Health and Economic Impact of Weather Events in the US
Storms and other severe weather events can cause both public health and economic problems for communities and municipalities. Many severe events can result in fatalities, injuries, and property damage, and preventing such outcomes to the extent possible is a key concern.
This project involves exploring the U.S. National Oceanic and Atmospheric Administration’s (NOAA) storm database. This database tracks characteristics of major storms and weather events in the United States, including when and where they occur, as well as estimates of any fatalities, injuries, and property damage.
Synopsis
By doing analysis on the storm event database, it is found that tornadoes are the most dangerous weather event to the population health. The second most dangerous event type is the excessive heat. The economic impact of weather events was also analyzed. Flash floods and thunderstorm winds caused billions of dollars in property damages between 1950 and 2011. The largest crop damage caused by drought, followed by flood and hails.
Data Processing
The following analysis is going to be performed on Storm Events Database, provided by National Climatic Data Center. The data is from a comma-separated-value file available here. There is also some documentation of the data available here.
Reading the data into a data frame.
storm_data <- read.csv(bzfile("data/repdata_data_StormData.csv.bz2"))Cleaning of data is necessary. Event types don’t have a specific format.
# number of unique event types
length(unique(storm_data$EVTYPE))## [1] 985# translate all letters to lowercase
event_types <- tolower(storm_data$EVTYPE)
# replace all punct. characters with a space
event_types <- gsub("[[:blank:][:punct:]+]", " ", event_types)
length(unique(event_types))## [1] 874# update the data frame
storm_data$EVTYPE <- event_typesSection - I: Effect over Population Health
We first aggregate the number of casualities by the event types to find those event types that are most harmful to population health.
library(plyr)
casualties <- ddply(storm_data, .(EVTYPE), summarize,
fatalities = sum(FATALITIES),
injuries = sum(INJURIES))
# Find events that caused most death and injury
fatal_events <- head(casualties[order(casualties$fatalities, decreasing = T), ], 10)
injury_events <- head(casualties[order(casualties$injuries, decreasing = T), ], 10)Top 10 events that caused largest number of deaths are
fatal_events[, c("EVTYPE", "fatalities")]## EVTYPE fatalities
## 741 tornado 5633
## 116 excessive heat 1903
## 138 flash flood 978
## 240 heat 937
## 410 lightning 816
## 762 tstm wind 504
## 154 flood 470
## 515 rip current 368
## 314 high wind 248
## 19 avalanche 224Top 10 events that caused most number of injuries are
injury_events[, c("EVTYPE", "injuries")]## EVTYPE injuries
## 741 tornado 91346
## 762 tstm wind 6957
## 154 flood 6789
## 116 excessive heat 6525
## 410 lightning 5230
## 240 heat 2100
## 382 ice storm 1975
## 138 flash flood 1777
## 671 thunderstorm wind 1488
## 209 hail 1361Section - II: Effect over Economy
Property damage and crop damage estimates are used to analyze the impact of weather events on the economy.
exp <- function(eval) {
# h -> hundred, k -> thousand, m -> million, b -> billion
if (eval %in% c('h', 'H'))
return(2)
else if (eval %in% c('k', 'K'))
return(3)
else if (eval %in% c('m', 'M'))
return(6)
else if (eval %in% c('b', 'B'))
return(9)
else if (!is.na(as.numeric(eval)))
return(as.numeric(eval))
else if (eval %in% c('', '-', '?', '+'))
return(0)
else {
stop("Invalid value")
}
}prop_dmg_exp <- sapply(storm_data$PROPDMGEXP, FUN=exp)
storm_data$prop_dmg <- storm_data$PROPDMG * (10 ** prop_dmg_exp)
crop_dmg_exp <- sapply(storm_data$CROPDMGEXP, FUN=exp)
storm_data$crop_dmg <- storm_data$CROPDMG * (10 ** crop_dmg_exp)# Compute the economic loss by event type
library(plyr)
econ_loss <- ddply(storm_data, .(EVTYPE), summarize,
prop_dmg = sum(prop_dmg),
crop_dmg = sum(crop_dmg))
# filter out events that caused no economic loss
econ_loss <- econ_loss[(econ_loss$prop_dmg > 0 | econ_loss$crop_dmg > 0), ]
prop_dmg_events <- head(econ_loss[order(econ_loss$prop_dmg, decreasing = T), ], 10)
crop_dmg_events <- head(econ_loss[order(econ_loss$crop_dmg, decreasing = T), ], 10)Top 10 events that caused most property damage (in dollars) are as follows
prop_dmg_events[, c("EVTYPE", "prop_dmg")]## EVTYPE prop_dmg
## 138 flash flood 6.820237e+13
## 697 thunderstorm winds 2.086532e+13
## 741 tornado 1.078951e+12
## 209 hail 3.157558e+11
## 410 lightning 1.729433e+11
## 154 flood 1.446577e+11
## 366 hurricane typhoon 6.930584e+10
## 166 flooding 5.920826e+10
## 585 storm surge 4.332354e+10
## 270 heavy snow 1.793259e+10Similarly, the events that caused biggest crop damage are
crop_dmg_events[, c("EVTYPE", "crop_dmg")]## EVTYPE crop_dmg
## 84 drought 13972566000
## 154 flood 5661968450
## 519 river flood 5029459000
## 382 ice storm 5022113500
## 209 hail 3025974480
## 357 hurricane 2741910000
## 366 hurricane typhoon 2607872800
## 138 flash flood 1421317100
## 125 extreme cold 1312973000
## 185 frost freeze 1094186000Results
Health impact of weather events
The following plot shows top dangerous weather event types.
library(ggplot2)## Warning: package 'ggplot2' was built under R version 3.1.3library(gridExtra)## Loading required package: grid# Set the levels in order
p1 <- ggplot(data=fatal_events,
aes(x=reorder(EVTYPE, fatalities), y=fatalities, fill=fatalities)) +
geom_bar(stat="identity") +
coord_flip() +
ylab("Total number of fatalities") +
xlab("Event type") +
theme(legend.position="none")
p2 <- ggplot(data=injury_events,
aes(x=reorder(EVTYPE, injuries), y=injuries, fill=injuries)) +
geom_bar(stat="identity") +
coord_flip() +
ylab("Total number of injuries") +
xlab("Event type") +
theme(legend.position="none")
grid.arrange(p1, p2, main="Top deadly weather events in the US (1950-2011)")
Economic impact of weather events
The following plot shows the most severe weather event types with respect to economic cost that they have costed since 1950s.
library(ggplot2)
library(gridExtra)
# Set the levels in order
p1 <- ggplot(data=prop_dmg_events,
aes(x=reorder(EVTYPE, prop_dmg), y=log10(prop_dmg), fill=prop_dmg )) +
geom_bar(stat="identity") +
coord_flip() +
xlab("Event type") +
ylab("Property damage in dollars (log-scale)") +
theme(legend.position="none")
p2 <- ggplot(data=crop_dmg_events,
aes(x=reorder(EVTYPE, crop_dmg), y=crop_dmg, fill=crop_dmg)) +
geom_bar(stat="identity") +
coord_flip() +
xlab("Event type") +
ylab("Crop damage in dollars") +
theme(legend.position="none")
grid.arrange(p1, p2, main="Weather costs to the US economy (1950-2011)")