GIS Applications to Water Quality Management

Transcription

1 Christian W. Locher NRS November 2004 GIS Applications to Water Quality Management Inland waters constitute less than 1% of the total water volume of the world yet we are all dependant on this resource for our survival. The development and use of GIS as a tool for assessing the trophic level and quality of inland waters has had a tremendous impact on water quality management. The data required for an effective water quality management program requires a large amount of repetitive data. Traditional methods of data collection, while accurate, can be costly, time consuming and requires considerable laboratory and logistical support. By appropriately using remote sensing we may be able to more effectively measure production, trophic level and the quality of our inland waters. Aquatic primary production can be defined as the mass of carbon fixed as newly grown organic material or the fixation of energy by autotrophs (macrophytes and algae) within the water column. A large number of inland water quality problems can be directly attributed to the over stimulation of primary production within a lake. While algae and macrophytes are vital to the health of a lake, their overabundance can lead to oxygen depletion, fish kills, odor problems, and even the release of toxins. These problems can limit the use of a lake and can be very expensive to restore the lake to its original state. GIS has the potential to allow managers to more effectively assess water quality, predict pollutant loadings and appropriately administer preventative or corrective water quality measures. Remote sensing technologies can augment the data collection and can provide a number of parameters including chlorophyll-a concentrations, turbidity, color, algal production rates, macrophyte growth and identification and water temperature. The primary production, trophic state and water quality of a lake can be estimated from these parameters. The effort and resources required to collect water quality data over a large area are onerous. Remote sensing allows users to collect and process this data a great deal faster than traditional sampling methods. Another advantage of GIS is data processing speed. Surveys of aquatic vegetation are routinely conducted to help determine a lakes trophic level. This process is tedious and requires an expert to visually classify macrophyte species from aerial photographs. It has been shown that digital classification of macrophytes can be completed 3.5 times faster and more accurate, 85% versus 83%, than the conventional method of visual classification. While this aspect of GIS has yet to reach maturity it shows great potential in the efficiency of data analysis and reduction in both manpower and cost when compared to current methods. While the data collection and analytical powers of GIS are extremely valuable its single most effective use is in the display and dissemination of

2 information. The most important aspect for water quality management is for scientists to be able to lucidly convey their findings to the stakeholders and the decision makers. Without the ability to communicate we simply cannot effectively manage our waterways. GIS provides a platform from which we can analyze and clearly disseminate data. A good example of this can be taken from Maidment et all (1996). Figure 1 clearly demonstrates that high levels of phosphorus pollutants can be expected to come from agricultural lands. Unfortunately most people cannot easily draw conclusions from this sort of data and most people, especially the lay person (decision makers), would quickly get lost in the complexity of the data and lose interest. Conversely by using data generated with GIS you can express the same information in a more palatable format. Figure 2 depicts the land use and phosphorus loading of the same study area. It is much easier for most people to understand and absorb data that is in this format. If effectively used for water quality management, GIS can reduce the cost of data acquisition, improve the data collected and reduce management costs. The potential benefits are substantial, particularly for applications that require repetitive data over a large spatial scope. The use of GIS to collect and analyze data and articulate research findings makes it a tremendous tool in the water quality management toolbox. As technology continues to advance so will GIS applications to water quality management. Annotated Bibliography 1) National Academy of Sciences: Panel on Inland Water Resources (1975). Practical Applications of Space Systems. The report of the Panel on Inland Water Resources to the Space Application Board. Published by the National Academy of Sciences. This document discusses possible applications of space borne technology and how they might be used to better water quality programs. It describes a basic framework for how to appropriately use remote sensing for resource conservation and management. While this article was a little dated it provided some very useful insight into how remote sensing got its start in water quality management and how technological advances have followed the framework laid out in this document. 2) U.S. Environmental Protection Agency (1988). Land and Reservoir Restoration Guidance Manuel. Office of Water Criteria and Standards Division Nonpoint Sources Branch, EPA, This document was extremely useful because it discussed the development, source and measurement of many aspects of water quality management. The case studies and examples provided insight into natural variability and how it effects water quality management. I found this document extremely useful because it helped me better understand the processes involved in assessing trophic levels and practical examples of solutions.

