The Ciliwung River Basin plays a vital role as one of Indonesia’s key national watersheds. However, it has been under significant stress in recent decades due to environmental degradation and substantial land-use changes.
This situation has pushed the Ciliwung into a precarious condition, which has resulted in frequent and severe flooding in the Greater Jakarta area. The most notable flood incident occurred last March.
Dr. Hatma Suryatmojo, a lecturer at the UGM Faculty of Forestry and a forest resources expert, stated that the hydrological crisis in the Ciliwung Watershed stems from a combination of deforestation upstream, uncontrolled urbanization in the midstream and downstream areas, and weak enforcement of spatial planning regulations.
According to him, deforestation in upstream areas like Puncak and Cisarua has significantly reduced water catchment capacity, while the conversion of green areas into residential zones, intensive agriculture, and tourism spots has further exacerbated degradation.
Dr. Suryatmojo noted that the forest and natural vegetation cover, which once played a key role in absorbing rainfall, now only accounts for about 9.7% of the total watershed area.
This figure falls far short of the ideal 30% needed to maintain hydrological balance. In contrast, built-up areas have reached around 72% of the watershed.
“The impact of limited infiltration areas is very real: rainwater no longer seeps into the soil every rainy season but flows directly over the surface. The Ciliwung River becomes the main channel for this runoff, contributing about 32% of the total flood volume in Jakarta,” he explained on Monday, Apr. 21, 2025.
Beyond flooding, the Ciliwung Watershed also faces a water quality crisis. The river is heavily polluted by domestic waste and garbage.
Data shows that the biochemical oxygen demand (BOD) reaches around 54 tons per day, while the river’s carrying capacity is only about 9.3 tons.
“This makes the Ciliwung Watershed critical not only from a hydrological perspective but also in terms of ecology and public health,” he stated.
Various policies have indeed been implemented, such as river normalization, the construction of dry dams, and reforestation. However, Dr. Suryatmojo argued that these efforts remain partial and overly technical.
“Long-term solutions must be based on an ecosystem approach. Forest rehabilitation in the upstream, riparian zone restoration and strict spatial planning control are essential steps,” he emphasized.
He also criticized the overly reactive approach taken by local governments, especially during the rainy season.
For instance, the Meteorology, Climatology, and Geophysics Agency (BMKG) modifies weather by seeding salt into clouds to reduce rainfall in Jakarta.
“I think this is a short-term, cosmetic measure that doesn’t address the root of the problem,” he said.
Dr. Suryatmojo pointed out that the four phases, mitigation, preparedness, emergency response, and recovery, remain weak from a disaster management perspective.
River normalization and infrastructure development have yet to tackle the root causes, while early warning systems and community responsiveness remain minimal.
“In the end, floods return, and recovery efforts remain temporary,” he added.
He described the situation as a “stagnant disaster cycle.” Year after year, the same areas are affected. There’s no increase in resilience, no relocation, and communities remain vulnerable.
“Flood disasters in Jakarta are like a recurring gathering—predictable in schedule, but the response is always last-minute,” he said.
In closing, Dr. Suryatmojo called on all stakeholders, government, academia, civil society, and the private sector, to actively engage in collaborative and sustainable management of the Ciliwung Watershed.
“Without a comprehensive conservation approach and firm enforcement of regulations, flood risks will continue to rise, and the impacts on downstream communities will grow increasingly severe,” he concluded.
Author: Rahma Khoirunnisa
Editor: Gusti Grehenson
Post-editor: Lintang Andwyna
Photograph: Ministry of Public Works and Housing