Ecological Warnings Follow Sumatra Floods As Experts Point To Deforestation

Yogyakarta - As search and rescue operations continue in Sumatra, environmental experts are analyzing the root causes behind the disaster's devastating scale. Dr. Hatma Suryatmojo, a hydrology and watershed conservation researcher from Gadjah Mada University (UGM), asserts that the recent floods were not an isolated event but part of an increasing pattern of hydro-meteorological disasters fueled by a combination of extreme weather and human activity. While intense rainfall, influenced by tropical cyclones, was the trigger, the destructive impact was severely worsened by the fragile state of natural fortifications in upstream areas.

The core issue, according to Dr. Hatma, is the degradation of forest ecosystems in the upstream regions of watersheds. Healthy forests act as giant sponges, absorbing rainwater into the ground and regulating its flow to rivers. Research shows intact tropical forests can intercept 15-35% of rainfall in their canopies and infiltrate up to 55% into the soil, leaving only 10-20% as direct runoff. Deforestation disrupts this natural hydrological cycle, removing these critical functions and causing most heavy rain to become direct surface runoff that floods downstream areas.

Decades of deforestation across Sumatra have critically compromised this natural defense system. Dr. Hatma provided a stark provincial breakdown: while Aceh had about 59% forest cover as of 2020, it lost over 700,000 hectares from 1990–2020. North Sumatra's condition is more alarming, with only about 29% forest cover remaining, often in fragmented parcels. West Sumatra, despite having roughly 54% forest cover, experiences one of the highest deforestation rates in the region.

This widespread land cover change has turned watersheds into conduits for disaster. When forests are lost, soil loses porosity and stability, leading to massive erosion and landslides. This sediment then flows into rivers, causing siltation and raising riverbeds, which further increases flood risk. The expert described the tragedy as an accumulation of "ecological debt" in upstream watersheds, where extreme weather was merely the trigger for damage made inevitable by environmental damage.

The solution, experts argue, requires a fundamental shift in mitigation strategy. Dr. Hatma stresses that future disaster risk reduction must balance structural approaches, like building dykes and normalizing rivers, with serious ecological approaches. Protecting remaining forests and conserving watersheds is not merely an environmental concern but a critical infrastructure investment for disaster prevention.

This ecological perspective adds a critical dimension to the ongoing national conversation about the disaster. While the government focuses on urgent financial and logistical responses, including the deployment of Rp 500 billion in Ready-to-Use Funds and 40 tons of aid, sustainable recovery will depend on addressing these underlying environmental vulnerabilities. The call from civil society for a "national disaster" declaration also resonates here, as such a status could potentially mobilize resources for large-scale, cross-provincial ecological restoration as part of the rehabilitation phase.

Without serious environmental restoration, the region remains vulnerable. As Dr. Hatma cautioned, with a tropical wet climate and ongoing environmental damage, Sumatra is like a "disaster time bomb," where every peak rainy season could bring a similar catastrophe in the future. The current disaster, therefore, stands as a severe warning about the tangible costs of ecological neglect.

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Tag: Climate Change Deforestation Ecological Disaster Environmental Degradation Hydrology UGM Expert Watershed Management