Impact of Lockdown on the Surface Water Quality in Kelani River, Sri Lanka

The COVID-19 lockdown has been regarded as a catalyst for the restoration of natural water bodies worldwide. Therefore, this study aims to investigate the impacts of the lockdown on the water quality of the Kelani River, Sri Lanka. The water quality downstream of the Kelani River Basin was greatly improved during the lockdown season, The concentration of biological oxygen demand (BOD) decreased downstream by ~46% during the lockdown, while that in the middle and upstream reduced by 7.1% and 5.0%, respectively. The concentration of chemical oxygen demand (COD) was diminished by around 65%, 52%, and 43% in downstream, middle stream, and upstream, respectively, in the lockdown season. However, in post-lockdown season, upstream showed the highest spatial variation in nitrate concentration, which may be due to excessive use of fertilizers in that region. Many industries temporarily shut down or scaled back operations during the lockdown, which allowed for a large reduction in the discharge of pollutants, particularly in the river’s downstream region. The river’s water quality showed a significant improvement as a result of temporarily suspending human activities

Co-development of an integrated assessment framework to evaluate the effectiveness and impact of selected nature-based water treatment technologies in Sri Lanka, The Philippines, and Vietnam

Water quality is a critical challenge in Asia in the context of growing industrialization, urbanization, and climate change. Nature-based solutions (NbS) could play an important role in reducing urban water pollution, while generating multiple co-benefits that could make cities more liveable and resilient. In this regard, a number of pilot and demonstration projects have been set up to explore their potential across cities in Asia. Their effectiveness and impacts, however, have not been adequately documented, thus how they can be sustained, replicated and up-scaled remain poorly understood. This study aims to contribute to addressing this challenge by co-developing an integrated assessment framework and employing it to understand how existing evaluations of NbS in the region can be improved. It focuses specifically on a set of nature-based solutions that have been employed for water treatment across six cities in Southeast Asia (two in each Sri Lanka, the Philippines, and Vietnam), namely, floating wetlands, constructed wetlands and maturation ponds. The study also suggests specific methodologies for capturing a set of core indicators considered relevant for assessing the effectiveness and capturing the multi-faceted impacts of the examined NbS