JBA Risk Management and the Met Office have compiled a comparison of the floods which struck both India and Canada concurrently in June 2013.
Communities in and around Calgary and Southern Alberta began to experience flooding on 20 June 2013 as waters in the Bow River rose after 190mm of rain fell in just over 24 hours. The whole river basin received 50.8mm of rain and the rivers through Calgary were flowing at about 5 times the levels they peaked at in the 2005 floods. In 2005, floods caused $275 million in damage but it is thought that the 2013 floods could cost up to three times that amount. It is already being dubbed by some as the most expensive flood in Canadian history, surpassing the 2011 flood in Southern Manitoba which caused losses of some $800 million. Other estimates put the figure at between $3 billion and $5 billion with losses after insurance being around $3.7 billion.
According to data from the Insurance Bureau of Canada, Alberta has accounted for 26% of the nation’s total disaster-related insurance claims but since 2009, this has shot up to 60%. Climate change has been suggested as a possible reason for this increase but whether or not this proves to be true, insurers are watching the debate keenly.
While flooding occurred in Canada, India was already experiencing serious flooding. In the earlier part of the month of June heavy rains had arrived sooner than expected, causing the Yamuna and Ganga rivers to swell and burst their banks. Worst hit were the states of Uttarakhand and Himachal Pradesh in the Himalayan foothills. 440% of the rain that normally falls in the first few weeks of June fell according to The Indian Meteorological Department, which reported record rainfall of 385 mm. National Highway 58 along with whole villages and settlements, such as Gaurikund, Ram Bada and Kedarnath, have been washed away. The market town of Sonprayag suffered heavy damage and loss of life. The death toll is growing daily as missing people are recovered from landslides. Some have estimated a possible death toll of 5,000.
Indian losses will be very high; life, property, whole villages and industries have been wiped out. Relief funds are pouring in to assist with the crisis. But it is expected that claims from the flooding in Uttarakhand will exceed 35 billion Indian rupees ($585.2 million) much of this being due to damage and interruption to business in the commercial sector.
Same location, shot on June 21 during the height of the floods
Meteorological background: Northern India
The Southwestern summer monsoons occur from June to September. Hot summers over the Indian subcontinent cause low pressure in the northern and central areas of India. This results in moisture laden winds moving from the Indian Ocean and rushing across the Indian subcontinent. As these winds are drawn towards the Himalayas, storm clouds develop. The monsoon accounts for some 80% of the rainfall in India, with some areas of the subcontinent getting up to 10,000mm annually.
This year the monsoon was some two to three weeks more advanced north than average – with the Indian Met Service reporting the normal date by which the Monsoon reaches the Northern India, Nepalese and Pakistani regions as being 1 to 15 July, compared with this year’s advance being 15 to 16 June: (http://www.imd.gov.in/section/nhac/dynamic/Monsoon_frame.htm).
This early extension into the North allowed this air to interact more readily with an upper trough that moved south to the lower latitudes of Northern India and Western Nepal. This resulted in forecasts of significant rainfall accumulations (up to 450mm (see figure below) and actual rainfall anomalies of up to 150mm. (http://www.imd.gov.in/section/nhac/dynamic/Monsoon_frame.htm)
UK Met Office global model showing rainfall accumulations for Northern India and Western Nepal
Extract from JBA’s India flood map showing the flood outlines for the 5-year return period (orange) and the 200-year return period (purple). Background map: Bing: copyright 2013 Microsoft Corporation and its data suppliers
Meteorological background: Canada
A slack area of low pressure over Idaho on Wednesday 19 June moved slowly east to the south of Alberta extending a trough of low pressure to the NW later on Wednesday and into Thursday 20 June, effectively stretching its fronts in an west-east orientation over southern Alberta. Warm air from the US mid-west was drawn northward and along the front, sparking a series of severe thunderstorms. With the pattern slow moving, these storms repeatedly affected the same area for 24-36 hours, leading to accumulations of over 200mm especially over the eastern Rockies and its foothills.
Map created by WPC