Grantee Research Project Results
Final Report: Development and Evaluation of Ecosystem Indicators for Urbanizing Midwestern Watersheds
EPA Grant Number: R825871Title: Development and Evaluation of Ecosystem Indicators for Urbanizing Midwestern Watersheds
Investigators: Spacie, Anne , Hondzo, Midhat , Engel, Bernard A. , Harbor, Jonathan M.
Institution: Purdue University
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1997 through September 30, 2000
Project Amount: $672,323
RFA: Ecosystem Indicators (1997) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
Urbanization is thought to have negative long-term impacts on stream ecosystems and yet the actual causal relationships between land use change and stream community response have not been well studied. The assumption has been that impervious area within an urban watershed leads to increased runoff during storm events. Such runoff might then contribute to greater erosion, stream channel instability, water quality degradation, and aquatic habitat disturbance. Yet specific predictions on long-term hydrologic impacts, expected changes in stream quality, and stream ecosystem response have been lacking. The focus of this project is on the development of predictive indicators of urbanization that are applicable to midwestern watersheds and stream ecosystems. Predictive models of hydrologic change are combined with field observations in urbanizing watersheds to develop a practical approach to measuring urban stream condition and forecasting impacts of future land-use change on aquatic resources.The objectives of this research project were to:
1. Quantify the impacts of urbanization on hydrologic regimes, water quality, and habitat structure of stream ecosystems using paired experimental watersheds, and to develop linked models that accurately predict these impacts.
2. Use the linked models as a virtual laboratory within which to generate and test indicators of urbanization and hydrologic change in terms of responses of fish and macroinvertebrate communities.
3. Use these models and indicators to assess the response of stream communities to alternative urbanization scenarios with extension to larger watersheds in the region.
The research examined eight 3rd order watersheds in central Indiana. Seven are in the greater Indianapolis area (Marion County) and one is located near Purdue University (Tippecanoe County). Additional streams also were used for particular aspects of the project.
Summary/Accomplishments (Outputs/Outcomes):
The small streams addressed in this project are runoff-dominated and highly variable in their flow characteristics. Stream biota may be affected adversely by transient conditions occurring at peak or low flow. Physical factors affecting the flow and temperature of such streams were examined by the development of a numerical model of one-dimensional unsteady stream flow and temperature (Younus, et al., 2000). This model was successful in predicting flow and temperature fluctuations every 15 minutes over a 25-day measurement period. The two most significant factors in determining stream temperature under these conditions were subsurface inflow and solar radiation, both of which could be altered by land use changes. Observed diurnal fluctuations in dissolved oxygen also were studied by applying an empirical model using the Extreme Value Method. This approach successfully predicted 15-min oxygen readings taken in two of the streams over a 50-day period (Indian and Little Eagle Creeks). Dissolved oxygen and temperature monitoring in these streams under late-summer low-flow conditions over 2 years suggest that neither high temperature nor low oxygen are likely limiting factors for stream communities in this region. Scouring during high flow and/or habitat loss during low flow are more probable limiting factors.Even though biological impacts may be defined by relatively short-term events, long-term hydrologic responses to land use change at the watershed scale also are important to understand and to forecast in light of the rapid urbanization of this region. A long-term hydrologic impact assessment (L-THIA) model to predict annual runoff and NPS pollutant loading has been developed using the curve number method (Bhaduri, et al., 2000). Input requirements include long-term climatic records, soil types, and land use information. The model is linked to a GIS for generation and management of model input and output data, and is directly accessible at a Web site (see URL below). Because of its convenience and utility, the L-THIA modeling approach is expected to be highly useful to regional planners and has already been adopted by the "Planning with POWER" program, a statewide extension program in support of watershed planning at the local level (URL below).
The L-THIA model was applied to Little Eagle Creek, which has undergone an 18 percent increase in urban (impervious) area between 1973 and 1991. This urbanization has led to an estimated 80 percent increase in annual average runoff volume (supported by USGS gage records) and estimated increases of more than 50 percent in annual average loads for Pb, Cu, and Zn. At the same time, estimated nutrient (N and P) loads decreased by 15 percent due to the loss of agricultural land. Water quality sampling done in conjunction with the biological surveys for this project showed that nutrient levels in the Indianapolis streams are actually lower than those predicted by L-THIA, and significantly lower than values for nearby rural streams.
