The six minute video illustrates three of the five transport processes that may follow detachment by drop impacts impacting shallow flow. Sediment transport by rain-impacted flow is important in transporting nutrients, pollutants and carbon from sheet and rill erosion areas where raindrop impact provides the main source of energy used to cause detachment. Splash may move detached particles through the air, but five transport processes can occur in rain impacted flows:
1. Continuous suspension in the flow.
2. Raindrop induced saltation.
3. Raindrop induced rolling.
4. Flow driven saltation.
5. Flow driven saltation.
The video demonstrates raindrop induced saltation and rolling that can, in addition to continuous suspension, transport soil particles and aggregates over slopes of very low gradient. The slope in the demonstration is zero. The file is 214 Mb (so allow sufficient time to download the video). The video shows two runs that were 5 mins long , and 10 mins long respectively. Flow depths were 4 to 5 mm deep and flow velocities were about 40 mm/s. The rain was made from hypodermic needles spaced 25 mm apart in a module mounted 3 m above the target. The rain intensity was 100 mm/hr drop size was 2.6 mm.
DOWNLOAD VIDEO Demonstrating Raindrop Induced Saltation and Rolling
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