The rainfall pattern seems to have changed much
During the South-West monsoon season (officially extends from June 1 to September 30), there is an increase in the frequency of heavy rainfall and which is not confined to some region; this is happening throughout the country. IMD official data for the last three decades suggest many cities in India get nearly their total rainfall of the season in a small window that sums up to just a few days to a few weeks. In 22 cities, 95 percent of monsoon precipitation occurs over three days to 27 days on average. For example, Delhi receives 95 percent of its monsoon rainfall in just 99 hours. Mumbai gets 50 percent of its monsoon rainfall in only five and half days.
Scientists said if we analyze the overall monsoon rainfall, there isn’t much change (year to year there may be change), and monsoon rainfall has been stable over the last 50 years. This increase in the intensity of rain, on the daily and hourly basis, is related to global warming.
Does extreme weather events relate to climate change?
The studies related to temperature proposes, the Indian Ocean has been warming, particularly the Arabian seaside at the fastest rate. For India, most of the water vapors and the subsequent precipitation comes from the Indian Ocean. The cyclones in the Arabian Sea was previously limited to the Gujarat state, the changes occurred in the past ten years made Kerala and Karnataka more vulnerable to the cyclones, the recent example is Ockhi. The Secretary of the Ministry of Earth Sciences Dr. Rajeevan said “weather prediction is robust, but in the last ten years, we have improved a lot regarding modeling. At the same time, climate change has added another component to the difficulties in weather prediction as it can add to the uncertainty”.
Concluding remark
In India, most of the flood management systems are not reinforced by science. No decision support system is available, except perhaps in, Bhakra Nangal dam. We essentially require full-fledged flood management systems using scientific methods for all the major rivers. At present, a qualitative forecast is prearranged at the district level for at least three-four days, bearing in mind the imperative need it should be well included in the models that can estimate probabilities as well like whether the rainfall will increase or decrease in the next few days. It is very useful for farmers and could be supportive is deciding an efficient disaster preparedness plan. Some parts of Kerala have been stranded because wetlands and lakes that represented as natural safeguards counter to floods have died out because of extensive urbanization and construction of infrastructure. There is an urgent need to make a policy-level decision that supports stringent laws against the offenders to avoid mining and industrial activities in the ecologically sensitive region and rampant construction in the cities. It is high time for the decision makers to think aggressively when climate change seems to be inevitable, what measures should be taken to mitigate climate extremes and disasters to reduce the destruction
No Flood forecasting by CWC
Kerala received no early flood warning from the Central Water Commission (CWC), the lone government agency sanctioned to do so. It was shocking to discover that the agency has no flood forecasting sites, it has only flood monitoring sites in Kerala. The CWC director of flood forecast monitoring said unlike other states, ‘Kerala did not submit a proposal for setting up flood forecasting stations’. The CWC is primarily into flood forecasting; flood risk analysis is underneath the area of State government, which has to frame its flood management plans grounded on that analysis.
NASA Satellite Image of Kerala Before and After August, 2018 floods
Excessive precipitation
The state has received 37.5 percent excess rainfall in the two and half months since the south-west monsoon made landfall in May end. Some districts such as Idukki have received 83.5 percent excess rainfall. The August rainfall in the state is 2.5 times the normal for the period. On 16 August Kerala received 137mm rainfall, ten times more than average in one day. Till August 17, average rainfall was 175 percent more than normal. If one compares the events of rainfall departure from the normal from 1875 onwards in 1931 rainfall in Kerala in August was 175 percent excess than the normal after that this is the year in which Kerala got excess precipitation.