Natural Hazards in Idaho and the Northwest
Idaho and the Pacific Northwest are prone to specific types of natural hazards based on geology, hydrology, climatology, and biogeography. Some of these hazards are of greater frequency and greater concern than others, although this frequency is often not proportionate to the mitigation effort taken to diminish the threat. We've already looked at the hazards posed by volcanoes, earthquakes, tsunamis, floods, and landslides. Let's look at some of the additional hazards faced by residents of the Northwest.
Wildfire
Wildfire is an annual hazard in the inland northwest, and perhaps the most widespread hazard in Idaho due to our dry summers, abundance of lightning, and flammable forest and rangeland vegetation. Wildfire has many ecological benefits, and is a natural part of a healthy Idaho forest ecosystem, but those benefits have to be balanced with the negative impacts of homes burning down and clean water and fisheries being negatively impacted. While the weather conducive to wildfires can't be mitigated, thankfully we can mitigate their negative impacts and their intensity by managing vegetation, and particularly by clearing flammable vegetation around homes and other important resources.
Wildfire is an annual hazard in the inland northwest, and perhaps the most widespread hazard in Idaho due to our dry summers, abundance of lightning, and flammable forest and rangeland vegetation. Wildfire has many ecological benefits, and is a natural part of a healthy Idaho forest ecosystem, but those benefits have to be balanced with the negative impacts of homes burning down and clean water and fisheries being negatively impacted. While the weather conducive to wildfires can't be mitigated, thankfully we can mitigate their negative impacts and their intensity by managing vegetation, and particularly by clearing flammable vegetation around homes and other important resources.
Drought
While rainfall diminishes each summer as part of the annual climatological cycle of the Northwest, a lack of normal rainfall over an extended period of several months is considered a drought. In the northwest, drought conditions have multiple negative impacts: there are limits to water usage for landscaping and gardening in residential areas, lake levels are sometimes too low to support recreation demands, crops suffer and show diminished yields, forests are stressed and more prone to invasions by bark beetles and other pests, and river levels are too low to fully support fish runs. If a drought is severe enough, it can significantly damage the local economy, as water masters are forced to make choices about who gets water and who doesn't. Many family farms went out of business during the last major drought on the Klamath River Basin in Oregon, because they were unable to receive the irrigation water they needed to keep their crops going.
Drought is both easy and difficult to mitigate for. On one hand, it is easy to implement water conservation practices that cumulatively lower water needs across an area experiencing drought. The challenge is often determining who has the most right to the limited water available. This is also why mitigating for drought is so difficult: it is difficult to know how much water is actually going to be available when, and some of the old water rights and farming practices were implemented during wetter decades.
While rainfall diminishes each summer as part of the annual climatological cycle of the Northwest, a lack of normal rainfall over an extended period of several months is considered a drought. In the northwest, drought conditions have multiple negative impacts: there are limits to water usage for landscaping and gardening in residential areas, lake levels are sometimes too low to support recreation demands, crops suffer and show diminished yields, forests are stressed and more prone to invasions by bark beetles and other pests, and river levels are too low to fully support fish runs. If a drought is severe enough, it can significantly damage the local economy, as water masters are forced to make choices about who gets water and who doesn't. Many family farms went out of business during the last major drought on the Klamath River Basin in Oregon, because they were unable to receive the irrigation water they needed to keep their crops going.
Drought is both easy and difficult to mitigate for. On one hand, it is easy to implement water conservation practices that cumulatively lower water needs across an area experiencing drought. The challenge is often determining who has the most right to the limited water available. This is also why mitigating for drought is so difficult: it is difficult to know how much water is actually going to be available when, and some of the old water rights and farming practices were implemented during wetter decades.
Freeze events, heavy snow, avalanches, and blizzards
In 2009, the temperature on the Palouse in late September was still ranging into the 90s. The plants had not yet started to shut down for winter (nor had the humans, for that matter). But only two weeks later, on October 10-11, the temperature dropped far below freezing (below 0 across much of the Palouse) for over 48 hours. This hard freeze prior to dormancy killed nearly a third of the fruit crops across the inland northwest, as well as thousands of acres of deciduous trees more broadly.
