Assessment of Metro Manila Urban Parks’ Cooling Effect Based on Landscape Metrics Using Threshold Value of Efficiency (TVoE) Approach

Abstract. In highly urbanized and climate-vulnerable cities such as Metro Manila, the Urban Heat Island (UHI) effect intensifies thermal stress. Urban parks can mitigate this by maximizing their cooling effect amidst the space constraints caused by urbanization. This involves the identification of optimal thresholds for spatial characteristics such as size, vegetation-water ratio, shape complexity, fragmentation, aggregation, and patch density to produce actionable values for realistic park design and planning. This study examines how compositional and configurational landscape metrics influence the cooling effects of 25 urban parks in Metro Manila. Land Surface Temperature (LST) was retrieved from Landsat 8 imagery using the split-window algorithm, while land cover was classified using a Random Forest model with 87.5% test accuracy. Landscape metrics were computed using FRAGSTATS, and four Park Cooling Effect Indices were derived: Park Cooling Area (PCA), Park Cooling Intensity (PCI), Park Cooling Efficiency (PCE), and Park Cooling Gradient (PCG). To determine the Threshold Value of Efficiency (TVoE), piecewise linear regression (PLR) was chosen among the regression models as it yielded the most interpretable and statistically valid TVoEs. Results show that vegetation metrics such as PLAND V (percentage landscape), CA V (total area), and ENN_MN (mean Euclidian nearest neighbor distance) significantly influence PCI and PCE, though often with negative relationships, which indicates diminishing returns beyond certain values. Meanwhile, water-based metrics such as PLAND W (percentage landscape) and AI W (aggregation index) showed moderate to strong associations with PCA and PCG, particularly when water patches were aggregated or well-distributed. These findings provide empirical thresholds to inform climate-responsive park planning and offer actionable insights for enhancing thermal resilience in dense urban settings.