The use of GIS to facilitate wetland creation and restoration Andy Arkway

Transcription

1 The use of GIS to facilitate wetland creation and restoration Andy Arkway The many values provided by wetlands to the human population have only been recognized fairly recently. Historically the primary means of dealing with wetlands has been to drain and fill them. In recent years we have begun to recognize their many roles, including improving water quality, providing flood control, and supplying wildlife habitat. 80% of America s breeding bird population and 50% of the 800 species of breeding migratory birds rely on wetlands (Wharton et al., 1982). One of the cornerstones of wetland protection in the United States was the adoption of no net loss policy. This goal grew out of the National Wetlands Policy Forum in The forum proposed one major objective: To achieve no overall net loss of the nation s wetlands base and to create and restore wetlands, where feasible to increase the quantity and quality of the nations wetlands resource base (National Wetlands Policy Forum, 1988). Despite the adoption of this policy by the first president Bush, it was never anticipated that all construction in wetlands could be halted. Instead destruction to wetlands was minimized when possible, and when that was not possible new wetlands were created to replace those that were lost. Creation of wetlands is not a simple task. Ultimately success depends in the correct combination of hydrology, geology, ecology and biochemistry. Consequently many early attempts where failures. A study in Florida found that of 40, mitigation projects only about half the requires acreage had been constructed and of those that were, 60% were judged to be incomplete or failures (Erwin, 1991). As a result of these difficulties efforts to increase success have concentrated on selecting suitable sites. The contribution of GIS to wetland restoration has concentrated on three areas. Site selection, site design, and evaluation of wetland function both pre and post restoration. GIS has proved to be powerful tool to increase the probability of success through proper site selection. Mazzotta (2002) makes an excellent case for the fact that historically the choice of location for restoration has been dictated more by social and political reasons than by objective ecological criteria. Even when scientific criteria are used, methods other than GIS, are expensive and time consuming. Much of the most valuable work revolves around the development of models, which predict various ecological conditions in an effort to select sites with better chance of success. Not surprisingly wetness is critical to the long-term viability of an wetland. To that end many authors used digital elevation models to predict wetness (O Neil, 1997 and Russell, 1997). While this technique will be effective when working with ground water depression wetlands, it would be worth including soils data as that can play a major role in the development of surface water slope wetlands. The second general use for GIS in wetland restoration is the its use in the design of the project. One of the most interesting examples of this type of use of GIS was on a restoration project on the shore of Lake Erie. Historical panchromatic images from were digitized and entered into ArcView, and used to create maps of the vegetation. This provided the opportunity for the simultaneous viewing of multiple datasets, the performance of distribution analysis and the production of hard copy maps. This information was used in order to have the restored wetland more closely mimic the original, thereby increasing its chances of success. After the restoration, large-scale infrared photos were taken annually. These were digitized and interpreted to delineate vegetation and biological changes following the restoration (Kowalski, 1999). This tracking of wetland progress post restoration is an example of the third application of GIS in support of wetland restoration. GIS provides an inexpensive, efficient means of tracking progress post restoration. Long term follow up to restoration projects is

2 surprisingly rare. This may be due in part its cost, and difficulty. Field studies to track the progress of a project are very time consuming. They require many hours of field work in what can be very difficult conditions. This is compounded by the fact that funds are usually scarce, and if given the choice many resource managers would, understandably, choose to spend what they have on trying to bring about further improvements. The problem, as the data from Erwin the second paragraph points out, is that such a large percentage of projects fail. GIS provides a cost effective means to track past projects so that mistakes are not repeated in the future. Literature Cited: Erwin, K.L An Evaluation of Wetland Mitigation in South Florida Water Management District. Vol 1. Final Report to South Florida Water Management District. West Palm Beach, FL.124 National Wetlands Policy Forum Protecting America s Wetlands: An Action Agenda, Conservation Foundation. Washington, DC. 69 Wharton, C. H., W.M. Kitchens, E.C. Pendleton, and T.W. Snipe The Ecology of Bottomland Hardwood Swamps of the Southeast: A Community Profile. FWS/OBS- 81/31.USFWS.133

