Planting materials across the river gotong-royong style.
TUCKED deep in the heart of Borneo, highland communities at Long Semadoh in Lawas are getting hands-on lessons on bio-engineering to restore the eroded banks of Upper Trusan River.
Long Semadoh is 914 metres above sea level on the Maligan Highlands. As the source of Trusan River, Maligan Highlands is an important water catchment area in Sarawak and also home to the Lun Bawang.
The majority of the people here are farmers who grow the fragrant Adan rice.
Over the years, the fertile valley, nourished and irrigated by Trusan River, has been transformed into productive paddy fields by the local communities.
As a result, cultivated areas increased and encroached onto the fragile riverbank buffers, exposing the shorelines to elements of nature such as increasing river flows and human factors such as land-use changes in the upstream. These have led to the erosion of riverbanks.
The problem got from bad to worse after occasional floods, damaging some paddy fields, and the erosion caused farmers to lose their land, resulting in income loss and negative impacts on people’s livelihoods and the overall river ecosystem.
Pilot project
Through the grassroots platform — Forum Masyarakat Adat Dataran Tinggi Borneo (Formadat) — WWF-Malaysia undertook a riverbank restoration pilot project at the request of the highland communities.
The project is supported by CIMB Islamic Bank from 2017 to 2019 with RM600,000 funding, according to WWF-Malaysia.
Extensive dialogues were held in 2017 and 2018 with the affected three villages — Puneng Trusan, Long Telingan, and Long Semadoh Rayeh.
A hydrological study along a 5.2 km stretch of river was carried out in collaboration with the University of Nottingham Malaysia Campus (UNMC), led by Professor Christopher Gibbins, to assess the conditions of the eroded riverbanks.
Science-based and sustainable solutions, made in consultation with the villagers, were proposed.
It was agreed that bio-engineering or nature-based methods to restore the riverbanks would be utilised – possibly the first of its kind for Sarawak — and the use of natural materials, especially those easily sourced from the villages, was encouraged.
WWF-Malaysia started with Puneng Trusan and Long Telingan. The villagers were trained on installing live-fencing, brush walls and geotextile mats, using coconut coir instead of the conventional concrete structure.
Previously, gabions were installed and locals planted bamboos but they did not have a proper restoration plan. During heavy downpours, these structures failed to hold up.
Other efforts included dredging the riverbeds and moving rocks to the banks, which also did not work in high river flow during the Monsoon, causing further erosion along the stretches downstream.
Installation of coconut coir geotextile mat at Long Telingan.
Erosion management
Factors of erosion at the catchment and river corridor and local site conditions must be included in any erosion management and strategy.
The installation of these bio-engineering methods was carried out by gotong-royong under professor Christopher Gibbins and Dr Teo Fang Yenn from UNMC.
It was hard work but the villagers enjoyed learning something new.
“We installed brush walls, brush mattresses, live-fencings and coconut coir geotextile mats at five degraded sites in Puneng Trusan and Long Telingan.
“We enjoyed the work, getting to learn something new and different,” said William Danor from Puneng Trusan.
Installation of live-fencing using bamboos at Puneng Trusan.
The 60-year-old added that in the past, the people did not know about ‘bio-engineering approach’ and depended on gabion installations to solve the problem of riverbank erosion but this method did not last.
“We never thought that natural materials from our surroundings could be used to restore the eroded riverbanks,” he marvelled.
Jelina Idung, from Puneng Trusan, said it had been a hectic time, juggling paddy planting and installing bio-engineering measures.
“But we managed to make time to help out. It’s good both villages could take turns and work together to finish the tasks.
“I’m a woman and I didn’t excuse myself from helping to carry materials to the sites,” the 55-year-old added.
Women helping to restore eroded riverbanks.
Phil Marten, 40, from Long Telingan, said the villagers looked forward to seeing the long-term result of the bio-engineering approach.
“It’s our first time trying this new method. We have gained some knowledge from Professor Gibbins. He patiently taught us to set up the installations.”
Long Telingan’s 60-year-old headman Alfred Balang Sibal chimed in: “It’s a blessing to have the opportunity to work with WWF-Malaysia and UNMC.
“We are also grateful for the funding from CIMB Islamic Bank. Without their help, the work couldn’t be done smoothly.”
On-site training on riverbank protection installation procedures with communities from Puneng Trusan and Long Telingan, under Professor Gibbins.
More restorations
The villagers hope more eroded riverbanks will be restored.
Through this project, they are not only protecting paddy fields along the riverbanks from erosion but also contributing to sustaining the environment.
WWF-Malaysia will be closely monitoring the effectiveness of the bio-engineering solutions, especially during the Monsoon, to see how well the structures withstand the strong water flow.
WWF-Malaysia is envisaging the application of bio-engineering approaches and adopting this project as a model for mitigating riverbank erosion that can be applied to other sites.
It encourages nature-based solutions by applying green technologies or practices which are in tune with Mother Nature.
This project also demonstrates the importance of community partnership and willingness to work together in solving common problems affecting their livelihoods.