Indications of land clearing have been found in the upstream areas of watersheds that experienced flash floods in West Sumatra and North Sumatra. The Indonesian National Police’s Criminal Investigation Agency identified a palm oil company suspected of clearing land and triggering flash floods in Goroga Village, South Tapanuli, North Sumatra. Based on satellite imagery, 110 land-clearing sites were detected in the Garoga watershed, causing river overflows that resulted in 47 fatalities and 22 people reported missing.
Regarding land degradation in upstream watershed areas that has led to flash floods, UGM expert in Soil and Water Conservation, Professor Ambar Kusumandari, stated that land clearing in upstream regions can have far-reaching impacts extending to middle and downstream areas.
The primary risk is hydrometeorological disasters such as flash floods, which have occurred in many areas of Sumatra.
“River currents capable of carrying large timber logs indicate severe degradation of upstream areas that should function as conservation and protected zones to sustain downstream ecosystems,” she said on Tuesday (Jan. 6).
Professor Kusumandari explained that disasters occurring downstream are the result of how upstream areas are managed. Forests that should serve as natural dams by intercepting rainfall through tree canopies have lost this function due to extensive land clearing.
“Without infiltration in upstream areas, rainwater flows directly over the surface in large volumes. Downstream rivers are unable to accommodate the excess water, resulting in flash floods,” she explained.
According to Professor Kusumandari, state-owned land in deforested upstream areas needs to undergo vegetative rehabilitation or reforestation, supported by appropriate mechanical measures to establish a strong ecosystem foundation.
Meanwhile, on community-owned land, agroforestry can be implemented by integrating forest trees with food or medicinal crops.
“Government-owned land should be prioritized as a protected forest. Meanwhile, community land can be managed to resemble forest ecosystems while still providing economic benefits,” she said.
For her, the necessary steps include imposing a moratorium on all activities that damage the environment, such as mining and large-scale plantations.
This should be followed by revisiting spatial planning in line with watershed management principles and by strengthening early warning systems using BMKG forecasts and existing disaster risk maps.
“We need to understand natural conditions and adapt human activities accordingly,” she concluded.
Author: Jesi
Editor: Gusti Grehenson
Post-editor: Rajendra Arya
Photograph: auriga.or.id