Assessment of Optimal Size of Urban Blue-Green Space Based on Cooling Effect as an Urban Heat Island Mitigation Strategy

Urban blue-green space (UBGS), through its natural cooling mechanisms, offers a potential solution to counter the urban heat island (UHI) phenomenon; however, the interaction connecting blue-green space and its cooling effect requires further quantitative analysis to determine its optimal size for achieving maximum cooling. This study synthesizes recent advances and debates on the cooling effects of blue space, green space, and urban parks. A comprehensive literature review was conducted using global academic databases, focusing on studies examining the thermal benefits of blue-green spaces and optimal-size-based UHI mitigation. Subsequently, relevant literature was examined. The findings reveal that previous research has primarily focused on the associations between diverse types of landscape, variation in temperature, and the measurement of cooling intensity. However, studies based on optimal size have received limited attention, reducing the scope for concrete direction for practical planning and management that would systematically integrate even the smallest blue or green space of the area for achieving maximum cooling. The chapter also highlights disagreements regarding the impact of geometry and landscape patterns (composition and configuration) of blue-green space on their cooling effectiveness. Furthermore, the chapter identifies uncertainties, such as the ideal share of blue-green space within a park, inadequacy in the advancement of water-cooling effect studies, and the reasons behind contradictory results on cooling effects as areas require further investigation. This chapter emphasizes the need for greater focus on quantifying how local climate and landscape features influence the cooling efficiency and optimal size requirements of blue-green spaces. This chapter offers a comprehensive interpretation of the issue and includes suggestions for viable climate adaptation planning.