Power Systems
The factor affecting run off are

 amount of vegetation and weather condition in the catchment area.
  all of above.
 the topography and nature of soil in the catchment area.
 rain fall pattern, shape and size of catchment area.

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Power Systems
An hydro-graph indicates

 the discharge at any time during the period under consideration.
All of these
 the maximum and minimum run off during the period.
 the average run off during the period.

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