No abstract

Monitoring spatial changes of surface heat island formation and temperature changes in sub-urban areas is vital in the freshwater lake management of urban areas as frequent phenomena related to climate change have undergone. The purpose of this study was to examine the Spatio-temporal pattern of urban heat island and land surface temperature and vegetation changes by using GI statistics, where hotspot analysis was also performed. The study further examined the effect of heat island and surface temperature on urban freshwater lakes where hot and cold spots identified had undergone a reclassification process. The results revealed that the increasing Land Surface Temperature (LST) due to modification and transformation of vegetated areas into concrete and synthetic built-up extents is one of the challenging problems in the selected suburbs. Both NDVI and LST hot spots and cold spots have changed compared to 2010. The LST showed considerable expansion of the hotspots within ten years rather than cold spots in all three suburbs. The freshwater lakes are in proximity to the city. All three lakes were finally reclassified as hotspot areas for LST, while Kesbewa Lake and Thalangama Lake were identified as NDVI hotspots where the vegetation cover had contracted by 2020. Even though Boralesgamuwa Lake is not recognized as an NDVI hotspot, the encroachment and expansion of the current hotspot area could be identified. The study's findings could be used to design sustainable cities in these suburbs more by prioritizing the conservation of urban ecosystems.

Freshwater wetlands are more threatened than any other ecosystem in the world. The current trend of freshwater wetland crisis arises a question ‘whether it is conversion or conservation of wetlands' which is absolutely a dilemma. Therefore, this study aims critical evaluation at wetland governance and sustainability of urban wetlands in Colombo. The results reveal that the Colombo wetlands have lost their territory from a moderate to a severe degree. The wetland loss is higher in Kaduwela, Kolonnawa, and Kesbewa areas. Recently the causes of Colombo wetland loss has moved with a new frame. Land grabbing and green grabbing are the cycles that transforming the geostrategically important urban wetlands into hybrid ecosystems. Due to this, the frequency of flash flood events and inundation time has increased than ever. It is important to ensure urban freshwater wetland sustainability and surveillance following sustainable development goals and it is time to have freshwater ethics.

No abstract