Focuses on reducing the source of sediment on slopes and in the torrent bed. This includes measures such as draining seepage water, removing hazardous rocks and trees, filling cracks, and installing 『Wood pile wattling』 to lower the probability of 『debris flow』 initiation.
Aims to reduce flow velocity and water content during the movement of the 『debris flow』. This includes installing sediment control dams (e.g., 『sand control dam』), horizontal grids, buffer forest belts, and diversion structures to mitigate the impact on downstream areas.
Involves managing accumulated sediment at the torrent mouth and on gentle terrain. Measures include establishing sediment retention basins, diversion dikes, and buffer forest belts to stabilize the torrent valley and channel, thereby reducing the hazard risk downstream.
A large amount of water is the primary cause of 『debris flow』, making its removal essential. Drainage pipes can be buried in the accumulated torrent bed or on the slope to channel and remove surface water or groundwater.
Thick layers of deposited material can trigger a 『debris flow』 if widespread 『surface runoff』 occurs. Installing 『bed control structures』 on the surface isolates the runoff, thereby lowering the risk.
Clearing thick sediment layers in the torrent bed and trimming the branches of unstable trees on the slopes reduces the likelihood of collapse and triggering a 『debris flow』.
Fissures should be filled, preferably with clay, to prevent the erratic flow of groundwater. Concurrently, dense vegetation planting on the slope enhances protection.
This method fixes unstable sediment, improves slope gradient, and prevents erosion. It also creates a favorable environment for vegetation growth, stabilizing easily collapsing slopes.
Utilizing a 『sand control dam』 or continuous check dams increases channel roughness and, through sediment accumulation, decreases the gradient of the torrent bed, thereby slowing the 『debris flow』.
Using permeable dams or horizontal grids allows water to infiltrate and sediments to be retained, achieving deceleration and water-sediment separation, thereby causing the 『debris flow』 to stop.
Installing a 『sand control dam』 within the torrent valley retains the 『debris flow』 inside the valley, preventing overflow and downstream sedimentation.
Forest belts serve as buffer zones, using vegetation to reduce the kinetic energy and transport volume of the 『debris flow』.
Installing a dam in wider, gentler sections of the valley creates capacity to contain the flowing sediment and reduce the burden on downstream areas.
Constructing dikes on the alluvial fan, at least 100 meters away from the torrent mouth and approximately 30–40 meters wide, safely contains the 『debris flow』 sediment within the basin.
Buffer forest belts attenuate kinetic energy and intercept sediment, mitigating the risk of downstream sedimentation.
When space is limited at the torrent mouth, diversion dikes or artificial channels are used to steer the 『debris flow』 into a safe area, discharging the flow.
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