Versatile bamboo reduces climate risk

Nepal’s diverse culture uses the bamboo plant for birth, death and all rituals in between. The versatile plant is also used for construction, to make musical instruments, to carry things, to write with, even to eat.

Now, bamboo groves are being used to protect villages near Chitwan National Park that are prone to frequent flooding due to climate breakdown.

It is the smaller streams that are dry in winter that are the most destructive during the monsoon. So, farmers in the village of Madi are planting bamboo forests along the banks of streams that block floods and stop soil erosion.

“Once the rainy season starts, we are afraid to close our eyes at night,” says Shanti Chapai, 58, who lives near the Patare Khola stream that burst its banks last year. 

On a recent visit, the Patare Khola was just a small stream, it is hard to imagine that it would become a raging river in the rainy season, bursting its banks and threatening farms and settlements.

Despite bamboo having everyday use for fencing, furniture and an important cash crop, farmers here were initially opposed to the idea of using it for flood control. They thought bamboo was an invasive species, and sucked up all the groundwater. 

But for the past 15 years, the architects at ABARI (Adobe and Bamboo Research Institute) have been experimenting with a thorny bamboo species like Bambusa bluemeana and Bambusa balcooa to restore degraded land and control floods. The area is now a dense bamboo grove greening the floodplain of the Patare Khola.

Sediment from last monsoon’s floods are deposited at the foot of the bamboo trees, proving that the plants stabilised the banks, protecting the surroundings by reducing the velocity of flood waters.

Madi’s villagers are now convinced that this is an effective bioengineering solution to floods. Bamboo is also fast-growing, and is ideal for reclaiming the eroded banks of rivers. Nepal has more than 50 species of bamboo, most of them found in the wetter eastern plains and foothills. But some species grow at altitudes of up to 4,000.

“Bamboo is a misunderstood plant in our culture because it is used for funeral rites and has a negative connotation,” says Nripal Adhikary ABARI, which builds bamboo and rammed earth buildings in Nepal. “It took a while to convince locals of its benefits.”

Monsoons in Nepal have always been synonymous with disasters, but extreme weather events caused by climate breakdown have made landslides and floods worse. Poor construction of roads, unregulated quarrying of sensitive watersheds, and encroachment along floodplains increase the risk.

But here in Madi, villagers have seen with their own eyes the direct benefit of bamboo for flood protection. Says farmer Phadendra Bhattarai: “Even though there was heavy rainfall, the extent of flood damage this monsoon was considerably less. The bamboo acted as a barrier and did not let the floods destroy our crops.” 

This tried and tested bamboo plantation can be replicated and upscaled across Nepal, and farmers in Kanchanpur in the western plains have also planted bamboo, napier and elephant grass along the banks of a river that unleashed destructive floods in 2018.

A thick strategic bamboo plantation can be made into a fence of porcupine structured embankment to provide protection in flood prone areas.

Floods in September in central Nepal killed 224 people with southern Lalitpur and Kavre being hardest hit. The Rosi Valley in Kavre was devastated, and settlements swept away entire slopes. But an area in the vicinity with bamboo plantation remained intact (pictured below).

Dhaneswar Baikiya Community Forest in Kavre is half a hectare of plot bamboo planted by the government in a pilot project in 2007 to study and research the moso bamboo Phyllostachys pubescens. It has been 17 years and the Ministry of Forests and Environment’s Forest Research and Training Center had long forgotten about it.

“Although no research has not been done here specifically in the plot, it is precisely this bamboo forest that saved villages down the mountains from major destruction,” says Badri Adhikari, custodian of the Community Forest. “Their expansive and entangled roots hold the soil firmly, protecting the slope’s stability.”

This plot may have been overlooked but there have been other efforts. All 12 districts of Lumbini province have initiated a bamboo plantation campaign to prevent erosion and flooding. 

Traditionally, too, bamboo is believed to control landslides, and it is not uncommon to see villagers along the mountains reviving depleted bamboo groves once they see its benefits. Bsides landslide protection, the bamboo also has many other uses.

Says Badri Adhikari: “The bamboo tree grows upwards in height during the summer and its roots expand in the winter. So, winter is the right time to prepare for the next monsoon of damaging floods.”

This article is brought to you by Nepali Times, in collaboration with INPS Japan and Soka Gakkai International, in consultative status with UN ECOSOC.