Application of Multispectral Imagery to Assessment of a Hydrodynamic Simulation of an Effluent Stream Entering the Clinch River

Home , Clinch River

Alfred J. Garrett, John M. Iwine, Amy D. Klng, Thomas K. Evers, Daniel A. Levlne, Clell Ford, and John L. Smyre

Abstract The ORR consists of 140 km2 of Federal land located in Oak This study investigates the feasibility of using remote sensing Ridge, Tennessee. Three DOE facilities are located on the Om: systems to estimate and model contaminant transport at known the Oak Ridge National Laboratory (ORNL), the Y-12 Center for hazardous waste sites. We used airborne (Daedalus) imagery Manufacturing, and the Former Gaseous Diffusion Site (K-25 and 3D hydrodynamic simulations to estimate the flow rate of Site]. These facilities were established as part of the Manhattan Poplar Creek as it enters the Clinch River, located on the U.S. Project in the 1940s. Scientific experiments conducted in sup- Department of Energy (DOE)Oak Ridge Reservation (ORR)in port of the Manhattan Project, and Atomic Energy Commission Tennessee. The collection of ground-truth data and the simu- and DOE activities since the Manhattan Project, led to the cre- lations were complicated by the variability of the Clinch River ation of hundreds of individual hazardous waste areas. flow, which we attempted to reproduce in the simulations. The Oak Ridge Environmental Management Program (EM) Comparisons of the Daedalus imagery to images created from was established in 1989 to conduct cleanup activities at the the simulations led to the conclusion that the Clinch River/ ORR. A comprehensive understanding of the location, content, Poplar Creek system shifts back and forth between three distinct and environmental characteristics of a waste area is required flow regimes that have different pollutant transport patterns. before a cleanup alternative can be chosen. Remedial investiga- Results of this research suggest that remote-sensing data com- tions and feasibility studies required by the Comprehensive bined with high-resolution numerical modeling and limited Emergency Response, Compensation, and Liability Act (CER- surface measurements might be able to define pollutant CLA) are conducted to determine the appropriate cleanup strat- transport in large bodies of water as well as methods that rely egy for each group of waste areas. only on more extensive suqace measurements. The Clinch River forms the southern and western boundaries of the ORR. The area of the Clinch River studied is downstream of most of the ORR. Poplar Creek, which flows directly lntroductlon through the reservation, empties into the CIinch River near the Project Descrlptlon K-25 Site. In this region, the Clinch River is about 150 m wide This project used airborne (Daedalus)imagery, color photogra- with typical depths of 8 to 10 m along the channel. The study phy, and surface measurements to analyze and model aqueous area also includes two Tennessee Valley Authority (TVA) reser- mixing and sediment transport as Poplar Creek enters the voirs, Melton Hill Lake and Watts Bar Lake. The Clinch River/ Clinch River, located on the U.S. Department of Energy (DOE) Poplar Creek confluence is part of the upper end of Watts Bar Oak Ridge Reservation (ORR) in Tennessee. Analysis and model- Lake. Upstream from the Clinch RiverIPoplar Creek confluence ing of the aqueous mixing process are based on the turbidity is Melton Hill Dam, which controls the flow rates and level of the and thermal differences between the ambient river conditions Clinch River near the ORR (MMES, 1995; SAIC, 1996). and surface water entering the river. Because the Clinch River Surface and groundwater drain from the ORR through a net- is the major integrator of all surface and groundwater contami- work of small tributaries of the Clinch River. Poplar Creek is nation from the ORR, investigators require the delineation of the primary Clinch River sub-basin that drains the area near the inflow mixing zones (spatial extent and temporal variations) in K-25 site. Poplar Creek flows for 8.9 km through the K-25 site order to develop efficient sampling plans to monitor actual con- and empties into the Clinch River 18.1 km downstream of Mel- taminant levels prior to restoration and long-term monitoring. ton Hill Dam. Poplar Creek is about 50 m wide, with water depths ranging up to 7 m. Plate 1is a natural color orthophoto- graphic mosaic which shows the Clinch River/Poplar Creek confluence and the close proximity of Poplar Creek to K-25 facil- A.J. Garrett is with the Savannah River Technology Center, ities. The white area in the Clinch River downstream from the Westinghouse Savannah River Company, Building 773-A, ([email protected]). Poplar Creek plume is sunglint. The flow rate in Poplar Creek Office A-1000, Aiken, SC 29808 was high and the water was very muddy when the color photo- J.M. hine is with Science Applications International Corpora- graphs in Plate 1 were taken. This produced a large, well- tion, 4001 North Fairfax Drive, Suite 725, Arlington, VA 22203. The remaining authors are with the Oak Ridge National Labora- tory, Lockheed Martin Energy Research Corporation, Oak Ridge, TN 37831. D.A. Levine is currently with the International Technology Photogrammetric Engineering & Remote Sensing Corporation, 312 Directors Drive, Knoxville, TN 37923-4799. Vol. 66, NO. 3, March 2000, pp. 329-335. C. Ford is currently with the Highlands Soil And Water Conser- 0099-1112/00/6603-329$3.00/0 vation District, USDAA Natural Resources Conservation Ser- 0 2000 American Society for Photogrammetry vices, 4505 George Blvd., Sebring, FL 33782-5837. and Remote Sensing

PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING March 2000 329 Winter discharge at Melton Hill Dam is typically 9500 cfs (270 m3/s),but is up to 19,500 cfs (550 m3/s)for short periods with intervening periods of zero discharge. A representative plot of stage data (water surface elevation) located near the mouth of Poplar Creek is shown in Plate 2. The figure shows sharp increases and decreases in Poplar Creek stage (with a lag of several hours) when the Melton Hill discharge is turned on and off (SAIC, 1996).

Previous Research Many researchers have combined remote sensing data, numerical modeling, and in situ measurements to understand the pro- cesses that control transport of pollutants and natural constituents of different surface water systems. Jensen et al. (1989) compared Landsat Thematic Mapper (TM)imagery to modeled salinity and suspended sediment distributions in a large lagoon adjacent to the Bay of Campeche. Their model solved the two-dimensional shallow water equations and mass conservation equations for salinity and Total Suspended Solids (TSS). Jensen et al. (1989) found that an atmospherically cor- rected chromaticity transformation of the TM data accounted for 79 percent of the modeled TSS variance. Nichol(1993) used Plate 1. Natural color ortho-photographic mosaic of the con- TM imagery (the 0.45- to 0.52-pm waveband combined with the fluence of Poplar Creek and the Clinch River. Buildings on 0.63- to 0.69-~mwaveband) to distinguish river plumes with the right are part of K-25. Note the mixing of the muddy high dissolved organic matter from adjacent oceanic waters off- Poplar Creek plume into the clear Clinch River. shore from Southeast Asia. Nichol found that the same river plumes could be identified in the 10.5-to 12.5-pm thermal TM waveband. Nichol used these results to derive imagery-based classes of water quality, which can be related to environmental standards for water use. Roberts et al. (1995) showed that defined turbidity plume in the Clinch River that stayed visible multispectral video imagery and statistical modeling could be further downstream than normal. used to determine TSS concentrations in lakes within Canada's In addition to the transport from the K-25 area, the east fork Mackenzie Delta. Jardine et al. (1993)also used a shallow-water of Poplar Creek carries run-off from the eastern, western, and model to help them interpret Advanced Very High Resolution northern portions of the Y-12 facility. The presence of known Radiometry (AVHRR) thermal imagery of oceanic fronts, upwell- hazardous waste concerns at the Y-12 and K-25 sites raises the ings, large eddies, and jets in the coastal regions offshore from possibility that Poplar Creek could carry contaminants into the northern British Columbia. Jardine et al. (1993) simulated tidal Clinch River (MMES, 1995; SAIC, 1996),which is why it was currents with the numerical model, which helped them to iden- selected for this research. tify the fronts, eddies, and other circulatory features in the Daily fluctuations of the Clinch River water level are AVHRR imagery. Miller and Cruise (1995) used a hydrologic caused by the generation of hydroelectric power at Melton Hill model to simulate runoff and sediment transport from a drain- Dam and alter the natural flow of Poplar Creek. age basin in Puerto Rico to coastal waters that contain coral reefs. They calibrated their model with spatial maps of sus- r pended sediment concentrations derived from Calibrated Air- borne Multispectral Scanner (CAMS) imagery. Miller and Cruise 224.65 (1995) found a highly significant negative correlation between 224.6 the modeled sediment transport and annual growth rates for the coral. Malm and Jonsson (1993) found that a simple energy 224.55 conservation model could be used to model the progression of 400 a thermal bar in Russia's Lake Ladoga, based on AVHRR imagery. 224.5 Finally, Zheng et al. (1993)derived estimates of total mass flow B 224.45 in and out of Delaware Bay and mean tidal velocity at the E 300 t t mouth of the Bay using space shuttle time-series photographs. C 224.4 s e 200 Data Collection 8 m.st This research combined ground-truth data derived from in situ sensors with remote-sensing data to drive hydrodynamic 100 224.9 model simulations of the transport of thermal energy and sus- 224.25 pended sediment via surface water. The primary ground-truth 0 parameters included both surface and sub-surface water mea- 224.2 surements of temperature, turbidity, and pH. The remote-sens-

