The 100 Year Flood Is Not What You Think It Is (Maybe) 

As a water resource engineer, I frequently have to explain the idea of the 100-year storm to people. I may just start showing this video instead! Nicely done.

This is precisely the content that I WANT to watch on RU-vid, but am never quite able to track down.

I think you did our job as civil engineer in educating the society and inspiring young people. Never stop posting!

As a Dutchman, this hits pretty hard today, with all the flooding.

That feel when 7 out of 9 of your friends in your standard deviation excel spreadsheet are made up

Another thing that really needs stressed is that "any given year" starts tomorrow. And another point, the flood plain is part of the river, just not always.

"Good enough." - The entire methodology of my hydrogeology class.

Another clear and understandable explanation Grady. I love your videos. I've worked in the engineering industry for almost 40 years and it still amazes me how the general public view statistical base data. To most it seems that 1 in 100 year floods means that the chance of a flood happening in these zones is once every 100 years. Statistics are obviously not well understood. Keep making these clear and simple videos. Maybe the public will start to understand their environment better. 🤞

I work for the USGS, was nice to see the recognition, thanks.

Very interesting video. As a CAD technician (Stantec Consulting,) focusing on water and wastewater facilities, I have often included flood plane data in drawings and (wrongly) assumed that it was "the worst flooding that has occurred in this area in the last 100 years". This was a excellent balance between presenting a "simplified" explanation without wandering into a "overly simplistic" one. This was a GREAT introduction to hydraulic engineering that has sparked my interest to looking into it a little further. Thanks much, and post more!

This is so interesting. I grew up in Central Texas. In 1998, we had a 100 year flood, then in 2002, a 400 year flood. It was very confusing for me as a kid.

I found these absolutely fascinating. The fact that you're a fellow Texan made me a subscriber.

That was good. You didn't insult anyone's intelligence or tried to joke through the hard stuff.

We need more RU-vid channels like this!

This same sort of misunderstanding of statistics happens in finance as well. For example many (most all I think) use a measure called "value at risk" to quantify the uncertainty in their portfolio. So for example after doing a bunch of highly dubious statistical work they may say that their value at risk is $5 million dollars with a 95% confidence interval and a 1-day holding period. So depending on how the confidence interval is defined, that can mean either 5% or 2.5% of the days will have a bigger loss than $5 million dollars. However nobody thinks about all the $4, $3, $2, and $1 million dollar losses that will encompass 50% of the days and can all get strung together if the market is against you. The 1 day holding period is key, if you cannot exit your position in 1 day the total losses from a market event can be well above the stated value at risk. A good rule of thumb is that if you can't get out of a position the total losses possible in a year are about 11 times higher than the stated value at risk, depending on the volatility and liquidity. And then because many financial and commodity markets are log-normal, the stuff inside the 5 or 2.5% can be dramatically larger than the stated value at risk. As the probability of occurrence is going down the impact is going up exponentially. This is how you get a bank failure or market crash. They don't happen very often, but when they do there is not much that can be done. Some very large trading shops have been taken down by events they thought couldn't happen based on statistics.

Grady: "we can't make everyone buy flood insurance" South Amboy NJ: hold my Bud Lite

In this case the 100 year flood actually was what I thought it was.

Just found the channel through Hydraulic Press Channel and I'm loving it, immediately subscribed! Really well put together videos with fantastic pacing and a pleasing balance between the accessibility and depth of the content.

Thank you so much for making this video! I have heard people talk about the 100 year flood, and completely misunderstood it. Your explanation was very clear and interesting!

Thanks for the video Grady. We all appreciate the effort you put into them 👍

Keep Making Cool Stuff! Studying Mech. Eng. in school right now, I really enjoy seeing these videos. It's a good reminder that engineering is more than just studying.

loving the new channel direction - keep it up!

Thank you for a good link to share with friends. Your videos are an interesting and efficient use of time, though I'm glad I can replay parts of it a few times when it's deep, so to speak. Approachable engineering and science material is a wonderful thing to share.

As a former civil engineer working with hydrology for bridge design, this is a fantastic video. Great explanation of the topic and the pieces that make this up. Keep up the great work. Your videos are informative and very entertaining!

Great video. As a fellow civil engineer, I have to explain this all the time. The other confusing issue for lay people is the 1% flood vs the 1% storm and why they dont occur during corresponsing rain events... Keep up the great work.

Mies van der Rohe built the Farmsworth House to sit right on the edge of the 100 year flood plain. Then for good measure, he raised the entire house 5 feet of the ground. Since it's completion,, it has been hit by two 500 year floods causing massive damage to the house.

Hey, thank you for explaining this. I do work as a junior architect and consistently find myself throwing basic property information like this on my general sheets. I didn't fully understand the difference between the flood plains (you would think we'd touch on it at uni at some point). Either way, I respect the work our Civil and Geotech consultants do--this was a great example of how their expertise is necessary--and allows me to do my work.

