Which effect complicates flood prediction in alluvial valleys?

💡 Explanation

Unpredictable channel avulsion—abrupt abandonment of a river channel and formation of a new one—frequently occurs in alluvial valleys because the low gradient and easily eroded sediments make the channels unstable; therefore, predictive models become unreliable rather than those accurately accounting for discharge or sediment load.

• Which effect on regional climate results when coastal upwelling ceases?
• Which soil horizon change results when earthworm introduction increases?
• Which risk increases following heavy agricultural irrigation over limestone?
• Which process maximizes the formation of fine-grained sediment deposits within an oxbow lake?
• Which effect occurs when wave refraction focuses on headlands?
• Which consequence results when a levee system catastrophically fails adjacent to an alluvial plain underlain by silt?