470 / 2024-04-09 15:01:41

Evaluating the performance of various Nature-based Solutions amidst climate change and extreme weather events: Case of water quality improvement and carbon storage

constructed wetlands,Nature-based Solutions,pollutant removal efficiency,soil organic carbon

Subtheme 5: Climate Change: Adaptation, Mitigation and Resilience > Topic 1: Hydrology and Water Resources response to climate change

Numerous studies noted that the increase in the global average temperature from pre-industrial times to present day has resulted in higher frequencies of extreme weather events, particularly heat waves, flooding, and winter storms. In response to the continuous negative impacts of climate change to urban areas, Nature-based Solutions (NbS) have been a topic of interest in previous literature, due to their capabilities to mitigate water-related social and environmental problems caused by continued population growth, watershed development, and climate change, while utilizing natural processes. In this study, the performance of various NbS, particularly constructed weltands (CWs) and other low impact development (LID) was evaluated with regards to pollutant removal efficiency and carbon storage. For the pollutant removal efficiency evaluation, 54 CWs from various land uses in South Korea were monitored during rainfall events with varying intensities, in which removal efficiencies for total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were obtained. Moreover, soil samples at various depths from CWs and various land use types in Cheonan City, South Korea were collected and tested for soil organic carbon (SOC). Results reveal that CWs exhibit higher removal performances at low rainfall depths due to the long hydraulic retention time. At the 0-20 mm range, removal efficiency was 71.7% for TSS, 67.8% for TP, 65.9% for BOD, 61.7% for TN, and 57.8% for COD. It was also found that the recommended subcatchment to catchment area ratio for each target pollutant removal efficiency of 60% are 3.2% for BOD, 2.5% for COD, 1.9% for TSS, 2.5% for TN, and 2.3% for TP. With regards to CWs’ capabilities to store SOC, it was found that CW sediments exhibited 7% to 86% greater SOC content than the open soils surrounding the CW facilities, indicating the relatively higher capability of NbS such as CWs to store carbon. The results of this study reveal the positive impact of NbS in addressing issues in stormwater runoff pollution and carbon neutrality. Findings from this study are seen as beneficial in developing NbS technologies as a response to climate change in areas with different climate characteristics.