Climate change fuels landslide risk for 10 lakh residents in Ctg

• Deforestation, uncontrolled hill razing, poor management blamed 
• Landslides occurring since 1960s, with casualties rising 
• Climate change has caused an 8% rise in monsoon rainfall 
• Many communities in the region live in high-risk landslide zones

Climate change is greatly increasing the risk of landslides in the Chattogram division, endangering the lives of 10 lakh residents, a new study shows. 

Conducted by the Department of Geography and Environmental Science at Chittagong University, the research links changing monsoon rainfall patterns, caused by climate change, to more frequent landslides in the area. 

Additional factors include deforestation, uncontrolled hill cutting, unplanned settlements, poor hill management, and the government's failure to act on landslide prevention recommendations. 

The study, led by two professors and involving 44 students from the 2015-16 academic year, was published in April 2024.

Landslides in Chattogram 

Bangladesh's hilly regions, including Greater Chattogram, Chittagong Hill Tracts, Cox's Bazar, and Sylhet districts, have a history of landslides.

The first recorded landslide happened in 1968 on the Kaptai-Chandraghona road, but no casualties were reported. The first known death from a landslide occurred in 1970 on the Ghagra-Rangamati road. Since 1990, the number of landslide casualties during the monsoon season has been rising in the division.

From 2000 to 2018, there were an average of 11 landslides each year, causing 34 deaths and 54 injuries annually. Over the past 17 years, Chattogram district has had the most landslides with 208 incidents, followed by Rangamati with 193, Cox's Bazar with 124, Bandarban with 118, and Khagrachhari with 87.

Increased rainfall due to climate change

Researchers have found that most landslides in the region from 1968 to 2019 happened in June and July during the monsoon season.

Chattogram and nearby areas get about 3,000mm of rain each year, with the highest amounts falling in these two months. On average, June and July receive 600mm of rain each month, or 20mm per day.

A UN Food and Agriculture Organisation report notes an 8% increase in monsoon rainfall in Bangladesh over the past 30 years. Heavy rain over a short period, such as more than 40mm in a single day, is a major trigger for landslides.

In June 2017, intense rainfall caused a severe landslide in Rangamati, killing 164 people, including 5 army personnel, and damaging around 3,000 homes. A 20km stretch of the Rangamati-Chattogram road was destroyed, isolating the districts for nearly three months.

The Roads and Highways Department reported that 145 spots along 264km of roads in Rangamati were affected, with 37 locations on seven major routes collapsing. This was the worst landslide disaster recorded in Bangladesh.

During this incident, 945mm of rain fell over five days, the highest amount in the past decade. Rangamati recorded its highest daily rainfall ever on 12 and 13 June 2017—365mm. Previously, the highest daily rainfall in Rangamati was 352mm on 21 July 1960.

Earlier, Chattogram city saw 408mm of rain in 24 hours on 11 June 2007, leading to landslides at six locations and 127 deaths.

Prof Mohammad Iqbal Sarwar, who led the research, explained that Chattogram used to have light, consistent rainfall during the monsoon. Climate change has increased the intensity of rain, which the mountains cannot manage, leading to more frequent landslides. Rising summer temperatures also contribute by drying and cracking the hills, making them more prone to collapse during the monsoon.

"Our research shows that climate change, combined with human activities, significantly increases the risk of landslides," he said.

How hills collapse

The hills in the division are made of sandy soil. In steep areas, deforestation creates cracks in the soil during the dry season, weakening its stability.

When the monsoon starts, rainwater enters these cracks and seeps deep into the soil, further weakening it. As rainfall increases, the extra water inside the soil creates pressure, causing the soil's stability to fail. Eventually, gravity causes the soil to collapse, either suddenly or gradually.

Stopping hill razing remains a challenge

The Chattogram Department of Environment (DoE) identified hill-razing at 53 locations between 2015 and 2023. Of these, 25 incidents happened in 2019. That year, the department fined 21 people and organisations a total of Tk41.33 lakh for illegal hill cutting.

Recently, the Chattogram Development Authority (CDA)6,558 vulnerable settlements: Ctg braces for new landslides, flooding amid incessant heavy downpourto build a 6km road from Bayezid to Faujdarhat area. Although the DoE allowed CDA to raze 2.5 lakh cubic meters of hills, the project resulted in razing 10.5 lakh cubic meters from 16 hills.

For this, CDA was fined Tk10.38 crore on 29 January 2020. Despite this, hill cutting continues year-round in areas like Salimpur Jungle, Latipur Jungle, and Jalalabad, often evading administrative control.

10 lakh people at risk of landslides

The DoE reports that there are 30 hazardous hills in Chattogram. Illegal settlements such as slums, residential areas, shops, and factories have been built on these hills, putting around 200,000 people at risk.

In Chattogram city, 17 risky hills have been identified. On seven government-owned hills, 304 families live, while 531 families reside on ten privately owned hills.

In Sitakunda, Jungle Salimpur is one of the most densely populated hill areas, with around 12,000 families (60,000 to 70,000 people) living there. Other heavily populated hills include Motijharna and Court Building Hill. Additionally, about 3,000 landless families (around 12,000 people) live in risky conditions on hills in Bairar Dhal, Banshbaria, Kumira, Sonaichhari, and Bhatiari.

In Cox's Bazar, nearly 12,000 people live on ten risky hills. Maheshkhali upazila has about 8,000 people in 22 hazardous locations, while Teknaf upazila has around 1,200 families on 23 risky hills, with 230 families in particularly dangerous conditions.

In the Chittagong Hill Tracts, about 30,000 families live in Bandarban's seven upazilas, 80,000 families in Rangamati's ten upazilas, and 60,000 families in Khagrachhari's nine upazilas. These families have lived on or at the base of steep hills for generations and face a constant risk of landslides.

Overall, research estimates that at least 10 lakh people live in high-risk areas on the hills of this division.

Neglected landslide prevention recommendations

After the 2007 landslide, the government formed an 11-member committee led by the Divisional Commissioner of Chattogram to address landslide causes and propose 22 prevention measures.

These recommendations included reforestation, building retaining walls and drainage systems, quickly removing water and sand, creating sustainable settlements, banning sand extraction and brick kilns near hills, and limiting construction close to hilly areas.

However, according to Atikur Rahman, general secretary of the Chattogram Hill Protection Committee, none of these measures have been implemented in the past 17 years. The administration's only response during heavy rainfall has been to relocate residents from risky areas to safer shelters.

The Chattogram Hill Management Committee Chairman and Divisional Commissioner Mohammad Tofayel Islam did not respond to requests for comment.

Researchers warn that if deforestation, hill razing, and unsafe settlement practices continue without action on these recommendations, the risk of deadly landslides will significantly increase.