Polluting our rivers, polluting the world


The Rajang River is home to numerous longhouses, and it has served as a vital transportation route for centuries. – Bernama photo

LAST week, I was pleased to receive the book, ‘About Sarawak Rajang River and the People: Living and Coping with Disasters’, written by Irene Ng Pei Yi. I was impressed by the book’s content, which contains stunning photographs and illustrations.

As the longest river in Sarawak and Malaysia, the Rajang River is home to numerous longhouses, and it has served as a vital transportation route for centuries. Trading posts sprouted along the river, and eventually, towns like Kapit and Sibu emerged.

One of the book’s most intriguing sections focuses on disaster coping mechanisms, with an emphasis on mitigating the effects of floods. Several approaches are described, including planting trees along the riverbanks as a natural barrier, relocating to higher ground, and improving the drainage system.

In Borneo, the 565-km Rajang River is the seventh longest river. The longest river lies in West Kalimantan, namely the Kapuas River. It stretches for over 1,143km, according to Encyclopedia Britannica. The Mahakam River in East Kalimantan is the second-longest river in Borneo, stretching up to 920km. The Mahakam Delta is home to dense and diverse mangrove forests. In Central and South Kalimantan, the mighty Barito River flows 890km from the Muller Mountain Range to the Java Sea, with the great city of Banjarmasin situated at its river mouth.

Interestingly, these three rivers are also the three longest rivers in Indonesia. Borneo’s river civilisations are fascinating, with unique cultures and ways of life that have developed over centuries along its many rivers.

Transboundary governance

The Murutic culture of the Pensiangan River system is a very interesting case that I have encountered. One intriguing aspect of this river network is that it crosses the border of Sabah and North Kalimantan, making it a unique case of a transboundary river system. The border divides the river network into two parts – the upstream portion remains in Sabah and is referred to as the Pensiangan River, while the midstream and downstream sections are located in North Kalimantan and are known as the Sembakung River and its tributaries.

The border also essentially divided the Murutic communities into two nationalities (referred to as ‘Dayak Agabag’ in Kalimantan), just as the case of Lundayeh and Lunbawang on the highlands as described in a previous article. For both sides, the rivers are essential sources of water, food, and transportation to sustain their way of life for centuries.

After returning from my field trip to Pensiangan last year, I stumbled upon an outstanding Ph.D. thesis by Nathan Bond, ‘Seeking the state from the margins’, which discussed the Tidong’s settlement along the Sembakung River. One chapter, in particular, caught my attention, which highlighted severe transboundary flooding.

These floods are commonly referred to as ‘Malaysian-sent floods’ by the Indonesians. Although some attribute the floods to land use changes in Sabah, doubts remain as the upstream has not experienced significant deforestation in recent decades. Nevertheless, there have been concerns regarding upstream pollution. As the floods kill off plants, some speculating that the water contained some sort of ‘racun’ or toxic substance from chemical waste dumped indiscriminately into the river on the Sabah side.

In any case, the floods are no good. The thesis vividly describes that the floods have left indelible marks on the affected communities, with almost every houses showing clear watermarks etched into its interior walls. In some cases, the floods have destroyed entire settlements, forcing residents to abandon their homes. The floods also have severe implications for livelihoods, not only destroying paddy but also fruit trees and domestic animals, such as chickens, ducks, goats, and cattle.

River pollution may become particularly challenging in situations where a river is shared between multiple countries.

One way to address these issues is through the development of transboundary water agreements between the affected countries. These bilateral or multilateral agreements can facilitate cooperation and coordination in river management, thereby reducing the risk of pollution and flooding.

From rivers to oceans

However, the problem may go beyond just two countries. Recently, a diagram illustrating the scale of oceanic plastic waste pollution went viral on LinkedIn and WhatsApp groups. Sadly, Malaysia ranked third on the list, with over 73,000 metric tonnes of plastic waste being dumped annually. While some may have assumed that coastal and water villages were the primary sources of plastic waste, the reality is quite different – the majority of plastic waste is derived from large rivers.

A study by a team of Dutch and German researchers, Meijer and co., has shown that over 1,000 rivers are responsible for 80% of plastic waste in the oceans. The Klang River is a major contributor, listed as the second largest source of oceanic plastic waste (1.33%). Even more concerning, heavy floods, such as those caused by heavy rainfall during December 2021, lead to a massive generation of post-flood waste, with some of it being channelled into the ocean via drains and rivers.

For Borneo, the Sarawak River is high on the list (0.34%), probably owing to rapid urbanisation. Considering the smaller population, the per capita contribution of Greater Kuching (assuming 1 million) to oceanic plastic waste seems to be 2-3 times higher than Klang Valley (assuming 9 million).

A shift in mindset?

Rivers are essential for Borneo’s environment and ecosystem, serving as the lifelines for the coastal and river communities who depend on them for livelihood and daily activities. Disposing of rubbish, including illegal dumping and littering, has been a major factor that worsens pollution and flood problems for water catchment ponds and waterways. In addition, climate change has dangerously increased flood risk.

It is also worth noting that rivers are also major sources of plastic waste that ends up in the ocean, causing harm to marine life and ecosystems. One cannot continue to live in a delusion that ocean pollution is ‘none of my business’. One immediate effect is that plastic waste can contaminate the seafood that we consume, leading to health problems.

In longer term, when marine ecosystems are degraded, they lose their ability to sequester carbon, which can contribute to further warming of the planet. It is obvious that there is an urgent need for a shift in mindset among individuals and industries to stop waste from entering waterways.

During our visit to the Borneo Cultures Museum last month, we came across an interactive computer game where kids could control a dragonfly to clean up polluted rivers around the world, including the Klang River. This was an eye-opening experience for both the children and the parents. The game helped to make the topic more relatable and engaging. We think that this innovative approach to educating children about environmental issues is a step in the right direction.

It is essential to create more targeted and engaging awareness programmes for people of all ages if we want to make a meaningful impact in combating water pollution. Effective education is a key tool in tackling this issue, and hopefully more people will join forces to explore creative ways to engage and inspire individuals and communities to take action.

Dr Goh Chun Sheng is a researcher at Harvard University. He is interested in exploring sustainable development in both Malaysian and Indonesian Borneo.

His book, ‘Transforming Borneo: From Land Exploitation to Sustainable Development’, was recently published by ISEAS – Yusof Ishak Institute in Singapore.