University

Résumé partiel
Meteorological disasters tend to become more frequency and intensity in China,in the context of global warming.These meteorological disasters have caused great negative impacts on human lives and socioeconomic wealth.As one of the major meteorological disasters,drought disaster poses a great threat to food security and restricts the sustainable development of agricultural and animal husbandry economy.The current studies and obtained achievements of drought are mainly focused on the traditional agricultural field about risk assessment.However,the grassland drought disaster and its impact on the animal husbandry economy is less well understood.China is a country with abundant grassland resources and ranks second in the world for the grassland area.Grassland system has an important ecological and economic value.However,significantly affected by human activities and climate change,the natural disasters occur frequently,especially grassland disaster,and cause the severe damages to the society in the grassland region.Therefore,this study proposes a topic on rapid evaluation of the grassland drought disaster loss,which aims to provide the scientific and important basis for developing policies of timely and effective disaster prevention and mitigation.Songnen Grassland was taken as a case study area,and the grassland was selected as the main hazard-bearing body.Based on the theory of regional disaster system,the impacts of grassland drought disaster on grassland yield and carrying capacity was rapid quantitatively evaluated by analyzing the relationships between the various drought intensity and the corresponding fluctuation of grassland NPP.This study set the following specific research contents : to analyze the background of grassland drought disaster from three aspects : hazard factor,hazard-formative environment,and hazard-bearing body ;to investigate the spatial and temporal variations by the Standardized Precipitation-Evapotranspiration Index(SPEI)used to represent drought intensity ;to estimate the monthly vegetation net primary product(NPP)using the Carnegie-Ames-Stanford Approach(CASA)model based on the MODIS NDVI dataset and meteorological data during 2005-2014,and analyze the spatiotemporal variations of vegetation NPP in the growth season of grassland(from April to September) ;to construct the loss rate curves of grassland drought disaster based on the CASA model and the field and indoor experiment in each growing stage ;and to achieve the rapid quantitatively evaluation of the grassland drought disaster loss for grassland yield and carrying capacity in typical case year in each growing stage based on the loss rate curves and the conversion relation between grassland NPP and grassland yield.The Main results are as follows :(1)The SPEI-6 indicated a decreasing but not significant during the growing season,with a rate of 0.12 /10 a.The break analysis showed the sharpest and significant drop rate was detected from 1970 to 2009 of 0.38 /10 a.There was a clear change point in 1993 from analysis of abrupt changes,at which the evident decreasing trend began.Moreover,wavelet analysis revealed that SPEI-6 exists 10-11 years in periodic variation over the Songnen Grassland.(2)From a spatial perspective,the SPEI-6 had the highest decreasing rate in the southern region,on the whole,ranging from 0.51 to 0.41 /10 a.Monthly,grassland drought tends to be alleviated in the northern and central regions for the past 55 years

Mots clés : Grassland drought disaster; Rapid evaluation of loss; loss rate curves; CASA model; Vegetation NPP;

Présentation (CNKI)

Page publiée le 9 février 2018