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The Infiltration Game - Soils and Flooding · PlanetGeo: The Geology Podcast

• 0:02
  SPEAKER_01: Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you.
• 0:12
  SPEAKER_00: A little bit of a cold.
• 0:13
  SPEAKER_00: Recording.
• 0:14
  SPEAKER_00: Yeah, I can hear that.
• 0:15
  SPEAKER_00: No, I went home.
• 0:16
  SPEAKER_00: When I was going to get my beer, I left my headphones on and I could hear you like clicking and scratching all the way out to my garage.
• 0:22
  SPEAKER_00: I was you are really lucky you didn't say anything bad about me.
• 0:27
  SPEAKER_01: One of the rare times when you walk out of the room and I don't say something bad about you.
• 0:31
  SPEAKER_00: I know.
• 0:33
  SPEAKER_00: Like you could have said, Oh, this guy is such a piece of work.
• 0:36
  SPEAKER_00: Why do I do this with him?
• 0:37
  SPEAKER_00: And you could have been totally serious and I'm listening and I'm a hundred feet away.
• 0:41
  SPEAKER_01: Here's the thing.
• 0:42
  SPEAKER_01: When recording's on, I know I have to be nice to you because our listeners are always defending you and they think I'm a little bit mean to you.
• 0:49
  SPEAKER_01: Well, do we have wounded Jesse today?
• 0:50
  SPEAKER_01: Like listen, no, not at all.
• 0:52
  SPEAKER_00: You need to suck it up.
• 0:54
  SPEAKER_00: I quit being so soft.
• 0:56
  SPEAKER_01: Okay, I have two questions for you, Chris.
• 0:57
  SPEAKER_01: You ready?
• 0:58
  SPEAKER_01: Yeah.
• 0:58
  SPEAKER_01: Go.
• 0:59
  SPEAKER_01: Okay.
• 0:59
  SPEAKER_01: First of all, do we have any updates from Joyce?
• 1:02
  SPEAKER_00: So uh not let me think now.
• 1:04
  SPEAKER_00: Not really.
• 1:05
  SPEAKER_00: I did tell her that we talked about her in her last recording.
• 1:09
  SPEAKER_01: Or about one of the Wait, she didn't know about it?
• 1:11
  SPEAKER_01: She fell asleep in the episode before we started talking about her?
• 1:14
  SPEAKER_00: I no, it's one that we haven't released yet.
• 1:16
  SPEAKER_00: Oh.
• 1:16
  SPEAKER_00: And I told her, I said, All right, mom, we talk about you.
• 1:19
  SPEAKER_00: And um what'd she say to that?
• 1:21
  SPEAKER_00: You need to be very defensive of your of your favorite youngest son.
• 1:27
  SPEAKER_01: That's pretty good.
• 1:29
  SPEAKER_01: Well, I'll uh I'll I'll tell you, one of my family members who shall go nameless sort of said, you know what?
• 1:34
  SPEAKER_01: Chris's mom is getting a lot of airtime on your podcast.
• 1:37
  SPEAKER_01: I think I should be getting some more airtime.
• 1:41
  SPEAKER_00: Oh, Linda, Linda, Linda is welcome.
• 1:44
  SPEAKER_00: Tell Linda though, she has to start emailing me.
• 1:46
  SPEAKER_01: That's true.
• 1:46
  SPEAKER_01: Joyce only gets airtime by emailing me.
• 1:48
  SPEAKER_01: Yeah, that's true.
• 1:49
  SPEAKER_01: That's true.
• 1:50
  unknown: That's right.
• 1:52
  SPEAKER_01: Question number two, Chris, which I I just noticed.
• 1:55
  SPEAKER_01: You know, we use Google Drive and Google Docs for this.
• 1:57
  SPEAKER_01: It's not an ad, we're not supported by Google, but we use Google Docs for our scripts.
• 2:01
  SPEAKER_01: And uh, you know, usually we might have like a rough outline open next to us while we're doing this.
• 2:06
  SPEAKER_01: I just noticed your name is Chris Bullheis, lowercase C, lowercase B.
• 2:11
  SPEAKER_01: Do I come in as Dr.
• 2:13
  SPEAKER_01: Jesse Rymank, you know, with the little like name tag that shows up?
• 2:16
  SPEAKER_00: Is there a doctor in front of it or not?
• 2:18
  SPEAKER_00: There is not, and I would do whatever I had to take, spend whatever amount of money I had to spend, climb whatever mountain I had to climb to make sure that was not the case.
• 2:27
  SPEAKER_00: Delete as many emails as you need to.
• 2:35
  SPEAKER_00: What'd you do?
• 2:35
  SPEAKER_01: I think it's the way it should be.
• 2:37
  SPEAKER_01: I think Google recognizes that you know one of us needs to be capitalized and one of us doesn't.
• 2:42
  SPEAKER_00: If if that's what you need, I can do that for you, Jesse.
• 2:45
  SPEAKER_00: Okay, if that if that helps you, if it helps you to tear me down, then go right ahead.
• 2:49
  SPEAKER_00: If that makes you feel better about yourself, everybody else out there knows what we call people like that.
• 2:55
  SPEAKER_01: Yeah, it's true.
• 2:56
  SPEAKER_01: It's true.
• 2:57
  SPEAKER_00: It's okay.
• 2:58
  SPEAKER_00: Uh well, okay, so you're just easing back into your professional life.
• 3:02
  SPEAKER_00: Like, what's going on at the Penn State University?
• 3:06
  SPEAKER_00: What do you what are you doing?
• 3:07
  SPEAKER_00: What are you doing there?
• 3:08
  SPEAKER_01: The Penn State University.
• 3:09
  SPEAKER_01: Well, we're in the throes of football season here.
• 3:11
  SPEAKER_01: Um you know, the the place just And you guys are good.
• 3:15
  SPEAKER_01: They're yeah, and uh lot of hype.
• 3:17
  SPEAKER_01: The place changes a lot in football season.
• 3:20
  SPEAKER_01: You know, there's a stat, Chris.
• 3:21
  SPEAKER_01: I didn't know this until I moved here, but the city of State College is like 40,000 permanent residents, maybe something like that.
• 3:27
  SPEAKER_01: During the school year, it blossoms to I don't know, 90,000 or 100,000 people with all the students that moved to campus, obviously.
• 3:35
  SPEAKER_01: But then six weekends a year, the home football games, the town becomes the third biggest city in Pennsylvania because a hundred thousand people come for the game, and then like two hundred thousand people come to Tailgate to just be near the game.
• 3:51
  SPEAKER_01: Oh my gosh, are you serious?
• 3:52
  SPEAKER_01: So it becomes this huge place.
• 3:54
  SPEAKER_01: I mean, it's the craziest thing.
• 3:55
  SPEAKER_01: You know, in Michigan, we always had these, like in the winter, some of the road signs would they'd had you know those like aluminum flaps that would kind of fold down over some signs, like they'd fold up a stop sign or a yield sign for the summer, and then in the winter they'd fold it down so that it's like visible.
• 4:10
  SPEAKER_01: We have that here, except it's all the street signs for football game weekends, so they'll like fold down and it'll be different directions.
• 4:18
  SPEAKER_01: If it's a football game weekend, you'll only be able to go one way on this road and they'll fold down, fold down the one-way road sign.
• 4:23
  SPEAKER_01: So, like the entire traffic pattern of the whole area changes on football game weekend.
• 4:27
  SPEAKER_01: It's crazy.
• 4:28
  SPEAKER_00: I had no idea.
• 4:29
  SPEAKER_00: Does anybody in the geology department at Penn State uh do seismic analysis?
• 4:35
  SPEAKER_00: Like, have you done any analysis of when touchdowns are scored and things like that at Penn State?
• 4:40
  SPEAKER_01: Yeah, they used to.
• 4:41
  SPEAKER_01: I think um there's a research group that is doing this crazy stuff that I I kind of struggle to understand, but they're using fiber optic cables to do seismic analysis, so you can like look at the travel times of light along the fiber optic cables and you can get some seismic data from that.
