Effect Of Drought In Songnen Plain Farmland Meadow Of Hundred Years

Based on the Songnen Plain as the study area,based on the land use / land cover data in the atlas,thematic map data and historical data as the data source,the TM remote sensing image in 2010,meteorological data and CRU reanalysis data,using geographic information system as the analysis tool,using the statistical analysis method of Songnen Plain,the characteristics of land use change and change the drought index,and reveals the influence of land use change on surface drying effect.The results show that:(1)In 1910 s,forest land,farmland land,grassland and marsh dominated land use type accounted for 97.5% of the total area in the study are,the grassland area the largest,most widely distributed and film distribution,the region accounted for 44.0%;followed by forest land,farmland landand,marsh dominated land,the region accounted for23.6%,20.5%,9.4%;land and other land area minimum waters,construction,proportion is minimal,dispersed distribution.2010 s is given priority to with farmland land and forest land,including farmland land,the largest proportion of 60.8% of the total,mainly by the central parts of the study area to the surrounding woodland increased,mainly in the eastern region of Songnen Plain;swamps and smaller,respectively accounted for 4.8% of the total area 7.9%;land and other land scattered water and construction.(2)Compared with 1910 s and 2010 s,between arable land,water area of construction land and other land,farmland land increased the most,followed the land for construction purposes.For the swamp,grassland and forest area is reduced.The main land use types in 1910s~2010s transformed between farmland,forest,grassland and marsh;the two land use types are the same,farmland,woodland area and continue to account for the largest proportion,both in the region accounted for 24.62% of the total area,and different land use type conversion in the area and the largest proportion of forest into farmland: the three types of forest into farmland,meadow into farmland,marsh turned into farmland.(3)Songnen Plain hundred years measured PDSI index was-0.13,which in 19151925 is the most humid,dry,climate tendency rate was 0.0002/10 a,not through the 0.05 probability level test,namely 100 years of the study area is to wet development,but this trend was not significant.Songnen plain analysis of PDSI index was-0.42,which in1915 1920 is the most humid,dry,climate tendency rate was-0.029/10 a,not through the0.1 probability level test.Therefore,the Songnen Plain hundred years showed no significant trend of drought.(4)The measured PDSI in Songnen Plain,the climate tendency rate changes between-0.16~0.14/10 a,and increased gradually from southeast to northwest.In the southeast of China,the PDSI value is gradually declining,showing a dry trend,while in the northwest,the PDSI is 110,and the climate tendency rate is positive.The Songnen Plain PDSI reanalysis climate tendency rate changes between-0.18~0.11/10 a.The change in the 0.11~0/10 a between the northwest of Songnen Plain,the climate tendency rate.The value of PDSI in these areas is rising gradually in the past 110 years,showing a trend of wet change.In the rest of the region,the PDSI climate tendency rate is negative,which shows a decreasing trend over the past century.(5)According to OMR method,according to the land use types of extraction and extraction of PDSI concentrated distribution area index average and climate tendency rate,comprehensive draws the conclusion: in the influence of land use change,Songnen Plain is the overall development toward drought.In the impact of land use types,the swamp played a role in alleviating the drying effect,that is,wet,and the rest of the class have an effect on the drought,that is,dry.Non cultivated land into cultivated land and sustainable non arable land into cultivated land,forest land,farmland,water swamp turn into cultivated land and other land into cultivated land to dry faster than continuous forest,swamp,waters and other land,and grassland into cultivated land,construction land into cultivated land dry faster than sustainable grassland,construction land is slow.