ASSESSMENT OF THE OCNELE MARI SALT MINE EXPLOITATION IMPACTS ON THE VEGETATION COVERAGE USING MULTISPECTRAL REMOTE SENSING DATA

摘要

In Romania there are several inactive or abandoned mine sites which can create a significant impact on theenvironment, affecting the use of local surface and groundwater. The environmental impacts that can occur at anabandoned mine site can be divided into several categories, amongst which: metal contamination of ground surfacewater and sediments, air emission and deposition, erosion, physical impacts (slope failure, structural stability oftailings impoundments, ground subsidence, unsafe structure, mine openings and vegetation contamination). The OcneleMari salt mine is one of disused mines affected by subsidence phenomena as a result of pillars dissolution byuncontrolled leaching processes that led to the formation of a huge cavern of up 10 .5 ha on horizontal direction and itsvolume of 2.5 million m3 of brine. The land deformation (subsidence and landslide) phenomenon influences vegetationcoverage changes. The object of the present study is to investigate the temporal changes of vegetation caused by saltexploitation using multispectral remote sensing data (Landsat 5, Landsat 7, ASTER and MODIS). We elaborated mapsfor the vegetation indices: normalized difference vegetation index - NDVI, leaf area specific index – SLAVI, normalizeddifference water index - NDWI - and thermal index. The change detection technique in vectorial format is applied onNDVI data in order to determine the areas affected by land degradation, with direct effects on vegetation coverage.Thus, an analysis of vegetation index NDVI proves the vegetation degradation in Field II of probes of the mining area,especially in the area of the 360-366 probes, with an area of 146700 m2. For the Field I of probes, sample 472, adecrease of 19 800 m2 of vegetation was noticed, while the third field, samples 431-433, decrease was determined to 30600 m2. The results confirmed feasibility of using remote sensing technique to assess the vegetation growth status in thesalt mining area.