Urban wetlands are affected by both human activities and climate changes. The spatio-temporal transformation and seasonal inundation determine the structure and functions of tropical wetland ecosystems. Information on the spatial and temporal changeability of inundation is necessary to understand to manage these ecosystems. The western region of Sri Lanka represents one of the most emerging growth centres in the country, and there is extreme pressure on the natural environment and wetland ecosystems. A combination of methods of Environmental History, Urban Ecology and Wetland Science based on Geographical Information System (GIS), Remote Sensing (RS) and fieldwork techniques have been applied to the research. Moreover, this research focuses on understanding and assessing the current potential spatial stress on a regional wetland ecosystem due to human interference. This study uses remote sensing images of two time periods (during 2001-2016) to interpret the chronological, spatial data of the wetland landscape changes over the 15 years time span. The result shows that the wetland system in this study area presents a trend of widely extent urban-rural situation with rapid land use changes of urban expansion, wetland degradation, and rapid growth of urban built-up lands and that different driving force make complicated patterns of this wetland ecosystem.
Results/Conclusions
Results indicated that the wetland ecology in the Muthurajawela marsh and Negombo lagoon system has decreased over the 15 years (2001-2016) with higher area governance built up. Conversely, it could recognize the altering percentage of built up (dry season - 62% wet season - 61%) is higher than Mangrove (dry season - 24% wet season- 31%) both dry and wet seasons from 2001 to 2016. The LU/LC mapping proved that the build-up was 24.88 km2, and 25.82 km2 in the dry season and 30.27 km2, and 30.80 km2 in the wet season 2001, and 2016, respectively. The mangrove was 6.62 km2, and 14.20 km2 in the dry season and 7.4 km2, and 14.07 km2 in wet season 2001 and 2016, respectively. LU/LC change analysis shows that the LU/LC change was expressed in the 2016 (0.36%) compared to the 2001 (0.27%), which primarily corresponded with the developments of human settlements, financial system, and numerous socioeconomic factors.