Research On Temporal And Spatial Variation For Land Cover In Mining Disturbed Zone

?Along with increasing of coal mining intensity, problems on surface subsidence have become increasingly prominent. Coal mining not only promotes economic development, but also damage ecological environment of mining areas seriously. According to mining subsidence, damage of land and water resources has seriously affected people's lives in mining areas and also restricted sustained, steady and healthy development of coal industry. Therefore remediation measures and land reclamation on mining subsidence have taken to be carried out so as to restore ecological environment of mining disturbed zone, which is very important.This paper carries on dynamic monitoring to coal mining environment utilizing multi-temporal remote sensing images, and study area is Luan coal mining in Changzhi City Shanxi Province, using Landsat7 ETM+ and four-year SPOTâ…¡/â…£satellite remote sensing images. SPOTâ…¡/â…£has seven phases from 2004 to 2007. SPOTâ…¡/â…£images obtaine land cover reflectance through atmospheric correction by way of FLAASH model, extract accurate NDVI according to land cover reflectance, receive function relationship between NDVI values and months through phase normalized, acquire NDVI annual integral quantity and can be quantitative comparison of the same period data finally. Study on NDVI in mining areas reveals temporal and spatial variation of land cover in predicting mining disturbed zone and provide theoretical basis and technical approach for land reclamation and ecological protection of subsidence areas. The paper analyzes spatial and temporal variations of land cover NDVI in mining disturbed zone, obtaining the following conclusions:(1) NDVI change of land cover in mining disturbed zone and mining disturbance has spatial correlation. Mean maximum NDVI of forest canopy in non-subsidence areas has steady increasing trend year by year, while mean maximum NDVI before mining in subsidence areas also has increasing trend, NDVI after mining then declines comparing with the same period NDVI in non-subsidence areas.(2) NDVI change of land cover in mining disturbed zone and mining disturbance has time-correlation. Vegetation index is relatively stable before mining subsidence, NDVI change after mining has a certain lag and shows decreasing trends gradually over time until steady and then goes in ascent period.(3) Due to influences of different mining geological conditions, affected degree of NDVI is distinct at the same time in different minings, vegetation damage degree by mining in thick bedrock thin topsoil conditions is worse than it in thin bedrock thick topsoil conditions .(4) Annual integral change of NDVI (YNDVI) in mining disturbance areas has the same trend as NDVI, showing decreasing trend year by year. Positive related between YNDVI and net primary productivity (NPP) indicates that destruction of plant growth state in disturbance areas and mining subsidence has causal relations.