Journal of Natural Disaster Science

EFFECTS OF TOPOGRAPHIC FACTORS ON LOCAL WIND PROPERTIES

Hidehiko UTSUNOMIYA
Professor, Department of Construction Engineering, Faculty of Engineering, Tokushima University
Fumiaki NAGAO
Research Associate, Department of Construction Engineering, Faculty of Engineering, Tokushima University
and
Tateki HIRAOKA
Graduate student, Tokushima University

(Received 24 September, 1987 and in revised form 3 December, 1987)

Abstract

The effects of opencuts made for road construction on the local wind environment in a complex terrain are discussed on the basis of results from a wind tunnel simulation. First, simple models with trapezoidal cross sections were used to determine which terrain parameters affect the downstream air flow. Results showed that the principal parameters with which to estimate the downstream flow are the width of the opencut and the ridge height.

The effect of wind direction also was investigated with a simplified peninsula model, that is, a half section of the simplified opencut model.

The results of wind tunnel simulations for a 1:1500 scale model and a distorted model (horizontal scale 1:1000, vertical scale 1:500) with and without a large opencut also are given. Wind tunnel tests showed that the opencut of a ridge line makes the wind environment in its downstream area worse. An effective countermeasure that restores the original wind velocity is to set up porous wind fences at key positions along the side of the constructed road.

In addition full scale wind measurements were made four times during the winter, when the wind was from the northwest. There was a high correlation between the full scale measurements and the 1:1500 scale wind tunnel simulation.

Key words

local wind environment, simulated wind tunnel measurement, full scale wind measurement, simplified terrain model