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Transforming Remote Sensing Data into Information and Applications 2 Meeting the Information Needs of End Users in the Coastal Zone Moving from demonstration projects to successful operational applications of remote sensing data requires that the desired information meet applications users’ needs, which depends in turn on users and technical experts being able to discuss and understand those needs. Identifying a prospective user’s requirements is essential. Often the process of developing applications for new end users, many of whom may be decision makers or policy makers in the public and private sectors, also requires research and/or the integration of multiple sources of data and information. Equally important are the conditions under which data and/or applications are made available to users, requiring that issues such as the timeliness, continuity, and stability of data; reliability of access; viability of data formats and processing; intellectual property rights; and operational cost-effectiveness be addressed satisfactorily. Examination of the case studies presented at the workshop and summarized in this chapter offered an opportunity to draw on the experience gained through applications of remote sensing in the coastal zone.1 The three cases selected for examination include the application of SeaWiFS data to monitor harmful algal blooms (HABs) that appear to be increasing in coastal waters,2 the use of airborne lidar bathymetry to monitor channel and harbor status to ensure safe navi- 1 A later workshop to be organized by the steering committee will explore opportunities for and barriers to the use of remote sensing data in the public sector, particularly in state and local governments. 2 Anderson, D., The Ecology and Oceanography of Harmful Algal Blooms (ECOHAB): A National Research Agenda. Woods Hole, Mass., Woods Hole Oceanographic Institution, 1995, p. 66.
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Transforming Remote Sensing Data into Information and Applications gallon, and the use of satellite and aerial remote sensing to determine water mass trajectories and so gauge the impacts on water quality of marine sewage disposal. UNIQUE CAPABILITIES, AND SOME CURRENT LIMITATIONS, OF REMOTE SENSING Satellite remote sensing can significantly enhance the information available from traditional data sources because it can provide synoptic views of large portions of Earth. Satellite imagery can also expand the spatial dimensions of limited and sometimes costly field or point-source sampling efforts. Some satellite sensors cover areas that may be physically or politically inaccessible or that are too vast to survey with traditional methods. Remote sensing can also provide consistent repeat coverage at relatively frequent intervals, making detection and monitoring of change feasible. Satellite-derived data and information are also useful for applications that require fine spatial resolution such as surveys of urban and suburban land use, land cover for agricultural purposes, and natural resources; surveys for coastal management; and measurements of water quality in limnological and oceanographic applications. The disadvantages of satellite remote sensing include the inability of many sensors to obtain data and information through cloud cover3 (although microwave sensors can image Earth through clouds) and the relatively low spatial resolution achievable with many satellite-borne Earth remote sensing instruments. In addition, the need to correct for atmospheric absorption and scattering and for the absorption of radiation through water on the ground can make it difficult to obtain desired data and information on particular variables. Satellite remote sensing creates large quantities of data that typically require extensive processing as well as storage and analysis. Finally, data from satellite remote sensing are often costly if purchased from private vendors or value-adding resellers, and this initial cost, together with intellectual property restrictions, can limit the dissemination of products from such sources. In many instances, there may be an advantage to combining the large-scale, synoptic data that are accessible from space with higher-resolution surveys of key locations that can be made from other platforms, such as aircraft. Aerial photography, for example, has a competitive advantage in applications that require fine spatial resolution of small areas or that involve areas subject to frequent cloud cover, especially in cases where repeat coverage is needed. Another advantage of aerial photography is that surveys can be scheduled for specific purposes and locations. Aircraft-carried instruments of other types, including visible, thermal, 3 Cloud cover can be particularly problematic for optical sensors that collect imagery over the West Coast. For example, marine stratus clouds often cover the West Coast during the morning overpass of the Landsat satellite.
