Relationsihp between land cover changes and water quality changes in Laguna de Bay, the Philippines, over the 2007-2015 period

Conference Paper

In this study, we assessed the relationship between land cover change and changes in water quality in the Laguna de Bay area of the Philippines. Land cover changes occurring between 2007 and 2015 were mapped using a combination of optical (Landsat-7/-8) and synthetic aperture radar (ALOS Palsar-1/-2) satellite imagery, and time-series water quality data from five different stations situated in the Laguna lake were obtained from the Lake Laguna Development Authority. To study the effects of land cover changes on water quality at these different stations, the lake and its surrounding watershed area was first subdivided into five non-overlapping zones based on the generation of Thiessen polygons. Then, in each of these five zones, regression modelling was performed to assess the correlation between the changes in land cover (annual changes of "built-up" land cover type in ha.) and the change in water quality parameters. In future work, we plan to use the regression modelling results to predict some potential impacts of future land cover changes in each zone as well as in in the entire Laguna de Bay area. We also explore other explanatory factors of the lake water quality changes (e.g. other types of land conversions, changes in agricultural and industrial practices).