# The recent WV flooding using opendata
## Comparing Conditions before and after the storm
## You need to have dplyr v0.5.0

library(dataRetrieval)
library(dplyr)
library(maps)

start_date <- "2016-06-22"
end_date <- "2016-06-25"

# Read in streamflow (Q) data using dataRetrieval
pcode <- '00060'
possiblesites <- whatNWISsites(startDt = start_date, endDt = end_date, parameterCd = pcode,
                               siteType="ST", stateCd = "WV", drainAreaMin=200)
iv <- readNWISdata(sites=possiblesites$site_no, startDate = start_date, endDate = end_date,
                   parameterCd = pcode, service = "iv")
siteInfo <- attr(iv, 'siteInfo')

# Calculate the percent change in flow from the day before the storm and the last day of the storm
percentChange <- function(values){ ((values[2] - values[1])/values[1])*100 }
col_df <- data.frame(threshold = c(0,100,200,500,Inf),
                     col = c("red", "lightblue", "steelblue1", "royalblue", "mediumblue"),
                     stringsAsFactors = FALSE)
legend_labels <- c(paste('<', head(col_df$threshold, -1)), paste(">", tail(col_df$threshold, 2)[1]))

iv_change <- iv %>% renameNWISColumns() %>%
  group_by(site_no) %>%
  filter(dateTime == min(dateTime) | dateTime == max(dateTime)) %>%
  summarize(changeQ = percentChange(Flow_Inst)) %>%
  left_join(siteInfo, by = 'site_no') %>%
  select(station_nm, site_no, changeQ, latitude = dec_lat_va, longitude = dec_lon_va) %>%
  mutate(siteColor = case_when(
    .$changeQ < col_df$threshold[1] ~ col_df$col[1],
    .$changeQ <= col_df$threshold[2] ~ col_df$col[2],
    .$changeQ <= col_df$threshold[3] ~ col_df$col[3],
    .$changeQ <= col_df$threshold[4] ~ col_df$col[4],
    TRUE ~ col_df$col[5]
  ))

# Map the results
par(mfrow=c(1,2), mai=c(0,0,0,0), oma = c(0,0,2,0))

map(database = 'county', regions = 'west virginia')
map(database = 'state', regions = 'west virginia', lwd=2, add=TRUE)
points(x = iv_change$longitude, y = iv_change$latitude, pch=20, col=iv_change$siteColor)

plot.new()
legend("center", legend = legend_labels, col = col_df$col,
       title = "% Change in Streamflow", pch = 20, bty='n')

title("Change in streamflow for West Virginia", outer=TRUE)
mtext(side=3, line=-1, outer=TRUE, font=3, text = paste("from", start_date, "to", end_date))