[00:00:22] Bridget Scanlon: I am pleased to welcome Hatim Sharif to the podcast. Hatim is a Professor in the Department of Civil and Environmental Engineering at the University of Texas in San Antonio (UTSA). His research focuses on hydrometeorology. And today we're going to discuss mostly flooding, the recent flooding in central Texas, and many previous floods.
So thank you so much, Hatim for joining me.
[00:00:45] Hatim Sharif: Thank you, Bridget. Yeah I work in hydrometeorology. I also, while teaching full time, I obtained a master of public health.
[00:00:53] Bridget Scanlon: Oh!
[00:00:53] Hatim Sharif: This is why I focus also on flood fatalities, why they happen. Actually, my research for my masters of public health was flood fatalities in Texas because Texas is number one in terms of flood fatalities so this is something familiar with Texas. Yeah.
[00:01:08] Bridget Scanlon: Right, right. Well, I think one of the things, Hatim, that's on everybody's mind is the recent flooding on July 4th, Independence Day, in the Hill Country. And you have done a lot of work in the Hill country on flooding issues. And I know you were following that. And so I think it's interesting to see what the forecasts were like before that flooding. I mean, National Weather Service had a forecast up June 30th before the July 4th flooding and the day before also emphasizing risk of flooding, but then of course it happened overnight. It was a holiday and all of those things.
So maybe you can give us your perspective on that flooding Hatim.
[00:01:51] Hatim Sharif: Yeah, this is a very interesting flooding and actually it is historic in many measures as we will discuss. Maybe I mentioned some measure, but it also highlights the problem with forecast. It highlights the problem with response, and it was a historic flood. So there was flood water expected, not to this degree.
So they expected like intense rainfall. But an important issue is also positioning of the storm. This is a major weakness of weather forecast. Usually, they do not position the storm like in the right location. And this matters a lot in the terms of the response of the watershed.
And I will mention some examples when we talk about this. For example, for this event when it happened, of course, it happened overnight. Precipitation was the peak. Of course, it was more than what was expected. And although they upgraded the forecast at night, there was a concentration of precipitation over a certain area over a three hour period some parts upstream from Camp Mystic, over the South fork of the Guadalupe River.
If you look at that, this is actually higher than the 1000 year storm, for the three hour storm. This is really something historic, never happened before. About 10 inches in three hours, the thousand year storm for three hours, like 9.37 inches. And this is, for example, tell you about one problem, the forecast and positioning of the storm.
And another thing, of course, it happened at night. And there is response even from team of emergency official, and team of people also who are exposed to this historic event was not as expected because they're not aware of what was going on. And then the term of the response of the watershed. Because of the storm was concentrated over the South Fork, so, the peak was much higher than what was recorded.
We have in this region, there was a historic flood in 1932 where the peak discharge at Hunt, which is a little bit down the stream from Camp Mystic, was about 206,000 cubic feet per second.
In 1987, there was a big event also, it was about 108,000 cubic feet per second.
Of course, the gauge stopped working during this event, but when USGS went and looked at high water marks, the peak for this event was 297,000 cubic feet. It's like 44% than the historic one of 2,000 or 8,000, which happened in 1932. Another thing is that in the one that happened in 1932, the North Fork had over 140 cubic feet per second, and the South Fork was 84,000. Here, 84,000 cubic feet per second. Here, the reverse happened. Over the North Fork was about 51,000 cubic feet per second. And the South Fork, it was about maybe close to 230,000 feet per second. That is actually above the unit peak discharge envelope for the US and for Texas.
Actually, this probably will prompt people to change the curve a little bit. This is much higher than in Texas and maybe one of the most one was the Seco creek flood in 1975. This is at the like envelope. This one, if you take the south fork, it was above the envelope. And if you take the Hunt water, gauge alone, like the two forks together, this is just near the envelope. So this is a historic flood in term measure. Or measure in term of concentrated rainfall, rainfall over a certain area, over a short period, and in term of also the rise of the stage and discharge. I think talking about the the fast response, I think that one of the radar gauge near Comfort. It showed a very sharp increase in the stage and velocity. That is very alarming and which will tell us the importance of monitoring. That's really, if people are watching that at that time, they would knew this is like a really historic event because very sharp rise in the discharge and the river stage.
