PITTSBURGH (KDKA) – Just lately we had some intense rainfall that precipitated intense flooding.
That may even be an understatement.
The rainfall was so heavy close to Oakdale that swift water rescue crews have been known as out to rescue individuals and roads have been closed as a result of the Oakdale space had life-threatening flooding.
Ray Petelin
When all is alleged and performed, that space noticed a 40 or 50-year flood!
However what does the time period “50-year flood” even imply? To assist clarify, let’s herald our pal Fred McMullen from the Nationwide Climate Service workplace in Pittsburgh.
You’ll be able to learn Elizabeth and I’s dialog with Fred beneath!
Elizabeth: Hello Fred! What’s a 50-year flood?
Fred: It actually encapsulates a rainfall occasion inside a sure time window. And so, once we say you realize, a 50-year flood, we’re in search of a sure precipitation quantity in a sure time window, after which over a location as a result of it varies by location. One of many misnomers that individuals have is that they suppose they will get a 100-year flood in back-to-back years. What we attempt to inform individuals is {that a} 100-year flood is simply actually a 1% probability of prevalence each single yr. So, when you have a 100-year flood at your own home, the subsequent yr, the chance continues to be 1%. However once more, I am providing you with only one, you’ll suppose it might be a little bit bit lower than the earlier yr.
Ray: What does this imply for individuals?
Fred: Say you’re taking a 30-year mortgage on your own home and a 1% probability of prevalence flood which is you realize, basically one in 50. You recognize, 150 to 100 years, has a 1% probability of prevalence, however over the lifetime of your mortgage, when you weren’t within the 100-year floodplain, there is a 26% probability that through the lifetime of your mortgage of 30 years that you may see a 100-year flood. So, over time these numbers go up there based mostly on the mathematics calculations.
Elizabeth: Can something change the definition of those floods?
Fred: We’ve river phases, after which we affiliate sure impacts at this degree, this highway closes. Stream channels can change over time, particularly those that have not had a flood in say 20 to 30 years, and we see impacts that you realize will not be taking place the place they was once, so these are a number of the adjustments that we have now. After which additionally with urbanization, you realize, we put extra homes in a location. There’s extra runoff into the stream, after which we sometimes see increased stream flows, after which that would result in extra flooding doubtlessly given extra runoff.
Ray: How do extra frequent and heavy rainfall occasions issue into this?
Fred: We have been going by a course of now the place we’re updating this atlas right here, so we’ll have you realize, extra knowledge, newer knowledge to permit us to type of tweak these numbers so some locations the place you do not see a number of improvement. Heavier rain occasions will result in, you realize, increased frequency. It could not result in the identical quantity of influence as you’ll in a spot that has large city sprawl however permits us to fine-tune the info to verify we have now an correct illustration as a result of the datasets are at all times shifting. Flooding happens at random intervals. It could possibly be that you just’re gonna have two or three years of actually moist years, then undergo a dry spell. California was actually dry, and reservoirs actually low. The final two winters we have had a number of rain occasions. Now the reservoirs have been again at, you realize, at full ranges. So it is a type of issues the place we tried to type of capsulate traits and traits and science traits within the environment and traits and whether or not anything,
PITTSBURGH (KDKA) – Just lately we had some intense rainfall that precipitated intense flooding.
That may even be an understatement.
The rainfall was so heavy close to Oakdale that swift water rescue crews have been known as out to rescue individuals and roads have been closed as a result of the Oakdale space had life-threatening flooding.
Ray Petelin
When all is alleged and performed, that space noticed a 40 or 50-year flood!
However what does the time period “50-year flood” even imply? To assist clarify, let’s herald our pal Fred McMullen from the Nationwide Climate Service workplace in Pittsburgh.
You’ll be able to learn Elizabeth and I’s dialog with Fred beneath!
Elizabeth: Hello Fred! What’s a 50-year flood?
Fred: It actually encapsulates a rainfall occasion inside a sure time window. And so, once we say you realize, a 50-year flood, we’re in search of a sure precipitation quantity in a sure time window, after which over a location as a result of it varies by location. One of many misnomers that individuals have is that they suppose they will get a 100-year flood in back-to-back years. What we attempt to inform individuals is {that a} 100-year flood is simply actually a 1% probability of prevalence each single yr. So, when you have a 100-year flood at your own home, the subsequent yr, the chance continues to be 1%. However once more, I am providing you with only one, you’ll suppose it might be a little bit bit lower than the earlier yr.
Ray: What does this imply for individuals?
Fred: Say you’re taking a 30-year mortgage on your own home and a 1% probability of prevalence flood which is you realize, basically one in 50. You recognize, 150 to 100 years, has a 1% probability of prevalence, however over the lifetime of your mortgage, when you weren’t within the 100-year floodplain, there is a 26% probability that through the lifetime of your mortgage of 30 years that you may see a 100-year flood. So, over time these numbers go up there based mostly on the mathematics calculations.
Elizabeth: Can something change the definition of those floods?
Fred: We’ve river phases, after which we affiliate sure impacts at this degree, this highway closes. Stream channels can change over time, particularly those that have not had a flood in say 20 to 30 years, and we see impacts that you realize will not be taking place the place they was once, so these are a number of the adjustments that we have now. After which additionally with urbanization, you realize, we put extra homes in a location. There’s extra runoff into the stream, after which we sometimes see increased stream flows, after which that would result in extra flooding doubtlessly given extra runoff.
Ray: How do extra frequent and heavy rainfall occasions issue into this?
Fred: We have been going by a course of now the place we’re updating this atlas right here, so we’ll have you realize, extra knowledge, newer knowledge to permit us to type of tweak these numbers so some locations the place you do not see a number of improvement. Heavier rain occasions will result in, you realize, increased frequency. It could not result in the identical quantity of influence as you’ll in a spot that has large city sprawl however permits us to fine-tune the info to verify we have now an correct illustration as a result of the datasets are at all times shifting. Flooding happens at random intervals. It could possibly be that you just’re gonna have two or three years of actually moist years, then undergo a dry spell. California was actually dry, and reservoirs actually low. The final two winters we have had a number of rain occasions. Now the reservoirs have been again at, you realize, at full ranges. So it is a type of issues the place we tried to type of capsulate traits and traits and science traits within the environment and traits and whether or not anything,