The increased runoff predicted by L-THIA and observed in USGS gage records for Indianapolis streams should lead to stream channel enlargement, either by lateral (bank) or downward erosion of the bed. This would be expected to cause changes in biota sensitive to substrate disturbance. Seven of the study streams in this project were surveyed for geomorphic stability (Doyle, et al., 2000). Two qualitative and seven quantitative stability measures were tested to distinguish between stable and degrading sites. Quantitative measures including shear stress, bankfull flow, and flow that mobilizes the bed were generally more successful predictors than the qualitative measures. Overall, urbanization was not a distinguishable causal factor in channel instability, but certain measures of channel instability were associated with higher levels of urbanizations.
Stream periphyton, macroinvertebrates, and fish communities were sampled and evaluated as possible urbanization indicators for this study. Periphyton biomass was similar between the rural and urban streams receiving significantly different NPS pollution, which suggests that nutrients (N and P) are not a critical factor structuring periphyton communities. Rather, light levels, which are generally higher at downstream sites or sites without riparian shading, appear to determine the amount of growth. High periphyton biomass was correlated with large diurnal fluctuations in dissolved oxygen. Little Eagle Creek had the lowest periphyton production, and also had the smallest dissolved oxygen changes of any stream measured. Experimental flumes were used to simulate the increased shear stress that occurs during stormflow peaks. Scouring of the periphyton occurred during such events, but regrowth was rapid. Greater community resistance was observed under the higher nutrient conditions, while greater resilience of the community was found at the lower nutrient levels.
The diversity of freshwater mussels (Unionidae) is particularly high in the rural streams of Indiana. Many of these are becoming rare throughout the Midwest. Although mussels were not a part of the original plan for this project, we were fortunate to obtain survey data for the small streams in Tippecanoe and Marion Counties. These observations (presence/absence) were matched with the channel stability metrics described above to examine the relationship between mussel occurrence and habitat. Most mussel species have a preference for substrates in stable, nonerosional sites. Increased runoff and channel instability could jeopardize the depositional habitats in urbanizing streams. Thus, we found that the urban streams have reduced mussel populations (present at 28 percent of urban sites) compared to similar rural streams (46 percent of sites). Sites with unstable channels and high shear stress (whether in urban or rural areas) were negatively correlated with the presence of mussels (p < 0.03) (Myers-Kinzie, et al., in press). Because of their slow growth, long life spans, poor dispersal, sensitivity to erosion, and complex reproductive requirements, it is clear that freshwater mussels are especially vulnerable to physical habitat degradation. The fact that they have not been routinely surveyed or studied as ecological indicators is a concern because their habitat requirements are so distinct from other stream organisms.
Aquatic insects and stream fishes, in contrast, have been extensively surveyed and studied for use as indicators of various environmental conditions. Even for these, however, changes in community structure that can be directly linked to the hydrologic changes of urbanization have rarely been reported. For the present study, insect and fish communities were sampled at three sites in each of the study streams over a 2-year period. It should be noted that the sites selected for this project were located in the best available habitats, as far as possible from any known point source discharges, construction activity, or other obvious disturbance. Only two of the streams (the most urban) receive storm sewer discharges.
A total of 35 insect families were found in eight watersheds. Metrics tested included proportion of clingers, scrapers, filterers/collectors, EPT organisms, chironomids, dominant two taxa, Diptera, ratios of Hydropsychidae/Trichoptera, Baetis/Ephemeroptera, and family-level Hilsenhoff indices. Using single-factor ANOVA of sites grouped by watershed, the most significant differences were revealed by the proportion clingers and the ratio of Baetis to total Ephemeroptera.
Regression showed that many metrics respond to increased imperviousness. The proportion of Diptera, family Hilsenhoff index, the ratio of Baetis to total Ephemeroptera, and proportion of Chironomidae increased significantly, while the proportion of clinger taxa, number of nonchironomid genera, number of Ephemeroptera, Plecoptera, and Trichoptera (EPT) genera and proportion of filterers/collectors significantly decreased. The proportion of scrapers showed no significant trend.
Of these, increased imperviousness was most clearly associated with a decrease in the proportion of clinger taxa (insects susceptible to substrate scouring) and an increase in the ratio of Baetis to total Ephemeroptera. The ratio of Baetis to total Ephemeropta is recommended as a new urbanization indicator. It was not highly correlated to the other commonly used metrics in this study, and therefore, would not provide redundant information. Both of these metrics show a clear change at very low levels of urbanizations (approximately 5 percent imperviousness). This is a level at which midwestern streams still appear unimpacted (having a good riparian buffer, typical riffle-pool development, clean gravel, etc.).
