Study On Grassland Fire Behavior And Simulation In Inner Mongolia

Inner Mongolia is a large province of grassland resources in China,and it is also a region with high fire-prone areas.The average annual grassland fire area ranks first in the country.Grassland fire is an inevitable disturbance factor in grassland ecosystem.If grassland fire is out of control,it will cause serious losses.The combustion and spreading mechanism of grassland fire is directly related to the formulation and implementation of policies such as grassland fire prediction and early warning,grassland fire ecological environment impact assessment and management.To solve the above problems,it is necessary to conduct in-depth and comprehensive quantitative research on grassland fire behavior.This paper mainly through to the Inner Mongolia grassland types of fuel in different field investigation and indoor combustion test,analyze of the Inner Mongolia prairie fuel combustion characteristics,and the space-time characteristics of fire,and through the prairie fire behavior model parameter localization,build suitable for Inner Mongolia grassland fire behavior model,using the Python programming language based on CA and GIS technology to the spread of grassland fire simulation,the final estimate of Inner Mongolia grassland fire carbon emissions.The results are as follows:(1)On the basis of field investigation,70 kinds of combustible materials of grassland in the fire-prone meadow grassland and typical grassland areas in Inner Mongolia were obtained.The cone calorimeter was used for combustion experiments.Get 10 combustion parameters of combustible material.By means of cluster analysis and principal component analysis of statistical methods,the low,medium and high degree of flammability of grassland types can be rated to provide parameter support for model simulation.The results showed that 19plantations such as sauerkraut and chrysanthemum were of higher flammability,and 25plantations such as Stipa grandis and Lilian are moderately flammable,and 26 plantations such as iris and scale gentian are less flammable.(2)Combining remote sensing and ground monitoring data,the temporal and spatial dynamics of Inner Mongolia grassland fire and fuel volume were analyzed.The results showed that the annual dynamics of fire in Inner Mongolia grassland showed a decreasing trend.During the 17 years from 2000 to 2016,the total grassland fire burning area was 5298.75 km~2,with an annual average of 311.69 km~2.Inner Mongolia grassland fire is mainly concentrated in spring,and the burning area in spring accounts for 57.75%of the total burning area.The grassland fire occurred in different seasons,and the grassland fire in April accounted for about1/3 of the total area.Autumn September,October is also the grassland fire season.From the perspective of spatial distribution,Inner Mongolia grassland fire is mainly distributed in hulun buir,xilingole and the grassland areas in the west of alshan.(3)Through a lot of field investigation and sampling,combined with the indoor combustion control experiment,the measurement parameters of fire carbon emission and the carbon emission per unit mass of combustible material in Inner Mongolia grassland were measured and calculated,and the temporal and spatial distribution pattern and change rule of fire carbon emission in Inner Mongolia grassland were analyzed.In the 17 years from 2000 to2016,the total carbon emission from grassland fire in Inner Mongolia was 2.23×10~7kg,and the average annual carbon emission was 1.31×10~6kg.There is little inter-annual change in carbon emissions.The slope of the trend line of the scatter plot of carbon emissions from2000 to 2016 is-4.57,indicating a slight downward trend.From the perspective of space,the carbon emission shows that the east central part of Inner Mongolia is a high-carbon emission area,while the west part is a low-emission area,and the overall trend is decreasing from east to west,especially in the border area.(4)This study is based on wang zhengfei’s original model.By means of field investigation and laboratory test combined with remote sensing technology,wang zhengfei’s fire speed model is modified.Two indexes,namely,Ks and Kw,are optimized and modified to localizing some model parameters.Combined with AHI/sunflower 8 data,the synchronous observation information of grassland fire occurrence was obtained,which was converted into real grassland fire process parameters,and then the spread rate of grassland fire(R)was calculated,and the constant c(c=0.35)was obtained,and the wind action coefficient of Kw was modified.According to the comparative analysis of the simulated value of the improved wang zhengfei fire model and the satellite remote sensing monitoring results,the comparison error between the calculated results and the monitoring results in the three periods of simulation and prediction is less than 10%,which shows that the accuracy of the simulation results of the improved parameter model has certain reliability.(5)Based on the improved wang zhengfei grassland fire spreading model,this study introduced Cellular Automaton(CA)into the model.By using Python programming language,Geographic Information System(GIS)technology and Arcpy site package,the CA-wang zhengfei grassland fire spreading model was constructed to realize dynamic simulation of grassland fire field.Based on the modified CA-wang zhengfei model Based on the modified CA-wang zhengfei model.The results of remote sensing monitoring of two grassland fires occurred successively in East Wuzhumuqi were compared.The results showed that:with the increase of the correction coefficient of fuel configuration,the fire spreading speed,fire line intensity and flame length all show an increasing trend.In addition,the overlap between the burned area of the four periods simulated by the model and the burned area of the actual monitored burned area accounts for 87.49%of the monitored burned area.The model combined by CA and GIS has certain application value.