While natural topography and excessive rainfall are obvious causes, floods are also caused by human intervention—like encroachment of river banks and wetlands, lack of drainage, unplanned urban growth, hill cutting and deforestation.
The Brahmaputra, a trans-boundary river and among the mightiest rivers in Asia, is braided and unstable in its entire reach in Assam except for a few places.
As per the Brahmaputra board’s latest annual report, the main reasons behind the instability of the river are high sedimentation and steep slopes. Additionally, the entire area falls in an earthquake-prone zone and experiences high rainfall.
The Brahmaputra board is a central government body that is tasked to carry out surveys and investigations in the Brahmaputra Valley and to prepare a master plan for the control of floods, bank erosion and improvement of drainage.
“Topography of Assam and meteorological factor (high rainfall) are the obvious reason behind Assam floods every year. Also, Brahmaputra is the largest water carrying river of India and the second-largest silt carrying river in the world. But the way we deal with rivers is further accentuating the disaster faced by the region," said Himanshu Thakkar, coordinator of South Asia Network on Dams, Rivers and People (SANDRP).
SANDRP is a network of organizations and individuals working on issues related to the water sector with a focus on large dams.
“The dams that are being built are further creating disasters. Not just that, the wetlands forests and local water bodies are being systematically destroyed which in turn is adding to the disaster vulnerability of the area," Thakkar added.
The region is also extremely vulnerable to breaches of embankments.
“Floods happen due to a breach of embankments. More than 80% of these embankments have not been reinforced in several decades because there is a huge contractor-administration nexus that benefits monetarily from a flood situation," said Kishalay Bhattacharjee, professor and commentator on the northeastern region.
According to data released by the Assam State Disaster Management Authority (ASDMA), 2017 has been the worst of the last four years in terms of floods.
In 2014, due to floods, 1,846 villages were affected and about 1.6 million people were displaced. In 2015, the number of affected villages was 1,031 and about 1.5 million people were displaced. The numbers saw a huge jump in 2016 with 2,893 villages affected and about 1.7 million people being displaced.
This year, about 2,450 villages have been already affected by floods and more than 1.7 million people across the districts of Lakhimpur, Biswanath, Karimganj, Kokrajhar, among others, displaced. The monsoon season is still ongoing.
ASDMA has set up 123 relief camps and 259 relief distribution centres across the state but the number of displaced is increasing. The camps are housing close to 29,000 refugees. The current death toll across 58 districts in Arunachal Pradesh, Assam and Manipur is 80.
Thakkar said authorities also need to improve the flood forecasting system and coordinate with local administrations.
“The central water commission (CWC) puts out flood forecasts but that’s not good enough as local administration is not able to use it. CWC also needs to take it into account rainfall data and not just upstream water flow. All such measures along with addressing man made causes can help reduce the level disaster in the region," he added.
Floods also are a cause of worry for the administration as they spread disease.
“Japanese Encephalitis has already spread here. We fear that other water-borne diseases such as jaundice and cholera will also affect the refugee camps because there are too many displaced people and the situation is only becoming worse with each passing day," said a senior union home ministry official, requesting anonymity.
A team from Niti Aayog and the union home ministry’s National Disaster Response Force (NDRF), led by union minister of state for home affairs Kiren Rijiju, carried out a ground assessment of the Assam floods earlier this week. The government has also drafted in experts from Isro for carrying out an assessment of the damage in the northeast by satellite.