• 4:56
  SPEAKER_01: So they do they can detect like football games and touchdowns and things like that.
• 5:00
  SPEAKER_01: And as we talked about in like literally our fourth episode, I think we talked about the seismic quieting of Earth during COVID when there's no trucks in the road and stuff and uh no football games.
• 5:09
  SPEAKER_01: And so we kind of we I think we touched on this in a going back now, what, three years?
• 5:13
  SPEAKER_00: Right, because University of Michigan has done this.
• 5:15
  SPEAKER_00: They can determine when Michigan scores a touchdown based on the seismic waves and the noise.
• 5:20
  SPEAKER_00: And yeah, it's crazy.
• 5:21
  SPEAKER_01: I saw an article recently, I think it was out of one of the Washington schools, where they did this for uh a Taylor Swift concert and saw the start of the all the Swifties stomping on the ground.
• 5:31
  SPEAKER_00: Okay, I have to ask you this because Can I identify Taylor Swift?
• 5:35
  SPEAKER_01: Yes, I can.
• 5:36
  SPEAKER_00: I can too.
• 5:37
  SPEAKER_00: She's not a limestone.
• 5:38
  SPEAKER_00: Okay.
• 5:39
  SPEAKER_00: Okay.
• 5:40
  SPEAKER_00: I can always identify Taylor Swift.
• 5:42
  SPEAKER_00: Would you love to go to a Taylor Swift concert?
• 5:45
  SPEAKER_00: Oh.
• 5:46
  SPEAKER_01: Wow, that's an interesting question.
• 5:48
  SPEAKER_01: Uh yeah, that's a good question.
• 5:51
  SPEAKER_01: I would probably go with the right group of people.
• 5:53
  SPEAKER_01: I I wouldn't maybe love to go.
• 5:55
  SPEAKER_01: Let's put it that way.
• 5:56
  SPEAKER_01: What about you?
• 5:57
  SPEAKER_00: Oh my gosh.
• 5:58
  SPEAKER_00: I would go alone if I had to.
• 6:00
  SPEAKER_00: I would dance.
• 6:02
  SPEAKER_00: Oh my gosh.
• 6:03
  SPEAKER_01: I would that is not the answer I was expecting.
• 6:07
  SPEAKER_01: I would go alone.
• 6:09
  SPEAKER_00: That's if I had to, I would rather go with Jenny.
• 6:12
  SPEAKER_00: Jenny would be my favorite person in the world to go with, but oh, I would go with anybody because I would have so much fun.
• 6:20
  SPEAKER_01: Yep.
• 6:21
  SPEAKER_01: Okay.
• 6:22
  SPEAKER_01: You and I and Tess and Jenny will go at some point to a Taylor Swift concert.
• 6:26
  SPEAKER_01: That would be just hilarious.
• 6:29
  SPEAKER_00: Oh you would, I think, be enlightened on my dancing.
• 6:33
  SPEAKER_01: I would get to know a side of Christopher Bullheis that I shockingly have never seen before.
• 6:38
  SPEAKER_01: I've never seen concert going Chris.
• 6:40
  SPEAKER_01: You have not.
• 6:40
  SPEAKER_00: I love live music.
• 6:43
  SPEAKER_00: You know, I've been to Red Rocks many times, and I'd love live music, and I am I become a dancing singing machine.
• 6:50
  SPEAKER_00: It's true.
• 6:52
  SPEAKER_01: Well, we know how to bribe Chris Bullheis now.
• 6:54
  SPEAKER_00: Well how did we get on Taylor Swift?
• 6:56
  SPEAKER_01: Where'd that come from?
• 6:57
  SPEAKER_01: Oh, seismic uh seismic analysis.
• 6:58
  SPEAKER_00: Oh, yeah.
• 6:59
  SPEAKER_00: Okay, that's right.
• 7:00
  SPEAKER_00: Yeah, in Washington or something.
• 7:01
  SPEAKER_00: Yeah.
• 7:02
  SPEAKER_00: Exactly.
• 7:02
  SPEAKER_00: All right, Jesse.
• 7:03
  SPEAKER_00: Shall we get down to business now?
• 7:05
  SPEAKER_00: Are we good to go now?
• 7:06
  SPEAKER_01: So today, Chris, we have another, we've had a great series of listener questions.
• 7:11
  SPEAKER_01: I mean, not that we don't have good listener questions all the time.
• 7:14
  SPEAKER_01: We just have had several that yeah, okay.
• 7:17
  SPEAKER_01: If you're listening to this and you've sent us a question, we haven't addressed it.
• 7:20
  SPEAKER_01: It's because it's not like in our frontal lobe.
• 7:22
  SPEAKER_01: We kind of get stuck in schools of thought.
• 7:25
  SPEAKER_01: I think we've been talking a lot about streams recently.
• 7:28
  SPEAKER_01: So anything related to streams is kind of like in our frontal lobe.
• 7:31
  SPEAKER_00: No, I'm sorry, just want to interrupt you.
• 7:33
  SPEAKER_00: And the other thing too, Jesse, is that we're getting now a lot of emails.
• 7:37
  SPEAKER_00: And so it's more difficult for us to do this and you know, respond to everybody and that kind of thing.
• 7:45
  SPEAKER_00: I mean, we've had a lot of growth and it's a it's a good problem to have, but we have to be selective just from volume.
• 7:53
  SPEAKER_01: Yeah, so that was a great humble brag, Chris, by the way.
• 7:56
  SPEAKER_01: But also, if you're if we haven't replied to you in a little while, you know, don't take offense to it.
• 8:00
  SPEAKER_01: We're we'll get to it.
• 8:01
  SPEAKER_01: You know, things got to click into place.
• 8:02
  SPEAKER_01: Like we're thinking about streams a lot.
• 8:04
  SPEAKER_01: So this email from Robert stood out really well as like, oh, yeah, totally.
• 8:07
  SPEAKER_01: That's an episode.
• 8:08
  SPEAKER_01: That's that's something that would totally fit in with what we're thinking about right now.
• 8:11
  SPEAKER_01: And it's sort of related.
• 8:12
  SPEAKER_01: The question from Robert related to devastating flood in Libya.
• 8:16
  SPEAKER_01: And the question he asked was, why does rain run off so quickly in arid environments and also on alluvial fan deposits, other than their steepness?
• 8:25
  SPEAKER_01: So the question is like, why arid regions do we get more flash floods?
• 8:29
  SPEAKER_01: I think if we could kind of distill that down, right, Chris?
• 8:31
  SPEAKER_01: Is that was that a fair assessment of sort of a distillation of the question?
• 8:35
  SPEAKER_00: I think so, because a lot of people think arid the ground is super, super dry that rain is going to soak into that very, very easily and very quickly.
• 8:44
  SPEAKER_00: And so you this wouldn't be a problem, but that's not what happens, and that's what we're gonna talk about as we dive into this thing that is called infiltration capacity a little bit later on.
• 8:55
  SPEAKER_00: Before we get into that though, let's set up what happened.
• 8:59
  SPEAKER_00: This has been all over the news, but let's just set this up so that everybody's on the same page.
• 9:04
  SPEAKER_00: So there was a recent Mediterranean storm that hit the northeast coast of Libya.
• 9:08
  SPEAKER_00: Two dams failed above the port city of Dirna.
• 9:12
  SPEAKER_00: I mean, they're not done yet with the death toll of this thing.
• 9:15
  SPEAKER_00: It's horrific.
• 9:16
  SPEAKER_00: It's a human tragedy that is hard to like put a thumb on.
• 9:20
  SPEAKER_00: Absolutely.
• 9:21
  SPEAKER_00: The storm that did this dropped 414 millimeters, which is about 16 inches of rain, in a day.
• 9:30
  SPEAKER_00: Now let's frame that with what's typical.
• 9:33
  SPEAKER_00: Usually this area sees 1.5 millimeters, about a tenth of an inch of rain during the entire month of September.
