Class: SmoFlow::RationalMethod

Inherits:
Object
  • Object
show all
Defined in:
lib/smo_flow/rational_method.rb

Overview

Calculates surface runoff flow using the Rational Method. Supports flow from rainfall intensity, rainfall depth, and timestep-based calculations.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(coefficient:, area:) ⇒ RationalMethod

Returns a new instance of RationalMethod.



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# File 'lib/smo_flow/rational_method.rb', line 9

def initialize(coefficient:, area:)
  validate!(coefficient, area)
  @coefficient = coefficient  # C — runoff coefficient (0..1)
  @area        = area         # A — catchment area in hectares
end

Instance Attribute Details

#area ⇒ Object (readonly)

Returns the value of attribute area.



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# File 'lib/smo_flow/rational_method.rb', line 7

def area
  @area
end

#coefficient ⇒ Object (readonly)

Returns the value of attribute coefficient.



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# File 'lib/smo_flow/rational_method.rb', line 7

def coefficient
  @coefficient
end

Instance Method Details

#depth_to_intensity(depth:, timestep:) ⇒ Object

Convert depth (mm) over a timestep (s) to intensity (mm/hr)

Raises:



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# File 'lib/smo_flow/rational_method.rb', line 31

def depth_to_intensity(depth:, timestep:)
  raise InvalidInput, "Depth must be positive"    unless depth.positive?
  raise InvalidInput, "Timestep must be positive" unless timestep.positive?

  (depth / timestep) * 3600.0
end

#flow_from_depth(depth:, timestep:) ⇒ Object

Q = 10 × C × A × d / Δt → returns m³/s

Raises:



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# File 'lib/smo_flow/rational_method.rb', line 23

def flow_from_depth(depth:, timestep:)
  raise InvalidInput, "Depth must be positive"    unless depth.positive?
  raise InvalidInput, "Timestep must be positive" unless timestep.positive?

  (10.0 * coefficient * area * depth) / timestep
end

#flow_from_intensity(intensity) ⇒ Object

Q = C × i × A / 360 → returns m³/s

Raises:



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# File 'lib/smo_flow/rational_method.rb', line 16

def flow_from_intensity(intensity)
  raise InvalidInput, "Intensity must be positive" unless intensity.positive?

  (coefficient * intensity * area) / 360.0
end

#flow_ls_from_intensity(intensity) ⇒ Object

Flow in L/s from intensity



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# File 'lib/smo_flow/rational_method.rb', line 46

def flow_ls_from_intensity(intensity)
  flow_from_intensity(intensity) * 1000.0
end

#volume(depth:) ⇒ Object

Runoff volume for a timestep in m³

Raises:



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# File 'lib/smo_flow/rational_method.rb', line 39

def volume(depth:)
  raise InvalidInput, "Depth must be positive" unless depth.positive?

  10.0 * coefficient * area * depth
end