Cooling island effect of urban lakes in hot waves under foehn and climate change

• Published in: Theoretical and applied climatology 2022-07, Vol.149 (1-2), p.817-830
• Main Authors: Le Phuc, Chi Lang, Nguyen, Hoang Son, Dao Dinh, Cham, Tran, Ngoc Bay, Pham, Quoc Bao, Nguyen, Xuan Cuong
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Aquatic resources; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Climate and human activity; Climate change; Climate science; Climatology; Cooling; Cooling effects; Cooling water; Earth and Environmental Science; Earth resources technology satellites; Earth Sciences; Foehn; Foehn winds; Global temperature changes; Heat; Heat waves; Heatwaves; Human influences; Imagery; Island effects; Lake water; Lakes; Landsat; Landsat satellites; Landscape; Liquid cooling; Mitigation; Monsoon climates; Original Paper; Remote sensing; Satellite imagery; Spaceborne remote sensing; Surface water; Temperature effects; Temperature gradients; Tropical climate; Tropical climates; Urban climatology; Urban heat islands; Urbanization; Waste Water Technology; Water levels; Water Management; Water Pollution Control; Water temperature; Winds
• ISSN: 0177-798X; 1434-4483
• DOI: 10.1007/s00704-022-04085-6

The central region of Vietnam has a tropical monsoon climate but often undergoes heat waves due to uncontrolled urbanization, foehn winds, and climate change. Water bodies are considered effective candidates for heat mitigation in cities through the water cooling island (WCI) effect. Quantifying the WCI capacity of water areas and related factors is necessary for sites with advantages of surface water. The current attempt used the WCI effect range ( L max ), temperature drop amplitude (Δ T max ), and temperature gradient ( G temp) to investigate the cooling effect of 20 lakes in the Thanh Noi region, Hue City. Data derived from high-resolution Google Earth, Landsat-8 Satellite Imagery Data, and ground truth. The results show that the average water temperature of the 20 studied lakes was about 36.61 °C, lower than the average temperature in the area with an urban heat island (UHI) of about 2.82 °C. The mean L max was 150 m, Δ T max was 1.52 °C, and G temp was 10.16 °C /km or 0.01 °C/m. Climate characteristics and human impacts had reduced the ability of the lakes to create WCI during the period when the lake water level was low. The factors that influenced the WCI significantly were the landscape shape index (LSI), the proportion of green (PG), and the percentage of impervious surfaces (PI). Most lakes with relatively simple LSI, high PG, and low PI obtained high WCI, suggesting that structural and landscape characteristics played a critical role in urban cooling.