-100 224.15 ing data consisted of natural color aerial photography and 0 2 4 6 8 101214161820222426289002048880404244404080 Daedalus multispectral and thermal imagery. Hour Ground-Truth Data Plate 2. Data illustrating relationship between Clinch River Ground-truth data collections near the confluence of Poplar flow and Poplar Creek stage (elevation).Opening and closing Creek with the Clinch River included a set of shoreline-based of Melton Hill Dam determines Clinch River flow. instruments and buoy-mounted sensors on the creek. The ground-truth study was designed to measure surface water

330 March 2000 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING temperatures in Poplar Creek for the calibration of remote-sensing data. Vertical and horizontal profiles of turbidity and temperature were used for initial and boundary conditions and to evaluate the hydrodynamic model. All ground-truth equipment was calibrated both prior to and after each field study to ensure data quality. Vertical profiles of temperature and turbidity were acquired in four distinct regions in the mixing zone: upstream Poplar Creek, Clinch River upstream from the Poplar Creek confluence, in the Poplar CreekIClinch River mixing zone, and Clinch River downstream from the Poplar Creek confluence. Data from the vertical profile transect in upstream Poplar Creek indicate similar trends of temperature and turbidity at each site, with temperature decreasing and turbidity increas- ing with depth (Figure 1).The turbidity profile in Figure 1is in Nephometric Turbidity Units (NTU)which are a relative measure of turbidity. Data for the upstream Clinch River transects show no variability in temperature with depth either within a given site, or between sites. The same can be said for turbidity values at the upstream Clinch River sites. As with temperature, there appears to be a turbidity signature in the Clinch River from Poplar Creek, one that is evident at the surface. A Hydrolab Surveyor 3 multi-parameter probe collected water quality data to supplement the vertical profile measurements. The Hydrolab unit consists of a submersible probe and data logger that records temperature, pH, dissolved oxygen, Plate 3. Temperatures mea- specific conductance, oxidation reduction potential, and tur- sured by Hydrolab submersible bidity. A field survey was conducted on 02 April 1996 with the probe on 02 April 1996. Temper- Hydrolab to obtain horizontal profile measurements. The pur- atures ranged from 10.2"C pose of this study was to observe, track, and measure the Pop- (blue)to 11.2"C (red). lar Creek turbiditylthermal plume as it entered and mixed with the Clinch River. A boat equipped with the Hydrolab unit and GPS equipment traversed the main channel of Poplar Creek and the mixing zone in the Clinch River. Temperatures measured by the Hydrolab are plotted in Plate 3. The temperatures sam- one-half the width of the Clinch River. The different conditions pled ranged only from about 10.2"C (blue) to 11.2"C (red). within and outside the plume were most evident in the temper- Changing flow conditions were observed during collection of ature and pH data. Flow in the Clinch River increased signifi- horizontal profiles with the Hydrolab. As the boat entered the cantly during data acquisition. The increased flow visibly Clinch River from Poplar Creek, there was a visible surface pushed the Poplar Creek plume against the right downstream plume from Poplar Creek extending between one-third and bank of the Clinch River. The warmer water in Poplar Creek and along the downstream bank of the Clinch River is apparent in Plate 3. The effects of changing flow conditions during the data collection are also apparent in Plate 3, i.e., different tracks Tmperatum CC) crossing the same area at different times show different 10.5 11 11.5 12 12.5 13 temperatures. 1 @. Although very useful as ground-truth data, the Hydrolab data are not easy to interpret because they combine temporal and spatial variability and they cover only a small part of the total surface area. In contrast, the remote-sensing data presented 0.5