• 9:42
  SPEAKER_01: So this is a massive event that happened.
• 9:46
  SPEAKER_01: Amazing amount of rain.
• 9:47
  SPEAKER_01: I mean, just an incredible amount of rain.
• 9:50
  SPEAKER_00: So that's what happened, and the results are just catastrophic beyond measure.
• 9:57
  SPEAKER_00: Let's talk about Jesse.
• 9:59
  SPEAKER_00: What are the things that contributed to making this so horrible?
• 10:04
  SPEAKER_01: Yeah, so I think Chris that we have to frame this Durna is built on an alluvial fan.
• 10:10
  SPEAKER_01: So let me define what an alluvial fan is really quickly.
• 10:13
  SPEAKER_01: And I think people have probably seen this, so it's kind of easy to visualize in your head.
• 10:17
  SPEAKER_01: Imagine you're flying in a plane over the desert and there's mountains to your left or to your right.
• 10:22
  SPEAKER_01: I just watched the movie Dune uh a while back again, and there's a lot of images of this of alluvial fans.
• 10:28
  SPEAKER_01: And so if you have big rocky mountains and you're in this desert landscape and you're flying over this valley, there will be a big gully, a big valley in the mountains, and where that dumps out onto the plain, there will be this kind of conical-shaped hill of sediment, and that is the alluvial fan.
• 10:46
  SPEAKER_01: It's basically a river flowing through the mountains, flowing steeply downhill, is carrying boulders, it's carrying sand, it's carrying silt, stuff of all sizes.
• 10:55
  SPEAKER_01: It flows out, hits that valley floor, and it slows down really quickly.
• 11:00
  SPEAKER_01: In really dry places, it evaporates really quickly and it just dumps all of the sediment into this really steep-sided, what's called alluvial fan.
• 11:08
  SPEAKER_01: It's usually kind of like a half cone shape or a quarter cone shape, where the top of the cone is pointing up in the valley.
• 11:14
  SPEAKER_00: Yeah, I think of them kind of like those Chinese fans, you know, that you make with folded paper and you fan them out, you know.
• 11:20
  SPEAKER_00: Yeah, absolutely.
• 11:21
  SPEAKER_00: And so, well, they look like this, right?
• 11:23
  SPEAKER_00: And the tip of that fan points upstream, it points up into the valley where the mountains are.
• 11:29
  SPEAKER_00: That's how I kind of explain it and and frame it.
• 11:31
  SPEAKER_01: And they're very common in mountainous regions, especially arid mountainous regions.
• 11:35
  SPEAKER_01: So ones that get a limited amount of rainfall don't have necessarily a ton of vegetation around kind of a desert environment.
• 11:40
  SPEAKER_01: Southwest U.S.
• 11:41
  SPEAKER_01: in the basin and range environment has loads of alluvial fans.
• 11:45
  SPEAKER_01: Any mountain valley that comes and dumps out onto the main valley floor will have an alluvial fan attached to it.
• 11:51
  SPEAKER_00: Basically, if you have a river coming out of the mountains, it's confined by a valley, it's steep sloped, and erosion is the dominant process.
• 11:59
  SPEAKER_00: It is moving stuff.
• 12:00
  SPEAKER_00: And then during these events, these flood events, it's moving massive amounts of material and massive size material.
• 12:06
  SPEAKER_00: That's right.
• 12:06
  SPEAKER_00: You know, in geology, we call that the competence and the capacity.
• 12:09
  SPEAKER_00: They go up exponentially, actually.
• 12:12
  SPEAKER_00: And then it comes down, it hits that broad valley floor, and it rapidly slows down.
• 12:16
  SPEAKER_00: So it changes from an erosive thing to a depositional environment very quickly.
• 12:21
  SPEAKER_00: And that's what results in this kind of like fan-shaped deposit.
• 12:25
  SPEAKER_00: And then I think they're really cool looking, actually.
• 12:28
  SPEAKER_00: And then if you have a lot of these in one area and they kind of coalesce together, you know, or the edges of the fans merge together, then that in geology we call that a bajada.
• 12:36
  SPEAKER_01: And so uh, you know, the visual here, you can look on on Google and and just look up Durna images, and you know, it's kind of cool to see this because the city is built right on alluvial fan, it dumps out into the ocean in this case.
• 12:47
  SPEAKER_01: So it's a mountain valley, a big river system, mountain valley coming out of the mountains, hitting the ocean, dumping an alluvial fan right there.
• 12:54
  SPEAKER_01: So we've got this relatively steep alluvial fan.
• 12:58
  SPEAKER_01: The sediment deposition there is relatively steep-sided and sort of loosely consolidated sediment.
• 13:03
  SPEAKER_01: So that's the the geological setting.
• 13:05
  SPEAKER_00: And then you know Well, there's one thing that I want to add to that, and that is that it's also in an arid climate.
• 13:11
  SPEAKER_00: And what you get with this then, you don't typically get drizzly rain.
• 13:16
  SPEAKER_00: Instead, you get cloudburst kind of events, these cloudburst type storms that result in rapid amounts of water hitting the ground that runs off, like surface runoff, instead of seeping into the ground, which we call infiltration.
• 13:32
  SPEAKER_00: And that's where we're gonna go here shortly.
• 13:34
  SPEAKER_01: And you know, there's a lot to be discussed, I think, in the especially in this sort of climate change area around the intensity of rainfall events and the intensity of weather events that we're experiencing globally as uh climate change as a potential driver for an increase in the intensity of these things.
• 13:50
  SPEAKER_01: We're not gonna really touch on that here.
• 13:51
  SPEAKER_01: We're just gonna leave it as suffice to say, this was a ton of rainfall in a very short amount of time.
• 13:56
  SPEAKER_01: So we got this intense, intense rain event, basically.
• 13:59
  SPEAKER_01: So that's the kind of recipe we're dealing with here.
• 14:02
  SPEAKER_01: And so, with that, Chris, I think we need to touch on this term you you briefly mentioned, which is infiltration capacity.
• 14:10
  SPEAKER_01: And this is really it's the ability of soil to soak up water and how much water and how quickly it can soak it up.
• 14:18
  SPEAKER_01: So it's kind of both the rate and amount of water that soil can soak up internally.
• 14:25
  SPEAKER_01: Think of the the water going into the soil versus running on the surface of the soil.
• 14:29
  SPEAKER_01: So we get surface runoff, which is running along the surface, and then we get infiltration, which is water percolating down into the soil, whatever's at the surface percolating down into that.
• 14:40
  SPEAKER_00: Jesse, do you talk about this with your intro classes infiltration capacity?
• 14:44
  SPEAKER_00: I mean, only the term kind of makes sense.
• 14:47
  SPEAKER_00: It to infiltrate means to penetrate into, and the capacity is its ability to allow this to happen.
• 14:53
  SPEAKER_01: Exactly.
• 14:54
  SPEAKER_01: So there's two important things there.
• 14:56
  SPEAKER_01: So to answer your question, we we kind of talk about it.
• 14:58
  SPEAKER_01: I mean, it's it's not a long uh discussion, but a little bit.
• 15:02
  SPEAKER_01: And there's a lab that it talks about stream runoff and things like that.
• 15:05
  SPEAKER_01: So it is kind of part of that discussion, but uh there's two important points to capacity.
• 15:10
  SPEAKER_01: First is the amount of water it can handle.
• 15:11
  SPEAKER_01: So how much volume can you put in there and how quickly can it absorb it?
• 15:15
  SPEAKER_01: Because if you're getting 16 inches of rain in 24 hours, you not only have to put a lot of water in the soil, you have to be able to push it in there really quickly.
• 15:24
  SPEAKER_01: It's not like you can just let it sit there and soak up over days and days.
• 15:27
  SPEAKER_01: It's got to go in really, really quickly.
• 15:29
  SPEAKER_00: All right, I've I have a question for you, maybe two questions.
• 15:32
  SPEAKER_00: One is I would like to see that lab that you do with your students.
