Soil Electrical Conductivity
Electrical conductivity of soil paste extracts from the Lower Arkansas River Valley, at sites upstream and downstream of the John Martin Reservoir.
data(ArkansasRiver)
The format is: List of 2 $ upstream : num [1:823] 2.37 3.53 3.06 3.35 3.07 ... $ downstream: num [1:435] 8.75 6.59 5.09 6.03 5.64 ...
Electrical conductivity is a measure of soil water salinity.
This data set was supplied by Eric Morway (emorway@usgs.gov).
Eric D. Morway and Timothy K. Gates (2011) Regional assessment of soil water salinity across an extensively irrigated river valley. Journal of Irrigation and Drainage Engineering, doi:10.1061/(ASCE)IR.1943-4774.0000411
data(ArkansasRiver)
lapply(ArkansasRiver, summary)
upstream <- ArkansasRiver[[1]]
downstream <- ArkansasRiver[[2]]
## Fit normal inverse Gaussian
## Hyperbolic can also be fitted but fit is not as good
fitUpstream <- nigFit(upstream)
summary(fitUpstream)
par(mfrow = c(2,2))
plot(fitUpstream)
fitDownstream <- nigFit(downstream)
summary(fitDownstream)
plot(fitDownstream)
par(mfrow = c(1,1))
## Combined plot to compare
## Reproduces Figure 3 from Morway and Gates (2011)
hist(upstream, col = "grey", xlab = "", ylab = "", cex.axis = 1.25,
main = "", breaks = seq(0,20, by = 1), xlim = c(0,15), las = 1,
ylim = c(0,0.5), freq = FALSE)
param <- coef(fitUpstream)
nigDens <- function(x) dnig(x, param = param)
curve(nigDens, 0, 15, n = 201, add = TRUE,
ylab = NULL, col = "red", lty = 1, lwd = 1.7)
hist(downstream, add = TRUE, col = "black", angle = 45, density = 15,
breaks = seq(0,20, by = 1), freq = FALSE)
param <- coef(fitDownstream)
nigDens <- function(x) dnig(x, param = param)
curve(nigDens, 0, 15, n = 201, add = TRUE,
ylab = NULL, col = "red", lty = 1, lwd = 1.7)
mtext(expression(EC[e]), side = 1, line = 3, cex = 1.25)
mtext("Frequency", side = 2, line = 3, cex = 1.25)
legend(x = 7.5, y = 0.250, c("Upstream Region","Downstream Region"),
col = c("black","black"), density = c(NA,25),
fill = c("grey","black"), angle = c(NA,45),
cex = 1.25, bty = "n", xpd = TRUE)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.