Cold weather is a way of life at northern latitudes, but extreme weather is a hazard for humans and our economies. A hard freeze either too early in autumn or too late in spring severely damages crops and wildlife. Blizzards and heavy snowfall events can make travel difficult, and vehicle accidents associated with freezing conditions kill humans across the region each year. Heavy snowfall also fells trees on power lines and homes, or damages homes and infrastructure directly.
Luckily, we are able to mitigate damage from these types of weather events through improved forecasting and stronger building codes. After the marina boat slips collapsed in Edmonds, Washington in 1996, they were rebuilt to withstand a heavier snow load, and homeowners will often remove trees that have a high probability of falling on homes in a wind or snow event.
However, the greatest mitigation measures taken ahead of cold events across the region are associated with travel. Cities and counties distribute de-icer on roads ahead of forecasts that project conditions for black ice to develop, and station snowplows and sanding trucks at strategic points. States close down mountain highways that are prone to avalanches. Flights are cancelled to minimize risk of plane crashes from icing and schools are pre-emptively closed to encourage residents to stay home during the worst of the storm. And, of course, every single driver who puts snow tires or studded tires on their vehicle in winter is mitigating for winter driving conditions (or they walk or take the bus instead of driving).
In 2009, the temperature on the Palouse in late September was still ranging into the 90s. The plants had not yet started to shut down for winter (nor had the humans, for that matter). But only two weeks later, on October 10-11, the temperature dropped far below freezing (below 0 across much of the Palouse) for over 48 hours. This hard freeze prior to dormancy killed nearly a third of the fruit crops across the inland northwest, as well as thousands of acres of deciduous trees more broadly.
Cold weather is a way of life at northern latitudes, but extreme weather is a hazard for humans and our economies. A hard freeze either too early in autumn or too late in spring severely damages crops and wildlife. Blizzards and heavy snowfall events can make travel difficult, and vehicle accidents associated with freezing conditions kill humans across the region each year. Heavy snowfall also fells trees on power lines and homes, or damages homes and infrastructure directly.
Luckily, we are able to mitigate damage from these types of weather events through improved forecasting and stronger building codes. After the marina boat slips collapsed in Edmonds, Washington in 1996, they were rebuilt to withstand a heavier snow load, and homeowners will often remove trees that have a high probability of falling on homes in a wind or snow event.
However, the greatest mitigation measures taken ahead of cold events across the region are associated with travel. Cities and counties distribute de-icer on roads ahead of forecasts that project conditions for black ice to develop, and station snowplows and sanding trucks at strategic points. States close down mountain highways that are prone to avalanches. Flights are cancelled to minimize risk of plane crashes from icing and schools are pre-emptively closed to encourage residents to stay home during the worst of the storm. And, of course, every single driver who puts snow tires or studded tires on their vehicle in winter is mitigating for winter driving conditions (or they walk or take the bus instead of driving).
Severe Thunderstorms
While severe thunderstorms in Idaho and the Northwest only rarely produce tornadoes, they still produce additional hazards for farmers and those who like to recreate in the region. One of the primary hazards associated with thunderstorms in the inland northwest is the development of large hail (covered in Module 4). Hail stones not only destroy crops across large, affected areas, they can also punch holes through buildings and vehicles, and a large enough hail stone on the head of a human can be life threatening.
Mitigating against severe storm-related loss in the region often takes the form of purchasing insurance, particularly for farmers. While they cannot save the crop from being destroyed, they buy insurance based on the probability of storm-induced loss occurring.
While severe thunderstorms in Idaho and the Northwest only rarely produce tornadoes, they still produce additional hazards for farmers and those who like to recreate in the region. One of the primary hazards associated with thunderstorms in the inland northwest is the development of large hail (covered in Module 4). Hail stones not only destroy crops across large, affected areas, they can also punch holes through buildings and vehicles, and a large enough hail stone on the head of a human can be life threatening.
Mitigating against severe storm-related loss in the region often takes the form of purchasing insurance, particularly for farmers. While they cannot save the crop from being destroyed, they buy insurance based on the probability of storm-induced loss occurring.
Log into BBLearn and complete "Assignment 7.7: Severe Thunderstorms."