• 15:36
  SPEAKER_00: Okay, so you need to send that to me.
• 15:37
  SPEAKER_00: We'll do.
• 15:38
  SPEAKER_00: The other thing is I feel like you need to emphasize this more.
• 15:42
  SPEAKER_00: I think this is a really important issue and topic, actually.
• 15:46
  SPEAKER_00: And it's something that I want to emphasize, especially as we get into the factors that affect infiltration capacity, because there is an anthropogenic issue that is created here with infiltration capacity.
• 15:59
  SPEAKER_00: That's a human-induced, direct and big time effect on runoff and then what happens to the rivers as a result.
• 16:08
  SPEAKER_00: So I feel like you need to have a discussion with your Penn State colleagues, and you need to move this up to this needs to be a more important topic.
• 16:16
  SPEAKER_00: It's socially relevant.
• 16:17
  SPEAKER_01: I I agree.
• 16:18
  SPEAKER_01: Um, it's it's one of those ones where when you look around our area, the difference or the variability in infiltration capacity is not much.
• 16:26
  SPEAKER_01: There's a lot of soil around here that has basically very similar infiltration capacity.
• 16:31
  SPEAKER_01: And so our stream exercise is relatively basic.
• 16:34
  SPEAKER_01: It's measuring the stream, it's looking at a stream cross-section.
• 16:37
  SPEAKER_01: We have a lot of meandering streams.
• 16:38
  SPEAKER_01: So our meandering stream discussions are much more relevant to this area because a lot of the stream issues we run into around here in Pennsylvania are ones where the humanity, society, has has sort of, you know, confined to meander in a certain way, and it's changing the downstream effects.
• 16:52
  SPEAKER_01: So that's like a more impactful process to talk about for this specific region.
• 16:58
  SPEAKER_01: But, anyways, I agree with you completely.
• 17:00
  SPEAKER_01: Infiltration capacity is a super important thing because we'll end with this, because this is one principle or one process we can change a lot as humanity.
• 17:09
  SPEAKER_00: That's right.
• 17:09
  SPEAKER_00: So we're gonna move that part of our discussion to the very end, then, Jesse.
• 17:13
  SPEAKER_00: And then at the end, I want to come back to it and say, do you still think that Penn State should not be moving this to the forefront of your discussion?
• 17:21
  SPEAKER_00: Because I'm not done with this.
• 17:22
  SPEAKER_00: I think it's like it's a I think it's a big deal.
• 17:24
  SPEAKER_00: I'm passionate about it, obviously.
• 17:25
  SPEAKER_00: And when I'm passionate about it, Jesse, it means I'm right.
• 17:28
  SPEAKER_01: Well, I mean, it doesn't everything mean you're right, Chris.
• 17:33
  SPEAKER_01: Um, so I think we can, Chris, move into, we've set the stage really well here with where Dirna is and and the sort of event we're talking about.
• 17:41
  SPEAKER_01: Let's talk about the key features or the key factors that influence the ability of the soil to soak up water, which is this infiltration capacity term.
• 17:49
  SPEAKER_01: The first one we've already touched on, I think it's the intensity and duration of rain.
• 17:54
  SPEAKER_01: So how much water are you getting and how quickly are you getting that?
• 17:59
  SPEAKER_01: Because ultimately your soil has to soak that thing up.
• 18:02
  SPEAKER_01: So that's one thing that that could impact it, right?
• 18:04
  SPEAKER_00: Because if you have this cloudburst thing that dumps a lot of rain in a very short period of time, that's going to favor a low infiltration capacity as opposed to something like a drizzly event that lasts a longer time, giving it then more time to soak in before it runs off the surface.
• 18:21
  SPEAKER_01: And so this is really a massive factor.
• 18:24
  SPEAKER_01: If you want to know am I going to flood, experience a flash flood or not, is you have to compare your soil infiltration capacity, which is kind of a fixed number, versus the amount of rain you're getting in that event.
• 18:37
  SPEAKER_01: And if the volume and speed rate of rain is greater than your infiltration capacity, you're going to flood.
• 18:43
  SPEAKER_01: It's kind of a law there that if it's greater than your infiltration capacity, it's going to flood.
• 18:47
  SPEAKER_01: If it's not, your soil can then soak up the amount of rain you're getting in that event, right?
• 18:51
  SPEAKER_01: And you're not at risk of flooding.
• 18:53
  SPEAKER_01: So it's a really important thing for predicting flood events and something people consider when you're looking at a drainage basin and seeing a weather event and trying to figure out is this a flooding event we need to worry about or not.
• 19:03
  SPEAKER_00: So let's move into the second variable, which is, I think, intuitive.
• 19:07
  SPEAKER_00: It's the slope of the land.
• 19:08
  SPEAKER_00: Slope of the land is how steep the topography is.
• 19:12
  SPEAKER_00: And we've already laid this out that Durna is on an alluvial fan and they tend to be steeper sloped.
• 19:18
  SPEAKER_00: Well, the steeper the slope, the lower the infiltration capacity because water needs time.
• 19:25
  SPEAKER_00: It needs time to soak into the ground, into the soil, into the regolith.
• 19:30
  SPEAKER_00: And with a steep slope, it doesn't have time.
• 19:33
  SPEAKER_00: So that favors surface runoff.
• 19:35
  SPEAKER_00: And surface runoff is the exact opposite of infiltration capacity.
• 19:40
  SPEAKER_01: Surface runoff is potential flood.
• 19:42
  SPEAKER_01: Right?
• 19:43
  SPEAKER_00: That's right.
• 19:44
  SPEAKER_00: So I think those two, Jesse, are the most intuitive intensity and duration, slope.
• 19:49
  SPEAKER_00: But now we get into some of these other things that maybe aren't as intuitive that can really dramatically affect infiltration capacity.
• 19:58
  SPEAKER_01: And I hate to admit this one, Chris.
• 20:00
  SPEAKER_01: Number three.
• 20:01
  SPEAKER_01: I really it kind of pains me to admit this, but biology matters here.
• 20:06
  SPEAKER_01: You said it.
• 20:07
  SPEAKER_01: I know you said it.
• 20:08
  SPEAKER_01: You made me say it this time.
• 20:10
  SPEAKER_01: But it does.
• 20:11
  SPEAKER_01: This is like we talked about with stream meanders and vegetated regions and non-vegetated regions, it changes the physics of stream meanders.
• 20:19
  SPEAKER_01: Biology changes the physics of soil infiltration capacity.
• 20:24
  SPEAKER_01: And there's a couple different ways in which it does that, Chris.
• 20:27
  SPEAKER_01: So so this is like vegetation matters or biology matters is the heading here for number three.
• 20:32
  SPEAKER_01: And there's a couple of subheadings, right?
• 20:35
  SPEAKER_00: Okay, so Jesse, let me interrupt you a second.
• 20:38
  SPEAKER_00: You're the one that said this, and I take issue with this.
• 20:41
  SPEAKER_00: You said this gets to the heart of Robert's question, dealing with the biology, the vegetation, the vegetative cover and what it does.
• 20:49
  SPEAKER_00: So you really think that this is the most important factor affecting what happened in Durna?
• 20:56
  SPEAKER_00: So I'm gonna let you run a little bit, okay, with this and explain why you're so passionate about the vegetative cover and what it did to make this such a horrible event.
• 21:06
  SPEAKER_01: Well, I think it's more what it didn't do.
• 21:08
  SPEAKER_01: And so in Durna, it's an arid region.
• 21:11
  SPEAKER_01: And the reason I think this is part of Robert's question is because Robert very uh intuitively said, why does rain run off so quickly in arid regions other than steepness?
• 21:19
  SPEAKER_01: So if we rule out steepness as a factor, then this one is to my mind the most important.
• 21:25
  SPEAKER_01: Soil without vegetation on it is more densely compacted.
• 21:30
  SPEAKER_01: Vegetation does a lot of stuff that breaks apart the soil.