3 Annotated Bibliography Davies, BR., J. Biggs, J.T. Lee, L. Thompson Identifying Optimum Locations for New Ponds. Aquatic Conservation. Marine and Freshwater Ecosystems 14(1):5-24 The authors of this study sought to predict optimum locations for the creation of new ponds. GIS was used to predict pond quality in existing locations based on environmental factors. These predictions were then tested by comparing predicted pond quality with actual quality. Aquatic plants were used as the benchmark for measuring pond quality. This field data was used to further refine the model wiich was then used to predict at which sites created ponds would be of the highest quality. Doemoetoerfy, Z., D. Reeder, P. Pomogyi Changes in the Macro-vegetation of the Kis-Balaton Wetlands over the Last Two Centuries: a GIS perspective. Hydrobiologia 506: In this study Doemoetoefry and Reeder used GIS to monitor the progress of a 8,000 ha restoration project in Hungary. The inital portion of the study, historical maps were used to chart changes to the vegetation over the past two centuries. Later the researchers produced a digital elevation model for the area. This DEM was used to produce a series of maps demonstrating extent of watercover and it s depth at different times. By comparing the vegetation maps with the maps of water levels, it was possible to make assumptions about the effects of water level on vegetation. Fletcher, R., R. Koford Changes in Breeding Bird Populations with Habitat Restoration in Northern Iowa. American Midland Naturalist 150:83-94 The effects of habitat loss and fragmentation on bird population were examined by comparing changes in bird populations with changes in land cover. Data on change and turnover in bird populations in the Prairie Pothole region of the U.S. was compared with GIS data on land cover types. Most restoration efforts in the area have concentrated on converting agriculture and pasture into grassland and wetland. Not surprisingly most bird species where found benifit from the change. The exception being killdeer which may be declining Kowalski, K.P, D. Wilcox Use of historical and geospatial data to guide the restoration of a Lake Erie coastal marsh. Wetlands 45(4): This study sought to determine the historical extent of a marsh prior to its degradation in order to more accurately restore it. Historical panchromatic aerial photos taken between 1940 and 1990 were digitized and used to delineate habitat types and the limits of the barrier beach. This data was used to better understand the relationships between water level, the status of the barrier beach and wetland condition. The current condition of the marsh was ascertained through the use of infrared images, which were acquired between 1990 and GPS was used to ground truth the interpretation and to simplify the georeferencing. Comparison of the two datasets insured that the restored marsh would more closely resemble the original. It was hoped that the reproduction of conditions that existed in the original marsh would increase the likely hood of success.

4 Mazzotta, M., G. Magnuson, J. Opaluch, R. Johnston Setting Priorities for Coastal Wetland Restoration. A GIS Based Tool that Combines Expert Assessments and Public Values. Earth System Monitor 12:(np) The purpose of this study was to propose the use of GIS to systematize and prioritize coastal wetlands for restoration. It points out that in the past, funding for restoration has often gone to those projects with strong support from the community. These watersheds and the ecosystems would be better served, and funding used more effectively if a more systemic approach where employed. Geomorphology, hydrology, land cover, disturbance and vegetation were classified using GIS. Vegetation types were identified through the examination of aerial infrared photos.. Suitability of the various sites for restoration was evaluated based on scores derived from these categories.. Melancon, E., V. Cheramie, J. Barras, R. Dugas, M. Lagarde Oyster Resource Zones Based on Wet and Dry Estuarine Cycles and its Implication to Coastal Restoration Efforts in Louisiana. Journal of Shellfish Research Journal of Shellfish Research 16: 272 The purpose of this study was to examine the effects of coastal wetland restoration on oyster bed production in Louisiana. Recent efforts to mitigate wetland loss in the area by state and federal agencies have resulted in the diversion of large amounts of freshwater in order to restore salinity patterns to historical patterns. In an effort to assess the impacts these changes will make on local oyster beds researchers used GIS to develop a 1:100,000 scale map of the habitats utilized by oysters in the estuary. The map is being used by state and federal resource managers to assess impacts on this economically important resource O'Neill, M., J. Schmidt, J. Dobrolski, C. Hawkins, C. Neale Identifying Sites for Riparian Wetland Westoration: Application of a Model to the Upper Arkansas River Basin. Restoration Ecology 5: This study sought to develop a model identify and prioritize sites for restoration in Arkansas. GIS was used to analyze geomorphology, hydrology, and vegetation at potential restoration sites. Each area was analyzed for soil moisture, disturbance regime and vegetation. Vegetation type was determined through the examination of infrared aerial photographs. Further GIS was used to categorize land cover into five categories. These two set of data where used to identify riparian sites for restoration or preservation. Richardson, M.S., et. al Prioritizing Wetland Restoration Activity Within a Wisconsin Watershed Using GIS Modeling. Journal of Soil & Water Conservation 54 (14): The authors of this study sought to study the effects of drained wetlands on water quality. GIS data was used to map drained wetlands. The watershed of each area of drained wetland was then mapped. These two datasets were used to predict the amount of sediment each area delivered into the watershed. This information permitted the wetlands to be prioritized for restoration. Property owners were contacted using a mailing list generated with GIs software

5 Russell, GD., C.P. Hawkins, M. O Neil The Role of GIS in Selecting Sites for Riparian Restoration Based on Hydrology and Land Use. Restoration Ecology 5(4): In this study Russell, Hawkins and O Neil study used GIS to assess the viability of a variety of riparian sites for restoration. This was done using a DEM supplied by USGS to calculate the relative potential wetness of each 30m pixel. This data was combined with land use land cover data acquired from the Landsat satellite. Sites were ranked according to their suitability for restoration based on potential wetness values, adjacency with existing riparian vegetation and size. White, N., D.E. Line, J Potts, W. Kirby-Smith, W Hunt Jump Run Creek Shellfish Restoration Project. Journal of Shellfish Research 17: (np) The purpose of this study was to assess techniques to mitigate the impacts of land use changes on a wetland in North Carolina. The major focus was on identifying anthropogenic sources of bacterial contamination. This information was combined with a GIS based analysis of the hydrology of the watershed and its boundries. The intersection of these two datasets made it possible to more effectively plan mitigation measures. Results included the determination of locations for the placement and the sizing of riparian buffer zone restoration.