 So we have time for questions. Please state your name. Thank you. Shafiq Samani with the World Bank. Just a couple of different questions, which is I know people have actually mapped coastal bathymetry with remote optical remote sensing data by just looking at the bands. Has that been used to I guess map rivers or potentially the bathymetry or depth? And I guess the second question is, and this is from what I've been reading, let's say our floods, which is they've actually used insular data to determine water surface elevation. And could that also be applied to streams as well just to see what that water surface elevation is? So insular has been used to measure water surface elevation. For example, in the Everglade, you can track changes in the water over time. I don't think it is visible for a river as of now because of the motion, the water surface has to be relatively... I know the answer. So I do that. You have to have emergent vegetation in order to map water surface change with NSAR because you have to have double bound scattering. And so it doesn't work in open water. So it won't work in rivers. It works in swamps where you have emergent vegetation. And regarding the bathymetry, I don't think there's been any... I'm not familiar with anything that's been widespread for river channel bathymetry with the various remote sensing products you talked about. I know ISAT-2 that's flying now, I haven't used the, it's up there. So we've got some data but there's a particular band on ISAT-2 that can penetrate water up to, I forget the depths they're talking about. But again, the challenge with that is the clarity of the water. So depending on the sediment load, you can't see through it. But if you have clear water, ISAT-2 will actually go down, I forget the number, multiple meters to potentially get some of that. But there's a lot of places it's not gonna work because of the sediment loads. Question for Burke. You didn't talk at all about possibly deducing flow phenomenon using this SkyTEM or, I think I've seen in the paradox base along the Dolores River SkyTEM study where you could see saline water discharge along the Dolores. Is there, are you optimistic about maybe mapping saline discharges near the surface? Yeah, so to clarify, SkyTEM is one flavor of airborne systems, many commercial systems out there. What we see, there's two primary controls on the electrical properties that we measure. One is geology and that's what I talk about. The other dominant one is salinity. So we've used this in the Everglades. So that was one of the earliest studies in the early 1990s to map seawater intrusion in the Everglades. And it's a dominant signal. It stands out and actually overwhelms the geological signal. You're right, in the Paradox Valley we've done the same thing, looking at saline water, same thing in the Southern Central Valley near Bakersfield, looking at saline water near some of the oil and gas fields. So those are two factors that are relatively easy to get out. I also work a lot in Alaska where we can distinguish frozen and unfrozen ground. So permafrost versus thawed ground. Causes a significant control on resistivity. One of the things that we generally don't see though is water itself, unless it's saline. We generally see the structures that may hold water but we often don't see the water itself. So I have a question for Ed. Swat elevation accuracy is plus minus 10 centimeters. I think that's a little too coarse, wouldn't you think? I mean, in a day you may have at the peak of summer evaporation 10 millimeters a day of evaporation. So 10 centimeters seems too much. Well, that's the, yeah, I mean in 10 centimeters. But that's the mission, I guess I'm talking more on the mission requirements. So they're hoping they could do better than that. But yeah, that's the reported number that we're gonna see from some of the products. And that's gonna be averaged over you know, certain areas required to make that measurement. Now the data itself is gonna be a point cloud. And so for a river, you're gonna have, it's gonna look like LiDAR data. You have all these points along the river with elevations that are again, trying to meet these mission requirements. I think once you do, and I've seen the talks, you do some spatial analysis of the measurements over reaches and the goal is to do better than that. But that again, that's more just specifying the mission requirements or something. Comedy is saying a school of minds. I had a question that didn't really come up in any of the presentations specifically, although maybe Jim, it's off the hook on this one, which is ground true thing. So how do we think about these data? And how do we know that what we're imaging from above has validity to people that are thinking at smaller scales? I mean, some of this is the resolution of the instrument and realize you can only get so small, but what do you do for your respective instruments in terms of ground truth or validation? I can go first, I guess. So relative to SWAT, so we're working on the CalVal program now for the satellite. And so what they've put together is we've got a series of three different level of calibration validation sites. So we have the best sites we're gonna have are gonna be instrumented with pressure transducers all along the sections of the river. They're gonna have all kinds of measurements made in situ during overpasses, during, there's gonna be a fast sampling phase at the beginning of the project. So there's gonna be a ton of field work along pretty long sections of unregulated river that's gonna represent our gold standard in terms of calibration validation. And then we're gonna look at sites that have USGS stream flow gauges and some additional beefing up of some of the measurements at those sites for a second tier level. And then we have down to a third tier level, which would be just more like a traditional gauge site that has levels. So again, the three different levels spread across, like it's actually planned to spread them across globally where we can do these different levels and sort of building that database now. On the geophysics side, it's a hard question because it's difficult to access the subsurface at the depths that we investigate. So boreholes are probably the best starting point. You can correlate with lithologies observed in boreholes. A number of the companies have standards that they'll go out and measure the same location and ensure that their systems measure at least the