Dynamic Risk Assessment And Prediction Of Grassland Fire Disaster In Inner Mongolia Under Climate Change

In recent years,the abnormal global climate change has led to the frequent occurrence of extreme weather events,drought and other meteorological disasters.At the same time,the fire risk level of grassland is also gradually rising.Grassland fire disaster are showing a new trend of frequent occurrence in spring and autumn and extending throughout the year.Affected by climate change,most parts of the world have entered a period of grassland fire disaster-prone.Over time,the long-term effects of climate change on the types of combustibles,the accumulation of combustibles,and the short-term effects on fire disaster risks and fire behaviors superimposed on each other,which will further increase the occurrence of grassland fires.Grassland fire disaster is an important part of natural disasters,and its risk assessment has attracted the attention of researchers from various countries.However,research on the impact of climate change and grassland fire disaster risk in China is relatively scattered,with less assessment of past impacts and weak assessment of future risks.China is a large grassland country.The natural grassland accounts for 41.7%of the whole land area.Among them,grassland fire disaster-prone areas account for 1/3 and frequent areas account for 1/6.Inner Mongolia is a high-incidence area for grassland fires disaster in northern China.Since the founding of the China,there have been more than 50000 grassland fires in pastoral areas,with a total of 200 million hm~2 of grassland affected,causing economic losses of more than 60 billion RMB,an average of more than 1 billion RMB per year.Inner Mongolia has abundant grassland resources,is an important agricultural production zone in China,and an important ecological barrier in the north.It is of great significance to the sustainable development of economy and society.Therefore,a study on the risk assessment and prediction of grassland fire disaster under the climate change is proposed to realize the transformation of grassland fire disaster management,from crisis management to risk management,and from post-disaster assessment to risk estimation in Inner Mongolia.This research starts from the starting from the continuum of soil-plant-atmosphere,takes different seasons and different vegetation types as the starting point,and takes the grassland fire disaster in Inner Mongolia as the research object.It uses the multi-source data such as meteorological data,remote sensing,basic geographic data,historical disaster statistics and field ground samples data.Under the understanding of the temporal and spatial distribution and evolution characteristics of grassland fire disasters and their impact mechanisms,based on the formation mechanism of disaster risk,construct a comprehensive grassland fire hazard evaluation system,combining field ground measurement data and remote sensing data to establish the vulnerability assessment model of grassland fire disaster,and then establish a new comprehensive grassland fire risk dynamic assessment method under climate change,and carry out dynamic assessment and grading division of grassland fire risks of different grassland types in different seasons.Furthermore,it is coupled with the Coupled Model Intercomparison Project 5(CMIP5)to predict the evolution characteristics of grassland fire risk in different seasons in Inner Mongolia under different carbon emission scenarios.The main content of the paper has the following aspects:(1)Temporal and spatial evolution and influencing factors of grassland fire disaster in Inner MongoliaThe temporal and spatial distribution and evolution characteristics of grassland fire disaster in different seasons in study area were discussed and analyzed by using MCD64A burned area data.The temporal and spatial distribution and evolution characteristics of grassland fire disaster is closely related to the distribution and variation of natural and human factors in the study area.The importance identification and contribution rate ranking of grassland fire disaster impact factors in different seasons were carried out by using random forest model(RF)to systematically reveal the impact of natural and human activities on grassland fire disaster in different seasons.The results show that the grassland fire disaster are concentrated in the eastern part of the study area,with the highest concentration in spring.On an interannual scale,grassland fires in the study area showed a decreasing trend from2001 to 2010,and an upward trend from 2009 to 2018.The ranking results of the contribution rate of influencing factors show that the NDVI has a higher contribution rate of grassland fires in each season,followed by factors related to water conditions.Through research on the relationship between influencing factors and grassland fires,it is found that the number of grassland fire disaster is positively correlated with factors related to temperature and precipitation.Its positively correlated with the frequency of drought in spring and autumn,negatively correlated with the frequency of drought in summer,and with the frequency of drought in winter is no obvious relationship.The number of grassland fires is positively correlated with the NDVI of the growing season,and the number of grassland fire disaster occurrences from more to less is:meadow grassland,typical grassland,desert grassland,and steppe desert.