So this was historic. And of course, unfortunately we have the hazard and exposure. We had people who are exposed to this. And of course vulnerability, it happened at night, people not able to respond and the effect was big. They're exposed to this and then the effect was really big on them.
So there are many factors that happen, but unfortunately this happens in many situations. Like especially if you talk about camping. I think it happened in Tennessee, in Kentucky, the big Thompson River flood in Colorado. That was historic one. Also, most of the people who were deceased, they were coming actually, and it happened overnight, like this one. So those events, usually they happen, not very often, but when they happen they were very devastating.
[00:07:23] Bridget Scanlon: Right, right.
[00:07:25] Hatim Sharif: Yeah. One thing I probably, people are maybe forget about in Texas. And this one eclipsed another flood that happened exactly three weeks before, Friday, also June 12th.
[00:07:37] Bridget Scanlon: Yeah. And I guess you're talking about the San Antonio flood, but let's, talk a little bit more about this flood before we get onto the San Antonio flood, Hatim. So, I mean, unique in terms of the rainfall intensity. And as you mentioned, it's oftentimes difficult to predict forecast to where the rain will occur.
And so there's much higher uncertainty on the location of the rainfall than there is in maybe other metrics like, the rainfall intensity or the rainfall amount. And that, of course, has huge implications for the flooding because if you're in one river basin versus another river basin then it will affect that.
And I think Witold Krajewski mentioned that recently in a webinar he gave for the American Institute of Hydrologists, the uncertainty in the location of the rainfall. And you mentioned the radar data. And I guess the National Weather Service uses the multi radar, multisensor system, where they incorporate the gauge data with the radar data, and I guess that's about, one kilometer resolution.
And they have it at a very high level, like two minutes, five minutes, and aggregate hourly. Yeah, right. For 18 hours. So, this is very important. And of course, this had a huge impact. You mentioned flood risk which includes both the hazard, also the exposure and the vulnerability. And 117 people died in Kerr County alone. So that was a huge impact so a huge flood risk. But I thought one of the nice things was that there were 165 people saved by helicopters during the flood.
So I guess, there was no way for them to get out. The roads were impassable. And so having those helicopters landing, that was a real plus.
[00:09:28] Hatim Sharif: Yes, that's right.
[00:09:30] Bridget Scanlon: So, I mean, the timeline for this event, the National Weather Service had predicted heavy rain on June 30th for July 3rd but then issued flood related warnings on the Guadalupe River on July 1st.
So there was a lot of warnings and then flood watch on Thursday, the day before at early afternoon, and then flood warning at 1:00 AM about 1:15 AM on Friday morning, July 4th. And emergency alert systems, and then flash flood emergency, then at 4:00 AM. But I mean, a lot of people didn't get the alerts and I think this has highlighted the importance of communication and trying to parlay this information to people.
And of course it's a holiday weekend, so we've got a lot of visitors at the camps. Also the kids, they don't oftentimes may not have their cell phones and all of this sort of thing. So, a lot of things converge to make it to amplify the risk.
[00:10:30] Hatim Sharif: That's right. Yeah. I think probably warning can be improved. Of course you have tools, I think like say there is flash flood warning and then say they upgrade the warning. This storm is intensifying. But people want, I think to know impact on the ground.
So, how will I be affected, like term of my location and also say timing. Like say maybe in one hour this area will be flooded. And also I think if the warning is, action oriented, that will be helpful. What do I need to do? Say, there is a warning for flash flood warning. Do I stay at home?
Do I need to not drive, for example, or, I think this is important. I think there is something also you mentioned that, a problem, I think, especially in Texas. You mentioned that some roads became impassable. So people have had to be rescued by helicopter. This is also a common issue in Texas where, and you mentioned existence of low water crossings because those creeks stayed dry most of the time actually. A few days before this event, the flow was zero in the South Fork, for example . So I think that is a big problem also in terms of rescue. Like efforts in terms of people what to do, if roads become impassable, how do I save yourself?
I think communicating the risk and what to do, I think that would help a lot. I think.
[00:11:53] Bridget Scanlon: Yeah, I think that's a very important team I agree with you. And I think, we do fire drills all the time. We need to have more training and more drills and all that sort of thing and scenario analysis, desktop analysis for communities and emergency managers, and all of these groups, to go through what if the rain bomb occurred here or there, or, and what would happen and how to deal with it. And I think if for the July 4th flooding, a number of factors, there were a number of ingredients that amplified the flooding. I guess you had a convergence of moisture from the Gulf of Mexico, from the Pacific, and also coming up through Mexico the ending of a tropical storm, and then that topographic convergence in the Hill Country.
