Abstract
Two studies were undertaken to determine the effect of paddy fields on summertime air temperature in urban fringe areas in Kasukabe City, Saitama Prefecture, Japan.
In the first study, air temperatures were measured at 45 observation stations which represented a range of paddy field distribution patterns from contiguous to highly segmented, and differences between air temperature of each observation station and that of a representative residential area were calculated. The maximum temperature difference was approximately 2°C, and a correlation between coverage ratio of paddy fields and temperature difference was identified: the greater the area of paddy fields the larger the temperature difference. Further analysis identified a strong relationship between segmentation level of paddy fields and air temperature for areas of moderate coverage ratio. For the same coverage ratio, areas with a few large paddy fields had larger temperature differences than areas with many smaller paddy fields. This suggests that segmentation of paddy fields reduced their effectiveness in cooling the airof surrounding residential areas.
In the second study, air temperatures were measured in transects along residential streets opening onto large paddy fields to identify the distance of the cooling effect of paddy fields to reach into surrounding residential areas.
Under the condition of average 2 m/s wind moving from paddy fields, the cooling effect was identified to reach a distance of 150 to 200m from the edge of paddy fields.
The results of the two studies suggest that both segmentation of paddy fields and a large-scaled residential development should be controlled when the effect of paddy fields on summertime air temperature in surrounding residential areas is expected.
