Open Cast Mine Monitoring And Ecological Effect Assessment Through Remote Sensing

Due to mining activities, open cast mine area has experienced a dramaticalterations in land surface. Meanwhile, soil and vegetation is destructed, and thermalenvironment effect is enhanced there. With application of remote sensing and GIS,this paper analyses the spatial distribution and change in land disturbed type,vegetation, land surface temperature and soil moisture from1987to2013. Moreover,it assessed the quality of reclamation based on above information. Landsat data isderived from1987,1996,2005,20012005,2010and2013. The main conclusions areas follows:(1) Frequency and intensity of mining activities determines the change degreeand change direction of land disturbance type. According to the characteristics ofmining activities in Pingshuo open cast area, the study area is divided into twoprimary types and five secondary types. Based on the remote sensing imageinterpretation, results are concluded that, from1987to2013, the excavated land areaincreased by6.32km2, the open-pit area increased by11.3km2, the industrial areaincreased by8.27km2, the un-reclaimed dump increased by17.69km2, the reclaimeddump increased by14.58km2. The change of each disturbed type happened with thesame direction of mining activities.(2) Mining activities disrupt both the vegetation and the vegetation growingcondition. While mine reclamation is carried out by planting vegetation with the aimof improving the natural environment. NDVI and vegetation fraction is calculatedfrom Landsat image. From1987to2013, the highest value of NDVI is found inreclaimed dump. The second highest value is found in un-disturbed area. The lowestvalue is found in open-pit. The value of NDVI in un-reclaimed dump, excavated areaand industry area is similar. The area shows a10.7km2increase in vegetation fractionfrom80%to100%, a3.02km2increase in vegetation fraction from40%to80%, and a13.65km2decrease in vegetation fraction from0%to40%.(3)Thermal environment is influenced by the change in land surface and theintensity of mining activities. Land surface temperature, as an important indicator ofthermal environment, can be retrieved from thermal band of Landsat image. From1987to2010, the mean land surface temperature increased by13.14℃. The highestvalue is found in the open-pit area and industrial area and the lowest value is found inthe reclaimed dump and un-disturbed land. The balance of the spatial distribution is influenced by the intensity and scope of disturbance. A game relationship existsbetween high-temperature area and low-temperature area.(4) Soil structure and soil moisture is affected under the combine effect of landuse types, vegetation, rainfall, topography and human activities. Soil moisture wasobtained from Landsat images. From1987to2010, the scope of damp area, moistarea and normal area shows a decreasing-increasing-decreasing-increasing trend. Inreclaimed dump, soil moisture is in a moist and normal state. In moist area and damparea, the water retention capacity in reclaimed dump is better than un-reclaimeddump.(5) Based on the factors, such as DEM, NDVI, land surface temperature and soilmoisture, an assessment model is established for ecological effect assessment. Allevaluation factors are used to generate an evaluation map with an overlay approach.From2001to2010, the effect of land reclamation is positive in reclaimed-dump.