Which factors significantly influence runoff from a catchment?

Introduction:Runoff is controlled by how, when, and where precipitation falls, and by how much the soil can absorb. Recognizing the multi-factor nature of runoff is central to flood estimation and watershed management.

Given Data / Assumptions:

• Options list storm form, intensity/duration, spatial distribution, antecedent moisture, and storm track.

Concept / Approach:Type (rain/snow) affects losses and melt. High intensity and long duration raise excess rainfall. Non-uniform distribution alters hydrograph shape. Dry/wet antecedent soil changes infiltration. Storm movement relative to the basin can synchronize tributary peaks and amplify the outlet peak.

Step-by-Step Solution:Assess each factor’s physical influence on rainfall excess and timing.Recognize that all listed factors act together in real storms.Select the comprehensive option.

Verification / Alternative check:Design manuals (unit hydrograph and SCS methods) explicitly include these factors via loss models and areal reduction/time-of-concentration methods.

Why Other Options Are Wrong:

• Any single factor alone omits important controls; “All the above” captures the full set.

Common Pitfalls:

• Considering only intensity and ignoring storm track/areal variability.

Final Answer:All the above.