Assessment of wind speed and spatial mapping across the Indian subcontinent

Abstract

Site specific assessment of wind speed becomes essential to analyze the susceptibility of any slender structure. With the increasing number of occurrences of extreme wind events in the Indian subcontinent, a quantitative measure of wind hazard based on recent developments becomes the need of the hour for India. The Indian standard (IS-875-part III) is a national code for reference to the basic wind speed in India essentially for infrastructural planning and design of midrise to tall structures and the specified basic wind speeds in the code are computed based on 50 years return period by Gumbel probability distribution. However, recent cyclones reported extreme wind events already exceeded the specified value in the code. The Gumbel distribution (Type I ) is applied in the present study by method of moments (MOM) on the long term wind data (yearly maxima) considering the last few decades (40 years) available for forecasting wind speed at different return periods. The AD (Anderson darling) test results are also accommodated to establish the accuracy of the tail behavior of the statistical distribution used, where the p-value is found to be less than 0.05. Further, in the present study, site specific basic wind speed map is also proposed considering latest event data. Indeed, based on the present study, 100 years return period for basic wind speed is recommended instead of 50 years to ensure enhanced structural safety and serviceability during its design life.