8- fi -I- T "---"--'- d II

'2 I 5 LO 15 10 I Turbldlty (NW)

-9-- lur#dHy + tmpmlun Plate 4. Output from numerical simulation showing three Figure 1. Typical plot of Poplar Creek Hydrolab data, showing temperature and turbidity profiles. Nephlo- metric Turbidity Units (NTu) are relative measures LL-distinct flow regimes for pollutant transport in the Clinch of turbidity. River/Poplar Creek system.

PHOTOGRAMM€rRIC ENGINEERING 81 REMOTE SENSING March 2000 331 in the following sections give a much more complete and coher- then raises the stage level to an intermediate level. The stabili- ent picture of the Poplar Creek turbiditylthermal plume as it zation at a slightly lower level is apparently caused by a second, enters and mixes with the Clinch River. smaller flow overshoot back into Poplar Creek (damped oscilla- tion). Similar flow reversals are not apparent in Plate 2 after dam Remotely Sensed Imagery openings, apparently because the initial high flow of 550 m3/s Daedalus and other imagery provide a basis for comparison to is rapidly followed by a decrease to 270 m3/s in most cases. the simulations discussed in the next section of this paper. Given the variability and uncertainty of the flow in the Overflights with the EG&G Daedalus 1268 multispectral scan- Clinch River downstream from Melton Hill Dam, it was neces- ner were conducted in 1992 and 1994. The thermal channels sary to investigate the behavior of plumes under different flow on the Daedalus sensors collect in the long-wave region, indi- conditions. Bathymetry data provided by ORNL was used to set cating differences in temperature between the ambient river up a computational grid that covered the lower end of Poplar conditions and the plume resulting from the inflow of Poplar Creek and nearby parts of the Clinch River. The bathymetry Creek. This research also used the visible channels, because data have a horizontal resolution of 5 m, which was retained in they showed the contrast between more turbid (muddy) water the 276- by 220-node grid. The vertical resolution of the of Poplar Creek and the clearer Clinch River. bathymetry data is 0.3 m, but because the river is as deep as 11 m, a 0.9-m vertical resolution was used in the grid to keep the number of vertical levels in the model computationally reason- Modeling of Thermal and Turbidity Plumes able. A three-hour simulation with the code started with zero For the purposes of this research, a plume is defined to be a flow in the Clinch River and a 30 m3/s flow in Poplar Creek. region within a body of water that has measurably different After one and one-half hours, the flow in the Clinch River was surface characteristics (temperature andlor particulate concen- increased instantaneously to 350 m3/sto simulate the opening tration) from the rest of that body of water. In most cases, of Melton Hill Dam. The Poplar Creek flow was set 5OC warmer plumes are created when a stream or river empties into a larger than the Clinch River, and the Creek turbidity level (particulate body of water, such as a larger river, bay, or ocean. concentration) was set to 0.01-cm3particles/cm3 water. The simulation described above was performed to gain a Code Description better understanding of the effect of opening Melton Hill Dam A 3D hydrodynamic code (Garrett, 1995; Garrett and Hayes, on the behavior of the Clinch River near the mouth of Poplar 1997)was used to simulate the mixing and dispersal of thermal Creek. The simulation used representative values of Clinch and turbidity plumes entering the Clinch River from Poplar River and Poplar Creek flows, but did not attempt to reproduce Creek. This finite-difference code solves the time dependent, any specific set of observed conditions. The simulation hydrostatic forms of the conservation equations for momen- showed that there are three distinct flow regimes for pollutant tum, the incompressible version of the mass conservation transport in the Clinch RiverIPoplar Creek system (Plate 4). equation, and the standard advection-diffusion form of the When the Clinch River flow is very low, the warmer (red),more energy conservation equation for a turbulent fluid. This code turbid water from Poplar