• 21:34
  SPEAKER_01: There's plant roots that are going down in it, there's dead organic matter in with the soil.
• 21:40
  SPEAKER_01: We have this soil horizon that's a lot of organic matter in there, and organic matter is not very dense, means it has a lot of porosity and permeability to soak up more water.
• 21:48
  SPEAKER_01: So there's a couple factors, a couple reasons why plant matter, organic matter, breaks up soil, takes the same amount of sediment, and makes it more voluminous, and therefore more ability to soak.
• 22:00
  SPEAKER_01: Up water.
• 22:00
  SPEAKER_00: That's right.
• 22:01
  SPEAKER_00: And another thing that vegetation does is it simply slows surface runoff down.
• 22:06
  SPEAKER_00: Think about it.
• 22:07
  SPEAKER_00: If you have water flowing over the surface, but it's flowing through grass, let's say, the water has to go around and you know, it's a very intricate path that it has to take and slowing it down.
• 22:18
  SPEAKER_00: And that's what the soil needs.
• 22:20
  SPEAKER_00: It needs time to absorb it.
• 22:22
  SPEAKER_00: So it also does that.
• 22:24
  SPEAKER_01: And you know, related to that, Chris, which is I think very intuitive to what most people imagine, a steep slope with sand, if you pour water across it, it's going to draw the sand down.
• 22:34
  SPEAKER_01: If you put trees or grass over that and you pour water on it, it's not going to erode as quickly.
• 22:40
  SPEAKER_01: And not eroding means that the water has to infiltrate into the soil more.
• 22:45
  SPEAKER_01: And so I think that's kind of an intuitive one.
• 22:46
  SPEAKER_01: Like just imagine a hillside that has trees on it and one that's barren that just has rocks and soil on it.
• 22:52
  SPEAKER_01: And if it's a big rain event with the trees, it's it's going to hold the soil in place more.
• 22:56
  SPEAKER_01: So it does a couple of things.
• 22:58
  SPEAKER_00: Ooh, something just popped into my head.
• 23:00
  SPEAKER_00: Can I can I do a little side tangent just a second, just real quick?
• 23:03
  SPEAKER_00: All right.
• 23:04
  SPEAKER_00: We have this problem in the Mississippi Valley here in the United States where agriculture is exposing fresh soil and fresh regolith, like in the fall and so on, when they go and cut this off, right?
• 23:16
  SPEAKER_00: If you combine this now freshly exposed soil with a cloudburst kind of event, heavy, big, intense raindroplets, right?
• 23:23
  SPEAKER_00: They impact the ground and they're dislodging sediment, which helps also you get runoff and a lot of erosion then because of that.
• 23:33
  SPEAKER_00: And so they're trying to get creative in the Mississippi Valley to deal with this.
• 23:37
  SPEAKER_00: Like as they cut their stuff off, they're just kind of more mulching it up and dropping it back onto the soil to act as kind of a protective covering to minimize this impact of fishing.
• 23:50
  SPEAKER_01: Wow.
• 23:51
  SPEAKER_01: You know, okay, another random side tangent here.
• 23:54
  SPEAKER_01: I just had a discussion with a colleague that I think you'd find very interesting.
• 23:57
  SPEAKER_01: So this colleague went and took a forestry class for reasons, but took like a uh a weekend, long weekend, like forestry clinic up in the northeast.
• 24:04
  SPEAKER_01: For reasons.
• 24:05
  SPEAKER_01: Yeah.
• 24:05
  SPEAKER_01: I mean, for fun, right?
• 24:07
  SPEAKER_01: Who doesn't?
• 24:07
  SPEAKER_01: Who doesn't go and take a forestry long weekend?
• 24:10
  SPEAKER_01: But this was up in the northeast, so like Maine, Vermont, New Hampshire, you know, upstate New York, that kind of area.
• 24:15
  SPEAKER_01: Picture that, the sort of white mountains, uh, the cat skills.
• 24:19
  SPEAKER_01: And one of the things they were talking about was the amount of beaver dams that used to be there sort of pre-industrialization, pre-European beaver trapping.
• 24:30
  SPEAKER_01: And the number was massive.
• 24:32
  SPEAKER_01: I'm making this number up, but it was something shockingly big, like 27 beaver dams per square mile, or something.
• 24:38
  SPEAKER_01: Something crazy, like crazy high amount.
• 24:40
  SPEAKER_01: You know, I when I envision upstate New York, Catskills, Chris, you and I drove have driven through there many times collecting rocks, like that area, right?
• 24:47
  SPEAKER_01: You've got these beautiful forested mountainsides with this beautiful clear stream, sort of pebbly bottom, rolling through it, you know, fly fisher guy hanging out there in the river.
• 24:58
  SPEAKER_01: Like that's the visual.
• 24:59
  SPEAKER_01: The conclusion was that stream never would have existed pre-European beaver trapping, because that would have just been a beaver dammed river.
• 25:06
  SPEAKER_01: So the conclusion is get rid of all the beavers, and actually the entire landscape erodes faster because there's not all these small little dams damming up the entire river system.
• 25:18
  SPEAKER_01: Sure.
• 25:18
  SPEAKER_01: So these clear running streams never used to be there.
• 25:21
  SPEAKER_01: That's a dramatic change to the entire landscape that all these rivers are running straight and faster and eroding quicker and carrying a bunch more sediment out to the ocean.
• 25:30
  SPEAKER_00: Anyway, that is a very interesting conversation, and I would put that in the category of a thought experiment.
• 25:35
  SPEAKER_01: Absolutely thought experiment.
• 25:37
  SPEAKER_01: Yeah, like because the the you know, this is where our conversation kind of went.
• 25:40
  SPEAKER_01: It was like, well, wait, the average erosion rate that we measure today, which people go out and measure this in Pennsylvania, like it's a really important parameter when we're thinking about how has the earth evolved over long time spans.
• 25:52
  SPEAKER_01: Like, what is the erosion rate?
• 25:53
  SPEAKER_01: Those all might be wrong, they might not apply more than 200 years ago.
• 25:58
  SPEAKER_01: We take that number we measure today and back calculate 10,000 years, we could be way off with that because we're using a number that is post-beaver, post-beaver life in the northeast, anyway.
• 26:09
  SPEAKER_00: That is interesting.
• 26:10
  SPEAKER_00: That is that is all right.
• 26:11
  SPEAKER_00: Hey, good side tangent, Jesse.
• 26:12
  SPEAKER_01: Okay, back at it here.
• 26:14
  SPEAKER_01: So biology matters for for this stuff for in soil infiltration rate for a variety of reasons.
• 26:20
  SPEAKER_01: It anchors the sediment, it breaks up the sediment, and actually dead organic matter in the soil itself adds a lot of porosity.
• 26:28
  SPEAKER_00: And dirna, arid climate, alluvial fan, probably not a lot of vegetation.
• 26:34
  SPEAKER_01: Not a lot of vegetation, exactly, exactly.
• 26:36
  SPEAKER_00: So low vegetation equals high runoff, low infiltration capacity, bottom line.
• 26:42
  SPEAKER_00: Okay.
• 26:42
  SPEAKER_00: All right.
• 26:43
  SPEAKER_00: Let's segue into the fourth variable that we're going to talk about, which is soil texture.
• 26:49
  SPEAKER_00: And there is some overlap with here, so let's kind of move fast through this.
• 26:53
  SPEAKER_00: But this is a broad kind of sweeping term.
• 26:56
  SPEAKER_00: But with soil texture, we're referring to things like porosity.
• 26:59
  SPEAKER_00: Generally speaking, soil that has a higher porosity means it has a higher percentage of air spaces between the grains.
• 27:07
  SPEAKER_00: It's got a lot of space between the grains.
• 27:09
  SPEAKER_00: Think of like pumice.
• 27:10
  SPEAKER_00: Maybe that's a bad example, but pumice has a really high porosity.
• 27:14
  SPEAKER_00: It wouldn't be very permeable and it wouldn't allow water to soak in because the pores aren't connected with each other.