Great vid! Liked the selfie shot with the rain gauge (I do that too) and the last shot of skipping a stone - always good to feel like I'm back out on the river. Keep up the good work!

The National Weather Service in the US also allows you to access the Hydrology Data because they also care about water flows in streams so they can issue flood watches and warnings. If you have a stream that floods often in your area, you are likely to have a flow gague on it someplace. Also Highway departments put data into the system, because many bridges essentially have a ruler built onto a pylon that is visible from shore. Some times those also mark record high water events.

Awesome video and especially applicable with Houston, hurricane Irma, etc. You do a really good job of presenting concise explanations striking a good balance between the technical side and using layman' terms.

Hey Grady, I just found your channel last night and Im getting obsessed with watching your videos. I just started my 3rd semester as an engineering student here in Virginia. I've only been here for about 2 years, but I was born and raised it Manchaca so it was cool to find out that you're a fellow Austinite. Thank you very much for your videos!

I KNEW IT! In one of your other videos I saw a highway underpass that looked very familiar... From Austin, you are!

Don't know how many times that I've tried to explain 100 year storms to people, I never do as well as you. Maybe someday explain retention basins and metered outfall. Don't know if that's in the code in Texas, but here in Ohio they've been a big part of the building code for about the last 20 years.

Thank you, your explanation gave me a much better understanding of flood plains and the 100 year flood. This will help me determine where I relocate. Your videos are the best!

Grady, I just discovered you a couple of years ago and now going back to watch your old videos. Your production value has increased a lot (not saying this to downplay your older videos but you're definitely getting better at your craft!).

This presentation is well done. It would be very helpful for engineers to understand the changes to hydraulic head by flows into and through storm water pits. I think that a lot of unexpected flooding occurs because we have built storm water pits that aggravate hydraulic head. If you do a report on this topic them please tell me. I am easy to find. Thanks.

I have been there and done that. After living thru a 100 year flood, seeing my entire city go under water. I know exactly what it is. Further I know what it is to deal with the aftermath, the cleanup, the destruction to families heirlooms. The pain and the healing.By far the clean up and getting back to life is the hardest part of a 100 year flood.

You've improved your editing a lot. And I like your humor. Even if it's weird, it's genuine. It is part of the world of top level engineers that you're exposing.

Thank you this was informative and you broke it down just right. I am trying to learn one new thing a week or so. Keep up the good work.

I think you forgot the link to the FEMA flood plain maps. Great video, though. Very interesting!

5:00 hey pervert why are you recording me? I was recording the stream gages I swear! tell that to the police

Yo! Travis County whats up! I grew up there, but now I'm in Atlantis (Houston). It's so cool to see local (somewhat) people creating amazing videos like this that are viewed by thousands of people across the world. Btw totally agree with changing the x-amount year flood system to an x-percent chance system, I was a little confused on why they used that terminology in my civil engineering classes last year. Can't wait to see the next video!

Thank you so much for the video. I have experienced catastrophic flooding many times in my life. This video gives a great perspective of how many variables come into play in circumstances that cause flooding. Thank you.

A great example of dynamic teaching using web technology will replace standard engineering courses. Comprehension is everything : )

The 100 year flood reminds me of a principle we use in electronics engineering called "mean time between failures". I've seen it mostly used to describe for measuring the failure rate for latching an asynchronous digital signal, where failure is when the latch goes metastable (i.e. oscillates between 0 and 1 by itself). The units are in time, but it really reflects a probability that it would fail, e.g. we want the mean time to be in days or years, but all that really means is we wan the probability of failure to be in the parts per billion/trillion.

This is what makes the internet, shared learning and collaboration and cooperation awesome! Thank you for adding to the body of knowledge ! This is a great point you should expand on ideas such as black swan or six sigma events!

Dude, your presentation is sweet to listen to. You have a fab (and calming) voice ;)

Missed a chance for a pun at 7:04: "[water] shapes every facet of our lives" and faucet of our lives!

that just made my brain hurt... but good stuff.

I have always been curious about all the stuff we see everyday, your book is the best thing I found this year. Keep up the good work .

Hi! Really appreciate this video. Thanks for makin it!

The number of dislikes on your video really doesn't matter, and as long as your video isn't factually incorrect, uninteresting to the point of tedium, or a controversial opinion, you're unlikely to have more than a few percent dislikes. Inviting the audience to honestly represent their feelings about a video using the like/dislike buttons or by leaving a comment is more endearing than directing them to hit "like" regardless, and won't negatively affect the outcome.

I've watched your channel for a while now, and I'm loving all the information (for an engineer to be)! What type of Basin Modelling software did you use? Secondly, how did you model the Flood Map Service? Thanks!

these videos have so much content and you actually learn something. and can take notes if you want to actually remember

This was really interesting. I am an architecture student and currently my class is working on projects in an area with several rivers. We were told to consider the 100 year flood plain and have all the data for it, but it was never explained to us how it worked. I kind of assumed more or less correctly, but this video really cleared up the uncertainty I had.

And with recent happenings in Texas, this video has made it's way in to the Recommended Videos again.

