Study On Spatial And Temporal Distribution Of Locust Disaster Using Remote Sensing In Kebudo Province,Mongolia

The locust plague is one of the three major natural disasters,which causes great damage in agriculture,forestry and animal husbandry.Many areas have suffered locust plague to varying degrees.Due to the climate anomalies and human factors and other reasons,in recent years the situation of locust plague has become more serious.Mongolia is also threatened by the locust plague and the Eclipophleps Serg Tarb is the main type of locusts in this country.It has the characteristics of rapid reproduction,large food intake and strong ability to spread,which seriously affects the natural growth of the grassland.The locusts on Mongolia's grassland have posed a threat to the sustainable development of the grassland's ecological environment and animal husbandry.Therefore,the study of monitoring locust plague has become extremely important,which cannot be ignored.The thesis adopts the area of locust plague,province Kebuduo,as the study area,with the spectral information of the vegetation damaged by Eclipophleps Serg Tarb.Based on the long-term data of vegetation coverage monitored by remote-sensing image,though the extent of damage,it draws the conclusion of the degree and distribution of the locust plague.That is,taking the period from June 1 to 30,2012(Growing Season)as the research period,the MODIS daily shadowgraph of the time zone is extracted.For the downloaded MODIS data,it carries out image fusion,projection transformation,resampling and other pretreatments,to get the values of vegetation indexes required by the thesis,namely,the values of NIR,NDVI and RVI.With the three indexes,it analyses the characteristics of the temporal and spatial variation of the vegetation coverage in the disaster area,which shows that the locust plague directly affects the changes in the vegetation growth and coverage.Based on this,changes in the vegetation growth and coverage can reflect the severity of locusts,thus using the three indexes to know the severity of locusts.Finally,the law of temporal and spatial variation of the locust plague is analyzed.The main conclusions are as follows:(1)In early June of 2012,the grassland vegetation in province Kebuduo reduced mainly in the central region along the mountain Alatai,especially Qiqig?Darvi and Manhan Significant changes rose in Mosite?Zhalait?Menhair and Dute.In mid-June of 2012,the grassland vegetation reduced mainly in the central and northwest regions.In late June,the Eclipophleps Serg Tarb finished the growth and came into the spawning period,so during this period there was no situation where a large number of vegetation was destroyed.The vegetation growth and distribution improved during this period,which basically accorded with the actual situation.Only small areas of the vegetation in Manhan ? Alatai and Burgan reduced.(2)The temporal variation pattern of the grassland's vegetation coverage in province Kebuduo in June of 2012 showed that the vegetation coverage was decreasing in early June and the low value period was from June 19 to 22.This was slightly different from the growing season of the vegetation in June.It indicated that during the study period,large-area locust plagues occurred in the grassland area of province Kebuduo,Mongolia,which was consistent with the actual situation.In late June,the vegetation coverage began to rise again,indicating that the situation of the vegetation improved during this period.(3)According to the severity of the locust plagues occurred in province Kebuduo,it finds out the characteristics of the temporal and spatial variation in different time.In mid-June of 2012,the area of mild locust plague in province Kebuduo increased from 18.43% to 25.10%,increasing by 6.67%,compared with that of early June.The area of the moderate locust plague increased by 11.98%.Similarly,the area of severe locust plague increased from 10.22% in early June to 21.50% in mid-June.In late June of 2012,the area of mild locust plague reduced by 11% and10.76%,respectively,compared with those of moderate locust plague and severe locust plague.In late June,there was no area of serious locust plague.(4)The locust plague-prone area was mainly on both sides of mountains Alatai;namely,the locust plagues occurred in the central region of province Kebuduo were more serious.There were suitable hydrothermal conditions and plants that could provide suitable habitat and food.In desert and semi-desert grassland areas,locust plagues were less likely to occur due to the sparse vegetation,which was consistent with the actual situation.