Creek flows over the colder Clinch also simulates the transport, diffusion, and deposition of small River (purple) and pools. Buoyancy forces cause spreading of particles in the water. It was assumed for this research that the the warm water both upstream and downstream (first frame of particle concentrations would be low and not significantly Plate 4). This pooling phase is a slow transient because the area affect the fluid density and the flow field. Only one particle covered by the warmer, more turbid water slowly increases size class (one micrometer) was modeled for this exploratory with time: research. Particle settling velocity was set equal to zero Plate 5 is a Daedalus thermal image (8.5 to 13.5 microme- because the ground-truth data collection did not include mea- ters) of the slow transient that shows pooling of warmer water surements of particle size distributions and other characteris- in the Clinch River near the mouth of Poplar Creek. The Daeda- tics such as reflectivity and density. Ziegler and Nesbit (1995) lus image was taken at approximately 0548 local time on 15 found that a large fraction of the particles in Watts Bar Lake are April 1992 and thus was a pre-dawn image. The water in Poplar small, with settling velocities of about 0.1 millimeters per sec- Creek was approximately 14°C and the Clinch River water was ond. So it appears that a settling velocity of zero is a reasonable about 10°C. Note that the warm water spread upstream as well approximation for the short travel times and distances of this as downstream in a pattern similar to that shown in the simula- research. Only qualitative comparisons were made between tion. The warm water did not spread as far in the simulation simulated and observed turbidity plumes. because only 1.5 hours of spreading were simulated before Melton Hill Dam was opened, whereas in reality the slow tran- Simulated and Observed Turbidity Plumes sient had been going on for about seven hours before the image The Tennessee Valley Authority (TVA) controls the flow in the in Plate 5 was taken. A seven-hour simulation (not shown) with Clinch River at the Melton Hill Dam 18 km upstream hom the the same 4°C gradient between Poplar Creek and the Clinch mouth of Poplar Creek. Under normal conditions, when there is River did produce an area of warm water that was closer to the no excess water to drain, the TVA releases water twice a day for warm pool area of Plate 5. However, there appears to be little power generation. Release rates are typically about 270 and 550 opportunity to derive quantitative flow information from the m3/s. Referring back to Plate 2, the Clinch River stage elevation slow transient. A small amount of residual flow was appar- at the mouth of Poplar Creek increases several hours after the ently responsible for the asymmetry in the pooling of warmer Melton Hill Dam is opened. When the Dam is closed again, water above and below the mouth of Poplar Creek in Plate 5. Plate 2 shows there is a lag of several hours before the stage ele- There is no way to determine the size of the residual flow, vation at Poplar Creek starts to drop. The stage drops sharply, because it was probably a combination of small streams and rebounds partially to a higher level, and then stabilizes at a groundwater inflow into the Clinch River. slightly lower level (see hours 14 to 20 and 38 to 44). The stage Although the temperature and turbidity distributions behavior is interpreted in the following way: the Clinch River caused by the slow transient probably cannot be accurately water level drops, and when that decrease in level reaches Pop- simulated, identification of the slow transient through analysis lar Creek, the Creek outflow accelerates and the momentum of imagery and hydrodynamic simulations is an important step builds up to the point that the outflow shoots past the equilib- in understanding pollutant transport in the Clinch River. It is rium point. That is when the minimum in the stage at the mouth important because, during the slow transient, pollutants from of Poplar Creek is observed. Reverse flow into Poplar Creek Poplar Creek are carried upstream as well as downstream in the

