 I understand one of the things that gets done after there's been a major hurricane event is to go out and try to create some sort of record of the water depths and the water surface that represents the flow from storm surge and flooding of rivers and so on. And I was wondering if you could explain to me a little bit how that data gets collected, what kind of turnaround time there is involved in doing that and what kind of logistically what it takes to go out and collect all that perishable data and put it together into some kind of comprehensive results. Well it's interesting you said perishable data because that's exactly what we call it and so it's important that we get out relatively quickly in the first week certainly to be able to start to collect that data before people begin to disturb the affected area. So particularly like when waterline data there's a distinct pattern between the way debris is spread by wind and by water so that's usually used by building science people. Well I'm not a building science expert but my understanding is that generally flooding base, flooding debris is is usually sort of collected in sort of these lines if I if I understand it correctly and wind tends to be more uniformly scattered over the area so usually building science experts are able to pretty accurately discern where that is. So could you look at things like where there's mud and absolutely there's a whole bunch of indicators that are large stands of trees might have all fallen in a particular direction or correct indicate wind rather than water right along those lines. So why is that data considered perishable? Well usually you know following a disaster people are interested in you know getting getting things squared away again so they begin to clean up and those clues that you just described and I talked about briefly are begin to be disturbed by people cleaning up so that's why it's perishable. On the high watermark side there typically are sort of like mud lines or there's a there's sort of this you know sort of like a pool that had drained slowly you can see where that waterline was and it becomes more and more difficult to find those those clear lines as time goes on. So you typically try to get out there in the first week to be able to find those points and mark them and what they do is they go out and flag them they spray paint on on a building on a structure something that's not going to move where that wind waterline is make a note of it and then the survey crew comes back and actually gets an accurate elevation of that of that high watermark point. Correct. The flaggers get a rough lat long sort of you know handheld GPS and then the surveyors come back and get more accurate you know elevation as well as XY data. So I'm do you typically have these are people going out in the field to do the flagging? Yes. Are they engineers are they technicians? It's it's a little of both typically for safety purposes we have two individuals go out so there's usually one more experienced person one more junior person that would go out and there's you know photo documentation and so forth that goes along with that. How are they recording data? Well we've built a whole sort of tool suite to collect data along from sort of cradle to grave on the high watermark stuff first side of it is the planning aspect you don't want to have points at too high a density or or or not enough density so there's a planning exercise to sort of make sure that you've got a good distribution of these high watermark points flagged. Once that happens then they come back into the centralized database and our QC and if they're considered appropriate and reasonable quality then they go to our survey crews which we have you know multiple crews throughout the area we dole those out and and the surveyors actually go out and collect the more detailed information. So you described employing people and planning and deciding where to send people and how many people to send and the density of points that you need to have collected. How do you very quick and you need to send people out almost immediately after the storm has passed how do you know the extent of damage at that point kind of information do you get that tells you roughly what total area you need to cover and where what areas are most affected. Well in the you know in historically it's been it's been really a sort of you know visual inspection kind of process you know I'm at such and such a town and this town is is not damaged or significantly damaged those sorts of things and that's where remote sensing can imagery can really help us post-event imagery to allow us to deploy people more effectively and to put them in the places that they really need to be. So you would need it quite quickly. Correct. A day or two after the event but it would not necessarily have to be incredibly accurate in terms of its geo referencing. That's correct. You need to just sort of get an overall big picture and be able to identify towns and roads and things that you can use in planning. Correct. You don't have to have actual really accurate coordinates off the imagery. Yeah and the team leaders you know essentially will tell a particular team I want you to go to this town or I want you to go to this quadrant of the town they won't tell them to go to a particular structure etc. It's up to the flaggers to identify a high watermark that they think is is is really clear and that they can get it you know collect well. So roughly geo reference image produced very quickly within one or two days after the event would be really helpful. It's very helpful for the planning. Absolutely. Now once the information is collected you have a lot of people out in the field collecting data, collecting elevations, collecting all these survey points and that you're going to use to eventually map a water surface. Is there some quality control process? How do you know if you have a thousand of these individual points that were collected? Is there a way to identify a bad point? Well there is. I mean obviously if there you know if there's large discontinuities between neighboring points that's a that's a pretty strong indicator. But generally from the quality standpoint it gets to looking at the photos that were collected by the flaggers to get a sense of you know how how well do we think this how well defined do we think this point is. And then once you have those points you sort of end up with this very blurry picture as a way I kind of think of it at the beginning of the process and it gets increasingly clear through time. And that you know the topographic information is valuable because if you can use the offset from the ground surface to the to the flag location even just you know rough flag information you can begin to start to see that water the eventual water surface elevation that will come from a high-water mark survey. And you can then you know the surveyors you can then overlay that