Assessment of wind speed and spatial mapping across the Indian subcontinent

Abstract

Site-specific assessment of wind speed is essential in analysing 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 has become the need of the hour for India. The Indian standard (IS 875: Part 3) is a national code for reference to the basic wind speed in India, essentially for infrastructural planning and design of mid-rise to tall structures, and the specified basic wind speeds in the code are computed based on a 50-year return period by using the Gumbel probability distribution. However, recently reported cyclones were extreme wind events that already exceeded the specified value in the code. The Gumbel distribution (type I) is applied in the present study by using the method of moments on the long-term wind data (yearly maxima) considering the past few decades (40 years) available for forecasting the wind speed at different return periods. The Anderson–Darling test results are also accommodated to establish the accuracy of the tail behaviour of the statistical distribution used, where the p-value is found to be less than 0.05. Further, in the present study, a site-specific basic wind speed map is also proposed considering latest event data. Indeed, based on the present study, a 100-year return period for basic wind speed is recommended instead of 50 years to ensure enhanced structural safety and serviceability during the design life.