• 27:20
  SPEAKER_00: But in soil, they often are.
• 27:22
  SPEAKER_00: And so high porosity, high permeability, high infiltrating.
• 27:26
  SPEAKER_00: I really don't like the packages.
• 27:27
  SPEAKER_01: You brought up pumice for reasons we've discussed previously on this podcast.
• 27:31
  SPEAKER_01: But how about a bucket of sand?
• 27:32
  SPEAKER_01: That's the analogy you use in class, right?
• 27:34
  SPEAKER_01: Is a bucket of sand.
• 27:35
  SPEAKER_01: A bucket of sand can hold a lot of water.
• 27:37
  SPEAKER_01: If you pour water into that five-gallon bucket full of sand, you know, you're gonna pour a bunch of water into that, right?
• 27:42
  SPEAKER_01: So there's a lot of extra space.
• 27:44
  SPEAKER_00: You know how much water?
• 27:45
  SPEAKER_00: How much?
• 27:46
  SPEAKER_00: You can pour about two and a half gallons of water in a five-gallon bucket of sand, which means the porosity is 50%.
• 27:53
  SPEAKER_01: 50% very good.
• 27:55
  SPEAKER_01: We often use fractions for porosity.
• 27:57
  SPEAKER_01: So 0.5 is the porosity of sand, right?
• 27:59
  SPEAKER_01: And different sediments have different porosities, right?
• 28:02
  SPEAKER_01: Another factor that affects soil texture is the sorting.
• 28:06
  SPEAKER_01: How well sorted is the soil?
• 28:09
  SPEAKER_01: And usually the better sorted, the higher the infiltration.
• 28:14
  SPEAKER_01: This can vary across different sediments.
• 28:16
  SPEAKER_01: So sand is a great one.
• 28:17
  SPEAKER_01: Really well sorted, loads of porosity.
• 28:20
  SPEAKER_01: Water can just pour through sandstone or sand sediment.
• 28:24
  SPEAKER_01: Clay is a harder one.
• 28:26
  SPEAKER_01: There's actually a lot of porosity in clay, but the pores are so small that it doesn't percolate through very fast.
• 28:32
  SPEAKER_01: The permeability is not high.
• 28:34
  SPEAKER_01: So you can't like push water through clay very readily, even though it can absorb a lot.
• 28:39
  SPEAKER_01: So it kind of depends, but basically, the more well sorted and the larger the grain size, the more um capacity the soil has.
• 28:46
  SPEAKER_00: That's right.
• 28:47
  SPEAKER_00: Let me provide an analogy of sorting, if you will.
• 28:49
  SPEAKER_00: If we take a mason jar and you fill it with a bunch of marbles, a bunch of like uh smaller BBs, and a bunch of sand, and you mix it all up and you dump it into this mason jar.
• 29:01
  SPEAKER_00: That has a lower porosity because it's not well sorted.
• 29:04
  SPEAKER_00: The grain sizes vary immensely from sand all the way up to marble size.
• 29:09
  SPEAKER_00: And what happens then is those smaller particles sit in what would be the porosity, the pore space.
• 29:15
  SPEAKER_00: And so that diminishes the porosity, which diminishes then the ability of water to seep through that stuff.
• 29:22
  SPEAKER_01: That's a that's a good analogy.
• 29:24
  SPEAKER_00: And then the last part of soil texture that we're gonna talk about is this soil compaction, and that I think it makes a lot of sense.
• 29:31
  SPEAKER_00: It's intuitive.
• 29:32
  SPEAKER_00: The more it's compacted, the lower the porosity, the lower the permeability, and the lower the infiltration capacity is.
• 29:39
  SPEAKER_00: But all of those fit into texture of the soil.
• 29:42
  SPEAKER_01: Yeah, and these can get really nuanced, like you know, very specific to a very specific region.
• 29:48
  SPEAKER_01: So one hillside can have multiple soil textures along it that are due to the different textures that are in that hillside.
• 29:54
  SPEAKER_01: So you can get highly variable soil textures.
• 29:58
  SPEAKER_01: All right, Chris, the last one, which is the most counterintuitive, is prior wetted condition.
• 30:04
  SPEAKER_01: And what we're saying here is wetted W-E-T-T-E-D.
• 30:08
  SPEAKER_01: So basically, is the soil dry, a little bit wet, or very wet?
• 30:13
  SPEAKER_01: And this is a counterintuitive one.
• 30:15
  SPEAKER_01: So, how do you break this down in class when you're talking about this?
• 30:18
  SPEAKER_00: Let me give this a shot.
• 30:19
  SPEAKER_00: So if the soil's saturated, then you don't get any infiltration.
• 30:23
  SPEAKER_00: So prior wetted condition, we're just saying, is the soil moist already?
• 30:28
  SPEAKER_00: Not saturated, because then you don't get any soaking in it.
• 30:31
  SPEAKER_00: If it's saturated, it's holding all that it can.
• 30:34
  SPEAKER_00: But if it's just moist, the infiltration capacity goes way up, and that's the part that's counterintuitive.
• 30:42
  SPEAKER_01: Um compared, let me interrupt, Chris, compared to a dry soil.
• 30:46
  SPEAKER_01: So it's kind of this Goldilocks thing, right?
• 30:49
  SPEAKER_01: You don't want to have no water in your soil.
• 30:51
  SPEAKER_01: That's gonna lower your infiltration capacity.
• 30:53
  SPEAKER_01: You don't want to have a lot of water because you just can't fit anymore then in your soil.
• 30:57
  SPEAKER_01: You want to have a little bit.
• 30:58
  SPEAKER_01: It's this kind of Goldilocks thing.
• 31:00
  SPEAKER_00: I show a video to my students, it's showing a moist lawn, then it shows a dried lawn, and then it shows no lawn that is very arid and just kind of like hard baked, right?
• 31:14
  SPEAKER_00: And it's just simply take a cup full of water, flip it over, and you can watch the water drain into the wet soil.
• 31:20
  SPEAKER_00: It just goes in like it's gone.
• 31:23
  SPEAKER_00: And the dry grass, it you flip the cup out and it seeps into it, but much, much slower.
• 31:30
  SPEAKER_00: And then if you take no grass and it's just really, really dry, the water just sits there, it won't soak in hardly at all.
• 31:37
  SPEAKER_00: Takes a very long time for it to soak in, and that's what you get in an area like Durna Libya is very, very dry, which favors runoff.
• 31:46
  SPEAKER_00: And we don't need to get into the weeds too far on this, but I think we can do something with this.
• 31:51
  SPEAKER_00: Why is the prior wetted condition, if the soil is already just moist, it's damp, why does it increase the infiltration capacity?
• 32:00
  SPEAKER_00: Well, again, Jesse, I hate to do this.
• 32:02
  SPEAKER_00: We go back to biology.
• 32:03
  SPEAKER_01: I know, I knew you were gonna go this way.
• 32:05
  SPEAKER_01: So can I can I tell you, I'm gonna tell you a story.
• 32:08
  SPEAKER_01: So I had my dad, my dad was a high school biology teacher, and uh, I had him in class, and I remember this lecture from him.
• 32:14
  SPEAKER_01: It's one of the only lectures I remember from my dad in biology class, and he was talking about You know, you just hurt your dad's heart a little bit there.
• 32:21
  SPEAKER_01: Well, he knows my uh my long-term memory is just terrible.
• 32:24
  SPEAKER_01: Um but this is he was describing capillary action, which is I think where you're going with this, right?
• 32:30
  SPEAKER_01: And the picture, the visual I have is he would he would take like a I think it was I might be getting this wrong, but so dad, you can let me know if if you listen to this and you're getting this wrong.
• 32:39
  SPEAKER_01: But basically, I think he I think he did it on the door, like on the wooden door of the classroom, and he'd put like one drop of water on the door, and it would bead up and it would kind of slowly like roll its way down.
