Farm Water Calculator: Additional information

Dam Volume Calculations

Below is a list of algorithms used to measure the fields for Dam Volume

Rectangle/Square Dam

The algorithm to calculate the dam volume:

• Batter slope = 3
• d = Depth
• L^t = Top length
• L^b = Bottom length
  • Bottom length = Top length - (2 x Depth x Batter Slope)
• W^t = Top width
• W^b = Bottom width
  • Bottom width = Top width - (2 x Depth x Batter Slope)
• Volume = ((L^t x W^t) + (L^b x W^b) + ((L^t + L^b) x (W^t + W^b))) divided by 6000 x d
  • ((Top length x Top width) + (Bottom length x Bottom width) + (( Top length + Bottom length) x (Top width + Bottom width))) / 6000 x depth

The algorithm to calculate the surface area:

• l = Length Top
• w = Width Top
• surface area = (l x w)
  • (Length x Width)

Circular Dam

The algorithm to calculate the dam volume:

• Batter slope = 3
• R_t = Top radius
• R_b = Base radius
  • Base radius = Top radius - (2 x Depth x Batter Slope)
• d = Depth
• π = Pi (3.14159)
• Volume = (ΠR_t² + ΠR_b² + (Π(R_t+R_b)²)) divided by 6000 x d
  • ((Pi x (Top radius)²) + (Pi x (Base radius)²) + (Pi x (Top radius + Base radius)²)) / 6000 x depth

The algorithm to calculate the surface area:

• π = Pi (3.14159)
• r = Radius Top
• surface area = (Πr²)
  • (Pi x (Radius)²)

Gully Dam

The algorithm to calculate the surface area:

• l = Length Top
• w = Width Top
• surface area = (0.5 x l x w)
  • (0.5 x Length x Width)

The algorithm to calculate the dam volume:

• Batter slope = 3
• A = surface area of water body when full (m²)
• d_m = Maximum depth of water
• Volume = (d_m x A x 0.4) divided by 1000
  • (Depth x Area x 0.4) / 1000

Evaporative Losses

The algorithm to calculate the evaporative losses requires information from the annual evaporation (mm).

• ae = Annual Evaporation
• a = Surface Area
• Evaporative losses = (ae x a x 0.67) divided by 1000000
  • (Annual Evaporation x Area x 0.67) / 1000000

Seepage Losses

The algorithm to calculate the seepage losses:

• dv = Dam volume
• Seepage losses = (dv x 0.1)
  • (Dam volume x 0.1

Rain on dam surface

The algorithm to calculate the rain on dam surfaces requires information from the annual rainfall (mm).

• a = Dam Surface Area (m²)
• r = Average rainfall (m²)
• Rain = (r x a)
  • (Average rainfall x Dam surface area)

Annual Average Rainfall & Evaporation