Slide 1
Water arrives with sediment
Rivers carry sediment as well as water, and their flows change over time.
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A river carries moving water and transported material together, with flows that change through time. An irrigation system must handle that combination. Dujiangyan's engineering joins several functions instead of treating diversion as the single act of taking water from a river.
Slide 2
First, divide the flow
Dujiangyan's Yuzui, or Fish Mouth division, splits the river into channels with different roles.
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Yuzui, the Fish Mouth division, separates the river into channels with different roles. The layout guides water toward the irrigation system while leaving another route for the river. The share of water entering each channel changes with conditions instead of staying fixed throughout the seasons.
Slide 3
Provide a route for excess
Feishayan, the Flying Sand Weir, helps manage excess water and sediment within Dujiangyan.
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Feishayan, the Flying Sand Weir, helps manage excess water and sediment. It works with the divided channels to route excess water and sediment away instead of letting them continue into the irrigation intake.
Slide 4
The intake belongs to the whole
Baopingkou, the Bottle Neck opening, controls entry toward Dujiangyan's irrigation network.
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Baopingkou, the Bottle Neck opening, controls entry toward the irrigation network. It is one component in a connected arrangement. Division upstream and the handling of excess flow and sediment affect what reaches this intake and passes onward.
Slide 5
Three parts, coupled problems
Dujiangyan connects water quantity, sediment and changing river conditions in one managed system.
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The system shows why water quantity, sediment and changing river conditions must be considered together. Its long history also includes continuing maintenance and modification. Ancient origins do not mean every visible component is unchanged ancient material or that the system works without care.
Sources
- Mount Qingcheng and the Dujiangyan Irrigation System
UNESCO World Heritage Centre