Grantee Research Project Results
Final Report: From Landscapes to Waterscapes: Integrating Framework for Urbanizing Watersheds
EPA Grant Number: R825760Title: From Landscapes to Waterscapes: Integrating Framework for Urbanizing Watersheds
Investigators: Diplas, Panayiotis , Shabman, Leonard A. , Cox, W. E. , Kibler, David F. , Benfield, Ernest F. , Bosch, Darrell J. , Orth, Donald J. , Stephenson, Stephen K. , Lohani, Vinod K. , Nagarkatti, P. S. , Dymond, R. , Mostaghimi, Saied
Institution: Virginia Tech
EPA Project Officer: Packard, Benjamin H
Project Period: October 15, 1997 through October 15, 2000 (Extended to August 31, 2001)
Project Amount: $849,266
RFA: Water and Watersheds Research (1997) RFA Text | Recipients Lists
Research Category: Water , Watersheds
Objective:
Urbanization, farming, and other types of land use change activities can significantly alter storm hydrographs and sediment erosion rates within a watershed. These effects can cause more frequent flooding and increased pollutant loading, which may result in the degradation of the physical and biological integrity of streams and other aquatic ecosystems. Regardless of these problems, watershed development appears inevitable. The central issue, therefore, is how to reconcile development with acceptable environmental quality at an affordable price. The overall goal of this project was to develop procedures for the assessment of the hydrologic, ecological, and economic consequences of alternative landscape scenarios occurring during the urbanization/sub-urbanization process. More specific objectives include: (1) development of a hydrologic framework for assessing impacts of alternative landscapes on surface and subsurface water flows; (2) development of procedures for predicting the response of fish and macroinvertebrate communities to urbanization-induced changes in water quantity, water quality, and other biological conditions; and (3) identification and assessment of policy and economic decisions consistent with alternative landscape scenarios, as well as estimation of the effects of alternative landscapes on land values and fiscal consequences for local governments. The Upper Roanoke River Watershed (URRW) and Back Creek, a subwatershed within URRW, are employed to test the operation of the modeling framework developed in the various components of this study.
Summary/Accomplishments (Outputs/Outcomes):
This study consisted of the following components: hydrology/hydraulics, biology,
economics/policy, and Geographical Information Systems (GIS). The main results
obtained by the first three components are summarized below. The other components
used GIS as a tool for data selection and development and for software interface
construction.
The goal of the hydrologic component was the development of a modeling framework
for evaluating the impact of land use activities on the surface hydrology, subsurface
flow regime, and the channel processes controlling aquatic habitat. The computer
models HSPF and MODFLOW were used to determine the changes in the surface and
subsurface runoff taking place within a subwatershed triggered by a certain
amount of development. The first tends to respond more rapidly, while the latter,
depending on the local geology, might take many years to reach quasi-steady
state conditions. Therefore, it is this longer time horizon that needs to be
considered when examining the impacts of land use change. The output from these
models becomes input to RMA-2V, a two-dimensional Finite Element Model used
to simulate the river flow.
The major linkages between land development and hydrological change were illustrated by using the Back Creek (148 km2 in area), a subwatershed in the upper Roanoke River system (1,479 km2 in area) in southwest Virginia. The surface water modeling indicated that increased raw imperviousness resulting from development is the most dominant indicator of hydrograph response. As a result, among several land development scenarios (low density, medium density/conventional, medium density/cluster, and high density) considered for a fixed number of new dwellings (15,300 new residents), the low density development produced the largest relative change in total runoff volume, and 1- to 10-year storm peaks. Incidentally, the low- density development has the higher impervious area per capita. More specifically, HSPF model results suggest a linear relationship between additional impervious land and both runoff volume and 10-year discharge peak. The relative magnitude of flood peak amplification is more pronounced for the higher frequency storm events. As one might expect, the more drastic the land conversion is (e.g., forest to impervious versus agricultural to impervious land), the greater the impact on the watershed hydrology would be.