data as that becomes available. So it's you know the goal is not to wait until all the every point in the data set is complete before you start to evaluate the next step. You want to sort of see these things and increase in clarity through the process. So I heard you say that some roughly geo-referenced imagery turned around very quickly would be helpful in terms of planning deploying mobilizing getting a getting everyone out in the field to collecting data. Once the point data comes back in if we had a more accurately geo-referenced image at that point we could compare the location of the point and what we can see on the aerial photo to the ground photos that were taken and make sure that the ground photo in the point is really located in place it's supposed to be. Yeah I think it's another it's another point that helps you kind of from the QC standpoint it makes sure that you've got what you think you have you know it's easy in the field to make those sort of disconnects between images and and textual records that you collect in the field. And I'm wondering about the topographic data for measuring the height of water above the ground surface that having a terrain model that represented the ground surface a fairly accurate terrain model to add that water depth on top. Yeah well that and that's very valuable in in the in the pre-survey portion of the project because you have you have no survey data you're only collecting relative elevations essentially from a flagger's perspective. So to have topographic data that you can you know Barrett data that you can use the the elevation that was observed by the flagger is an offset then you've got you do have that water surface elevation you're kind of mimicking what the surveyors will ultimately give you. And once we come up with this water surface that's been a three-dimensional water surface that represents the extent and the depth of flooding how is that used? Well it's used for you know a variety of reasons. A couple of them are one to be used to validate models storm surge models and things like that ad-sirc and surge models like that. And also to look at the effectiveness of floodplain maps as they go through and and reevaluate those maps they may use that data to to validate whether they're accurate or not. To be comparing a real storm to a theoretical storm that's represented on a flood map. That's right. Tell someone whether or not that flood map really needs to be updated. That's right, that's right. There's another application I understand that has to do with we talked about it early on delineating the difference between wind damage and water damage. Why is that important? Well I'm not an expert in this either but from my understanding of where that gets used and it's been a pretty it's been a pretty visibly publicly visible problem is insurance companies insurance companies flood damage will pay for flood damage not for damage caused by winds. There's a there's a big push to understand where that wind water line is and what structures are affected by flooding and which ones are affected by wind. So my homeowner's insurance would pay for wind damage to my house. Flood insurance. That's my understanding, yes. So knowing where the line is between water damage and wind damage is an important part of the storm insurance claims settlement that sort of thing. Correct. How is that currently done? Is that also you mentioned in our earlier our conversation that as people go out in the field they're looking for clues the debris field direction of trees falling certain kinds of damage to structures. It's been typically the wind water delineation is done by sending people out in the field to make observation. Yes absolutely and historically I know in some storms they've even sent individuals on like helicopters where they're able to to see that pattern from the air which is exactly remote sensing can help you keep you off helicopters but to be able to start to roughly put that line in so that when you get individuals out out on the ground you're able to target those folks to the right locations. So if we were able to as geospatial professionals or remote sensing experts again provide that kind of accurately geo-referenced imagery then a lot of this wind water delineation might be able to be done in the office rather than in the field. Certainly for the planning aspects of it and to put people in the right location yeah it could be done in the office or be done even in a distributed environment where you may have more senior individuals that may not be geographically even in in the location of the affected area could actually provide assistance in targeting people on the ground and making sure that you know we're using those resources effectively because it's very costly to have people there. Right and then the people that are sent to the field could be in a sense more validating the remote sensing result rather than picking up being the only source of data. Right. It would be more of a ground-truthing and it could be done maybe you know a small percentage of points would need to be collected to validate the remote sensing results rather than trying to gather all the data. Yeah I could certainly see an instance where over time you know as sort of people began to train their eye if you will using remote sensed imagery to be able to identify those lines you could maybe begin to start to sample if you will on the ground and be very efficient in doing that. Does the windwater delineation often follow topographic features? I'm imagining that you know flooding would follow topography therefore having not only an aerial image but also some kind of three-dimensional topographic data to combine with it might give some clues as to where the delineation is between wind and water damage. It's certainly a strong indicator but you know there's there's a lot of processes involved with wave run-up and all those sorts of things coastal engineering type processes that are way too difficult to try to model with simple topography but yeah it is it's a strong indicator. So I'm getting the sense that the remote sensing could be a really valuable support tool in planning, in validating field results, and in also making some sort of large-scale depictions of the record of the storm that could really enhance a lot of the traditional field survey techniques. Oh absolutely I mean you could use it through the entire disaster life cycle and you know certainly in the in the response phase that we've been primarily talking about but also in preparedness and mitigation and so forth. So yeah it's it can be used in many many locations many places throughout that cycle. Well this has been really helpful and I think based on our conversation I could potentially put together some technical specifications for remote sensing imagery that we could kind of have ready at hand in an emergency response situation. Okay thanks for your time. All right thank you.