A thing or two about rainfall..

India Meteorological Department classifies rainfall in the following categories:-

> 65mm as heavy,
> 85mm as very heavy and
> 250mm as exceptionally heavy precipitation

One of the resource persons (Dr KJ Ramesh, Scientist, Dept of Science and Technology, Govt of Meghalaya) in the Disaster Preparedness Workshop which I attended at Shillong recently (10-11Jun08) stated that due to climate change/global warming we could expect an increase of 20-40% in the annual rainfall in the future
BUT he went on to say this increase would be accompanied by a DECREASE in the number of days of precipitation.
In other words we will have days with sharp concentrated bursts of heavy/very heavy rain interspersed with days with minimal rain...

Thus in Sep07, it rained the entire monthly rainfall ie 650mm within the first week and by the 16Sep07, we had had 950mm of rain ie 150% of our monthly average ie - hence the devastation.

Also here is the rainfall data in Darjeeling for the past few days (24hr period ie from midnight to midnight) :-

15Jun08............ 1.01mm
16Jun08............ 4.06mm
17Jun08............ 92.2mm
18Jun08............ 127mm
19Jun08............ 56.8mm
20Jun08........... 59.9mm

What we have to understand is that so long as rain fall is distributed evenly over the entire month it maybe still okay - it is the “cloud burst” type of scenarios we have to be wary about….and rather sadly the frequency of this type of phenomenon seems to be increasing.

The heavy rainfall between 17-19Jun08 has already taken its toll…

Placed below are excerpts from today's newspaper

The Telegraph (21Jun08)

Rain triggers landslides & red alert

- ‘Moderate’ monsoon downpour expected in the next 24 hours - Cracks appear on hospital walls OUR BUREAU

Siliguri, June 20: Incessant rain throughout north Bengal has led to landslides in the hills and an announcement of red alert on both banks of the Teesta. The alert is meant for the areas starting from Domohoni, on the outskirts of Jalpaiguri town, to Bangladesh.

With the south-west monsoon setting in, north Bengal, especially the Jalpaiguri and Darjeeling districts, and Sikkim witnessed heavy to very heavy rainfall since yesterday.

The highest rainfall was recorded at Sevoke (230.8mm), followed by Bagdogra, Siliguri, Gajaldoba, Domohoni and Jalpaiguri . Of these, Sevoke, Gajaldoba, Domohoni and Jalpaiguri are located on the banks of the Teesta.

According to sources at the Regional Met Office in Jalpaiguri, rainfall above 65mm in 24 hours is considered heavy, above 125mm very heavy and above 250mm extreme heavy rainfall.

“The data of locations close to the Teesta available with us shows very heavy rainfall. This has contributed to the rise of water level in the Teesta,” the sources said.

Last year’s data, however, showed that rainfall on the same date in these areas was low. Sevoke had recorded 25mm, Jalpaiguri 0.1mm, Siliguri 4.4mm, Bagdogra 3.6mm, Domohoni 0.4mm and Gajaldoba 4.6mm. “The less rain was because of the late arrival of the monsoon,” an official at the Met Office said.

The last few days’ incessant rain also triggered landslide at Hatisuray, 25km from Siliguri on NH31A, and blocked the road for nearly six hours.

The highway is already deserted because of the strike called by the Gorkha Janmukti Morcha.

“The landslide occurred around 7am, disrupting the road link,” said Prankrishna Das, the officer-in-charge of the Sevoke police outpost. It however, disrupted the movement of army vehicles and ambulances to Sikkim and Kalimpong.

The debris was cleared by afternoon and the road communication was restored by the Border Roads Organisation, Das added.

The rain also affected Siliguri and surrounding areas, with residents of low-lying places like Samarnagar, Shitalapara, Santoshinagar, Ganganagar and Champasari, facing water logging this morning.

“We have received reports of water logging in some wards but the level receded by afternoon,” mayor Bikash Ghosh said. “We have sent workers of the conservancy department to the areas.”

The Siliguri Municipal Corporation has also opened a flood control cell and has cancelled the leaves of all employees in the conservancy and public welfare departments.

Weather experts hinted at rainfall throughout the sub-Himalayan Bengal in the next 24 hours.

“The monsoon clouds are hovering over north Bengal. We expect light to moderate rainfall,” said Subir Sarkar, the in-charge of the weather station at North Bengal University. “Yesterday, the NBU campus and nearby areas experienced an extreme heavy rainfall of 251 mm.”

The rainfall has also brought down the temperature. In Siliguri, the highest and lowest temperature were recorded at 25.4 and 23.4 degrees Celsius, respectively, Sarkar said.

