Measurement of the Cooling Efficiency of Pavement-watering as an Urban Heat Island Mitigation Technique

The Paris region (Ile-de-France) was amongst the hardest hit by the August 2003 heat wave, due in part to subsequent amplification of its urban heat island. This has created high heat-wave awareness in climate change adaptation studies for the city of Paris. Over the summer of 2013, pavement watering was studied experimentally in two locations as a climate change adaptation method. Pavement watering was found to lower pavement surface temperatures by several degrees for several hours after watering, while also strongly reducing its cooling rate a few hours before and after sunset. Heat flux and storage at a depth of 5 cm in the pavement were also found to have been significantly reduced, especially during direct sunlight exposure, but also when the pavement was in the shade. Uninterrupted watering appears necessary during direct sunlight exposure of the pavement to maximize efficiency.