And also, I guess it was a very slow moving system, so a lot of rain fell because it was slow moving at high intensity. And I think, when we chatted before Hatim, you mentioned that the flood waters were moving downstream, and that direction then amplifies the force of the floods and the depth of the floods.
Maybe you can describe that a little bit.
[00:13:00] Hatim Sharif: Yeah, I think let's start with the storm. I think usually this is happening because you have this flash flood alley, like usually at the Balcones escarpment, so usually moisture comes from the gulf. And of course at that time it was warm. And then of course more moisture going into the atmosphere.
And then they add the moisture or the air, moist air mass like move inland, it reaches the escarpment, it's lifted. So like, condensation enhance and storm development intensifies. And then also, yeah, the storm become a little bit stored there because of the topography. And then of course they dump a lot of rain.
At that time, there was a lot of moisture in the atmosphere. And then the response also related, because this is like the hill country, so it's steep slopes. Also, the landscape is dissected by many, small streams and channels that are like, it is a high drainage intensity area because of the topography of the limestone. Efficiently, they move water very quickly to larger creeks and streams. So the response is fast, the soil layer is not deep, so there is not much. They get soaked very quickly. So runoff with the steep slope and then this efficient drainage network, the response is very fast. This is why it's called flash flood alley. So for that reason, yeah, the response was fast and then the storm, and then the response was very quick.
It happened at that time.
[00:14:32] Bridget Scanlon: Yeah. Yeah. And when we chatted before Hatim, you mentioned the importance of now casting and I was just looking up the National Weather Services. I think testing some now casting approach that's heavily driven by the recent data and to develop these quantitative precipitation estimations.
And so I think now casting and short term forecasting are very important.
[00:14:59] Hatim Sharif: I think that will be very helpful, yeah. As we mentioned earlier, I think those forecasts, usually they have problems, especially with location of the intense cells. I think now casting, because it is simpler than the full numerical weather model.
They run fast. You can run them every five minutes and they give you short term forecasting like for up to an hour or 90 minutes. So they are fed by real time data from radar. Which should tell you about how the storm is evolving and also the movement of the storm. So it'll provide, I think, probably much better estimates because it's very short lead time, so it gives better estimates how the storm is developing, what will happen in the next hour or so.
And then I think, if you have a monitoring also monitoring the situation on the ground, I think this can be fed into some hydraulic models. And then it'll provide very useful, prediction of terms of flooding, the inundated area in terms of time and location.
And I think that the also now casting system are improving, now people are using machine learning so they can run much faster than before. So you get data from the radar and gage, and then you can do some extrapolation of the storm. So with the help of machine learning, I think they can provide very useful information that can save lives during those situations.
[00:16:23] Bridget Scanlon: Right, right. And the National Weather Service provides these nowcasts and forecasts and as you mentioned, the rainfall data is fed into the models and National Weather service, I think, uses the national water model and then develops information on stage height and compared with the gauges, and also the flow velocities and things like that. So, very helpful. And then you've also got the River Forecast Centers. And I'm not sure if they're using the national water model also, or if-
[00:16:53] Hatim Sharif: Yeah, probably. Yeah. They're using it. Yeah.
[00:16:56] Bridget Scanlon: HEF system: Hydrologic ensemble forecast system or some things like that.
So a lot of different types of models. And then, you've also got all of the monitoring that's going on. The radar, the rain gauges, but also the USGS on gauge data. And that's very important. And you mentioned the Hunt gauge and I guess they estimated that rose to 37ft and a half feet during this recent flooding.
[00:17:22] Hatim Sharif: Actually this what was measured, but actually it stopped at that time. But it is well above 40. When they did the high water mark was well above 40. Yeah.
[00:17:31] Bridget Scanlon: Oh okay.
[00:17:32] Hatim Sharif: So it stopped measuring at 37.52, but it was much higher than that.
[00:17:38] Bridget Scanlon: And I saw David Maidment gave a short presentation at a recent meeting and he has installed a lot of gauges on bridges with the Texas Department of Transportation. And in his work, he was emphasizing that there was a velocity spike at the Comfort station, which is downstream of that region at about 8:20 AM.
