Study On Evaluation Of Forest Surface Fuel Flammability

Forest fires are frequently occurring forest disasters with sudden and destructive characteristics,resulting in huge losses of forest resources.It’s a serious threat to social security.Forest fire forecast is one of the key measures in the management of forest fire regime,which provides a scientific basis for decision making fire management.In view of the field surface fuel flammability difficult to dynamic evaluation problem and the surface fuel flammability affected by meteorological environment,select forest farmof North China Forestry Experimental Center of China Academy of Forestry as the study area,and select Pinus tabulaeformis forest combustible surface fuel、Quercus variabilis forest surface fuel、bush surface fuel as the study material.With the application of GIS digital terrain analysis technology、infrared image analysis technology and computer simulation technology,the study has a surface fuels dynamic evaluation to achieve precise evaluation of flammability.Based on the dynamic meteorological data and the surface fuel combustion experiment,a model for the comprehensive evaluation of the surface fuel combustion was established.At the same time,it puts forward the method and the process of the combustion of the ground surface.The comprehensive dynamic evaluation of the surface fuel combustion is realized.The study’s result effectively improve the accuracy of forecasting forest fire risk,while providing a scientific basis for grassroots forest fire prevention.The main results and conclusions are as follows:(1)Several mountain meteorological interpolation models are established.It realizes the mountain fire weather environment simulation.Using the fire weather data of online meteorological station real-time field monitoring in state forest farm,based on digital terrain analysis(DTA),study on fire weather spatial interpolation.The successful prediction of forest fire meteorological factors on value.Temperature,precipitation,humidity and wind speed four fire weather factor were predicted by PRISM interpolation model,MTCLIM interpolation model and WindNijia interpolation software.The prediction accuracy of mountain fire weather interpolation model are relatively high.Daily temperature PRISM spatial interpolation model prediction accuracy for MAE at 0.34-0.57 DEG C,RMSE at 0.36-0.59 DEG C.The daily precipitation PRISM spatial interpolation model for prediction accuracy: MAE is 1.68 mm,RMSE is 2.26 mm.The precision of atmospheric humidity MTCLIM spatial interpolation model: MAE in the range of 3.07-6.21%,RMSE in the range of 1.78-5.84%,the average relative error is less than 25%.(2)The prediction model of surface fuel moisture content is established.The dynamic prediction of water content is realized.The principle of phase change of surface fuel moisture content is studied.Based on the precipitation,temperature,humidity,wind speed and other fire weather dynamic data,surface combustible drying characteristics and evapotranspiration mechanism model,the research constructs the surface fuel moisture content piecewise prediction model.By analyzing the surface fuel loss characteristics,the water content prediction model is established,and the prediction accuracy is relatively high.Study found that error indicators are: MAE is 1.19,MRE is 7.2%.In the moisture content prediction model of wave stage,the correction coefficient of Penman-Monteith model is 0.33.Pinus tabulaeformis under different temperature filtration characteristics of the different surface fuel material.When the temperature is higher,the evaporation rate,the greater the filtration characteristic curve is steep.(3)A new evaluation method and method of surface fuel combustion is presented.The dynamic comprehensive evaluation of combustion is realized.Based on infrared image analysis technology,clustering analysis method and ignition observation experiment,the dynamic comprehensive evaluation of the combustion of surface combustible material using infrared observation index is studied.Based on the database of the combustion property,the extraction of the evaluation rules for the combustion grade of the surface fuel is studied.The combustion properties of fuel with different water content in the archive.The grade evaluation of surface fuel combustion is realized.Three types of surface combustible burning level evaluation rules of Pinus tabulaeformis surface flammability assessment for the set of four water rate step size for 48.6%,30.0%,21.2%,10.8%.The water level of the evaluation is based on the rate of size 48.1%,42.5%,27.8%,22.4% surface fuel combustion Vitex scrub.The water level of the evaluation is based on the rate of size 29.3%,22.6%,15.8%,11.2% of Quercus variabilis forest surface fuel combustion.