Subsurface flow modeling for the Back Creek (BC) subwatershed provided results that are consistent with those of the surface modeling (i.e., the low density scenario caused the greatest decrease on the hydraulic head and base flow water discharge from the streams within BC). It also indicated that the upland areas were the locations most sensitive to land use change, especially when water withdrawal was involved. Furthermore, expansion of existing communities seems to produce a more subdued response as compared to the case of developing new locations to accommodate the influx of new residents.
One major difference between streams in heavily developed areas as compared to those found in less developed areas is in terms of channel topography or complexity. Biologists have identified channel complexity as an important ingredient of stream ecology. A new strategy was devised for modeling the localized flow patterns generated by these topographic features. This new approach considers boulders and other mesoscale obstructions to the flow as part of the bed topography, instead of roughness elements. Three spatial hydraulic metrics were developed that can be used to locate and distinguish between flow features of biological importance. Coupled with other factors such as temperature, substrate, and tree cover, they can be employed in stream habitat assessment studies and stream restoration projects. Two of these studies, kinetic energy gradient and vorticity metrics, describe flow complexity surrounding a point, while the circulation metric extends the concept to an arbitrary area of interest. Comparison between urbanized and forested streams from the upper Roanoke River watershed supports the use of the metrics proposed here. The former, having been heavily engineered, exhibits rather simple geometry, low values of the metrics, and reduced biological diversity. The latter represents a more natural (complex) setting, with greater values of the metrics and abundance of species.
The biology group made some general observations and considered the changes
in the physical processes of watersheds due to urbanization and their impacts
on fish and macroinvertebrate communities. Extensive fish data collected from
the upper Roanoke River watershed (URRW) showed an increase in fish species
richness with stream width and watershed area, with small sites averaging 10.8
species, medium sites 13.8 species, and large sites 23.3 species. Small sites
had more trophic and reproductive generalists, while specialized species were
limited to larger sites. Fourteen species increased in density from small to
large sites. Regarding the impact of land use practices, fish communities suffer
at relatively low levels (as low as 2 percent) of disturbance. Metric scores,
reflecting biological integrity, started declining precipitously as the degree
of disturbed land increased and leveled out between 10 percent and 20 percent
disturbance. Biological integrity was generally low beyond 20 percent disturbance.
A similar trend occured when using the percent of disturbed land in buffers
for analysis.
Nine subwatersheds within URRW, drained by second or third order streams, were selected for extensive field sampling to determine the impact of land use change on macroinvertebrate communities. Three of them were forested, three in early stages of urban development, and three in established residential areas. Macroinvertebrate assemblages responded negatively to the development within the riparian corridor, due to reduced mean substrate particle sizes, increased stream temperature, and altered light regimes. The percent of non-forest land at the 2000 m sub-corridor scale was the best indicator of macroinvertebrate density, while taxa richness and other parameters were most strongly related to land cover within 200 m sub-corridors. Immunotoxicological tests, conducted by using Tilapia as a model laboratory species and other fish species collected from different areas of the Roanoke River exhibiting various degrees of pollution, indicated that fish may serve as an excellent biomarker for environmental pollutants/water quality, and therefore may act as warning systems for human health hazards.
Economic analysis of available data from the metropolitan area of Washington, DC, and Roanoke County of Virginia indicate that home buyers and local governments derive benefits from sprawling development. Reducing residential lot size would impose a significant cost on localities in terms of foregone property tax revenues. However, many of the public service costs are not influenced by settlement form. For example, education expenditures, the largest component of local government costs, are not particularly sensitive to spatial arrangement type. Furthermore, service costs that are sensitive to spatial arrangements of development, such as road, sewer, and water line construction, often would be transferred to the developer and home buyer. Therefore, localities such as the Roanoke Valley, which have large amounts of land relative to population, may have difficulty justifying more dense development. The establishment of subcenters offering commercial and employment opportunities alleviate household travel costs; they are not perceived to be an impediment to future sprawling development.