same response over a known location. At the USGS, we typically require that they do that at the beginning of the survey. They fly over a short test line where we have some ground truth data, whether that be boreholes or other ground-based geophysics, and ensure that the data sets are at least consistent with those. For the INSA data, it's actually relatively easy. We compare with GPS data, which is also remote sensing, but does require a receiver on the ground. And we can also compare with leveling surveys that are entirely ground-based. So anything that measure deformation, basically. And so for GRACE staff, they've been going, so Calval site where in places where there's no signal to make sure that you don't see signal. We have been comparing in places where they have some independent observation, being able to close the water body over the glacier. On the ice sheet, we have added independent data at the show, and we look at the spatial variability in the signal. But otherwise, we compare with ground water while observation, but again, you have to be in a place where they're measuring the same thing. So you have to have it actually zero. But I do think that we add a lot of feedback in terms of our observation to just be confident. And we try to just do it back on that with a robust error budget, when we look at it. I have a question for you, Isabella. So GRACE measures total water storage. How do you, what's the largest uncertainty in getting at the ground water component? So I guess it depends what we call ground water, if you want. So I think that how I see it, I see that we're looking, we're looking at the total water storage, and then we have added observation, and we try to see that I guess it was part of one example. How can we, we have soil moisture that represents the portion, and so that can we just figure out the way which separate the different component. We can look at some surface water. We have some area where we look at a reservoir signal. We look at, so at the end, I think that to really understand say what is like, what do we call ground water, I guess. Because ground water, so the amount of soil moisture is not just the top, that is what I call, soil moisture is like include also the root zone. To look at what is deep water is harder. You have to either use a model to say, so I guess the approach would be similar to what we did in the case of showing the GFDL model. We validate, close the water budget. We look if, when the things don't agree, and then we can use that model to look at the partition, and what is missing. We have a question from online. This is from Prabhakar Clement at University of Alabama. And it's for Jim Butler. What about scale effects of net inflow? Grace data, for example, is such a large scale. How can we interpret net inflow from it? Well, today we've learned that there may be some possibilities of working at smaller scales with grace and other data. So I think that's kind of what I was getting at. But I'll leave that to others, because I'm not an expert on the grace possibilities. Maybe I can. I think it depends. So there are like different approaches. You can try to extract the signal. So if you have an aquifer, there is, you know, and again, you're talking about net flow, but if you wanna look at the change, and then you have to account to the change the grace is again, is the total change. So we have to remove if there is, you know, like some, what is not just, you know, in the ground, but you can, you know, again, close the water budget for a specific, you know, drainage basin, and then, you know, look at other, you know, at other component to make sure to isolate that the component is as it in and out from the ground. What could I just respond? I mean, even though a comedy designated me as being off the hook, I think this issue of ground truthing is extremely important. And one of the areas that we're working with Ryan and others on is trying to get at remotely sensed pumping estimates and compare them to the ground truth of the meter data that we have. So I think that's got a lot of potential. So I just wanted to give a shout out to that work. I have a question for Ed, just from my understanding of SWAT, so you were mentioning a 10 centimeter requirement, but that's for the elevation, right? And it's gonna give you slope of the river, and that's a big part of what would be used to estimate the discharge, right? But then my question is, can you apply the calibration of SWAT from one river where you actually have discharge measurements to another one where you don't have discharge observations? I'm not sure if those are just transferable. Yeah, so again, I don't know the actual number right now. There's about six, seven, maybe eight discharge algorithms that are using these measurements of width, so river width, the elevation and the slope, and change in elevation to get change in area, and so all of them are doing something to estimate some missing bathymetry, and then doing something for roughness, and roughness may be static, roughness may change with discharge or water surface elevation and discharge rate, and so the product for discharge doesn't have a mission requirement in terms of accuracy. It's gonna be tough to estimate, but because there's so many different discharge algorithms, what we're seeing, obviously, some work better in certain types of rivers than others in terms of how they're trying to estimate these missing quantities. So there's not gonna be a discharge product per se that comes out that's one number. It's gonna be all of the algorithms and the values that they get for the missing bathymetry and the roughness that you could plug into something like a Manning's equation and have discharge, so for each river, you're actually gonna get a whole bunch of discharges for each of the different methods that come from that, and so the studies are really ongoing right now to try to quantify which approaches work better for which types of hydrodynamic situation in terms of the braided rivers are a real challenge. Some rivers have backwater effects, some don't have backwater effects, and so trying to map out all of the various scenarios is something that's getting worked on now, and then again, testing the algorithms in all these different situations to see if we can say one works better than other or just use them all to sort of lock in on uncertainty. Okay, I think we'll stop here and go to the panel session. I'm sorry, can I ask you a question?