We have been discussing what happens in the absence of water lately, namely drought, but too much can cause landslides and flooding. Flooding basically happens when a large volume of water changes states into a liquid over a small area, or if more water flows through a channel than usual due to improper damming. Flash flooding happens when that water condenses (precipitates) rapidly on to land in such a high volume as to overcome drainage systems where they occur in populated areas. They are especially prevalent in desert regions, as when it rains it pours in such regions. Sometimes flash floods happen when water is forced through narrow channels in high volumes. This is the situation in the breathtaking but deadly Slot Canyons in Utah (pictured below,) where the narrow crevices regularly claim the lives of hikers. All of what we’ve mentioned so far is what happens when gas changes states. A far more common cause of flooding is when ice turns to water.
Melting ice can cause flooding in a couple ways. Ice can cause improper damming. That is, ice can dam up water and then lose stability, unleashing a torrent of water downstream, or more commonly, the ice can simply melt and add volume to the stream, usually a river, and increase the energy and volume of the stream. Much more rarely, the ice at the source of a river can melt. That ice is glacial, and while some of that glacial ice melts every year, it typically feeds its river a more or less typical amount. When larger portions of it melt, the river has more water, which of course increases its energy. It is this type of flood that is currently affecting Iceland. A large swath of the Vatnajökull glacier has melted, and is threatening to wash out some major roads, but fortunately not the ring road around the country. ridges are considered safe.
In North Carolina, heavy rains inundated the town of High Point. The flooding caused four accidents, and left two people in need of rescue. One man was trapped in the floodwaters in his car. It is always the best idea to stay off the roads if you can avoid traveling at all. Streams can be faster moving than they appear, and tires are not designed to be submerged. They are inefficient underwater or nearly underwater, so a non-negligible amount of water is difficult to impossible to drive through. Fast moving water does not have a lot of pressure, but does have a lot of energy. That energy can carry trees, other cars, even houses downstream. Anyone stuck in a car is at the mercy of nature and emergency services, which may respectively be uncooperative or not always be immediately available. Driving during major flooding is dangerous.
Unfortunately, the tragic events we reorted on are in no way a full reflection of what has been going on in the world. If you would like to see all of our headlines from the past week, please click here.