hydroGOF (version 0.4-0)

ve: Volumetric Efficiency

Description

Volumetric efficiency between sim and obs, with treatment of missing values.

Usage

VE(sim, obs, ...)
# S3 method for default
VE(sim, obs, na.rm=TRUE, ...)
# S3 method for data.frame
VE(sim, obs, na.rm=TRUE, ...)
# S3 method for matrix
VE(sim, obs, na.rm=TRUE, ...)
# S3 method for zoo
VE(sim, obs, na.rm=TRUE, ...)

Arguments

sim

numeric, zoo, matrix or data.frame with simulated values

obs

numeric, zoo, matrix or data.frame with observed values

na.rm

a logical value indicating whether 'NA' should be stripped before the computation proceeds. When an 'NA' value is found at the i-th position in obs OR sim, the i-th value of obs AND sim are removed before the computation.

…

further arguments passed to or from other methods.

Value

Volumetric efficiency between sim and obs.

If sim and obs are matrixes, the returned value is a vector, with the Volumetric efficiency between each column of sim and obs.

Details

$$ VE = 1 -\frac { \sum_{i=1}^N { \left| S_i - O_i \right| } } { \sum_{i=1}^N { \left( O_i \right) } } $$

Volumetric efficiency was proposed in order to circumvent some problems associated to the Nash-Sutcliffe efficiency. It ranges from 0 to 1 and represents the fraction of water delivered at the proper time; its compliment represents the fractional volumetric mistmach (Criss and Winston, 2008).

References

Criss, R. E. and Winston, W. E. (2008), Do Nash values have value? Discussion and alternate proposals. Hydrological Processes, 22: 2723-2725. doi: 10.1002/hyp.7072

See Also

gof, ggof, NSE

Examples

# NOT RUN {
obs <- 1:10
sim <- 1:10
VE(sim, obs)

obs <- 1:10
sim <- 2:11
VE(sim, obs)

##################
# Loading daily streamflows of the Ega River (Spain), from 1961 to 1970
require(zoo)
data(EgaEnEstellaQts)
obs <- EgaEnEstellaQts

# Generating a simulated daily time series, initially equal to the observed series
sim <- obs 

# Computing the volumetric efficiency for the "best" case
VE(sim=sim, obs=obs)

# Randomly changing the first 2000 elements of 'sim', by using a normal distribution 
# with mean 10 and standard deviation equal to 1 (default of 'rnorm').
sim[1:2000] <- obs[1:2000] + rnorm(2000, mean=10)

# Computing the new volumetric efficiency
VE(sim=sim, obs=obs)
# }