Christopher J. Woltemade

A watershed modeling analysis of fluvial geomorphologic influences on flood peak attenuation

Flood peak attenuation caused by storage of flood water on overbank surfaces effectively reduces the magnitude of peak discharges in some, but not all watersheds. Several geomorphic factors that affect the storage and conveyance of flood water were investigated to assess their quantitative influence on downstream peak discharges. The MIKE11 rainfall-runoff and hydrodynamic models were calibrated for the Grant River watershed, southwestern Wisconsin. Alternative geomorphic conditions were modeled and compared to the original case. Results indicate that channel-floodplain-terrace morphology, valley width, stream slope, and hydraulic roughness each influence peak discharges, especially for moderate magnitude (5- to 50-year recurrence interval) floods. Peak discharges varied by as much as 49% between simulations depending on geomorphic conditions. Watersheds that effectively attenuate produce peak discharges that are strongly correlated with total runoff. Watersheds that attenuate little produce peak discharges that exhibit greater variance due to storm intensity and duration.

DESIGN, IMPLEMENTATION, AND ASSESSMENT OF AN UNDERGRADUATE INTERDISCIPLINARY WATERSHED RESEARCH LABORATORY

In 1999 Shippensburg University established the Burd Run Interdisciplinary Watershed Research Laboratory. The Laboratory uses a local watershed to provide intensive undergraduate field training in the collection and analysis of environmental data, which are then compiled into a comprehensive statistical and spatial watershed database. Geographic information systems serve as the projects organizational focus, providing a powerful tool for data display, analysis and snaring. We emphasize a systems approach that links disciplinary perspectives across courses in geology, geography, biology, and teacher education. Important linkages among watershed characteristics, water quality, and aquatic ecology are emphasized over several semesters, allowing students to build and integrate scientific skills throughout their education using the watershed as a common case study. The Burd Run Interdisciplinary Watershed Research Laboratory provides an easily adaptable conceptual model for improving environmental science education at teaching-oriented institutions nationwide. Its success is largely attributable to three factors: (I) the project is student-centered and goal specific; (2) the selected watershed is accessible, diverse, and at a manageable scale; and (3) the 17-member Laboratory Advisory Board provides for continuous revision, adaptation, and improvement.

A STUDENT-CENTERED FIELD PROJECT COMPARING NEXRAD AND RAIN GAUGE PRECIPITATION VALUES IN MOUNTAINOUS TERRAIN

A team of undergraduate geoscience students compared Next Generation Weather Radar (NEXRAD) estimates of storm total precipitation to measurements from a network of 20 rain gauges. Student researchers gained valuable experience in field data collection, global positioning systems (GPS), geographic information systems (GIS), Internet data access and downloading, computer graphic analysis, descriptive statistics, and conference presentation. The project emphasized problem-solving techniques, positive interdependence and individual accountability. The study evaluated 31 storms delivering >= 0.30 inches total precipitation to one or more gauges in the 51.8 km2 Burd Run watershed, which drains a low mountainous area of south-central Pennsylvania. Rain gauge measurements fell within the corresponding range of radar estimates in less than half (46.8%) of all cases. Departures between rain gauge and radar estimates were more common for large storms (total precipitation >= 1.00 in at one or more gauges) than for smaller storms (0.30 - 0.99 in). Students explored the environmental reasons for data departures. SI units are used throughout this paper except in the case of precipitation measurements. We maintain the National Weather Service standard of using English units (inches) when discussing precipitation values.

Economic Efficiency of Residential Water Conservation Programs in a Pennsylvania Public Water Utility

This study examines the economic efficiency of implementing a residential water conservation program in a small Pennsylvania public water utility. Local demographic data and results from similar programs elsewhere were used to estimate potential water conservation for three programs: rebates for low-flow toilets, rebates for high-efficiency washing machines, and in-home water audits. Future water supply and wastewater treatment demand were estimated. The net present value of constructing, operating, and maintaining new capacity infrastructure (water supply, water storage tanks, and wastewater treatment plant capacity), as well as the costs of the conservation programs, was calculated for a range of scenarios that included future demand growth, construction costs, interest rates, and levels of participation in the conservation programs. Results indicate that investing in residential water conservation would be cost-effective for a small number of scenarios that generally combine higher growth rates, higher interest rates, higher construction costs, and relatively modest public participation in conservation. The results are affected by the timing of necessary supply-side investments relative to the most significant water conservation gains, the relatively inexpensive local water supply costs, and the relatively high local wastewater treatment costs. Water conservation might be cost-effective for a wider range of conditions in communities facing scarce and expensive water supply options.

Stream Temperature Spatial Variability Reflects Geomorphology, Hydrology, and Microclimate: Navarro River Watershed, California

Stream temperatures are critical to coldwater fish and vary with microclimate, geomorphology, and hydrology, including influx of groundwater. Spatial variability of stream temperatures was examined at reach and watershed scales within the 816 km2 Navarro River watershed in California. Field monitoring and numerical modeling illustrate that stream temperatures were highest at sites with high solar incidence (low shading and wide streams), long travel times, and low discharge. Microclimate helps explain deviation from the general pattern of streams warming with increasing drainage area. Reach-scale field observations of channel width and groundwater influx explain variation in stream temperatures not captured by watershed-scale models.