Context:

• This year’s floods in Assam have been merciless. The Brahmaputra Valley that encompasses the Northeast part of India witnesses floods almost every year, leaving behind a tale of death and destruction. 
  • In recent years, however, the extent of devastation due to floods has increased significantly. 

About Flood:

• A flood is an overflow of water that submerges land that is usually dry. 
• In the sense of “flowing water”, the word may also be applied to the inflow of the tide. 
• There are three common type of floods: 
• Flash Floods:
  • Caused by rapid and extensive rainfalls
• River Floods:
  • Caused when consistent rain or snow  melt forces a river to exceed capacity. 
• Coastal Floods:
  • Caused by storm surges associated with tropical cyclones and tsunami.

Why Assam Gets Flooded Every Year?
The Brahmaputra factor: 

• Assam is situated at the foothills of the Himalayas and comprises two valleys namely Brahmaputra and Barak.
• It flows through Assam over a length of around 650 km with an average width of 5.46 km, making it the principal river that crisscrosses the floodplains. 
• Coming from the Kailash range (high elevation), the river gets highly sedimented by the time it enters Assam (low elevation). 
• Due to this flattening of the slope, there is a sudden drop in velocity and the river deposits huge quantities of sediment and other debris collected from hilly terrains on the riverbed, raising its level. 
• During summers, the sedimentation increases as soil erodes with the melting of glaciers. 

The Monsoon Factor: 

• The monsoon is intense in the Northeast. 
• According to the State Disaster Management Authority, annual rainfall averages around 2900 mm with maximum precipitation in June and  July. 
• The Water Resources Ministry of Assam states that 85% of the annual rainfall in the Brahmaputra basin takes place during  the monsoon months. 
• Besides, the valley gets a good amount of rainfall in April and May due to thunderstorm activities which account for flooding during heavy rain in June, when the soil is already saturated. 

Riverbank Erosion: 

• As sedimented rivers move through the state along with their tributaries, they take with them soil and sediment from banks. 
• Soil erodes and rivers expand as it gets more area and this results in flooding. This erosion of the land alongside rivers has emerged as a serious problem for Assam.
• The width of Brahmaputra has increased up to 15 km due to bank erosion at some places in Assam. 

Human intervention:

• Construction of Embankments: 
  • Embankments are constructed to confine the course of a river. This solution, however, has evolved to be an added challenge over time in Assam.
  • Construction of embankments first started in Assam in the 1960s to control floods. 
  • Six decades later, most of these embankments have either outlived their utility or are in bad condition. Many others were washed away. 
  • Every year, as floods follow monsoon, river water breaches these barriers and inundated houses and land. 
• Population Boom: 
  • Population boom in the State has put more pressure on the State’s ecology.
  • The population density of Brahmaputra valley has highly increased as per the 2011 census, according to a report by the Brahmaputra Board. 
  • The board under the Ministry of Jai Shakti monitors the Brahmaputra and Barak Valley and covers States under the Brahmaputra basin. 

Climate change:

• A Report by the State government states that extreme rainfall events will increase by 38%. 
• Heavy rainfall replacing continuous low or normal rainfall during monsoon combined with the melting of glaciers due to rising temperatures will mean: 
• Rivers from the Himalayas will be carrying more water and sediment  even before they enter Assam where smaller rivers are swelled up due to incessant rainfall. 
• This increases the possibility of frequent flash floods in low-lying areas. 

Other Factors Worsened the Flood Situation: Deforestation, Hill Cutting, Encroachments, Destruction of Wetlands, Lack of Drainage System in the State, Unplanned Urban Growth, Construction of Dams, Hydro Projects, Irrigation Projects, etc.

Advantages of Floods in the Northeast Region: 

• Raising of Lowlands: Every year, the Brahmaputra and its tributaries transport billions of tonnes of sediment, mainly from the Eastern Himalayas. This raised the lowlands and regularly adjusted river beds. 
• Rejuvenation of Ecosystem: Floods cause disruption and damage but they also generate a bounty of fish and rejuvenate flood-plain ecosystems all along the Brahmaputra, including in the Kaziranga. 
• Shaping of the State: The entire Assam landscape has been shaped over millions of years with the help of an active monsoonal environment and mighty rivers that carry sediments weathered from the still-rising Himalayas. 

Adverse Effect of Floods on Assam: 

• Kaziranga National Park: 
  • More than 15% of the Kaziranga National Park has been inundated  with the Brahmaputra flowing above the danger level, an official statement noted. 
• Effects on Infrastructure:
  • Train services  got disrupted as water affected railway tracks at several places.
  • All modes of transport went on halt except Boats, which charged as much as ₹100 per 100 m in some areas to make up for their inability to fish or ferry people to rivers for a living. 
  • Roads and bridges have suffered serious damage. 
• Effects on Animals:
  • Animals are also killed by poachers who take advantage of their vulnerability.
  • Human-animal Conflict: Animals also move towards villages in floods, this leads to human-animal conflict. 

Measures Need to be Taken: 

• Information Communications: It should be ensured that more credible information is made available so that preparedness can be improved and residents can be alerted. 
  • Experts have indicated that the region needs more institutionalized and technologically advanced systems to allow for credible and fast warning systems. 
• Protecting Kaziranga: Emphasis needs to be put on securing animal corridors and ensuring a safe passage to the Karbi hills. 
  • Need for a landscape-scale conservation approach that recognises the value of the Karbi Anglong hills. 
  • The highlands of Karbi Anglong, where the animals take refuge, are the lifeline of the park during the floods. 
• Constructing Sluice Gates: Sluice Gates should be constructed on tributaries of Brahmaputra and other rivers. It would prove to be an effective step.
  • Sluice Gate’s valves are designed to seal in one direction and commonly are used to control water levels and flow rates in rivers and canals.
  • They also are used in wastewater treatment plants. 
• Other Measures: A Centre for Disaster Management should be established in Assam to carry out studies for effective implementation of measures.

Way Forward:

• People’s Resilience: The rapid transformation in rainfall characteristics and flooding patterns demand building people’s resilience. 
• Sustainable Land Management: Construction projects that impede the movement of water and sediment across the floodplain must be reconsidered. 
  • Encouraging responsible land management practices, such as avoiding excessive excavation and deforestation, can help preserve the natural landscape and prevent soil erosion. 
• Early Warning Systems: The region’s historical experiences offer several valuable lessons in adaptation to floods. At the same time, climate-imposed exigencies demand new paradigms of early-warning and response systems and securing livelihoods and economies.
• Improved Infrastructure and Drainage systems: Investing in well-designed and adequately maintained infrastructure, including drainage systems, can help manage and redirect excess water during heavy rainfall events. 

News Source: The Indian Express