Can the past floods in Germany, Belgium, Austria be in this line? Nobody expected this.

Very interesting video! I live in a flood plain area and did my own work determining our risk on a new home. I had the advantage of having the TVA as a great resource. Thanks for this excellent video!

Thanks for the nice video. I just studied NRCS TR-55 at my hydrogy class and this video really helped me understand a lot!

@5:02 I ride my bike by that gauge every day on my way to work!

It's nice that it comes today in my recommendation. Is it because of the events in Germany?

This is one of if not the first video that decently explains storm water concepts! Thank you so much! You should make a video on what a Storm water pollution prevention plan (SWPPP) is! ;) (Thats what I needed to learn, usually I look to RU-vid to learn about stuff I have no idea on, but there was almost nothing on the subject which was kinda disappointing because it is something that is important to consider. Ive been subed for awhile so this was a pleasant surprise! Thanks for all of your hard work.

Something wonderful about watching videos that deal with things I deal with and have to design around at work. Ah rational method, hydroflow. So much storm water design in some areas for well pad design.

The fact that this video appeared on my feed right after Hurricane Harvey.

Woo woo, Hydrology major represent.

I adore this channel You are one of the reasons I have decided to go back to school and finish my engineering degree Thank you, Sir 🙏

I work in the Engineering Department in Bridgeport Connecticut City Hall. I get people in my office all the time complaining about being in a flood zone and saying "I've lived there 30 years and I've never been flooded!" Now I'll just show them this video to save myself some time of explaining. Thanks!

Well you got my sub easy information to digest on a curiosity click :3

Mmm, that is actually exactly what I thought the 100 year flood was. The only people confused were the people who think that they can be "due" when gambling or something.

i wish i had seen this video when we studied engineering hydrology last year . thanks a lot . u made my concept more clear.

I really appreciate that you share quality engineering videos for young aspirants to learn and design future communities.

5:04 nice.

Physicist here: Measuring something to 1% is no walk in the park. This is even more true when you're talking about understanding the shape of a distribution out in the 1% tails. Even if you have a theoretical basis for the shape of the distribution, the 1% tails are generally mucked up by instrumentation effects, noise, background, etc., etc. So, if you think the technical parts of this seemed hard, I suspect it is even harder than it appears while, simultaneously, requiring a substantial amount of prayer and a fair bit preparing to run to high ground anyway. Nice video!

Rofl that 2 second clip of you taking a selfie was a brilliant treasure of comedy that I hope everyone payed attention to.

Yo, not even done with the video and I subbed. Great stuff. Really gets me psyched to become an engineer.

Fish jumps in foreground → 0:43

>engineering >users imperial measurements

After 7/8 videos, you Sir have me subscribed (: Amazing content and integrated mathematical knowledge, I am very happy to have found you

I've worked in natural resources and ag conservation for 20 years, land use planning for 5 years. I really enjoyed and learned information, specifically the probability of high water calculations with EXCEL, and it was very useful. One suggestion is how to determine Bank Full and 2 times bank full determination. Another, using engineering/land survey tools, is to show how to determine channel depth. I look forward to more videos!

ha, Civils, with your using imperial units, and you're huge estimations, and your concrete canoes.

What's the probability of a 100 year storm occurring in a 100 years if it's normally distributed? The answer is not obvious.

This is inspirational

I love learning new things and you certainly made that easy. Thank you

Oh, so the 100-year flood actually IS what I thought it was.

5:02 Nnnice

Now I need to get a rainfall gauge so I can check it obsessively and brag to my friends. Excellent video.

This was a very helpful video. Thank you, and keep up the great work!

7:37 missing closed parenthesis

Meme a killer ass videos in the sense of they're informative and they're fun to watch keep it up man you put it all together really nice and really well

Thanks for all of the work you do for this channel, it's very interesting content.

Great job of shedding light on a very complex subject in a brief video.

Thanks.This is an unusually clear explanation of engineering, statistics, social risk, and law in one video. Keep at it!

Great video! Answered so many questions for me.

I find your videos valuable, informative and well produced. Thanks for your efforts. Please keep it up.

As a hydrologist, that is a beautifully put together video. Essential watching for all engineers and Earth scientists in this field. Thank you.

5:00 I really appreciate the beauty of this stream guage.

Is there a video on how to get into engineering as a living and a career like Best schools to go to that aren’t super expensive especially for someone that’s NEVER been into math or engineering at all..I started watching your videos and everything you explain makes so much sense and seems intuitive once you break it down

This explains a lot. for someone who's been through many floods, I didn't understand the "year" concept. But you didn't mention snow fall and frost rate. things we need to worry about up north.

This was a great video. Watching your channel is one of the best parts of my mornings.

The incidence rate is probably a good idea. We definitely had news reporters mis-explaining the 500 year flood when I was young. I think they were told it was expected to be a 100 year flood before turning out to be a 500 year flood, but I distinctly recall a news report saying the 500 year and 100 year floods overlapped as if the water worked like cicadas.