The Chao Phraya river basin is home to 57% of Thailand’s population, including Bangkok, and generates 66% of the country’s gross domestic product. Photo credit: ADB.
Deploying a natural approach to manage rivers entails the conservation, rehabilitation, and management of ecosystems to increase resilience to climate change.
The Chao Phraya is Thailand’s lifeblood. However, floods and droughts around this major river basin have also taken lives, while causing billions in economic losses.
In 2011, the river took more than 600 lives after its banks burst due to heavier than usual monsoon rains. It was the country’s worst flooding since 1942. The Ministry of Finance estimated economic losses and damage at $45 billion.
In 2020, amidst Thailand’s worst drought in 4 decades, Chao Phraya’s water level sank too low to keep tidal seawater out, affecting supply for drinking and irrigation. The drought was estimated to cost the country $1.3 billion.
Need for resilience
With Thailand among the top 10 countries in the world most affected by climate change, more frequent extreme weather events have made it more urgent to improve resilience in managing rivers like Chao Phraya and in ensuring river health is taken into account in water management plans.
A lot is at stake. Chao Phraya, which spans 365 kilometers, flows through the country’s fertile central plain and plays a critical role in irrigating rice paddies. The river basin is also home to 57% of Thailand’s population, including Bangkok, and generates 66% of the country’s gross domestic product.
Thirteen years since the 2011 floods which affected almost 14 million people, Chao Phraya continues to be a flood hotspot. During this year’s monsoon season in September and October, authorities issued flood risk warnings in areas along the river.
The government also remains on alert for droughts. Last year, the Royal Irrigation Department called on the public to save water, and farmers to use rainwater runoff for irrigation as water levels in reservoirs along the Chao Phraya fell due to El Niño.
A case for a natural river management approach
Soon after the devastating floods of 2011, the government drew up a $9.4-billion water management and flood prevention plan to prevent similar disasters from happening. The plan entails the construction of dikes, reservoirs, floodways and flood diversion channels, and irrigation systems.
Realizing the need for a more sustainable approach to river management, the government last year embarked on a $17.53-million project that adopts a more nature-friendly approach to managing the Yom and Nan Rivers. Nan, along with principal confluent Yom, is among the principal tributaries of Chao Pharaoh.
The project deploys an ecosystem-based approach to water management, entailing the conservation, rehabilitation, and management of biodiversity and ecosystems to increase resilience to climate change. The system deploys low-cost nature-based solutions in water management to protect lives, livelihoods, and infrastructure, while advancing the achievement of multiple Sustainable Development Goals.
The project, which is supported by the United Nations Development Programme, will directly benefit 62,000 people in the provinces of Phitsanulok, Sukhothai, and Uttaradit in the northern region of Thailand. The provinces are part of the greater Chao Phraya river basin. Approximately 471,561 people in the project districts are also expected to indirectly benefit, with wider benefits for 25 million people living in the greater Chao Phraya river basin.
The project will also help build the resilience of farmers in the Yom and Nan river basins through improved climate information and forecasts, the introduction of more climate-resilient agricultural practices, and expanded access to markets and finance. It also seeks to upgrade critical infrastructure such as irrigation canals and floodgates, taking advantage of ecosystem-based adaptation approaches.
Similarly, the Philippines has adopted an ecosystems-based approach to manage flood risks in three major river basins. The project will upgrade and construct flood protection infrastructure in the Abra river basin in the country’s northern Luzon region and the Ranao/Agus and Tagum–Libuganon river basins in the southern Mindanao region.
The project takes into account future climate change impacts and incorporates nature-based solutions such as restoring and reconnecting old river channels for natural drainage and reinforcing riverbanks with mangroves and vegetation planting.
Nature-based solutions leverage on the intrinsic abilities of natural river systems to deliver climate resilience at a lower cost than traditional infrastructure development while minimizing negative environmental and social impacts. The approach is science-based and follows the principles of participatory water resources management. Solutions include planting mangroves, restoring wetlands, and building bioswales.
The project is financed through a $303-million loan from the Asian Development Bank (ADB).
A low-cost alternative
ADB has advocated for a natural river management approach in dealing with river flooding and to increase resilience to climate change. According to a 2021 ADB technical study, the construction of hard or gray infrastructure, such as dams, embankments, canals, dikes, and levees, is often the first line of defense against flooding. These interventions though not only tend to neglect the dynamics and natural functions of rivers but also often give priority to the subsequent (and increasingly expensive) maintenance of the infrastructure over river health. “Without proper master planning and with only a short-term focus on return on investment, gray infrastructure can result in natural resource degradation,” the study said. Instead, it advocated for natural river management, a concept developed as part of an overall approach to harnessing and respecting the natural functions of rivers and developing sustainable river management practices, under nature-based solutions.
Drawing heavily on the concepts of ecosystem services, integrated water resources management, and integrated river basin management, natural river management does not advocate natural solutions alone.
Instead, it serves as a guide in including nature-based solutions and nonstructural measures in river projects in close harmony with standard engineered interventions. Natural river management provides a basis for embedding a planning process of proactively choosing where to intervene, through a risk-based approach, and where to let the river follow its natural course.
Successful cases
The study said there is no one-size fits-all solution for riverine concerns. It cited examples across the world where natural river management was successfully adopted.
In the Netherlands, different natural river management approaches to flood safety were adopted at two rivers, with positive outcomes for both. Creating a side channel at Nijmegen–Lent improved the local discharge capacity of the Waal River, while in Zwolle, widening the IJssel River floodplain provided a buffer for excess water during periods of high river discharge. Both approaches took away space from agriculture, but also offered the opportunity to restore, or even increase, the natural values of the rivers.
In Australia, restoring the Tomago Wetlands not only created a buffer against flooding and controlled erosion but also improved water quality.
While it is beneficial to restore natural river dynamics by partially or fully removing built embankments—as was done at Australia’s Upper Drava River and Japan’s Moizari River—alternative nature-based bank solutions can be explored.
Thailand can draw from several such examples in managing flood and drought risks along the Chao Phraya. The ADB technical study said, "Taking a long-term perspective and using an approach that is centered on the functioning of the natural river system and the people that live near rivers can prevent mistakes and avoid future costs."