• 32:52
  SPEAKER_01: And then he'd take his finger and wipe a finger streak of water down it and put a drop of water at the top of that, and the bead of water would disappear immediately, and a bead of water would appear at the bottom of the finger streak he put.
• 33:04
  SPEAKER_01: It was something along those lines where water beads up when there's no more water around, but if there's water already there, it readily soaks up into the pre-existing water.
• 33:16
  SPEAKER_01: Is that where you're going with this or not?
• 33:17
  SPEAKER_01: I just have this visual in my head.
• 33:19
  SPEAKER_00: I am, and that's a really good visual, actually.
• 33:21
  SPEAKER_00: Well done, Ron.
• 33:22
  SPEAKER_00: Yes.
• 33:23
  SPEAKER_00: Um so I said we need to go to biology to do this because in biology you talk about the polarity of water quite a bit.
• 33:31
  SPEAKER_00: So just a little bit of chemistry, just indulge me a little bit here, and you can cut me off.
• 33:35
  SPEAKER_01: Oh, Chris, I am all about the chemistry.
• 33:37
  SPEAKER_01: Come on, man.
• 33:38
  SPEAKER_00: Yeah.
• 33:39
  SPEAKER_00: So water is what they call a polar molecule, which means the molecule itself has an even distribution of electrons and protons.
• 33:48
  SPEAKER_00: But the thing is, the structure of the water molecule, they are not evenly distributed.
• 33:54
  SPEAKER_00: In other words, it's lopsided where the protons are on one side of the molecule and the electrons are on another side of the molecule.
• 34:01
  SPEAKER_00: So even though the overall molecule is neutral, no net charge, the molecule behaves like it does have a charge.
• 34:09
  SPEAKER_00: And so if you take individual water molecules.
• 34:12
  SPEAKER_01: Let me just interrupt there real quick, because you know, the the the visual here is we've got H2O, and the H's are both on one side of the O.
• 34:19
  SPEAKER_01: And so you kind of have like a little bar magnet.
• 34:21
  SPEAKER_01: You've got a positive end and a negative end, roughly, or a positive side and a negative side.
• 34:26
  SPEAKER_01: That's kind of what you're describing here.
• 34:28
  SPEAKER_00: That's right.
• 34:28
  SPEAKER_00: And so water then behaves like it carries this electric charge.
• 34:33
  SPEAKER_00: Well, the electrical nature of matter is that opposites attract.
• 34:38
  SPEAKER_00: So water molecules can orient themselves where the positive end of a molecule is attracted to the negative end of another water molecule, a nearby water molecule, where it feels that electrical pull.
• 34:49
  SPEAKER_00: And that's what causes water to beat up on like a freshly waxed car, is this polarity, uneven lopsided distribution of electrical charge, which allows water to orient and then feel the pull of that attraction and beat up like that.
• 35:06
  SPEAKER_00: That's what's happening, right?
• 35:08
  SPEAKER_00: So if you have soil that's wet in the pore space below the surface, it's going to attract because of its polarity, it's going to attract water above it on the surface and draw it down into the soil.
• 35:21
  SPEAKER_01: Exactly right.
• 35:22
  SPEAKER_01: And the and the the reason that the biologists talk about this is this is how plants get water from their roots up to their leaves, right?
• 35:28
  SPEAKER_01: This is how a big, tall tree pulls water all the way up from the roots, is this capillary action, little capillaries in there.
• 35:34
  SPEAKER_01: And this is why plants, if they die, they can you can get them too dry that you can't recover them, is because the capillary is all dried out and they can't get water up there.
• 35:44
  SPEAKER_01: But if they have a continuous stream of water, they can pull water up and pull nutrients up with that all the way up to the the top of the tree.
• 35:51
  SPEAKER_01: So that's why biologists talk about this capillary action.
• 35:54
  SPEAKER_01: That's exactly what's going on in soil, except it's drawing it down.
• 35:57
  SPEAKER_01: Okay, so this capillary action is drawing water down into the soil if there's prior wetting.
• 36:02
  SPEAKER_01: If the soil is completely dry, it beads up on the surface, which makes it spends more time on the surface, is more likely to run off as opposed to infiltrate.
• 36:11
  SPEAKER_01: So another point here.
• 36:13
  SPEAKER_00: Another nod to biology.
• 36:15
  SPEAKER_00: There we go.
• 36:16
  SPEAKER_00: Okay.
• 36:16
  SPEAKER_00: Or just a nod to chemistry.
• 36:18
  SPEAKER_00: Let's say that.
• 36:18
  SPEAKER_00: Let's forget about it.
• 36:20
  SPEAKER_00: Strike that out.
• 36:21
  SPEAKER_00: It's a nod to chemistry.
• 36:22
  SPEAKER_00: It's not about biology, actually.
• 36:24
  SPEAKER_00: It's chemistry.
• 36:25
  SPEAKER_00: Uh it actually is about chemistry, but biologists use it a lot because it explains actually a lot of things.
• 36:31
  SPEAKER_00: Yeah.
• 36:32
  SPEAKER_00: The polarity of the water molecule.
• 36:33
  SPEAKER_00: Yeah.
• 36:34
  SPEAKER_00: Um, one thing, Jesse, real quick, that I do.
• 36:37
  SPEAKER_00: I I'll take a blow up a balloon and I'll take like some fur and I'll create some static electricity on that balloon.
• 36:43
  SPEAKER_00: So I'll charge it, right?
• 36:45
  SPEAKER_00: And then I turn on a very small trickle but constant trickle of water out of my faucet.
• 36:51
  SPEAKER_00: And I'll put the balloon then that I just gave a charge to, and I'll put it near the trickle, and it'll bend the water dramatically.
• 36:57
  SPEAKER_01: Oh, yeah.
• 36:58
  SPEAKER_01: Yeah, yeah, yeah.
• 36:58
  SPEAKER_01: That's a good idea.
• 36:59
  SPEAKER_00: It's tracted to that charged balloon surface.
• 37:02
  SPEAKER_00: And so you can like bring it all the way around that trickle of water, and so all the students can just see it like bend really dramatically.
• 37:10
  SPEAKER_01: Yeah, yeah, yeah.
• 37:10
  SPEAKER_01: That's a good visual.
• 37:11
  SPEAKER_00: And again, it's just polarity, right?
• 37:13
  SPEAKER_00: But that that's a big time thing with what happens in arid climates with this kind of like hard-baked soil that has no moisture in it, so it's not going to pull it down.
• 37:24
  SPEAKER_01: So I I think, Chris, that that leads nicely into a non-natural or an anthropogenic effect that we're having.
• 37:31
  SPEAKER_01: And this kind of comes back full circle to our discussion about the importance of stream infiltration for society, and and something we really have to worry about is the most important thing, or one of the major important things that's at play here is that we like to build surfaces that have very low capacity for infiltration.
• 37:49
  SPEAKER_01: Anything made of concrete, anything made of asphalt, roads, parking locks, sidewalks, roofs-I mean, all of this stuff, it's like rock.
• 37:58
  SPEAKER_01: It's like pure rock, basically.
• 38:00
  SPEAKER_01: It has an infiltration capacity of next to nothing.
• 38:03
  SPEAKER_01: And so basically, all the water that hits that will run off it instead of infiltrate into the soil beneath it.
• 38:09
  SPEAKER_01: Even if the soil beneath it would have a very high natural uh infiltration capacity, the water can't get to it.
• 38:15
  SPEAKER_00: That's right.
• 38:16
  SPEAKER_00: And that's why I said that this is a really important thing because if you do, let's say, a Google Earth image of a city or anything really that has human structures on it, you can easily do then a grid search of you know what's the percentage of impervious surfaces because humans built that, like and like you said, roofs and parking lots and storm sewers and all this stuff, right?
• 38:40
  SPEAKER_00: And none of that is soaking into the ground, all of it's going, it's running off the surface, and then it's getting to rivers really, really fast.
• 38:49
  SPEAKER_00: And that's the opposite of what we want.
• 38:51
  SPEAKER_00: Again, water needs time, we're not giving it time.