And that preceeded the flood wave by about an hour. So it gives you additional warning.
[00:18:06] Hatim Sharif: That's right. Yeah.
[00:18:07] Bridget Scanlon: Came about an hour later.
[00:18:09] Hatim Sharif: I think
[00:18:10] Bridget Scanlon: also, I guess on the bridges.
[00:18:12] Hatim Sharif: Yeah. Monitoring I think is very important. It provides very useful. And in Texas we have thousands of bridges. You mentioned we have thousands of lower water crossing, but we have thousands of bridges. I think if we install just radar, gauges on bridges, I think that will provide very useful information in real time, And those are, simpler than traditional rain gauge and they can provide real time data.
[00:18:37] Bridget Scanlon: Right, right.
[00:18:38] Hatim Sharif: The traditional stream gauge provided time that will be very helpful. I think, if we have some forecasting system, like hydraulic forecasting system, I think just the type of information will be very useful in understanding the evolution of the flood on the ground. So this will provide information to people who can understand. I think there was a point, I think you mentioned earlier, I didn't discuss more, you said maybe we do fire drills. So emergency manager also they should be trained and those things. I think we can run hydraulic models offline.
We can simulate thousands of events and tell them what will happen. If, for example, you have this type of storm in term of inundated areas so they can, and if you have a good interface, show them exactly what will happen on the ground, how, what will happen to the roadway network, which roads become impassable.
If this flooding happens, how do you plan your rescue efforts? In this case? Maybe, of course, we need say, helicopter in this situation and in this situation maybe we'll use other roads. This can continue all year. Because you can run those models and with the help of machine learning, you can generate thousands of scenarios of flooding and so that you can, those people will be very ready if something happens. They can yeah, have a, develop a very quick rescue plan.
[00:20:04] Bridget Scanlon: Yeah, and I think, if the people look at where the nearest USGS gauging station is to them, they can sign up for flood alerts at the USGS website. And also the USGS has developed flood inundation models relative to the stage at the gauge, to show which areas would be inundated if the stage at the gauge was at such a height and things like that.
So, so there are lot of tools and things out there but I think it's trying to get people accustomed to them and to looking at the data and to understanding the data. I think this would be important.
[00:20:38] Hatim Sharif: Yeah, I think, yeah, education is very important. Maybe it kind of start off so it's like say, high school or college students, teach them about what to do in this situation, what will happen. And those apps I think are very helpful. You mentioned the one in Norfolk, Virginia.
I think that was helpful. And of course that helps include tidal flooding. Tide can be predicted very accurately. That is usually not the case here. There is a lot of uncertainty and then we need to communicate the uncertainty associated with flash flooding. Yeah, I think, people can work on this, communicating and educating people. You mentioned "turn around, don't drown" might not work for everybody. I think your younger generations, they need other messaging. Yeah. So that maybe you'll..
[00:21:24] Bridget Scanlon: So you mentioned the San Antonio floods earlier, Hatim, and you live in San Antonio, so maybe you can describe that flooding because we didn't really hear a lot about it because it was eclipsed by the July 4th flooding. Maybe you can describe the San Antonio flooding that occurred before the July 4th flooding and what happened in San Antonio?
I think about maybe 15 people lost their lives and occurred in the city and, maybe you can describe that.
[00:21:55] Hatim Sharif: Yeah I think the Kerr county flood was a typical flash flood. It's a fluvial flash flood associated with the channel itself, like the River Creek Channel, so that is fluvial. The one in San Antonio, it was fluvial and pluvial so it is like flooding in urban areas where like, roads are flooded, but a creek was also flooded.
This is a combination and typically in urban area, it is pluvial fusion. That was also historic event in some measures because there like 13 people died. 11 of them, they were killed within a stretch of 1.5 miles. So that is also, I think for San Antonio's historic. People just die and those people are not like in a van or something.
Each individual, they died. And also I think that where their car was swept away probably is in a small area. So, where this creek intersected, flooded over to the next service road. People are leaving the highway or going to the highway. They came and this part adjacent to the highway, the frontage road was flooded and then they got swept away into the creek and then 15 cars were swept away in this location and 11 people died. The other two died in another location. But 11 people died within a 1.5 mile. That's also historic and also in term of things that are important. Usually people when they look at the storm, they say a hundred year storm, they look at like, say 24 hour storm or something.
