Remote sensing methodology for the estimation of methane emissions from Chinese lakes

The present research has been carried out in the framework of the cooperation on environmental protection between the Italian and the Chinese governments. The study was aimed at connecting remote sensing and GIS applications, integrated by on-site investigations, with the estimation of greenhouse gases emissions. Remote sensing techniques, jointly with site investigation on the sites of interest, were used to perform water quality analysis in selected lakes in China and to design a preliminary model for the estimation of methane emissions from water. Three test lakes were selected according to their characteristics in methane emission, which were evaluated using satellite data from the sensor SCIAMACHY on the trend of emission of methane from the ground throughout the year. Remote sensing supported in the indirect monitoring of water quality with focus on parameters that can be correlated as chemical precursors to the production of methane. Within this research, Landsat ETM+ satellite images were used as input for a dedicated remote sensing analysis application to retrieve values of chlorophyll, SM, and colored dissolved organic carbon for three selected water bodies used as test sites. Water sampling campaigns were also carried out in the three test sites from April to September 2007. The samples were analyzed and the results, together with historical water quality data, were used to calibrate, validate and interpret the results of the remote sensing analysis. Water quality parameters measured with remote sensing analysis and validated with field and historical data were used to propose a preliminary methane emission model on one test site (Hongze Lake), based on the evaluation of field or historical data of parameters acting as precursors or products of methanogenesis processes. In this way the results of methanogenesis processes and methane production were quantitatively assessed, yielding a preliminary methane emission model that can be further applied and valid- - ated on other water bodies.