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Statesman News Service (21Jun2008)

More landslides in Kurseong

KURSEONG, June 20: More landslides triggered by the continuous rain over the past few days occurred in the Kurseong sub division today. The premises of one Gabriel Franci's house at ward no 2 of the Kurseong Municipality collapsed and his house was damaged in a slide.
The Kurseong Sub-divisional relief officer, Mrs Aasha Mukhia Lama informed that a public path near GDNS hall in Kurseong town collapsed this making life difficult for people residing in the area.
According to her, the house of Sangeeta Rai in ward no. 2 has also collapsed. The victim has been provided with tarpaulin. The relief department has pitched shelter points at different places to accommodate slide victims and food grain was being distributed among the victims.
The slides also affected Roshan Chetrri's house at Giddha-Pahar and the house of Dawa Lama at Sepoydhura as well. Large chunks of rocks rolled down the hillside on National Highway 55 at Dungay Kothi, near Mahanadi holding up movement of school vehicles.

Statesman News Service (21Jun08)

Cracks in Darjeeling district hospital

DARJEELING, June 20: The Darjeeling District Hospital has developed cracks in its structure following incessant rainfall the past few days. The rear portion of the building has sustained the fault causing panic among the patients.
“The hospital administration suggested us to stay back at our own risk. With such inclement weather conditions a calamity could occur in the night catching us helpless. So we are leaving the hospital,” said Mr Faizun Ahmed, whose daughter was admitted to the hospital for treatment yesterday.
Others like Balkumar Chettri of Lapchu whose brother is admitted with viral fever chose to stay back despite the caution. “It will be difficult to take my patient back in this bandh. Moreover, he has not recovered fully and we do not want to take chances with his health. If there is a crisis, it is the responsibility of the administration to make alternative arrangements,” he demanded.
The district hospital, which has already drawn flak from the locals for its pitiable condition had also earned the disapproval of the Union Health Minister Mr Anbumani Ramadoss during his recent visit to the hospital.
However, the hospital administration, the district administration along with the Darjeeling Municipality is taking necessary measures to overcome the crisis situation. Arrangements are being made to shift the 100 patients from the vulnerable zone to a safer place. “Around 60 patients would be shifted to the nearby Marwari Sahayak Samiti and the rest 40 will be relocated within the hospital,” informed the CMOH, Dr S Bhowmik.
PWD engineers surveyed the hospital today and repair work will begin from tomorrow. “The patients would be shifted back to the hospital after the repair works are over,” the CMOH added.
Regarding the discharge of some patients following the development of cracks on the hospital building the CMOH clarified: “Only those who have fully recovered have been discharged. As for the serious cases we take full responsibility of their safety.” The district administration has provided the hospital with tarpaulins to meet an emergency if any in the night, he added.

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Sikkim Express (21Jun08)

Landslides cut off road communication across the State Our Correspondent
RANGPO, June 20: Following incessant rains in the morning, fresh landslides occurred at several places around Rangpo bazaar this morning.
The landslides disrupted the Rangpo-Rongli, Rangpo-Pandam, Rangpo-Gangtok roads for some time but were soon cleared for traffic.
The Rangpo-Namchi road was also closed since morning due to heavy landslides at Narak Jhora. It was opened in the afternoon.

Heavy rains wash away portion of footpath in Ranipool

Staff Reporter GANGTOK, June 20: Following incessant rains over the past two days, a portion of the newly constructed footpath, near 7th Mile near Ranipool along the National Highway 31A was washed away this morning. The force of the flowing rain water almost hit the house of one Kala Chettri, which is located just below the footpath. The Sub Divisional Magistrate, East AB Karki and other officials from the State Public Heath Engineering Department and Rural Management and Development Department today visited the site. “After a thorough inspection, we have declared the zone as unsafe,” the SDM told SIKKIM EXPRESS. A cow belonging to Ms Chettri was slight injured with the stones brought down by the slides. No casualties were reported. “We heard a loud sound as if the entire footpath was falling above our house,” the house owner said. Likewise, the torrential rains also washed away the pedestrian footpath joining DPH and Hospital Dara last night. “Heaps of garbage is dumped into the jhora by the residents in this stretch as a result of which the landslide had occurred,” the SDM said. _______________________________________________

Perhaps the most worrisome part in all this is that the monsoons have just begun in this part of the world ... and we have 3 months of rains ahead with the soil getting more saturated with every shower.

praful rao

My thanks to Mr Bon Pradhan of Compuset, Darjeeling for supplying last week's rainfall data for Darjeeling