Land use decisions are made within the framework of private property rights as constrained by local/state/federal legislation and programs. The balance between the rights of property owners and the role of government as the protector of the public interest has changed significantly over time. Landowners traditionally have had substantial freedom to develop land, but recognition of the negative consequences of uncontrolled development on other landowners, costs of government, and environmental quality has resulted in policy and institutional mechanisms to control socially undesirable impacts. These measures have incorporated a mix of regulation, financial incentives, and other approaches. Recognition of the interjurisdictional nature of implementing environmentally sensitive settlement patterns, and recognition of the need for involvement of all the levels of government from local to federal, emphasizes the importance of coordination. Recently, several states have adopted legislation to facilitate this process. For example, Virginia legislation created a Watershed Planning and Permitting Coordinating Task Force to "foster the development of watershed planning by localities." Without such efforts to facilitate interjurisdictional coordination, boundary problems may prove to be an insurmountable obstacle to local efforts to develop and implement land use controls that address environmental quality issues effectively.
Journal Articles on this Report : 10 Displayed | Download in RIS Format
Other project views: | All 48 publications | 11 publications in selected types | All 10 journal articles |
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Type | Citation | ||
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Bosch DJ, Lohani VK, Dymond RL, Kibler DF, Stephenson K. Hydrological and fiscal impacts of residential development: Virginia case study. Journal of Water Resources Planning and Management - ASCE 2003;129(2):107-114. |
R825760 (Final) |
not available |
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Crowder DW, Diplas P. Using two-dimensional hydrodynamic models at scales of ecological importance. Journal of Hydrology, Volume 230, Issues 3-4, 8 May 2000, Pages 172-191. |
R825760 (1999) R825760 (2000) R825760 (Final) |
not available |
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Crowder DW, Diplas P. Evaluating spatially explicit metrics of stream energy gradients using hydrodynamic model simulations. Canadian Journal of Fisheries and Aquatic Sciences 2000;57(7):1497-1507. |
R825760 (1999) R825760 (2000) R825760 (Final) |
not available |
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Crowder DW, Diplas P. Assessing changes in watershed flow regimes with spatially explicit hydraulic models. Journal of the American Water Resources Association 2002;38(2):397-408. |
R825760 (Final) |
not available |
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Crowder DW, Diplas P. Vorticity and circulation: spatial metrics for evaluating flow complexity in stream habitats. Canadian Journal of Fisheries and Aquatic Sciences 2002;59(4):633-645. |
R825760 (Final) |
not available |
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Kamath AB, Nagarkatti PS, Nagarkatti M. Characterization of phenotypic alterations induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin on thymocytes in vivo and its effect on apoptosis. Toxicology and Applied Pharmacology 1998;150:117-124. |
R825760 (1999) R825760 (2000) R825760 (Final) |
not available |
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Kamath AB, Camacho I, Nagarkatti PS, Nagarkatti M. Role of Fas-Fas ligand interactions in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity: increased resistance of thymocytes from Fas-deficient (lpr) and Fas ligand-defective (gld) mice to TCDD-induced toxicity. Toxicology and Applied Pharmacology 1999;160:141-155. |
R825760 (1999) R825760 (2000) R825760 (Final) |
not available |
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Lohani V, Kibler DF, Chanat J. Constructing a problem solving environment tool for hydrologic assessment of land use change. Journal of the American Water Resources Association 2002;38(2):439-452. |
R825760 (Final) |
not available |
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Sponseller RA, Benfield EF. Influences of land use on leaf breakdown in southern Appalachian headwater streams: a multiple-scale analysis. Journal of the North American Benthological Society 2001;20(1):44-59. |
R825760 (1999) R825760 (2000) R825760 (Final) |
not available |
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Sponseller RA, Benfield EF, Valett HM. Relationships between land use, spatial scale and stream macroinvertebrate communities. Freshwater Biology 2001;46(10):1409-1424. |
R825760 (Final) |
not available |
Supplemental Keywords:
environmentally conscious development, ecosystems indicators, aquatic habitat protection, integrated assessment, watershed management., RFA, Scientific Discipline, Water, Hydrology, Water & Watershed, Ecological Risk Assessment, Ecology and Ecosystems, Watersheds, urbanization, valuation of watersheds, decision making, sediment transport, integrated assessment, aquatic ecosystems, water quality, design criteria, ecology assessment models, public policy, water management options, land use, stakeholder feedbackProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.