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2005 Progress Report: Framework for Sustainable Watershed Management
EPA Grant Number: X3831781Title: Framework for Sustainable Watershed Management
Investigators: Najjar, Ken
Institution: Delaware River Basin Commission
EPA Project Officer: Bauer, Diana
Project Period: October 1, 2004 through May 31, 2008
Project Period Covered by this Report: October 1, 2004 through May 31, 2005
Project Amount: $102,500
RFA: Collaborative Science & Technology Network for Sustainability (2004)
Research Category: Pollution Prevention/Sustainable Development
Description:
Objective:This study takes place in the Pocono Mountains where the existing environmental resources are the region’s largest economic multiplier. The area also is experiencing the state’s second highest rate of population growth. Local concerns about sustaining water resources have stimulated an interdisciplinary modeling effort that informs the protection of baseflows in highquality streams threatened by rapid development. The project uses wild trout populations as an indicator species to gauge baseflows, as strategies that protect wild trout habitat will help sustain the creek’s water resources. The project integrates science, policymaking, community outreach, and public education through a unique iterative planning process.
Building on the foundation of an earlier pilot study of Pocono Creek, the objective of the current project is use models to develop the underlying knowledge and policy approaches required to ensure long-term sustainability of the creek’s water resources. The project has three phases: (1) technical, (2) policy development, and (3) community watershed event. The technical phase involves collecting data and building groundwater and hydraulics models. The outputs (i.e., surface water/groundwater interface, stream flows, projected impact of development on watershed hydrology, and land use scenarios) will be inputs to the third model that will calculate the flow regime necessary to support wild trout habitat. The policy development phase will use the technical information to devise strategies that will protect the conditions necessary to ensure wild trout habitat will be sustained. At the concluding community watershed event, strategies will be rolled out to key decision makers through a process that fosters collaboration and strategy implementation.
Progress Summary:Project Organization
This project is a cooperative agreement between DRBC and EPA. USGS is also a partner. Organizational functions were assigned to an administrative steering committee and support teams for the technical, policy, and outreach phases of the project. The project’s reiterative nature calls for a flexible scope, which is assessed regularly to meet the needs of the changing local conditions and changes in process and/or methodologies when necessary. The technical phase of the project is nearly complete. The groundwater flow model (capturing groundwater recharge, creek discharge, and groundwater withdrawals) and the distributed hydrologic model (capturing reductions in recharge due to impervious surfaces) have been completed. Calibration data has been collected. The remaining model to be developed is the Trout Habitat Flow model.
United States Geological Survey Groundwater Flow Model
A calibrated three-dimensional groundwater-flow model capable of simulating groundwater/surface-water interactions in the Pocono Creek Watershed was developed successfully. The groundwater flow model can evaluate the effect of groundwater withdrawals on stream baseflow and the corresponding impact on stream habitat. It also can estimate the potential reduction in stream baseflow caused by reduction in recharge from urbanization.
The model includes an upper layer representative of the unconsolidated surficial glacial deposits that are connected directly to the stream system and a lower layer representing fractured bedrock. The surface-water divide between the Pocono Creek Watershed and adjacent watersheds were considered to be a no-flow boundary. The model used the United States Geological Survey (USGS) MODFLOW computer program with the Groundwater Modeling System (GMS) as the interface (Environmental Modeling Systems, Inc., 2004). Aquifer-stream interactions were simulated using the stream-aquifer package of Prudic (1989). The model is capable of simulating groundwater discharge to Pocono Creek with various recharge and pumping rates.
Bedrock geology data were imported into the model from the digitized geographic information system (GIS) geologic map of Berg and others (1980). Thickness of the bedrock aquifer was determined by statistical analysis of available depth of water-bearing zone data. Hydraulic conductivity of the bedrock aquifer was estimated based on analysis of available aquifer-test and specific-capacity data.
Surficial glacial geology was imported into the model from the digitized (GIS) surficial geology maps of Berg and others (1977), Bucek (1971), and Epstein (1969, 1973, and 1990) that were provided to the USGS by EPA. Thickness of glacial deposits were estimated based on casing depths from the USGS Ground Water Site Inventory database and the Pennsylvania Topographic and Geologic Survey Pennsylvania Ground Water System. Hydraulic conductivity of the glacial deposits will be estimated from available data and literature values.
A seepage study, consisting of stream baseflow discharge measurements made with current meters at selected locations, was made in October. Water levels in wells in the watershed were measured at the same time as the seepage measurements are made.
Eight wells in the watershed were equipped with transducers and continuous measurement data loggers. This will provide data on aquifer response to precipitation and seasonal and annual water-level fluctuations. Water levels were measured from September 2004 to June 2006. Model calibration was based on available hydraulic data and data from the aquifer test, the seepage studies, groundwater-level monitoring data, the USGS Pocono Creek streamflow-measurement station (01441495), and water budgets for the Pocono Creek Watershed (Sloto and Buxton, 2005).
