areaFunction: Hypsographic Functions for Conical Lake Geometry
In rSALMO: Simulation of ecological lake models

The functions calculate area resp. volume of a lake with an ellipsoidic depth profile.

areaFunction(level, zmax, amax)

volumeFunction(level, zmax, amax)

vol2level(vol, zmax, amax)

`level`	vector of water level above ground
`zmax`	maximum lake depth
`amax`	surface area of the lake surface for `level = zmax`
`vol`	vector of given volume(s)

level <- seq(0, 50, 1)
amax  <- 9e6
zmax  <- 50
area <- areaFunction(level, zmax, amax)
vol  <- volumeFunction(level, zmax, amax)
plot(vol, cumsum(area), type="l")
(vol - cumsum(area)) / vol