By the way, during this time around July 4th, there was flooding near San Angelo area. Actually, in some locations, the precipitation exceeded the 1000 year, 24 hour storm. But it didn't result in many fatalities because it happens over the whole day and then there is time to react and so on.
But concentrated precipitation is very dangerous in San Antonio. This happened at Beitel Creek. For Beitel Creek. The one hour precipitation actually broke all records just in one hour, 3.9 inches in one hour. This is what led to this very fast and peak over this creek, which like it's flooded and then flooded adjacent service road.
So, the response was very fast, same thing. And then it caused this flooding, which also I think in term of, if people were educated about the danger of driving into flood water, probably this would have prevented some of these fatalities. And I think you mentioned that I studied fatalities in Texas.
Maybe this changes, of course, every time when there is an event but, maybe more than 70% of people who die in floods, especially in flash floods in Texas because they drive into flood waters. Unlike the case of Camp Mystic and this one. But this is a typical, situation where people intentionally drive into flood water and then they get swept away because people underestimate the power of the water. And so if less than one foot and water is moving fast enough, it can sweep away an SUV. And this exactly what happened during this event, I think.
[00:25:11] Bridget Scanlon: Right. Yeah. And so you mentioned the different types of flooding. The pluvial flooding, is rain just falling on the land before it reaches the river? And so it's overland flow or, that sort of thing, pluvial flooding. And then fluvial is within the stream channel and over topping the banks and all of that related to-
[00:25:29] Hatim Sharif: That's right. Yeah.
[00:25:30] Bridget Scanlon: So Beitel Creek flood, and Loop 410 in San Antonio. Then all those vehicles were washed away. And so that was really-
[00:25:39] Hatim Sharif: A combination of pluvial and fluvial, yeah.
[00:25:42] Bridget Scanlon: Right, yeah. And the other thing, I mean, there have been the other big floods that occurred in Texas that we remember is the Wimberley floods from Memorial Day in 2015 was another big flood.
And that was in the Blanco River basin which is adjacent to the Guadalupe River Basin in the Hill country. And that happened after a long-term drought with drought conditions, I guess, from 2011 to 2014. And I guess, there were about 12 fatalities again, another holiday weekend.
A lot of people there that maybe not familiar with the area, but extreme flooding because of the position of the storm cells over the headwaters. And also during that period, there had been a lot of rain prior to the flooding, and so the soils were saturated. And so, that also amplified the flooding.
So you did a paper on the Wimberley flood, right?
[00:26:37] Hatim Sharif: Yeah, we did the paper on the Wimberley flood, yeah. There are many factors I think that affected that. The movement of storm itself is a factor and I, yeah, by the way, we didn't mention that for the Kerr county flood. Also, the storm, like over the South fork was moving down the stream. This will also enhance the response of the, I don't know if response, but this, because this is a historic event, probably the direction orientation of the storm would have it contributed, but probably not by much because this is a really big event. But for Wimberly flood, it made a difference how the storm was moving.
And also I think the conditions and also I think land use changes had some impact during that flood. And that flood was mostly fluvial also. But I think the runoff response was affected by the land use also. And then orientation, movement, of storm was a factor. And also I think, as I mentioned, there was a forecast of this intense precipitation, but how exactly where and how it would be moving, that made a big difference.
So even if somebody knew the forecast and forecast is correct, but you wouldn't know how it'll move, where it'll hit the watershed, and then the response relies on that. And then that one also resulted in people swept away. People died like in their cabins or homes. And this is a problem in Texas, by the way, like say for Texas, usually, Texas is not like a very humid state, but 21% of the land of Texas falls within the hundred year flood zone. And about 15% of the population of Texas either live, or work in an area within the flood hazard zone. So that is like very remarkable of Texas. It's not like a very humid state, but I think we have so many creeks in Texas because of the nature of the topography and they flood, not often, but they flood. When they flood, people are exposed and then we have these types of catastrophe that happen.
This is what makes Texas number one in term of flood fatalities.
[00:28:47] Bridget Scanlon: Right, right. And when you describe the Wimberley flood, I think, that the West Gulf River Forecast Center, underestimated that flash flood and I guess the rainfall concentrated over like a seven hour period from 7:00 PM on the 23rd of May, so it was Memorial Day weekend, and then until 8:00 PM on the 24th.
