Private weather agency Skymet said on Monday that the rains will be triggered by the northward shifting of the trough line — on which monsoon rainfall largely hinges — towards the Himalayan foothills around July 13-14. The trough line is a low-pressure that stretches from west to east and takes along the heavy rain belt with it when it shifts.

In Bihar, heavy rains and floods have claimed 29 lives, according to Bihar State Disaster Management Authority. NERC reported that recent flooding had affected 1.554 million people in the state.

The rivers Burhi Gandak, Bagmati, Ganga, Kosi and Sone are all above danger levels according to NERC, with further heavy rain expected. In 24 hours to 29 September 2019, Rosera recorded 290mm of rain and Bihpur and Koilwar both 270mm.

According to a CWC report of 29 September, the Kosi at Baltara, Khangaria stood at 34.9m (danger is 33.85m). The level of the Ganga at Bhagalpur was 34.24m (danger is 33.68m) and the Ganga at Patna Gandhighat was at 49.42m (danger 48.6m). The Sone river at Maner, Patna district, stood at 52.34m (danger 52m)

Nineteen teams from the National Disaster Response Force (NDRF) have been deployed to affected areas. Teams from the Indian Air Force have also been deployed.

The city of Patna and the surrounding district has been particularly badly affected. According to NERC, flooding has also affected areas of Buxar, Bhojpur, Samastipur, Lakhisarai, Begusarai, Khagaria, Bhagalpur, Munger, Katihar and Saran districts

Bihar is surrounded by Nepal in the north, West Bengal in the east, Uttar Pradesh in the west and  Jharkhand towards the south. There are several rivers that run through the state: Ganga, Sone, Punpun, Falgu, Karmanasa, Durgavati, Kosi, Gandak and the Ghaghara, to name a few. Nearly 85% of the state’s land is under cultivation. Bihar also receives heavy rainfall all through June to October.

The state of Bihar has been facing floods since for a long time. It accounts for almost half of India’s average annual flood losses. In the year 1914, Bengal and Bihar faced floods. In the year 1934, Bihar was shaken by an earthquake which was again followed by floods.

The state has been facing floods ever since, but the frequency of floods has become high in recent years. There have been floods almost every year from 1979 which have caused extensive damage. Lakhs of people have lost their lives and their homes. The state has faced infrastructural losses worth crores of rupees.

In 2008, more than half of Bihar was submerged under water. The state witnessed its worst floods ever with more than 30 lakh people in more than 1500 villages spread across 16 out of 37 districts being affected. The worst affected districts were Araria, Saharsa, Supaul and Madhepura.

After the floods in 2008, Bihar faced a drought for two years and again in 2011, nearly 100 villages were flooded by the Bagmati river. Much of Bihar’s misery has been caused by the Kosi river, which is a major tributary of Ganges.

The Kosi river system drains about 60,000 km2 of eastern Nepal and southern Tibet before it enters Bihar. The basin includes almost half of the world’s 8,000 m plus peaks. North of the India-Nepal border, it is known as the Sapt Kosi or “Seven Rivers” in reference to its seven tributaries: Indrawati, Sunkosi, Tambakosi, Lihku Khola, Dudhkosi, Arun and Tamur. Its three main tributaries i.e. Sunkosi, Arun and Tamur join the river at Tribeni. Downstream of the Tibreni, the Sapt Kosi flows through a narrow gauge of 11km, before spreading over the Gangetic plains. As a result of the sudden decrease in slope below the mouth of the gorge, an inland delta is formed. It is interesting to note that the river has shifted more than 100 km westward in the past 200 years.

Figure: Sapt Kosi is formed by seven rivers in south-east Nepal. Image Courtesy: Hydrologic regime of the Sapt Kosi Basin, Nepal – Richard Kattelmann, University of California.

Figure: Sapt Kosi is formed by seven rivers in south-east Nepal. Image Courtesy: Hydrologic regime of the Sapt Kosi Basin, Nepal – Richard Kattelmann, University of California

What causes floods?

There has been increased conversion of forests to agricultural and continuous deforestation  which significantly contributes to the flood damage in India. There was an increase in the annual run off in the Sapt Kosi from the 1950s until the 1980s, but the rainfall also increased correspondingly at several stations in the basin.

Another reason for the flood damage is that Bihar lies in foot of Himalayas and have very low plain. 

The state government has built about 3000 kms of dam, but the flow of the river has grown 2.5 times resulting in the failure of dam in every flood.

So the big question is the state of Bihar prepared? The Disaster Management Department, Government of Bihar has come out with a number of schemes.

  • Procurement of motor boats and other necessary accessories like life jackets, mahajals, tents, etc. for 28 flood-prone districts.
  • To improve the response mechanism and tackle the impact of natural disasters effectively, a State Disaster Response Force (SDRF) is to be established on the similar pattern of National Disaster Response Force (NDRF).
  • A number of warehouses will be constructed to store the relief and rescue materials and to keep them safe and secure.
  • Establishment of Emergency Operation Centres (EOC) in all the districts to carry out rescue and relief work effectively.
  • Since the communication system often becomes dysfunctional, procurement and proper maintenance of communication systems has been taken into account. Satellite phones, GPS instruments, hand packs, walkie – talkies will be procured.
  • An Early Disaster Warning System is to be established.
  • A plan has been prepared to generate awareness among the masses about the ways and means of mitigating the risk of disaster.

The budget for the above scheme crosses 5000 crores.

What more can be done?

A number of structural measures can be taken up in the state:

  • Detention Basins: The state area has a number of depressions locally called chaurs which act as detention basins. These chaurs absorb a considerable amount of water of the first flood of the season. No man made detention basins or improvements in natural chaurs has been done.
  • Dam: All the rivers have been embankment in the state. River Kosi is embankment on both the sides. But there are few gaps in these embankments which reduce its effectiveness. The maintenance and repair of these embankments must be taken into account.
  • Channel Improvement: is not a usual practice.

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