Research On Ecological Monitoring And Restoration In Arid And Semi-arid Mining Area Based On Remote Sensing

Coal mining activities can promote economics,but at the same time,it will destoy the ecological environment of mines.The damage to ecological environment such as storing up of gangue,subsidence,decrease of water level will directly threat the ecological safety of mining areas and social sustainable development.With the coal exploitation rapidly transfering to western area,where the ecological environment is fragile,the contradctions between mineral resource exploitation and safety of ecological environment is increasingly prominent.Based on the above background,this dissertation take Wuhai mining area,which is located in arid and semiarid region as a case study.To systematically study the ecological evolvement rule of Wuhai mining area and make quantitatively evaluate the ecological damage of Wuhai mining area,theories of ecology,geography,mining subsidence and restoring machanics,and methods such as passive remote sense,GIS,GPS and mathematical model are apllied in this dissertation.On these bases,rational ecological restoration strategies are proposed.The results of this dissretation are as follows:Firstly,researches on land use and land cover changes show that between 2005 and 2015,land use conversion in study area is more frequent,levels of vegetation cover decreases,landscape fragmentation continues to improve and the development of mine area ecological system is in a bad situation.Between 2000 and 2015,area changes of forest grass land and bare land in study area is obvious.During this period,due to the coal interference,forest grass land area transfered to bare land from 2000 to 2009.From 2009 to 2015,bare land area transfered back to forest grass area,which got the ecological environment recovered in certain extent.Vegetation coverage showed an obvious change trend in time and space.From 2000 to 2009,the middle and high vegetation coverage area gradually shrank,low vegetation coverage area gradually increased,especially the NDVI value of desert district in the southern study area reduced obviously.While from 2009 to 2015,the vegetation coverage showed an increasing trend from westnorth to eastsouth.The landscape pattern changes showed that the patch density raised,the increase of ecological vulnerability enhanced the degree of landscape fragmentation continually.The discrete degree of landscape increased,shannon diversity index and shannon evenness index continued to rise,and the level of landscape diversity increased.Secondly,study on the variation of surface deformation shows that,from overall perspective,some region in study area appeared surface subsidence disaster in different degrees,with the maximum surface subsidence value over 800 mm.From research on distribution of district surface subsidence,surface subsidence disaster main occurred in middle and eastern mountain area that rich in coal resources,and Wuda mine area located in the west of Yellow River.Subsidence basin presented as a series of irrugular concentric ellipse.From the surface subsidence scale in study area,there was a total of 230.03km2 of land surface subsidence disaster,taking up 13.78% of the whole study area.Serious subsidence zone was 44.98km2(2.69%);relative serious subsidence area was 101.33 km2(6.07%);area that affected by subsidence was 83.72 km2(5.01%).Thirdly,ecological storation strategy of study area shows that,see from the entire ecological damage situation of study area,under the strong disturbance of mining activities,ecological environment of arid and semi-arid mining area is damaged dramatically.Take mining working face as a center,the damage drgree decrease radially to all around,and the ecological damage index of the severe damaged region that concentrated on eastern mountain area,middle mountain area and west of Yellow River,reaches 4.5 to 8.0.View from ecological restoration strategy partition,to maximize ecological and economic benefits,there are different strategies in different areas.For ecological environment severe damaged area,manual restoration should be the priority;for moderate damaged areas,the restoration close to nature is firstly considered;for gently damaged areas,give priority to natural restoration.