And so that storm was near stationary and then, dumped a lot of rain on the headwaters of the Blanco River. And then you had that fluvial flooding and then washed away houses and things like that. So it
[00:29:20] Hatim Sharif: That's right. Yeah.
[00:29:22] Bridget Scanlon: And bridges and stuff. Yeah. Yeah. And so this is it, I guess, typical of what you describe as the hill country, the flash flood alley, with
[00:29:33] Hatim Sharif: That's right. Yeah. Yeah. Night storms and then, actually, several of the historic floods in Texas, or the one that will usually result in this type of fatalities, happen over times of like, holidays. Yeah. Always like this. We have July 4th, we have Memorial Day, we had Thanksgiving Day flood, we had at one time. In actually Halloween. Yeah. So we you have them during, yeah. Okay. And also everywhere else, I think like people who die while camping or something in some other location of the country, yeah, people are camping and just dying. Yeah. So now, yeah.
[00:30:13] Bridget Scanlon: Yeah. I really liked your analysis of flood fatalities. The most recent work you did, where you examined data from 1959 to 2019, so a 61 year period, looking at flood fatalities throughout the US and I didn't understand that you had this background in human health. Public health.
[00:30:33] Hatim Sharif: I have a master of public health. Yeah. Yeah.
[00:30:36] Bridget Scanlon: And as you mentioned, flash flooding of 40% of the fatalities linked to flash flooding and in that paper you discuss- I mean, Katrina resulted in huge fatalities like 1,880 people I think died during Katrina. So that was huge.
The take home message that I got from that paper was that a lot of the fatalities resolved from people in vehicles, like almost 60%. And then people in water, the term used "in water", so they're walking into flood water intentionally. And that was 28%. So that's almost 90%.
But what was interesting also is that you had camping was 1%. So, I mean, people in vehicles then, they think they can drive through the water or maybe they can't back up, or maybe they have no way out or.
[00:31:25] Hatim Sharif: I think the response, maybe people communication also saying, understand this more than me, but I think usually some people, and it happened actually in San Antonio several times, some people, when there, there is a storm, I need to go home. So they leave their work place, they need to go home. I need to pick my kids from school. So they try, the action is not like, they never think of maybe I should stay in my place. This is why people respond. And many of those fatalities happen at night, I think. You cannot properly estimate the velocity of the water and the depth of the water. So, usually, you think if you are in a big car, you think you are safe and so on.
So I think we need to educate people, especially for driving at night. I think at one time, in Austin, they tried to add some information in, like, the driver manual, and people get a driver license. They understand about flooding and the force of the water during those, flooding. Like, if a street is flooding, you shouldn't drive into a flooded street. This is, I think, one big issue in Texas. One big problem. And one of the reasons why we have so many fatalities. When we say intentionally they going to water, is that drive or walk? They, of course, they do not want to kill themselves, but they are not aware of the danger.
So they think they can cross. They think and yeah.
[00:32:43] Bridget Scanlon: And you mentioned the mantras like, turn around, don't drown. Think Keri Stephens here at the Moody School at the university conducted interviews with people trying to understand the psychology of people with the flooding disasters. And a lot of people think that their vehicle, their big truck can get through it, and so.
[00:33:02] Hatim Sharif: Right. Yeah.
[00:33:03] Bridget Scanlon: So she was suggesting to change the messaging because their trucks are very valuable to them, and so, she was suggesting a messaging like, keep your car high and dry.
[00:33:12] Hatim Sharif: Yeah, maybe. I think that, yeah, I think that's right. That will work with many people. Yeah. Just save your car from this and yeah. Yeah. Probably. Yeah. Especially the young generation. Yeah, that's right. But I think those are helping. I think when we looked at also. Because the population of Texas in is changing and people are moving into Texas.
And so I think if you take like. Like, say, divides fatalities by the population. I think it is improving and I think education is part of that. Yeah. So I think communicating the risk might help further, I think, yeah. We have, of course this, big events like this that happen and every year we have some people dying.
Actually, by the way, like in Texas, I think every year some people die in floods in Texas, except for 2011. Because you mentioned that the big drought. Actually this, when you look from 1959 until now, every year some people die in Texas except for that year. So I think education will help communicating the risk.
