Which primary erosional process initially shapes the V-shaped valley that develops into an alluvial fan system?

💡 Explanation

When steep slopes experience persistent rainfall, hydraulic action from concentrated water flow erodes downwards because the water's force dislodges and transports material, initiating the valley. Therefore, hydraulic action is the primary process, rather than glacial abrasion, chemical dissolution, or sediment attrition which require other specific conditions to predominate.

• Which process dominates surface topography development within a braided stream's alluvial zone during flood events?
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