The model is calibrated to hydrologic conditions at the time of the seepage study, which corresponds closely to long-term average conditions. Long-term average conditions were determined by correlating discharge at the Pocono Creek streamflow measurement station with discharge at a long-term streamflow-measurement station in an adjacent watershed underlain by the same geologic units. The model input is ground-water recharge; output from the model is the groundwater discharge to the Pocono Creek. A steady-state simulation approximates long-term average conditions in the Pocono Creek Watershed.
The effect of groundwater withdrawals on stream baseflow were simulated by using hypothetical pumping wells in selected subbasins. This establishes the link between groundwater withdrawals and streamflow depletion. The maximum reduction in stream baseflow was determined for each scenario by using steady-state simulations. The reduction in streamflow that causes a 5 percent habitat loss will be provided by the Pennsylvania Fish and Boat Commission using the Pennsylvania Instream Flow Model (Denslinger and others, 1998). The model will be used to determine the groundwater withdrawal rate that would cause a streamflow loss corresponding to a 5 percent habitat loss.
The effect of reduction in recharge on stream baseflow caused by increased impervious area attributed to urbanization also was simulated by using the reduction in recharge provided by EPA from the distributed hydrologic model, described below. The same scenario was simulated, one with no reduction in recharge and one with reduced recharge, and compared to estimate the effect on stream baseflow.
Data Collection
A monitoring program has been ongoing. EPA’s Office of Research and Development (ORD) Edison, New Jersey, supplied in-stream equipment and training to support the collection of flow information. The program records water temperature in Pocono Creek and several tributaries. Automated logging equipment (YSI 6600 sondes) also records dissolved oxygen, pH, conductivity, water depth, and turbidity at three locations throughout the basin. In two locations, installed flow meters (American Sigma 950) record the depth and flow velocity that is used to estimate the flowrate in subwatersheds. Tipping buck rain gauges are installed at two locations to monitor and document the total rain fall the spatial heterogeneity.
The Distributed Hydrologic Model
A Soil and Water Assessment Tool (SWAT) model was developed by EPA. Adapted to be used as watershed hydrologic model, it is able to quantify the impact of land-use changes on peak runoff during storm events and low flows during base-flow periods. The goal is to identify a relationship between land-use changes (increased imperviousness) on the frequency of peak runoff and low and high flows, and identify areas in the watershed that may contribute mostly to anticipated changes.
Run on a Graphical User Interface within a GIS, the SWAT has a process-based runoff, channel, and baseflow components and operates on a daily time step and combines digital elevation maps (DEM), soil, and land-use maps, and channel characteristics with excess runoff and channel flow simulators.
The model was calibrated based on database supplied by the Delaware River Basin Commission. The data includes DEM, land-use maps, GIS soil data, and streamflow measurements obtained from a USGS gauge station located upstream from the mouth of the watershed. Climate data, including precipitation measurements, were obtained from the nearest National Oceanic and Atmospheric Administration gage stations. Next Generation Radar Rainfall also was evaluated as an alternative source for spatiotemporal precipitation.
The model is calibrated and verified, and its predictive uncertainty is quantified to examine forecast capability through time series analysis and Monte Carlo simulation. The model can simulate hypothetical scenarios of land-use changes (increased imperviousness) with stochastically generated rainfall events. The model results will quantify potential impacts of land use changes on ground water recharge and frequencies of low and high flows.
The USGS Ground Water Model and EPA’s ORD Distributed Hydrologic Model have been developed, run, and final reports are expected in August. The models have established existing conditions and projected outcomes from withdrawals and development impacts. Using a 20-year framework and build-out scenarios, the impacts from withdrawals on baseflow and the impact from development on flow were determined.
Future Activities:The investigators did not report any future activities. The remaining technical phase activity is to develop the trout habitat flow regime model.
Next is the policy development phase, which will use the technical information to devise strategies that will protect the conditions necessary to ensure wild trout habitat will be sustained. Finally, at the concluding community watershed event, strategies will be rolled out to key decision makers through a process that fosters collaboration and strategy implementation.
Journal Articles:No journal articles submitted with this report: View all 1 publications for this project
Supplemental Keywords:baseflows, wild trout habitat, Pocono Creek, watershed management, glacial geology, surficial geology, ground-water discharge,
Relevant Websites:
http://www.epa.gov/ordntrnt/ORD/NRMRL/lrpcd/esm/projects/117863.htm
http://www.state.nj.us/drbc/pocono.htm 
http://pubs.usgs.gov/sir/2005/5113/
http://water.usgs.gov/nrp/gwsoftware/modflow2005/modflow2005.html
http://www.ems-i.com/GMS/GMS_Overview/gms_overview.html
Progress and Final Reports:
Original Abstract
2007 Progress Report