Monitoring the environmental conditions in landfill sites: a case study of Fyli - Ano Liosia, Attica Region, Greece

Landfills constitute a major environmental issue that needs to be handled, especially when they are located near large urban areas. In landfills, end up most of the city non-hazardous solid waste (mainly household waste), which are not appropriate for recovery/recycling and thus they are disposed in the ground for decomposition process. Monitoring of such sites is significantly important, due to the fact that the decomposition process - which includes the release of hot gases - is harmful to the environment and to the human health.  The increase of Land Surface Temperature (LST) in landfill sites and the methane gas emissions, which contribute to the greenhouse effect, can be monitored using remote sensing methods and techniques. This type of monitoring is very important for safeguarding the surrounding environment, especially in environmentally sensitive areas, as are those located close to densely populated areas, and therefore, many studies have been carried out focusing on the monitoring of the environmental impacts of landfills through remote sensing. In relevance with previous literature, the current study aims at monitoring the environmental impact of the active landfill site of Fyli – Ano Liosia, Attica, Greece. For the needs of the study, time series of Land Surface Temperature (LST) have been processed as extracted from Landsat 8-9 satellite imagery. The analyzed time period is from January 2021 to December 2022. LST data have been extracted from two areas within the landfill, one in the active landfill area and the second one in an area that has been rehabilitated and is no longer active. Furthermore, we selected to study LST data from a bare soil area which is located at a short distance from the landfill in order to find temperature deviation caused by the decomposition processes. The land surface temperatures inside the landfill have been compared with those of the bare soil as well as with the air temperature, which is provided by the weather station of Ano Liosia of METEO (infrastructure of National Observatory of Athens for weather forecasting). It has been observed that the LST in the active area of ​​the landfill is higher by 1°C-2°C compared to that in the inactive area of ​​the landfill, and by 2°C-3°C compared to the bare soil LST. A reversal of this phenomenon has been observed during the snowy winter months due to different snowmelt rates and possibly due to a slowdown of the decomposition process. The air temperature was found to be significantly lower than the LST, as expected.