332 March 2000 PHOTOGRAMMmRIC ENGINEERING & REMOTE SENSING Clinch River. If the pollutants include particles that settle tional to the flow coming out of the source, in this case Poplar within a few hours, the slow transient would cause deposition Creek. The observed Poplar Creek flow rate was 4.0 m**3/s at of those contaminants in the bed of the river upstream fromthe the time the image in Plate 6 was taken. The other free variable mouth of Poplar Creek. This insight probably would not have is the flow in the Clinch River, which has some uncertainty due been gained if only ground-truth data had been available for to the frequent opening and closing of Melton Hill Dam. analysis. After some experimentation, it appears that the best indi- The slow transient terminates when Melton Hill Dam cator of Poplar Creek flow is an integral quantity defined by the opens and the Clinch River current rapidly increases to veloci- excess thermal energy of the Poplar Creek water relative to the ties of around 0.5 mls. River elevation increases by about 0.25 cooler Clinch River water. This is not truly a conservative m, and there is a temporary flow reversal back into Poplar quantity, because heat is lost to the atmosphere, but over short Creek (see second frame of Plate 4). This phase is termed the fast time periods the excess thermal energy of the Poplar Creek transient, and is characterized by rapidly changing flow field, plume should be nearly conserved as it is carried downstream turbidity, and temperature distributions. The surface wave, cre- and mixes with the Clinch River. The excess thermal energy ated by opening the dam, travels at a rate of several meters per (ETE)is defined as second downstream, enters Poplar Creek, and reflects at the upper end. This simulated reflection is not completely realis- tic, because the computational domain ends not far from the mouth of Poplar Creek. However, ORNL personnel have observed flow reversals in Poplar Creek (see discussion of Plate 2). In this equation pis the density of water, cpis the specific heat of Because the fast transient is brief, no images of that flow regime water, Ax and Ay are pixel dimensions, Az is an arbitrary con- were collected. The simulation produced multiple-wave reflec- stant water depth, 'I;. is the water temperature at a given pixel tions in the Clinch RiverIPoplar Creek system that decreased location, and To is the ambient water temperature unaffected by in amplitude with time, ultimately leading to a true steady-state the plume. Figure 2 is a plot of the Ems derived from simula- flow regime. The steady-state flow regime is shown in the third tions of Poplar Creek that used 2,4, and lom* * 31s flow rates for frame of Plate 4. Poplar Creek, compared to the range of possible values for the Plate 6 compares an observed example of the steady-state observed Em. The uncertainty of the ETE is partly due to the regime (Plates 6a and 6b) with the corresponding simulated uncertainty in the value of the ambient Clinch River tempera- image (Plate 6c). The observed Daedalus image was taken at ture, which although fairly uniform was not constant. There approximately 1440 local time on 22 March 1994. Water flow- was also some uncertainty about the boundaries of the river, so ing out of Poplar Creek is often warmer and visibly more turbid some land pixels were probably included in at least some of the than the water in the Clinch River, as seen in this image, Plate Em calculations. The Em values from the simulations increase 6a shows the turbidity plume (Daedalus channel 4,0.50 to 0.55 steadily with the flow rate, and the computed ETE for 4 m**3/s pm) and Plate 6b shows the thermal plume (Daedalus channel falls within the uncertainty range. Figure 2 shows that uncer- 12,8.5to 13.5 pm). Plates 6a and 6b show that the turbidity and tainty in the computed Em implies a large uncertainty in the thermal plumes overlap nearly exactly. This is not surprising, Poplar Creek flow. This uncertainty in predicted Poplar Creek because the warmth and turbidity of Poplar Creek waters are flow ranges from 3.5 to about 9.0 mX*3/s.It may be possible to essentially conservative properties over short travel distances. reduce the uncertainty of these flow estimates with a larger data- The plume in Plate 6 is typical of those observed when there is base of imagery and ground truth. This would allow a site-spe- a strong current in the Clinch River. Under those flow condi- cific correlation to be developed that relates measured flow rates tions, the Poplar Creek plume is pressed against the bank and to ETEs derived from thermal imagery. mixes with the much larger volume Clinch River flow until it is no longer visible at the bend in the river more than a kilome- Simulated and Observed Temperature Profiles ter downstream. The discussion in the previous section compared visible and The thermal image (Plate 6b) was calibrated in degrees Cel- thermal imagery to simulations. As noted in the Data Collec- sius, whereas the turbidity plume (Plate 6a) was not calibrated tion section, project scientists also took temperature and tur- because the ground-truth data were taken in Nephalometric bidity profiles in Poplar Creek and the Clinch River. This Turbidity Units (NTU),which are relative measures of turbidity. The temperatures in Plates 6b and 6c range from about 9.7% in the Clinch River upstream from Poplar Creek (black area) to 3 about 12°C in Poplar Creek (red). It can be seen that the simulated plume is broader but not as warm as the real plume and 2.6 - has a smooth boundary, whereas the real plume has a jagged A boundary defined by the locations of numerous turbulent r " 2- eddies. Part of this difference in appearance can be attributed to ~ofuro~ the smoothing caused by numerical diffusion and the time and in ob-~gd m space averaging that always occurs as a result of approximating 1 1.5- a body of water with a finite set of discrete nodes. In contrast, the image of the real plume was created almost instantaneously, I 1- .- so there is very little time and space averaging in it. If several g images like Plate 6b were taken over a period of time that was 0.6 - long relative to the travel time of the turbulent eddies and aver- aged, the result would look much more like Plate 6c. 07 One of the objectives of this project is to determine what 1294587891011 quantitative pollutant transport information can be derived Flar Raw (In%) from remote-sensing data. The steady-state flow phase is probably the only phase in which it is possible to derive flow and Figure 2. Computed and observed Excess Thermal Energies transport information from analyses of individual images, such (ETE) of Poplar Creek thermal plume relative to Clinch River as the one shown in Plate 6. The basic assumption is that the for 22 March 1994 Daedalus image. size of the turbidity or thermal plume will somehow be propor-

PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING March 2000 333 0.0

Statbn 9 observed

-0- Station 9 simulated + StationlOobsenred + Station 10 simulated

9.5 10.0 10.5 11.0 11.5 120 TEMPERATURE ("C) Plate 5. Thermal image of warmer (14°C) water from Poplar Creek pooling in the Figure 3. Observed and computed tempera- cooler (10°C) Clinch River during a period ture profiles in Poplar Creek and Clinch River. when the current was very weak because Station 9 was in mouth of Poplar Creek and Melton Hill Dam was closed. Note that Station 10 was 1km downstream in Clinch warm water spread upstream and down- River. stream. This image is an example of the slow transient shown in Plate 4. simulated and observed temperature profiles taken near the mouth of Poplar Creek (Station 9) and about one kilometer downstream from the mouth (Station 10). The simulated pro- information can be used to validate the model in the vertical files shown in Figure 3 were taken from a four-hour simulation dimension. Because particulate concentrations and sizes were ending at 1230 local time on 26 March 1996, which is about the not measured along with turbidity, there is not enough informa- time ORNL took the vertical profiles data at the different tran- tion available to model and reproduce the turbidity profiles. sect locations. The numerical simulation used a Clinch River Simulation of the temperature distribution was fairly straight- flow of 275 m3/sbased on data taken at Melton Hill Dam and a forward, because the temperature of the Clinch River upstream Poplar Creek flow of 12.7 m3/sbased on stream stage measure- from Poplar Creek was measured, as was the temperature of ments. The Clinch River flow may have decreased during mea- Poplar Creek well upstream from its mouth. Figure 3 shows surement of the vertical profiles, because Melton Hill Dam was closed about two hours before the end of the data collection. But Plate 2 indicates that the lag between closing of Melton Hill Dam and the corresponding drop in stage at Poplar Creek is several hours, so the 275 m3/sflow used in the simulation is rea- C sonable. The observed and simulated profiles shown in Figure 3 are evidence that the model can do a fairly good job at repro- ducing vertical temperature structure in the Clinch RiverIPop- lar Creek system. These results, along with the imagery analysis presented in previous sections, indicate that the model can Flik L , , reliably simulate transport in all three dimensions. Conclusions Based on this exploratory research, it appears that high-resolution hydrodynamic codes can reproduce turbidity and thermal plumes observed with remote-sensing systems. This conclusion suggests that remote-sensing data combined with high- resolution numerical modeling and limited surface measurements could define pollutant transport in large bodies of water as well as methods that rely only on more extensive surface measurements. Due to limited validation to date and uncer- LA tainty about Clinch River flow rates, this conclusion is largely qualitative at present. To make this conclusion more quantita- Plate 6. 22 March 1994 Daedalus visibleI,! (a) and thermal tive, future research needs to combine more direct measure- (b) images and simulated thermal (c) image of a steady-state ments of stream flow rates and temperature and turbidity Poplar Creek plume flowing downstream and mixing in the profiles with imagery in visible and thermal wavebands. Clinch River. Visible image is uncalibrated radiance from The results from this field study and analysis emphasize Daedalus channel 4 (0.50 to 0.55 pm). Temperatures in the effects of changing flow conditions on the highly dynamic observed and simulated thermal images range from about mixing zone of the Clinch River and Poplar Creek. The time- 9.7"C (black) to 12.0°C (red). dependent simulations of the Clinch River/Poplar Creek confluence by the 3D hydrodynamic model showed reasonable