Evaluation of fish community metrics for these same sites generally supported the negative relationship with imperviousness, but fewer of the metrics tested were clearly significant. Of these, the frequently used index of overall fish habitat (QHEI) was clearly correlated (negatively) to watershed imperviousness. Overall quality of the fish community (as measured by the index of biotic integrity, IBI) declined with imperviousness. The proportion of darters and sculpins was significantly related to channel instability and percent imperviousness. However, many other metrics, such as proportion of insectivores, were not associated with imperviousness or any of the habitat characteristics tested.
In summary, this project has produced an array of tools for use in evaluating the response of midwestern watersheds and streams to increase urbanization. The dynamic hydrology, temperature, and oxygen models are most applicable for engineers, biologists, and water quality managers working with specific stream reaches. The L-THIA approach is ideal for planners and others looking at larger scale, long-range situations. Specific urbanization indicators have been tested using channel geomorphology, freshwater mussels, aquatic insects, and fish that have good potential for widespread application in the region.
Journal Articles on this Report : 8 Displayed | Download in RIS Format
Other project views: | All 35 publications | 9 publications in selected types | All 8 journal articles |
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Bhaduri B, Harbor J, Engel B, Grove M. Assessing watershed-scale, long-term hydrologic impacts of land-use change using a GIS-NPS model. Environmental Management 2000;26(6):643-658. |
R825871 (2001) R825871 (Final) |
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Bhaduri B, Minner M, Tatalovich S, Harbor J. Long-term hydrologic impact of urbanization: A tale of two models. Journal of Water Resources Planning and Management 2001;127(1):13-19. |
R825871 (2001) R825871 (Final) |
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Doyle MW, Harbor JM, Rich CF, Spacie A. Examining the effects of urbanization on streams using indicators of geomorphic stability. Physical Geography 2000;21(2):155-181. |
R825871 (2001) R825871 (Final) |
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Grove M, Harbor J, Engel B. Composite vs. distributed curve numbers: effects on estimates of storm runoff depths. Journal of the American Water Resources Association 1998;34(5):1015-1023. |
R825871 (2001) R825871 (Final) |
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Grove M, Harbor J, Engel B, Muthukrishnan S. Impacts of urbanization on surface hydrology, Little Eagle Creek, Indiana, and analysis of LTHIA model sensitivity to data resolution. Physical Geography 2001;22(2):135-153. |
R825871 (Final) |
Exit |
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Myers-Kinzie M, Spacie A, Rich C, Doyle M. Relationship of unionid mussel occurrence to channel stability in urban streams. Verhandlungen International Vereinigung Limnologie 2002, 28: 1-5. |
R825871 (2001) R825871 (Final) |
not available |
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Pandey S, Gunn R, Lim KJ, Engel B, Harbor J. Developing a Web-enabled tool to assess long-term hydrologic impacts of land-use change: information technology issues and a case study. Urban and Regional Information Systems Association Journal 2000;12(4):5-21. |
R825871 (Final) |
Exit Exit |
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Younus M, Hondzo M, Engel BA. Stream temperature dynamics in upland agricultural watersheds: measurements and modeling. Journal of Environmental Engineering 2000;126(6):518-526. |
R825871 (1999) R825871 (2001) R825871 (Final) |
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Supplemental Keywords:
watersheds, ecological effects, ecosystem, indicators, scaling, aquatic, habitat, integrated assessment, engineering, ecology, hydrology, modeling, Midwest, Indiana, IN, EPA Region V, integrated assessment., RFA, Scientific Discipline, Geographic Area, Water, Ecosystem Protection/Environmental Exposure & Risk, Hydrology, Midwest, Water & Watershed, Ecosystem/Assessment/Indicators, Ecosystem Protection, State, Ecological Effects - Environmental Exposure & Risk, Wet Weather Flows, Environmental Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, EPA Region, Watersheds, aquatic ecosystem, hydrologic dynamics, ecological exposure, anthropogenic processes, urbanization, aquatic, nutrient transport, anthropogenic stresses, ecological effects, remote sensing, risk assessment, scaling, suburban watersheds, Indiana, aquaculture, aquatic biota , ecosystem assessment, satellite images, watershed protection, ecosystem evaluation, runoff, urban runoff, stream ecosystems, urban ecosystems, urban watersheds, modeling, large-scale regional studies, integrated assessment, regional scale, water quality, stream flow, aquatic ecosystems, Indianapolis, ecosystem health, environmental stress, remotely sensed data, Region 5, IN, dissolved oxygen , ecological indicators, fish , aquatic biotaRelevant Websites:
http://danpatch.ecn.purdue.edu/~sprawl/LTHIA7/
(the L-THIA model)
http://www.planningwithpower.org/
(the Planning with POWER program)
http://www.eas.purdue.edu/geomorph/
(research on geomorphology)
Progress 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.