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Transforming Remote Sensing Data into Information and Applications and microwave sensors, provide high-resolution data of many kinds and thus represent an important part of the mix of remote sensing capabilities for Earth observation. Among the disadvantages of aircraft remote sensing are the relatively limited spatial coverage that can be obtained compared to satellite instruments, the recurring expense of deploying multiple flights, weather restrictions, and lack of synopticity over large scales. MEETING USER REQUIREMENTS: OBSERVATIONS BASED ON THE CASE STUDIES The three case studies presented at the workshop by government agency officials and a private sector representative (Boxes 2.1, 2.2, and 2.3) outline projects developed for the application of remote sensing, describe the challenges in developing data and information, and provide examples of barriers and bottlenecks to producing useful applications. The information needs of the coastal zone managers who are the applications users in these case studies address a range of problems. The cases are not representative of all remote sensing applications developments; rather, they illustrate the types of challenges that can arise in moving from research to information and applications. On balance, the case studies presented at the workshop suggest that successful remote sensing applications are likely to be those that draw on the unique characteristics of the data and cannot be accomplished in a cost-effective manner with other sources of data. Discussions at the workshop emphasized that it is the good correspondence between the information requirements of end users and the specific attributes of remote sensing data that will make the use of the technology advantageous. Remote sensing data that do not meet the specific information needs of end users or whose use does not fit into their accepted practices must be transformed into usable information to enable users to apply the technology. The case studies and discussions at the workshop also highlighted the importance of easily understood demonstration projects. Potential end users were willing to participate in a demonstration project, especially when they were not required to contribute financially to the project. In turn, user feedback provided those conducting the demonstration project with valuable information on the effectiveness of the application in time to modify the demonstration before completion. Demonstration projects are one means of bridging the gap between the information needs of end users and unprocessed remote sensing data. A common thread in the case studies and other examples of remote sensing applications in the coastal zone was the requirement to obtain consistent data and information over regular intervals on key ecosystem variables that might serve as indices of change. Remote sensing can be an attractive technology for monitoring coastal ecosystems, whose high spatial and temporal variability mean that data must be collected over large areas and for long periods to enable identification of trends. Such large-scale sampling from boats and ships alone is prohibi-
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Transforming Remote Sensing Data into Information and Applications BOX 2.1 Applying SeaWiFS Data to Monitoring Harmful Algal Blooms The Challenge Marine planktonic algae, or phytoplankton, are essential elements of the marine environment, but some species are detrimental, forming harmful algal blooms (HABs). Toxic HAB species, such as the dinoflagellate Gymnodinium breve (G. breve), cause “red tides” that can harm fish and wildlife, cause illness in humans, and have a significant economic impact. Sampling HABs effectively is a difficult problem because of the large areas of ocean they may cover and the logistical costs of traditional sampling. Improved monitoring of HABs would increase understanding of the inception of HABs and the conditions that promote their growth. Rapid identification of HABs is essential for state managers to protect public health. Satellite imagery of ocean color has the potential to provide information on the distribution and abundance of HABs at high frequency and with suitable spatial and temporal resolution. Remote Sensing Application In partnership with the National Oceanic and Atmospheric Administration (NOAA) and the Naval Research Laboratory, the Environmental Protection Agency (EPA) Advanced Monitoring Initiative program sponsored a demonstration project to use satellite data from the Sea-viewing Wide Field-of-view Sensor (Sea-WiFS) ocean color instrument to help detect outbreaks in the Gulf of Mexico of the potentially harmful G. breve from its optical signature. Regional SeaWiFS data on chlorophyll concentration have the potential to give an early warning of G. breve blooms. This program was designed to develop algorithms for using SeaWiFS data to monitor G. breve and to communicate the results to health officials charged with identifying health and safety issues related to changing environmental conditions. lively expensive, except in the most confined of water bodies. In the Chesapeake Bay and in the Mississippi River plume in the Gulf of Mexico-both highly fertilized regions that are manifesting water quality problems associated with anthropogenic nutrient loading from their large watersheds-intensive monitoring programs have been developed that are being augmented effectively with remote sensing. The case studies illustrated both barriers to developing effective applications and bottlenecks that slow or complicate the process. For example, in the Army Corps of Engineers SHOALS project, which uses airborne lidar to survey navigation channels and harbors, the long lead time from concept to application was a
