Flood and landslide disasters of Assam

Gunin Borah

(The writer is the HOD of Geography, Biswanath College, Chariali and he can be reached at Email ID: borah.gunin@gmail.com )

The unique geo-climatic condition of the region makes Assam and the entire North-East Region of India very prone to natural disasters like flood-erosion, earthquake and landslides. The state of Assam experiences perennial flood, river bank erosion, landslides, and other environmental catastrophes. Disasters cause sudden disruption in the normal life of a society, along with enormous damage to property associated with high casualty of human life. A review of past disasters indicates that the state has had to bear the devastation of two natural disasters, i.e., flood and earthquake.

Assam with its vast network of rivers is prone to natural disasters like flood and erosion which has a negative impact on overall development of the state. The rivers Brahmaputra and Barak, with more than 50 tributaries feeding them, cause flood devastation in the monsoon period every year. The flood and erosion problem of Assam is singularly different from the other states in so far as extent and duration of flooding and magnitude of the erosion is concerned. The flood problem of Assam is further aggravated due to flash floods by the rivers flowing down from neighboring states like Arunachal Pradesh, Meghalaya, Nagaland etc.

The flood prone area of the state, as assessed by Rashtriya Barh Ayog (RBA), is 31.05 lakh hectares against the total area of the state of 78.523 lakh hectares, i.e,, about 39.58 per cent of the total land area of Assam. This is about 9.40 per cent of the total flood-prone area of the country. Records show that the average annual area affected by flood is 9.31 lakhs hactares.

Recently, North-East India has been witnessing heavy rainfall activity since mid-April. The rain was more of a welcome respite from the punishing summer heat, but the conditions intensified considerably in the past week, influenced by the presence of Cyclone 'Asani' in the Bay of Bengal.

According to the latest bulletin, Assam received 545.00 mm rainfall since May 6, 2022. Incessant rains have triggered floods in 27 districts, including among others Biswanath, Bongaigaon, Cachar, Dhemaji, Dhubri, Dibrugarh, Hojai, Karbi Anglong, Kokrajhar, Lakhimpur, Nagaon, Nalbari, Jorhat, and Kamrup Metro districts. Districts affected by landslides include Dima Hasao, Hailakandi, and Karimganj. According to the Assam State Disaster Management Authority, a total of 197, 248 people in 20 districts have been affected by the floods at the time of writing this article. The total area of cropland affected is 16,645.61 hectares in the state.

Surface communication in the state has taken a major hit as well. More than nine spots in the mountainous territory have been wrecked by the flash flood and significant landslides, cutting off essential train and road communication from other parts of the state and region. Railway lines at Jatinga-Harangajao and Mahur- Phaiding were snapped due to landslides as well. The Indian Air Force (IAF) and Northeast Frontier Railway (NFR) evacuated around 2,000 passengers from the affected areas. At the same time, over 25 train services to Tripura, Mizoram, and south Assam had to be canceled.

Assam faces the annual calamity of floods during the monsoon months, when incessant rains batter the Northeastern states. But the yearly event seems to have arrived early this year, with Assam already having witnessed several instances of flooding and landslides in the last few days, resulting in loss of life and property. The India Meteorological Department (IMD) has forecast isolated heavy to heavy rainfall over Assam for the next five days until Saturday, May 21 and possibly beyond. Thunderstorms and lightning may accompany the rain in several districts of the state in the coming days.

The precipitating factors of recurrent floods in Assam are both natural and anthropogenic in origin. High potent rainfall regime, deforestation, and easily erodible geological formations in the upper catchments accelerate the rate of basin erosion, rapid channel aggressions, intense land-use pressure, explosive population growth especially in the flood-prone belt and ad-hoc type of temporary flood control measures are some of dominant factors that cause and intensify floods.

The most important cause of frequent flooding in this region is the extremely dynamic monsoon regime, and the unique physiographic settings of the river basins. Floods had become a perennial episode after the devastating earthquake of August 15, 1950.

Assam and other Northeastern hilly states are prone to heavy natural and artificial landslides. Landslides and earthquakes send in a lot of debris and sediments to the rivers, causing the river beds to rise up and become shallow. The shallow river beds lead to greater floods in the river basin.

There are a lot of anthropogenic as well as human induced factors like destruction of wetlands, oxbow lakes, deforestation, illegal cutting of hill slopes, earth filling the natural ponds, swamps, canals, encroachment of river banks, etc. Among the man-made reasons, the key cause of flood in Assam is releasing of excess water from dams situated upstream in Bhutan, Arunachal Pradesh, Nagaland, and Meghalaya. The unregulated release of excess water creates floods in the plains of Assam, leaving thousands of people homeless every year during the summer monsoon period.

Various flood management activities taken up for short-term and medium-term measures by the Brahmaputra Board, Water Resource Department of Assam and Ministry of Water Resources under various policy initiatives. As the flood in Assam is a recurring problem every year, the Government of India should declare it as a national disaster, so remedial measures can be adopted for the state. Both the Central and State Government must take necessary measures for the control and mitigation of floods in Assam and North-East India with long term master plans.