334 March 2000 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING agreement with observed plumes. Results fromthis study pro- Malm, J., and L. Jonsson, 1993. A study of the thermal bar in Lake vided useful guidance in developing an environmental moni- Ladoga using water surface temperature data from satellite toring plan, specifically,where and under what conditions images, Remote Sensing of Environment, 44:35-46. to collect samples and what kind of descriptive informa- Martin-Marietta Energy Systems (MMES), 1995. Remedial Investiga- tion should be collected during each sampling event. This tion/FeasibiIify Study for the Clinch River/PopIar Creek Operable approach also provides an effective method for characterizing Unit, Vol. 1, Main Text, DOE/OR/Ol-1393Vl&Dl, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 557 p. and other sites where in large bodies of water is a concern. Miller, R.L.. and J.F. Cruise, 1995. Effects of suspended sediments on coral growth: evidence from remote sensing and hydrologic modeling, Remote Sensing of Environment, 53:177-187. Nichol, J.E., 1993. Remote sensing of water quality in the Singapore- References Johor-Riau growth triangle, Remote Sensing of Environment, 43:139-148. ~mett,A.J., 1995. ALGE: A 3-0Thermal Plume Prediction Code for Roberts, A,, C. Kiman, and L. Lesback, 1995. Suspended sediment Lakes, Rivers and Estuaries, SRTC-NN-95-25, Savannah River concentration estimation from multi-spectral video imagery, Technology Center, Aiken, South Carolina, 76 p. International Journal of Remote Sensing, 169439-2455. Garrett, A.J., and D.W. Hayes, 1997. Cooling lake simulations compared SAIC Corporation, 1996. Groundwater Remedial Site Evaluation to thermal imagery and dye tracers, Journal of Hydraulic Engi- Report (RSER) for Oak Ridge K-25 Site, Vol. 1, Main Text, DOE/ neering, 123(10):885-894. OR101-1468Vl&Dl, Oak Ridge, Tennessee, 500 p. Jardine, I.D., K.A. Thornson, M.G. Foreman, and P.H. LeBlond, 1993. Zheng, Q., X. Yanl and V. Klemas? 1993. Derivation of hlaware Bay Remote sensing of coastal sea-surface features off northern British tidal Parameters from space shuttle ~hoto~a~h~,Remote Sensing Columbia, Remote Sensing of Environment, 45:73-84. of Environment, 45:51-59. Nisbet, fine- Jensen, J.R., B. Kjerfve, E,W. Ramsey 111, K.E, Magill, C. Medeiros, and ZieglerJ C'K'l and J.E. Sneed, 1989. Remote sensing and numerical modeling of grained sediment transport in large reservoir, Journal of Hydraulic suspended sediment in Laguna de Teminos, Campeche, Mexico, Engineering, 121:773-781. Remote Sensing of Environment, 28:33-44. (Received 30 April 1998; revised and accepted 23 March 1999)

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