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Transforming Remote Sensing Data into Information and Applications Results The demonstration program verified the usefulness of space-based SeaWiFS data for monitoring G. breve in the Gulf of Mexico. The correspondence between SeaWiFS data on chlorophyll concentrations1 and cell concentrations of G. breve determined from ship samples suggests that satellite imagery may be useful for early detection and tracking of these harmful algal blooms (HABs). The use of SeaWiFS data to identify bloom locations and track population movements allows more extensive collection of in situ samples from appropriate locations, thus augmenting more costly and less effective sampling approaches. The program has transitioned into an operational effort: States identify a potential bloom event, NOAA’s Coast Watch Program collects relevant SeaWiFS data, NOAA scientists analyze the data, and the states redirect their sampling accordingly. The program has also identified an apparent relationship between bloom events and climate. There are indications that an absence of blooms during some years and an abundance in others might be linked to large-scale weather patterns, such as El Niño and La Niña events. Improved coordination is essential to ensure that the findings of the demonstration project are transmitted to partners in the states. Efficient, cost-effective, and understandable communication of reports on HABs is integral to the success of efforts at the local level to monitor HABs. Barriers Barriers to the development of applications included confusion about access to and distribution of SeaWiFs data; competition among partners and institutional barriers; costs and difficulties in coordinating a multiagency, multistate project; and development of an effective means, perhaps modeled after the daily weather reports, to communicate HAB reports to a state user. 1 Chlorophyll is a ubiquitous plant pigment occurring in all phytoplankton taxa, and careful verification of indications from ocean color images is essential to use this tool in predicting or monitoring HABs. significant deterrent to developing future applications (Box 2.2). In the demonstration project using data from the ocean color sensor SeaWiFS to identify HABs, a period of scientific and technical research was required to enable the use of imagery as a tool for predicting when and where blooms might occur (Box 2.1). In both cases, the common impediment to effectively transferring remote sensing technology to prospective information users was the gap between user requirements and the technical capabilities of the data. Remote sensing data are not a “magic bullet”; they have advantages and disadvantages that will affect their utility for practical applications. Often, developing applications of value for end users will require coupling remote sensing data with other data and/or doing additional research aimed at creating new, useful data products. Remote sensing
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Transforming Remote Sensing Data into Information and Applications BOX 2.2 U.S. Army Corps of Engineers SHOALS Airborne Lidar Bathymetry Program The Challenge The U.S. Army Corps of Engineers (USACE) is responsible for maintaining approximately 25,000 km of navigation channels and more than 600 ports and harbors. These channels must be assessed, often annually, for the movement of sand and sediment into shoals that impede safe navigation. Many channels require repeated dredging. Conventional hydrographic surveys using boats with acoustic fathometers are costly, slow, and do not meet all the USACE requirements for navigation and shore protection project monitoring. Remote Sensing Application USACE developed an airborne lidar system that allowed it to survey more channels without increasing its budget. The lidar technology works by transmitting green and infrared laser signals into the water. The green signal reflects off the sea bottom, and the infrared signal reflects off the water’s surface; the time differential between the two signals provides the water depth. The USACE’S objective was to stimulate private industry interest and investment in the technology by demonstrating the viability of lidar through the development of the Scanning Hydrographic Operations Airborne Lidar Survey (SHOALS). SHOALS was initiated in 1994. After demonstrating the technology and characterizing its capabilities, the USACE adopted the technology and SHOALS for operational use. SHOALS remains a government-owned, privately operated system. Results The lidar system can survey waters too shallow to allow boats to collect data and can extend the hydrographic survey onto the beach or shore. The information obtained by SHOALS at a navigation project, including ebb and flood shoals, adja data are usually just one element of an effective application and seldom offer a complete solution. In the case studies described in Boxes 2.1 through 2.3, the scale of the spatial coverage provided by remote sensing is of paramount importance, facilitating detection of potentially harmful events over hundreds to thousands of square kilometers, such as the movement of sewage effluent or the development of HABs. To yield a predictive tool, however, data obtained by remote sensing must be integrated with confirming evidence gathered from other sources, such as counts of bacteria or measures of concentrations of toxins in the case of sewage effluent, and species enumeration and identification in the case of HABs. Achieving a match between the needs of users and the potential of remote sensing data to address those needs is accomplished through research and the integration of data and information from multiple sources, including remote sensing. This
