Researchers have recently discovered a trend within annual monsoon measurements toward fewer, more extreme downpours -- and this raises the concern of more potential floods and other natural disasters. Monsoons are needed to nourish crops and supply water for farming communities, but too much of the monsoon rains can devastate crops and livestock as well -- a delicate balance is always required.
B. N. Goswami of the Indian Institute of Tropical Meteorology and his colleagues studied rain gauge data from 1,803 stations scattered throughout central India from 1951 to 2000. His findings indicated that there was a wide range of rainfall during that period, as expected. The amounts ranged from a maximum downpour of nearly 23 inches in one day to no precipitation at all. The average -- according to Goswami -- was just under a quarter-inch for a single day.
After determining the actual rainfall amounts, Goswami and his researchers divided storms into several categories ranging from light to very heavy. When they looked at the last few decades of the 20th century, lighter-rainfall events declined significantly while heavier counterparts increased.
Goswami noted that "Heavy and very heavy rain events over central India have increased significantly since the 1950s � also, the magnitude of the very heavy events in a given year has shown a clear increasing trend."
Goswami added that "As the weak and moderate events decrease, their contribution to the mean decreased while the increasing number of heavy and very heavy events make an increasing contribution to the mean � these two opposing contributions roughly balance each other and keep the mean unchanged."
The average -- although remaining unchanged -- still does not preclude that area from the potential for extreme downpours and flooding, which can end up being catastrophic. The research team led by Goswami stated that this fact is an important and increasing risk going forward.
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