Uchimizu: A Cool(ing) Tradition to Locally Decrease Air Temperature

Uchimizu: A Cool(ing) Tradition to Locally Decrease Air Temperature

Solcerova, A. (TU Delft Water Resources)
van Emmerik, T.H.M. (TU Delft Water Resources)
Hilgersom, K.P. (TU Delft Water Resources)
van de Ven, F.H.M. (TU Delft Water Resources; Deltares)
van de Giesen, N.C. (TU Delft Water Resources)

2018-06-06

The urban heat island effect was first described 200 years ago, but the development of ways to mitigate heat in urban areas reaches much further into the past. Uchimizu is a 17th century Japanese tradition, in which water is sprinkled around houses to cool the ground surface and air by evaporation. Unfortunately, the number of published studies that have quantified the cooling effects of uchimizu are limited and only use surface temperature or air temperature at a single height as a measure of the cooling effect. In this research, a dense three-dimensional Distributed Temperature Sensing (DTS) setup was used to measure air temperature with high spatial and temporal resolution within one cubic meter of air above an urban surface. Six experiments were performed to systematically study the effects of (1) the amount of applied water; (2) the initial surface temperature; and (3) shading on the cooling effect of uchimizu. The measurements showed a decrease in air temperature of up to 1.5 ◦C at a height of 2 m, and up to 6 ◦C for near-ground temperature. The strongest cooling was measured in the shade experiment. For water applied in quantities of 1 mm and 2 mm, there was no clear difference in cooling effect, but after application of a large amount of water (>5 mm), the strong near-ground cooling effect was approximately twice as high as when only 1 mm of water was applied. The dense measurement grid used in this research also enabled us to detect the rising turbulent eddies created by the heated surface.

meteorology
urban heat island
urban climate
experimental hydrology
DTS
evaporative cooling
energy balance
OA-Fund TU Delft

http://resolver.tudelft.nl/uuid:0faddc77-7800-4aae-a485-194895a08359

https://doi.org/10.3390/w10060741

2073-4441

Water, 10 (6)

Institutional Repository

journal article

© 2018 A. Solcerova, T.H.M. van Emmerik, K.P. Hilgersom, F.H.M. van de Ven, N.C. van de Giesen