3 3) David Maidment (1993). GIS and Hydrologic Modeling. Environmental Modeling with GIS. Oxford University Publishers 1993: This report by Maidment et all was very helpful in understanding how GIS can be used to assess water quality. The integration modeling water quality and GIS to assess non-point sources of pollution was insightful and showed great potential for further use. This report was well written and clear. It helped me in my understanding of how GIS can more effectively be applied to water quality management. 4) M.C. Waldron, Peter Steves and J.T. Finn (2001). Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes. Water Resource Investigations Report Department of Forestry and Wildlife Management, University of Massachusetts, Amherst. Waldron et al discusses the use of LandSat Thematic mapping in conjunction with local measurements (chlorophyll concentrations, Secchi disk measurements, etc) to assess the trophic state and quality of 97 lakes in Massachusetts. The methods and applications described in this paper clearly show that while some aspects of remote sensing are difficult to integrate into a water quality program it has great potential. This paper gives a realistic view of the current state of remote sensing capabilities in regards to water quality management programs. 5) P. Baruah, M. Tamura, and Y. Yasuoka (2002). Collaborating Remote Sensing with historical limnological data to map primary productivity at a Eutrophic Lake. Asian Conference on Remote Sensing, Institute of Industrial Science, University of Tokyo, Japan. This conference proceeding paper provides an outstanding example of how GIS can be used to measure primary production in a eutrophic lake. It provides a detailed description of the experimental methods and approaches that not only list their successes with GIS but the problems and the limitations they encountered throughout. This is an enlightening paper and was very well written. 6) K. Hulkkonen, S. Partanen, and A. Kanninen (2003). Remote Sensing as a tool in the Aquatic Macrophyte Mapping of a Eutrophic Lake: A Comparison between Visual and Digital Classifications. Scandinavian Research Conference on Geographic Information Systems 2003, Department of Surveying, Helsinki University of Technology. This conference paper provides an interesting insight into the use of GIS and remote sensing for measuring production within lakes, particularly macrophyte growth. It demonstrates how macrophyte overgrowth affects both water quality and desired recreational value of lakes. This paper describes the functionality and efficiency of digital classification of macrophytes taxa compared to visual classification. It was very well written and demonstrated a very effective use of GIS in water quality management.

4 7) L. Olsson and P. Pilesjo (2002). Approaches to spatially distributed hydrological modelling in a GIS environment. Environmental Modelling with GIS and Remote Sensing. Taylor and Francis Publishers, December This book was useful because it described different approaches to spatial modeling of water bodies within a GIS environment. It covered many aspects of how GIS can be effectively applied to modeling and a water quality program. The book was very useful because it approached hydrological modeling from a simplistic standpoint and helped me to better understand the variables within a hydrologic system. 8) J. Moore, D. Schindler, M. Scheuerell, D. Smith, and J. Frodge (2003). Lake Eutrophication at the Urban Fringe, Seattle Region, USA. AMBIO: A Journal of the Human Environment, Vol. XXXII, No. 1, Feb This article discussed the application of eutrophication, its primary sources and it effects in regards to a water quality program. Moore et all, describe the condition of lakes within the Seattle region, the primary culprits of eutrophication and possible solutions. This paper was useful because it was clearly written, lucid and helped me better understand the process of eutrophication and its water quality applications. Additional References 1) David Maidment and W. Saunders (1996). A GIS Assessment of Nonpoint Source Pollution in the San Antonio-Nuences Coastal Basin. Center for Research in Water Resources Online Report Bureau of Engineering Research, University of Texas at Austin. 2) John Fisher (1970). Criterion for Recognition of Estuarine Water Pollution by Aerial Remote Sensing. Technical Completion Report, Project No. OWR: A- 031-RI. June ) R. Osgood, P. Brezonik, and L. Hatch (2002). Methods for Classifying Lakes Based on Measures of Development Impacts. University of Minnesota Water Resource Center Technical Report 143, January ) P.L. Brezonik, S.M. Kloiber, L. Olmanson, and M. Bauer (2002) Satellite and GIS Tools to Assess Lake Quality. University of Minnesota Water Resources Center Technical Report 145, May ) Robert Black and Alan Haggland (2003). Characterization of Instream Hydraulic and Riparian Habitat Conditions and Stream Temperatures of the Upper White River Basin, Washington, using Multispectral Imaging Systems. U.S. Geological Survey Water Resources Investigations Report Washington State Department of Ecology.

5 Figure 1 Relationship between Land use and pollutant loading in Nueces Basin

6 Figure 2 Land Use (Left) and Total Phosphorus Loading (Right) in Nueces Basin