I think it is already helping and it'll help I think. Yeah.
[00:34:19] Bridget Scanlon: Right. And, of course, you mentioned the 2011 drought, which was really severe. But after the Kerr County flooding everything, the Highland Lakes that provide water to the city of Austin, they're over 90% full at the moment.
[00:34:34] Hatim Sharif: Yeah.
[00:34:34] Bridget Scanlon: Help fill up the reservoir. So,
[00:34:36] Hatim Sharif: That is some benefit from just floods. Yeah. Texas. Usually people say, yeah, floods follow droughts. You are in a drought then we get floods and so it's the same thing. People are worrying about lack of water now, they have just too much water. It's concentrated in term of location and and time. That this is why it becomes very dangerous.
Yeah.
[00:34:57] Bridget Scanlon: And I wonder, Hatim, if when you say floods follow droughts, it may be because we need a flood to end a drought because we've built up so much cumulative deficit over longer term droughts now three or four years
[00:35:10] Hatim Sharif: That's right yeah.
[00:35:10] Bridget Scanlon: droughts, that we need a flood.
[00:35:13] Hatim Sharif: Yeah, but hopefully we need floods that usually cover larger area and then distribute it over time. Not like intense precipitation over certain location. Yeah. Short periods of time. Yeah.
[00:35:26] Bridget Scanlon: And I think, in the past, the Texas Water Development Board, most of their planning was related to drought, for the drought of record, which was in many cases, the fifties drought or the 2011 drought. But in recent years, then they have emphasized flood planning and there's the state flood plan and 15 regional flood plans have been developed and they have a
[00:35:47] Hatim Sharif: And they contributed to that plan? Yeah.
[00:35:49] Bridget Scanlon: Yeah. Yeah. So that's really helpful for people to understand. And they talk about, the low water crossings, about 3000 of them and where they're located and everything. And then the number of buildings and everything that are within the hundred year flood plain.
Are the 1% risk of flooding or the 500 year floodplain? 0.2%. So, a lot of buildings and people, as you mentioned, living in floodplains. So I think.
[00:36:15] Hatim Sharif: Right. Yeah.
[00:36:16] Bridget Scanlon: 1 million buildings they suggested within the a hundred year floodplain and about an additional 800,000 buildings within the 500 year floodplain.
So very important to understand these things and to, and these reports and all of the data they're pulling together. Fantastic.
[00:36:35] Hatim Sharif: Yeah, that's right. Yeah. I think this is important. I think especially for rural Texas, I think. Usually municipalities and cities, they have enough resources to have the flood plain developed like accurately. And, but I think if you look at FEMA maps themselves, you find in rural areas is they're just rough estimates.
They're not developed like using detailed modeling because there is not enough resources for that. I think. And some of them, actually some areas, like in some of the counties they are, they do not have like, well developed flood map. So I think like a state effort, like the Texas water development will help, so that all counties, they have like, well developed flood zones and this will help I think.
But another factor I think is, regulation. I think we, in, in municipalities, they have some regulation not to build on flood zone, but I think those cannot be enforced in some counties. So outside cities I think, but also maybe some state efforts can help in that. Actually this was the case in Camp Mystic I think it's not sure some of parts of the camp was in the flood zone and then it was removed for some reason, is no longer in the flood zone. It's not clear why that happened but I think accurate delineation of the flood zones might help. Of course, this is thousand year event or something, of course. Well beyond a hundred year, but at least it could have reduced losses, especially the life loss I think. I think this plan will help. Yeah. This flooding plan for Texas, I think will help, especially in rural areas.
[00:38:13] Bridget Scanlon: Right. And I think also, building on the geomorphology and looking at geologic flooding and taking advantage of knowing the topography and the geology and the geomorphology will help us build a more credible, reliable flood maps and,
[00:38:29] Hatim Sharif: That's right. Yeah.
[00:38:30] Bridget Scanlon: help too.
[00:38:31] Hatim Sharif: Yeah.
[00:38:32] Bridget Scanlon: And I know David Maidment had a meeting recently after the Kerr County flooding and was asking, what can we do better? He also spoke with the legislators in the local meetings down in Kerr County. And David has been working with the Texas Department of Transportation installing radar gauges and river bridges with the Texas Department of Transportation. So they get the stage and the velocity and some of the data he showed from the recent flooding, showing the pulse preceded the increase in stage by about an hour at the Comfort station. I think provided additional warning, so, the flood pressure pulse came earlier, and so we could use those data also.