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Transforming Remote Sensing Data into Information and Applications cent shorelines, channels, and dredge disposal areas, exceeds what conventional surveys can produce cost-effectively and thus contributes to a more complete understanding of sediment movement in and around USACE navigation projects. SHOALS has helped to enable new business practices within the USACE that should lead to improved navigation channel maintenance. Strategic partnering by district planning, engineering, and operations has provided for regional, rather than individual, project approaches to sediment management. SHOALS has supported this new business initiative because of its ability to rapidly and cost-effectively conduct regional scale coastal surveys. In addition to improved partnerships with the districts, the SHOALS program has partnered with the U.S. Navy and the National Ocean Service of the National Oceanic and Atmospheric Administration and has conducted surveys for the U.S. Geological Survey, state governments, and several foreign countries. The program has also extended its applications to include nautical charting, shoreline mapping, coastal monitoring, coral reef mapping, and military operations. Barriers The initial institutional barriers to implementing SHOALS surveys in the USACE centered on issues related to acceptance of a new way of doing business. The data collectors, those using boats for hydrographic surveys, resisted because it was not their system. There were questions about survey costs and about how to compare costs of conventional versus remotely sensed hydrographic surveys. This issue was complicated by the fact that a typical conventional navigation project survey does not produce the same product as a SHOALS survey. Data users, on the other hand, were much quicker to order a SHOALS survey. However, they had problems initially because the data files were much larger than those obtained with conventional surveys, and few computer tools and models existed to allow easy utilization of the data. The usefulness of the SHOALS system is limited in areas of poor water quality and at depths over 60 meters. This led to a multiplatform approach that uses boats in areas where the lidar is not effective. does not represent a barrier for coastal managers, who are used to working with multiple sources of data. IMPROVING THE PROSPECTS FOR REMOTE SENSING TECHNOLOGY TRANSFER As discussed in Chapter 1, the crux of the technology transfer process is transforming raw data from remote sensing into useful information. Discussions at the workshop and material in the case studies presented there stressed that a key element in this process is collaboration between remote sensing experts and end users to ensure a match between what the data can provide and what information is needed. Eventually the active role of technical experts in developing new applications will become routine as the applications become operational and the end users develop expertise sufficient to make use of the products.
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Transforming Remote Sensing Data into Information and Applications BOX 2.3 Satellite and Aerial Remote Sensing for Monitoring Coastal Sewage Discharge The Challenge Coastal pollution from sewage effluent is a major problem in southern California and other U.S. coastal regions. Inadequate containment may result in beach closings and long-term pollution with significant health and economic impacts. In southern California, beach closures during the tourist season result in the loss of millions of dollars of revenue to local businesses. In some cases, cities or their sanitation districts may be fined appreciable sums for lack of compliance. Monitoring discharges is essential for U.S. coastal sanitation districts that operate under the jurisdiction of an Environmental Protection Agency (EPA) permit process. Renewal of permits is dependent on evidence of compliance derived from regular field monitoring of physical and biological properties. Most sampling is done only on a weekly or monthly basis because of the high costs of field sampling. This schedule leaves large gaps when the sanitation districts and other agencies may lack information on the trajectories of wastewater plumes. Remote Sensing Application Incorporating satellite and aerial remote sensing into sewage outfall monitoring programs offers several advantages: (1) large areas can be sampled synoptically at high spatial and temporal resolution for costs significantly lower than those of traditional field surveys; (2) limited field data from key locations can be significantly extended by combining them with remotely sensed information that permits spatial interpolation to broad regional coverage; and (3) gaps in coverage from field sampling can be filled using remotely sensed data of improved frequency and regularity of coverage, and these data can serve as an early-warning system for undetected sewage effluent events. Ocean Imaging Corp. organized a feasibility study with the Orange County Sanitation District to develop new commercial applications for remote sensing of temperature, ocean color, and turbidity. The study used primarily time series of sea surface temperature data from the Advanced Very High Resolution Radiometer (AVHRR) sensor to compute upper-layer currents and estimates of turbidity derived from visible AVHRR data. Unlike skilled technical practitioners who are generally knowledgeable about remote sensing and have the expertise to analyze the data and imagery, many end users, who often have very different backgrounds and skills, are generally not equipped to interpret remote sensing data without significant technical assistance or training. In addition, many end users have little interest in remote sensing per se or in the technical characteristics of the additional information integral to applications that can help their decision making. Thus, workshop participants pointed out, education is needed to increase end users’ awareness of remote sensing capabilities. In addition to understanding the broad characteristics of remotely sensed data, applications users should be encouraged to discuss their
