Section 4: Soil and Water Conservation Engineering
Hydrology
Subtopic: Runoff estimation
Question Statement:
A 10 ha watershed: rainfall 15 mm, ET 5 mm, infiltration 4.5 mm, deep percolation 2.2 mm, detention storage 0.5 mm, other abstraction losses 0.3 mm during a storm. Neglecting other surface storages, find the total overland flow (m³). (Answer in integer)
Official Answer Key:
470
Step-by-Step Solution & Explanation
Overland-flow depth = Rainfall − ET − Infiltration − Detention storage − Other losses (deep percolation is a sub-component of infiltration and not subtracted again separately) = 15 − 5 − 4.5 − 0.5 − 0.3 = 4.7 mm. Volume = 4.7 mm × 10 ha = (4.7/1000 m) × 100000 m² = 470 m³.
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