United States Environmental Monitoring February 1991 Environmental Protection Systems Laboratory Agency P.O. Box 93478 Las Vegas NV 89193-3478 TECHNOLOGY SUPPORT PROJECT &EPA Topographic Mapping for Environmental Assessment INTRODUCTION The location, extent, and historical change in the nature of hazardous waste sites is of great importance to the Environmental Protection Agency, and can be docu- mented through the creation of topographic maps. The Environmental Monitoring Systems Laboratory in Las Vegas is the Agency's center for mapping and related remote sensing technologies. Topographic (elevation) maps are simple, effective, and graphic tools for record- ing the quantitative and qualitative characteristics of hazardous waste sites. These maps are most often created from aerial photo- graphs and, since national archives of coverage date back more than fifty years, maps can be created that reflect historical site condi- tions. TECHNIQUE A typical topographic map- ping project begins with a request from an RPM to the EMSL-LV Advanced Monitor- ing Systems Division (AMD). The EMSL-LV provides a cost estimate and arranges for all necessary geodetic surveys, aerial photographic overflights, and map produc- tion. No permission is needed for a flyover, so aerial photography is of particular value In situations where uncooperative owners deny intrusive sampling. A spe- cially calibrated aerial camera is used to insure accurate photography for later use in the map production process. Once the film is developed, it is placed in a special instru- ment (stereoplotter) which creates a model of the terrain to produce a contour map. The map may be generated as hardcopy, or in digital form for later use with Geographic Information Systems (GIS). The same aerial photographs can be interpreted to assess the remediation actions at the site. SCOPE In addition to basic positional information about ground elevation and locations of objects, maps can serve as the base for a targeted sampling grid, or for record- ing specialized information such as land disposal activity, population distribution, geologic fractures, vegetation communities, wetlands delineation, and land use. When compared with histori- cal aerial photographs these maps can provide both qualitative and quantitative information on changes in volume and elevation (e.g., last year there was a mound three times larger than the present one; or, between 1988 and 1990, there were 100,000 cubic yards of material placed in the land- fill). Topographic information is entered into ARC-INFO (EPA's GIS software) for future referral. The informa- tion on these maps can provide answers to critical environmental questions such as the probable sources of contamination and the ultimate destiny of dis- charges. ------- ADVANTAGES AND LIMITATIONS Topographic mapping is a mature technology that is expanding to meet the needs of the environmental commu- nity. Advances in computer technology and optical sciences have enhanced remote sensing capabilities over the years - and continue to do so. Advantage* Legally defensible data Permanent historical record Digital or analog format Geographic relationships are clearly demonstrated Quantitative measurements can be made Limitations Seasonal and weather restric- tions Complexity of technology FUTURE PLANS Remote sensing and map- ping technologies continue to develop and hold great promise for practical environ- mental usage. The basic topographic mapping process is being augmented by a series of related monitoring techniques that will provide new thematic mapping products. Among these are: the use of orthophotography which is hard-copy imagery corrected to map-quality standards; land use/land cover mapping from satellite data; and the development of various digital products in a Geographic Information Systems format. The increased need for accurate information will continue to drive remote sensing and topographic mapping growth in the 1990s. REFERENCES U.S. Environmental Protection Agency. 1984. Photogrammetric Mapping Program for Haz- ardous Waste Sites. An EMSL-LV publication. Remote Sensing and Interpretation, Lillesand, T. M., and R. W. Kiefer, John Wiley and Sons, 1979, especially Chapter 5. FOR FURTHER INFORMATION For specific information on topographic mapping, contact: Mr. Paul Olson EPIC-LV Environmental Monitoring Systems Laboratory P.O. Box 93478 Las Vegas, Nevada 89193-3478 (702) 798-2288 FTS 546-2288 FAX/FTS 545-2692 vo*'°/vv ^ -T- %> ^ I echnology *2- ° O z * Project £? Xx**/ For further information on technology support, contact: Mr. Ken Brown, Manager Technology Support Center U.S. Environmental Protection Agency Environmental Monitoring Systems Laboratory P.O. Box 93478 Las Vegas, NV 89193-3478 (702) 798-2270/734-3207 FTS 545-2270 FAX/FTS 545-2637 ------- |