So I think they're installing those over a lot of bridges and more monitoring, as you said. And I think after the Wimberley floods, they installed an additional three gauges upstream of Wimberley to improve the monitoring, so more monitoring.
[00:39:32] Hatim Sharif: Yeah, and I think, I'm sure the responses this time will be bigger. I think we'll have more monitoring. And I think also we need to enhance like weather station to improve also the numerical weather models. I think some regions of Texas say there is like some huge gaps in term of monitoring the weather itself. So I think that also will be part of that. So that will improve forecasting, like, numerical model forecasting. And so monitoring will help, I think. But as you mentioned, also, I think training is very important, a training of emergency people educating the public, because of course, if people don't respond to all those warnings, there is no benefit to the community. So I think term of educating, training and having many drills for emergency managers, and also educating the public, telling them what to respond improving our communication how we communicate the risk to people during those events. I think this will very helpful.
And of course using technology, like you mentioned, I think would be helpful. Like the example of Norfolk, Virginia.
[00:40:40] Bridget Scanlon: Right. The example that you mentioned from Norfolk, Virginia was incorporating flood information into the Waze app that people use for driving. And so, they get information from drivers then that feeds back into the systems or provides on the ground real data.
You mentioned tidal conditions and coastal flooding there, but also regular pluvial and fluvial flooding. So that would be really helpful if people are in vehicles and since you said that about 70% of the flood fatalities from your previous analysis were from people in vehicles.
So I think that would be very beneficial. And as you said, expanding the stream gauge network, the rain gauge network, and flood inundation mapping. And, when we think about the hurricane system that we have I mean there's a lot of forecasting done for hurricanes in Texas and Clint Dawson works intensely in that area.
And what they emphasize is the importance of having funding for operations. So it's one thing to set up the system, but the other thing is to keep it going. And as you mentioned, many of these regions are dry, maybe 95% of the time. And so to keep the monitoring network operational will be very important.
[00:41:58] Hatim Sharif: Yeah. I think, yeah, all those are important. I think one thing probably that can happen, I think since we have a lot of resources now to, to that it'll be good I think if, like, say researchers work on recreating this event starting from the storm because now we know a lot about this storm and then run detailed hydro model to simulate how the flood draws.
Okay. We have some information from gauge and also we can run detailed hydro lake model to show exactly what happened over time, how this flooding evolved over land. Also get information of about people who unfortunately were deceased, where did they die? And people who save themself, we can get this information.
How did they save? So we can recreate this event, adding of course, which roads were became impassable. What happened? How did those people die? And then we can do some scenario. How could we prevent this if we, of course, knew this information ahead time, or if this happens again.
What was the best course of action for people who are in camps, for people like emergency managers? What they do, and I think, this will help us, if something like this happens, maybe how we could communicate the risk if we understand what happened, exactly why so many people died.
What did the people who saved their life, what did they do? And the number of people who were saved by emergency manager, how were they able to save them? I think this will be a very good learning experience and it'll help us, I think, in term of science and communicating the risk, and also training those emergency managers.
[00:43:41] Bridget Scanlon: Right. and I think Keri Stephens and Suzanne Pierce, here at the University of Texas, have funding from National Science Foundation to work with communities and to get a lot of that information, people that survived and people that didn't, and what exactly happened so we can learn from it and, we can all do these virtual scenarios.
And what if the rain fell here? And,
[00:44:03] Hatim Sharif: That is also another fight. Yeah.
[00:44:05] Bridget Scanlon: Yeah. So all of these different things that we can test so.
[00:44:09] Hatim Sharif: Right. We have like a very good case study, I think a really very good case study in term of understanding what happened and learning from it. Yeah.
[00:44:19] Bridget Scanlon: Right. So, thank you so much Hatim. Our guest today was Hatim Sharif, who is a professor in the Department of Civil and Environmental Engineering at the University of Texas at San Antonio. And thanks for all your research on flooding, especially in flash flood alley in Texas and also on the public health aspects and the fatalities.
[00:44:41] Hatim Sharif: Thank you Bridget. Thank you very much. Good to be with you.