• 38:55
  SPEAKER_00: And so this is one of the reasons why we're seeing dramatic rises in, let's say, 500-year flood events.
• 39:03
  SPEAKER_00: We're contributing to that because if you take, like you said with the whole beaver thing, right?
• 39:08
  SPEAKER_00: Take the beavers away, and what does it look like?
• 39:10
  SPEAKER_00: Well, take the humans away.
• 39:12
  SPEAKER_00: And what was the path of water to get to a river compared to what it is now?
• 39:17
  SPEAKER_00: I actually, uh, a number of years ago, I had some students do three three students did an independent study, and they did a one square mile area that encompassed our school, our high school, and they did the math on it, calculated all of the impervious surfaces from roofs and parking lots, driveways, roads, everything that they could count, right?
• 39:37
  SPEAKER_00: And then they compared it to what it would be like if there were no human structures there.
• 39:44
  SPEAKER_00: And then they compared the rate of flow to the rivers, how fast the water was getting there because of us.
• 39:51
  SPEAKER_00: And we used green dye dumping it onto parking lots at the same time that a cloud burst happened, you know, and watching that green dye to show up in the river, it's dramatic.
• 40:02
  SPEAKER_00: I mean, it was getting there a minimum of a thousand times faster than it otherwise would have.
• 40:06
  SPEAKER_01: Yeah, yeah.
• 40:07
  SPEAKER_01: And it's a really important thing, and there are solutions out there, you know, there's more permeable concrete types, there are ways to sort of build in natural links to the groundwater system.
• 40:18
  SPEAKER_01: So basically making little pockets of your parking lot that water can percolate through and get into the soil beneath it and then kind of recharge the groundwater that way.
• 40:29
  SPEAKER_01: So there's ways around this that that are engineering, creative engineering ways around it.
• 40:33
  SPEAKER_00: That is a very, very cool engineering practice that's going on with these permeable asphalt and concrete around parking lots and things like this.
• 40:42
  SPEAKER_00: You can do driveways with it.
• 40:43
  SPEAKER_00: Think about that a second.
• 40:45
  SPEAKER_00: You would have no puddles on your driveway at all, it just soaks right in and it soaks through really fast.
• 40:50
  SPEAKER_00: Very cool technology.
• 40:52
  SPEAKER_00: Okay, Jesse, we have one thing yet to cover with human impact on flooding.
• 40:57
  SPEAKER_01: Yeah, and that exactly really flooding.
• 40:59
  SPEAKER_01: This is a a bit of a separate thing from soil infiltration rate or soil infiltration capacity.
• 41:06
  SPEAKER_01: Um, but it impacted this event in Libya.
• 41:09
  SPEAKER_01: It's dams.
• 41:10
  SPEAKER_01: We have a tendency as humans to watch for the biggest flood event and then build a dam to hold in the biggest flood event.
• 41:18
  SPEAKER_01: And we are now in a point where we're experiencing a lot of very large flood events that are bigger than what we engineered for.
• 41:27
  SPEAKER_00: Is that safe to say, Chris, that that we are Yeah, it's it's in part because of what we just got done talking about, but absolutely.
• 41:34
  SPEAKER_00: Plus, you throw in climate change and we're getting bigger, more frequent events like this.
• 41:39
  SPEAKER_00: So absolutely.
• 41:40
  SPEAKER_00: But I have another thought too, Jesse, is that I feel like we're way more likely to build and construct an expensive dam in the first place than we are likely to maintain that structure in perpetuity.
• 41:55
  SPEAKER_01: Yeah, no, that uh I I agree completely.
• 41:58
  SPEAKER_01: I think there's a lot more, um, there's a lot more money to build new stuff than there is to fix old stuff in many, uh, in many aspects of life.
• 42:05
  SPEAKER_01: I think this happened uh in in the the flood that happened in Durma was a couple of upstream dams broke because the flood event was just so large, it overflowed the dam, broke the dam, went downstream, broke the next one, and uh and and there you go.
• 42:20
  SPEAKER_01: It makes a catastrophe, a massive catastrophe when that happens.
• 42:25
  SPEAKER_00: So, anyway, circle back to the top, Jesse.
• 42:28
  SPEAKER_00: I think Penn State needs to move this whole topic.
• 42:31
  SPEAKER_01: I forgot.
• 42:32
  SPEAKER_01: I thought you were gonna forget, Chris, but you're like an elephant over there.
• 42:36
  SPEAKER_00: I I like an elephant.
• 42:39
  SPEAKER_00: Okay.
• 42:39
  SPEAKER_00: Um, that's good.
• 42:41
  SPEAKER_00: I like that.
• 42:41
  SPEAKER_00: I just think it's really important.
• 42:43
  SPEAKER_00: I think it's something that is so relevant, uh, is the anthropogenic side to this whole thing.
• 42:48
  SPEAKER_00: I think it can't be neglected.
• 42:50
  SPEAKER_01: So I agree.
• 42:51
  SPEAKER_01: I agree.
• 42:51
  SPEAKER_01: I spend three days on talking about you know geochronology and about 15 minutes talking about stream combat.
• 42:57
  SPEAKER_01: No, I'm kidding.
• 42:58
  SPEAKER_00: You're a typical professor, aren't you?
• 43:00
  SPEAKER_00: I focus on what I like.
• 43:02
  SPEAKER_01: You're gonna sit there and listen to what I want to talk about.
• 43:05
  SPEAKER_01: That's right.
• 43:07
  SPEAKER_00: You know what though, there's a part of that that I think is so good.
• 43:11
  SPEAKER_00: The individuality that a professor can bring to the to the classroom is pretty awesome.
• 43:16
  SPEAKER_01: There is some benefit to that.
• 43:17
  SPEAKER_01: Although we do, this is the the class I teach, the the intro to geology class, um, there's three sections.
• 43:23
  SPEAKER_01: And so we have to maintain, I think it's like 80% similarity, and we usually get pretty close to maintaining that.
• 43:28
  SPEAKER_01: So because it's like got the same you know, course number, we have to be broadly similar across the sections.
• 43:33
  SPEAKER_00: So see here, I have a solution to that too.
• 43:36
  SPEAKER_00: You just have Penn State hire me, I'll teach all your intro-level geology classes.
• 43:41
  SPEAKER_00: I'm the only one that teaches it, and I can do exactly what I want then.
• 43:44
  SPEAKER_01: Man, listen, man, I've been preaching this for a long time around here.
• 43:48
  SPEAKER_01: That we just you know what?
• 43:49
  SPEAKER_01: Let's just go hire this guy.
• 43:52
  SPEAKER_01: It'd be amazing.
• 43:53
  SPEAKER_01: How fun with that, how good would that be?
• 43:55
  SPEAKER_01: And you know what?
• 43:56
  SPEAKER_01: Our students would probably get a lot more out of it.
• 43:58
  SPEAKER_00: So another shameless plug by Chris Bullhouse.
• 44:03
  SPEAKER_01: So with yeah, that's right, that's right.
• 44:04
  SPEAKER_01: Humble brag.
• 44:05
  SPEAKER_01: Um, with that, I think, Chris, that's a wrap.
• 44:08
  SPEAKER_01: I mean, great, great question, Robert.
• 44:10
  SPEAKER_01: It uh it provided, I think, a really uh I think interesting and very important discussion about kind of the upstream side.
• 44:16
  SPEAKER_01: We're moving upstream from uh streams.
• 44:18
  SPEAKER_01: We've been on the stream thing, and and now we're talking about kind of what happens before we get to a stream.
• 44:23
  SPEAKER_01: Uh it's kind of interesting, take on it.
• 44:25
  SPEAKER_01: So, hey, with that, keep sending us emails.
• 44:27
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• 44:28
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• 44:30
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• 44:32
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• 44:39
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• 44:43
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• 44:52
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• 44:56
  SPEAKER_01: That's right.
• 44:56
  SPEAKER_00: Have a good week.
• 44:57
  SPEAKER_00: Cheers.