18 August, 2006

What led to floods?

From Gargi Parsai's report in The Hindu

Expert says the authorities waited for the dams to fill up before releasing the water

The dams had 47 per cent water before the monsoon
This is "negligence" of operations


NEW DELHI : It seems that mismanagement and negligent operations of the large reservoirs on the rivers cause the floods in Gujarat, Maharashtra, Madhya Pradesh, Karnataka and Andhra Pradesh.

Himanshu Thakkar of the South Asia Network on Dams, Rivers and People, claims that the big dams that were expected to regulate water flows were actually responsible for the floods in these States that also happen to have the largest number of big reservoirs. Dams in these States had an average of 47 per cent storage before the monsoon set it, which in itself was a potential for causing floods.

Demanding a probe into what caused floods in these States and whether they were avoidable, Mr. Thakkar said action should be taken against those responsible for "mismanagement."

"The nation has paid huge costs in creating these reservoir capacities, and negligence in the dam operations is leading to disastrous consequences which are entirely avoidable," he said.

Storage

Officials from the Central Water Commission told that normally dams were supposed to be emptied out before monsoon by releasing water for irrigation and other purposes. "Reservoir storages are built up at the end of the monsoon, to prevent floods downstream."

But as per the Central Water Commission statistics, in the Tapi basin, various dams had upto 41 per cent storage before monsoon.

In the Narmada basin, the Tawa dam was already filled up to 22.58 per cent before the monsoon.

Likewise, in the Krishna basin, the Koyna dam was filled up to 25.19 per cent, the Khadakvasla up to 12.5 per cent, the Narayanpur up to 44.1 per cent, the Srisailam up to 17 per cent and the Nagarjunsagar was filled up to 47.08 per cent.

In the Godavari basin, the Jayakwasi had a storage of 28.33 per cent and in the Sabarmati basin, the Dharoi dam was filled up to 42.59 per cent.

Mr. Thakkar said releases from the dams — under instruction from the State Irrigation departments — after the onset of the monsoon were normally kept under wraps. More often than not, the secrecy hid gross neglect and mismanagement, as had happened this year.

He alleged that the large-scale loss of lives and businesses in Surat could have been avoided by early, regulated releases when it was known that the Ukai dam across the Tapi was filling up fast. The dam was 51 per cent full on July 20, 77.54 per cent full on August 3 and 100 per cent on August 7. Even when it was getting high inflows of up to nine to ten lakh cusecs, the authorities waited for the dam to fill up before releasing water. This meant the sudden release of up to 10 lakh cusecs for several days, leading to unprecedented flooding. This, when the Tapi downstream from dam had a drainage capacity of only about 3.5 lakh cusecs. The releases also coincided with high tide, leading to prolonged flooding.

Mr. Thakkar claimed that in the Sardar Sarovar Project also, the main canal was opened by just 0.5 metres on August 2, releasing just about 580 cusecs,when inflows were over 98,000 cusecs. Downstream releases were just around 21,000 cusecs. This led to a build-up of water, of up to 128 metres, leading to "illegal and avoidable" submergence of land, houses and habitats of thousands of rural and tribal families. The situation was similar in the Krishna, Godavari and Sabarmati basins.

2 comments:

shiraz satarawala said...

Serious floods have caused havoc in the Krishna basin in the last 2 years. Mahabaleshwar is the source of the Krishna river and it's tributaries, Venna and Koyna rivers. There are 2 dams built on the Krishna river - Dhom and Balkavdi. The Kanher dam is built across the Venna river and the Koyna dam across the Koyna river. All these dams are located in Satara District, Maharashtra. Mahabaleshwar is considered the water tower of Western Maharashtra. Mahabaleshwar is located in the Western Ghats of Maharaashtra. Mahabaleshwar receives the 2nd highest rainfall in the world - 250 inches average. In the last 2 years the monsoon has been very heavy and the region has recorded over 330 inches of rain. The dams get full within a short period and the gates are opened at the last moment causing flooding down stream. The floods have ruined furtile farm lands and washed away many villages and life and property lost. The situation needs to be studied in detail by experts and flood control measures need to be implemented immediately.

త్రివిక్రమ్ Trivikram said...

Thank you very much Shiraz, for your valuable inputs. It is sad but true that "the dams get full within a short period and the gates are opened at the last moment causing flooding down stream. The floods have ruined fertile farm lands and washed away many villages and life and property lost." They are all purely man-made floods.