Assessment on Impact of Risky Trees on the Sustainable Management of Urban Green Spaces Using Geospatial Technology: Special Reference to Colombo Municipal Area in Sri Lanka

Urban green spaces are fundamental elements of sustainable cities, providing ecological, social, and health benefits within the overall constructed environment that is the living urban environment. Nevertheless, the existence of risky trees, which may be structurally unstable, diseased, or likely to fail, presents a substantive threat to the safety, equity, and sustainability of green spaces. This study seeks to assess the implications of risky trees for the sustainable management of urban green spaces utilizing geospatial technology, using the Colombo Municipal Area as an illustrated case. The main objective is to explore the influence of risky trees on urban green space management sustainably in the urban realm using geospatial technology. The specific objectives are to map the spatial distribution of risky trees in urban green spaces using geospatial approaches, assess risk rating and contributing causes, and develop management recommendations for urban tree risk management to support public safety and planning strategically for urban trees. In this methodology, field observations, Geographic Information Systems (GIS) and LiDAR data were utilized to map tree locations and features of the tree canopy. To evaluate risk, weighted overlay, buffer analysis, hotspot and kernel density mapping, correlation, and regression were all applied as analytical tools. Risk scoring and indexing clarified the most hazardous trees and categorized trees based on risk level, while Multi-Criteria Decision Analysis (MCDA) helped direct sustainable management strategies. Data collection took place along designated roads selected in Kurunduwatta and Thimbirigasyaya GNDs where trees were purposively sampled based on tree density and urban activity. Tree characteristics and tree defects were the principal risk factors, but they were highly influenced by environmental variables and distance to the nearest road edge and buildings. Overall, the study found 75 trees to have high risk, 29 trees to have moderate risk and 19 trees to have low risk. The study concludes that risky urban trees pose serious threats to public safety and to the sustainable management of the green spaces located in the Colombo Municipal Area. A modified sustainable tree risk management strategy that utilizes a geospatial tool is suggested to prioritize the maintenance and/or removal of risky trees and aid in future urban planning.