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Transforming Remote Sensing Data into Information and Applications Results Both products of the study were found to be useful for detecting anomalous discharge-surfacing events and for helping to separate beach contamination events caused by an outfall from those caused by tidal or rain-caused discharges of stagnant water from nearby lagoons. The current analyses, which were verified by field sampling, helped estimate the possibility of effluent reaching the beaches. Follow-on projects for EPA evaluated other remote sensing data types (radar, optical, and multispectral) for monitoring new outfall and sewage runoff in San Diego and across the border with Mexico. Barriers The pace of remote sensing technology transfer for coastal runoff and effluent discharge applications is hampered by the following: Data timeliness. In most monitoring situations, especially when a spill or similar event is occurring, data must be processed, analyzed, and delivered to the end user in less than 24 hours to be useful for guiding management or remedial efforts. This is possible only with data from AVHRR, the Sea-viewing Wide Field-of-View Sensor, and possibly the Moderate Resolution Imaging Spectrometer, which offer poor spatial resolution for most applications. Data cost. All synthetic aperture radar and high-resolution optical remote sensing data are currently priced too high to be affordable for effective continuous coastal monitoring efforts. Given the constantly changing ocean environment, remotely sensed data lose their value extremely quickly-yesterday’s image has little or no value today. Resistance to increased monitoring capability. Remote sensing cannot replace field monitoring, which is needed to sense bacteria, ammonia, or similar variables directly. Adding remote sensing to field sampling programs raises the potential for more frequent apparent positive signals that will only complicate meeting current monitoring, performance, and compliance requirements. There is little incentive for the districts to spend funds that will further complicate their situation. information needs with technical personnel. A survey by NOAA’s Coastal Services Center,4 discussed at the workshop, indicated that coastal managers may not communicate their specific needs to technical personnel with sufficient clarity to permit them to develop appropriate applications of remote sensing data. Moreover, many who develop sensors, collect and analyze data, and develop products to address scientific or technical questions are unable to communicate 4 NOAA Coastal Services Center, “Coastal Resource Management Customer Survey,” Charleston, South Carolina, NOAA Coastal Services Center, 1999.
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Transforming Remote Sensing Data into Information and Applications with prospective users who lack essential technical expertise. This gap in communication constitutes a significant barrier to technology transfer. Coastal managers, who may use ocean color information from SeaWiFS to identify areas of high chlorophyll concentrations that accompany the development of harmful algal blooms, rely on information derived from the remote sensing data and made available to them by technically cognizant intermediaries in the transfer process (see Box 2.1). In this case, remote sensing data on the potential development of a HAB event, as indicated by high concentrations of chlorophyll in a satellite ocean color scene, must be coupled with additional data on the species of algae associated with the high concentration of chlorophyll, such as the data that can be obtained by analyzing in situ water samples. The remote sensing data must be turned into useful information that can be used effectively by the coastal managers to make decisions about health impacts on wildlife and humans. Education and training are of paramount importance in linking user needs and remote sensing capabilities and in informing those with technical expertise about the day-to-day challenges faced by existing end users and potential new users. From the end users’ perspective, data and information from remote sensing can be used most effectively by those with a level of expertise that includes an understanding of the more sophisticated aspects of the underlying technologies. For example, an end user who is familiar with remote sensing theory and appropriate image analysis methods is more likely to use data obtained by remote sensing than is a novice who lacks this understanding. Well-trained people are, therefore, one of the most important components of the remote sensing technology transfer process. Increased awareness of remote sensing’s potential to meet end users’ needs will also stimulate the use of remote sensing applications and help to encourage the emergence of a viable market for remote sensing information and services. In the SHOALS project, for example, aircraft lidar for bathymetric surveys initially complemented more traditional shipboard approaches to gathering data, demonstrating the potential for obtaining additional information by employing remote sensing technologies to address the problem of monitoring harbor and channel depths. The role of education and training in developing remote sensing information products, knowledge, and services is addressed in Chapter 3. Collaboration in day-to-day problem solving can also help to bridge the gap between users and technologists. In addition, value-adding companies, which employ technical experts who provide remote sensing products, information, and services and who act as intermediaries in matching a customer’s needs with the company’s remote sensing capabilities, can facilitate understanding of the operating and decision-making processes of these two different communities. Workshop participants also proposed “externships” as a means of fostering the exchange of staff between federal agencies that produce remote sensing data and products and the agencies that use them.
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Transforming Remote Sensing Data into Information and Applications Finally, applications users usually require a stable and continuing supply of information, whether from remote sensing or other sources, and may opt for continuity of mediocre or even inadequate data rather than rely on an undependable source of superior data. They may also be deterred from obtaining new types of data if technical uncertainties associated with collecting or accessing the data appear to be high. Remote sensing data whose availability is limited are of little practical value to an end user who requires a regular stream of data to meet his or her information needs. Such issues must be addressed if remote sensing technology transfer is to succeed.
Representative terms from entire chapter: