## 5 The ECOAL Project Implementation
### The GIS Open-Source Desktop Application for Monitoring the Combustion Process  
In order to monitor the temperature variations in the S. Pedro da Cova self-burning coal waste pile, a GIS desktop application named GIS-ECOAL was developed in a GIS open-source environment to produce dynamic temperature maps [9]. The main focus of this step was the creation of an application with a user-friendly graphic interface that automatically generates several interpolation maps with the temperature records. Also, a video composed of a sequence of individual maps, allowing for the evaluation of the temperature dynamics in a specific area, was generated. The interpolation maps were based on the kriging method as it provides optimal interpolation estimation for a given coordinate location, as well as variance estimation for the interpolation value. The video was created in _webm_ format, and could be displayed by any video player program. The application also provided the possibility of direct video visualization in the application graphic interface. Moreover, the application has another functionality: evaluating the temperature dynamic of a specific point in the field, through a  
Figure 15: (**A**) Change in ammonia concentration over five days in the left gas spot of Figure 7C; (**B**) details of variation over one day (17 March 2015).  
graphic representation of the temperature values as a function of time, complemented by a report with maximum and minimum temperature information and a table with a statistical analysis for each day. The table is created in text format, with statistical variables related to each day, such as average, median value, maximum and minimum temperature, standard deviation, coefficient of variation, and amplitude.  
Valuable information about the variation in temperature at different moments of a day and the distribution and dispersion of the combustion activity and intensity in the fire area could be obtained from the analysis of the individual maps, since the combustion process in the coal waste pile was spatially very heterogeneous. For instance, one main area of more intense combustion was recognized, the large red part at the bottom of the monitored area (Figure 16), and the identification of significantly higher temperatures in the left and upper corner of the waste pile (more yellowish areas) indicated that the combustion activity may be increasing in this area. The identification of this new focus of combustion was only possible through the maps and video analysis created by the GIS-ECOAL application. The plot functionality was also tested with three points and the analysis demonstrated that temperatures at point 1, which is located in an area with intense combustion activity, are higher than 90 \({}^{\circ}\)C while, at point 2, the temperatures vary between 50 \({}^{\circ}\)C and 60 \({}^{\circ}\)C and, at point 3, are generally between 40 \({}^{\circ}\)C and 50 \({}^{\circ}\)C.  
The identification of the temperatures associated with the combustion process and the main and/or new focus of the combustion activity could be estimated from the maps generated. The video analysis allowed for the dynamic and continuous visualization of the combustion process in the monitored area, contributing to the prediction of evolution scenarios and helping to establish mitigation measures and appropriate management practices.