(2)Risk evaluation of grassland fire using multi-source data fusion in Inner MongoliaFrom the perspective of soil-plant-atmosphere system.First,the Fire Source Hazard Index(FSHI)of grassland fire disaster was established by using three different fire source factors.Second,the vegetation coverage,vegetation type and soil moisture are used to establish the Fire Fuel Hazard Index(FFHI).Then,the probability of grassland fire occurrence under the combined effects of multiple climatic factors is calculated as the Fire Environmental Hazard Index(FEHI).Finally,the above three indexes are used to establish the different seasons and different grassland types in Inner Mongolia.The grassland fire disaster comprehensive risk assessment model is used to conduct risk assessment and zoning of grassland fire disaster in Inner Mongolia.The results show that the fire risk of grassland has obvious seasonal and regional heterogeneity.Among them,the extremely high risk is mainly distributed in Hulunbuir meadow steppe area,the medium and high risk is distributed in the meadow steppe area of the study area,and the low risk is distributed in the desert steppe area.(3)Vulnerability assessment of grassland fire risk in Inner MongoliaThe annual grass yield of the study area was inversed by combining the field measured biomass data and remote sensing data of three different years.According to the grassland fire disaster area,the grass yield loss caused by previous grassland fire was calculated to characterize the grassland fire disaster sensitivity in the study area.The vulnerability assessment model of Inner Mongolia grassland fire was established by using the exposure of regional disaster bearing body and the management ability of grassland fire.The results show that the vulnerability of grassland fire in Inner Mongolia has a wide range and high grade in spring,followed by autumn,winter and summer.In spatial distribution,the extremely high vulnerability is mainly concentrated in the meadow steppe area in the southeast of Hulunbuir City,the high vulnerability is distributed in the east of the typical steppe area,and the moderate vulnerability is distributed in the west of the typical steppe area.(4)Dynamic assessment risk of grassland fire disaster in Inner MongoliaBased on the two-factor theory of comprehensive disaster risk,according to the natural and social attributes of grassland fire disaster,and based on the comprehensive risk and vulnerability of disaster bearing body of grassland fire disaster in Inner Mongolia,the risk assessment model of grassland fire disaster in Inner Mongolia under climate change is established.The typical years of grassland fire disaster risk explosion(2003,2008)and less typical years of grassland fire(2013)in the study area and the typical years of 2001 are analyzed,dynamic risk assessment and zoning of grassland fire in 2018.The results show that the grassland fire risk was mainly concentrated in spring in 2003 in the study area,with a wide range of risks and strong clustering of extremely high risk.The grassland fire risk was mainly concentrated in autumn in 2005,and the extremely high risk was concentrated in the northeastern corner of the East Ujumqin Banner of the Xilin Gol League to the border area between Aershan City of Xing'an League and Mongolia.In 2013,there was no extremely high level of fire risk in the study area.From the perspective of the entire research time scale(2001-2018),grassland fire risk is mainly concentrated in the three seasons of spring,summer and autumn,and the risk in winter is relatively low in Inner Mongolia.Among them,the extremely high risk is mainly concentrated in the meadow grassland areas in the central and eastern Inner Mongolia.(5)Risk prediction of grassland fire disaster in Inner Mongolia under RCPs scenariosThis chapter uses the coupling of the CMIP5 climate change model and the risk of grassland fire disaster assessment model to predict the grassland fire disaster risk in the middle(2040-2060)and end(2080-2100)of the 21st century under the RCP4.5and RCP8.5 scenarios in Inner Mongolia.Under the premise that the vulnerability remains unchanged,further predict the evolution characteristics of the grassland fire disaster risk in Inner Mongolia under different RCPs scenarios in the future.The results show that with the increase in the concentration of greenhouse gas emissions,the future climate of the study area will continue to be warmer and humid.The prediction of the future changes of different grassland types found that the eastern meadow grassland boundary of the study area expands and the area increases under the RCP4.5/8.5 scenario;The typical grassland area moves obviously to the west under the RCP4.5 scenario,and invades significantly to the east under the RCP8.5scenario;The area of the desert grassland is reduced,and there is a slight insignificant movement to the east and south.The intensity of grassland fire risk in RCP4.5scenario is higher than that in RCP8.5 scenario in the middle of the 21st century,and the distribution range of moderate and above level risk in RCP8.5 scenario is wider.At the end of the period,the grassland fire risk level under RCP8.5 scenario was higher,for example,the proportion of extreme high risk area increased by 19.5%and17.8%compared with the base period and RCP4.5 scenario.The increase of grassland fire risk in spring is the largest,followed by summer,autumn again,and winter is the smallest.