Increasing Trend of Rainfall Over Agumbe, Western Ghats, India in the Scenario of Global Warming

摘要

There are quite a number of conflicting conclusions about inter-annual trends of the monsoon rainfall over South Asia as a result of global warming. Western Ghats, next to Himalayas are the principal watershed areas for the rivers of India. In this study, an attempt has been made to understand the inter-seasonal and inter-annual patterns rainfall over Agumbe – popularly known as the Cheerapunji of the South India. Since this region is particularly influenced by the south-west monsoon, the monthly rainfall data of this station from 1963 to 2010 have been studied to understand the long-term trend in rainfall as a consequence of global warming. Seasonally, the maximum amount in rainfall occurs during the summer followed by fall, spring and the least during winter (84.31 to 98.98%, 0 to 9.92%, 0 to 8.23% and 0 to 0.41% respectively). Though the rainfall of the study area is generally in phase with that of all India summer rainfall, however, there is an increasing trend of both inter-annual and seasonal rainfall suggesting the induction of global warming in supplying moisture from the Indian Ocean. The rate of increase has been found to be maximum during the summer, followed by spring and fall seasons with a pronounced increasing in the annual rainfall (22.85, 4.29, 2.82 and 28.58 mm/yr respectively). Generally, the annual lows and highs are generally in agreement with El Ni?o and La Ni?a years respectively. However, about 80% of the rainfall data fall within the mean of 7304 mm and 1087 mm 1σ standard deviation. Despite increasing in rainfall, the major part of the study area suffers from the shortage of water resource particularly during the spring season. Therefore, this study suggests for a better management of the water resource in high rainfall terrain.