Practitioners of watershed management are increasingly turning to computer models to understand and make decisions about the diverse problems that occur in the watershed. Such models can provide insight into how human interactions with the landscape affect water quality and quantity. Additional modeling tools trace how those effects ripple through ecosystems, economies, and other systems. In the past, models were stand-alone and process-specific, aimed at solving problems related to a narrow discipline. For example, hydrologic models analyzed the quantity of flow through waterways. Separate ecological models probed the cycling of nutrients in those waterways. An emerging trend for watershed-based models is to link them to a geographic information system (GIS), which provides the basis for integrating data, algorithms, and methods from each discipline of interest. This integration capability makes GIS a very powerful tool for the watershed manager. The GIS in this study within the Upper Roanoke River Watershed integrates modeling efforts from the fields of hydrology, economics, and ecology. The main goal of this study is to demonstrate the effectiveness of GIS as an integrating and computational aid for making sound decisions about a watershed. A secondary goal is to include GIS functionality in a prototype software application for evaluating the effects of land management decisions. The application, named DesktopL2W, can be a significant tool for choosing how and where development should occur within the boundaries of a watershed. The three major results of the study are: (1) a library of spatial data that is valuable for watershed analysis; (2) a set of procedures for undertaking a GIS integration project; and (3) the DesktopL2W software product with its usefulness to planners and others who are interested in how development affects the watershed. In addition, discussion of technical issues, such as selection of data formats and spatial and temporal resolution, provides insight into the complexities associated with a GIS integration effort. / Master of Science

Due to recent changes in agricultural practices the nutrient load in our waterways has increased causing eutrophication and hypoxia. Many legislative actions have taken place because of this problem, including the Clean Water Act of 1972 (CWA), and many different nutrient reduction plans. The CWA governs that impaired waterways must be monitored to meet total maximum daily loads (TMDL) for each watershed. TMDL's must be assessed using data collected over a period of time so that reduction techniques can be administered. TMDL assessments are usually conducted by the United States Geological Survey (USGS) through many different monitoring programs. The USGS programs include collecting streamflow and nutrient concentration data and using the information to estimate nutrient loads. Generally, grab sampling is the method of choice for concentrations. Grab samples do not accurately assess the total load as generally only 6-8 samples can be collected over a year due to financial and logistical constraints, while concentrations vary within a span of hours and days. Research applications involve the use of automated sensors (e.g., ISCO) that allow for more frequent sampling in order to overcome this issue but are expensive to purchase and maintain. Thus the development of an inexpensive, passive sampler would be of much interest in estimating load. The Passive Surface Flux Meter (PSFM), an integrative sampler that estimates the total solute load over a storm event, is such an alternative. The PSFM is composed of two sorbents one to collect the contaminant of choice and another to determine the flow through the device. Ion-exchange resin was used to collect nitrates, while Granular Activated Carbon dosed with a suite of alcohols were used to determine flow through the sampler. This thesis sets forth the fundamental theories behind the PSFM, and investigates its ability to measure nutrient fluxes in the field. In-situ deployments within Clear Creek watershed in Iowa were conducted using a modification of the PSFM design by Boland (2011). There was a strong linear relationship between the loads estimated by the PSFM, and "true" load based on USGS stream gage data, and Nitratax sensor data. This implies that the device could be calibrated to work in the field. However, it was determined that the design underestimated the true load in the stream by 29%. This was attributed to the nonlinear relationship between the external velocity and the flow through the sampler, which weighted the results towards the high flow events. To overcome this constraint, a new design is proposed in which flow through the sampler varies linearly with the transient head at the inlet. Flume experiments done under different flow depths proved that linearity conditions were satisfied. Using the results from the laboratory experiments recommendations were made for design of an in-situ deployment of the new design.

The development and use of web-enabled tools for watershed modeling and decision-making have gained popularity lately with the increase in internet speed and accessibility. Most of the web-enabled tools available today address the watershed problems related to a narrow discipline like hydrology, or ecology etc. This thesis presents the work done in the development of a web-enabled integrated system, named WebL2W, which can address watershed problems in a more holistic approach. WebL2W integrates models from hydrology, economics, and biology in a single shell. The integration is performed using GIS as a common platform for database and interface management. A user accesses the system over the web and chooses pre-selected land development patterns to create a 'what if' scenario. The hydrologic model simulates effects of the scenario on annual runoff volume, flood peaks of various return periods, and ground water recharge. The economics model evaluates the changes in land value, tax revenue, and government expenditures as a result of the new land development scenario. The biology model evaluates effects of new land uses to fish habitats in the watershed. The design of the system is based on current software engineering practices such as object oriented programming (OOP) and relational database management system (RDBMS). The implementation uses the Visual Basic programming environment and Active Server Pages. / Master of Science

Reliable estimates of river discharge and sediment transport to the ocean from large tidal rivers are vital for water resources management, efficient river and harbor management, navigational purposes, and climate analyses. Due to the difficulties inherent in measuring tidal-river discharge, hydrological and sedimentological records are typically too short to adequately characterize long-term (decadal) trends. Also, uncertainties associated with observation and calibration of hydrological models suggest a need for more accurate methods based on longer records of hydrodynamic parameters (e.g. tides). Tidal theory indicates that tides and river discharge interact through quadratic bed friction, which diminishes and distorts the tidal wave as discharge increases. In this study, using tidal constituents, astronomical forcing and a model of the frictional interaction of flow and tides, I propose a novel Tidal Discharge Estimate (TDE) to predict freshwater discharge with an approximate averaging interval of 18 days for time periods with tidal data but no river flow records. Next, using continuous wavelet analysis of tidal properties, I develop a method of estimating river discharge using tides measured on multiple gages along tidal rivers to improve the time-resolution and accuracy of TDE. The applicability of the Multiple-gauge Discharge Estimate (MTDE) is first demonstrated in the two largest tidal-fluvial systems of the Pacific Northwest, the Columbia River Estuary (CRE) and Fraser River Estuary (FRE). A numerical model of an idealized estuary with similar forcing as the FRE and CRE is next run under different hydrologic and morphologic scenarios to evaluate the effect of convergence, friction, and river flow variations on the applicability of MTDE. The TDE method was applied to the San Francisco Bay, using the continuous hourly tide record available since 1858. Results show that TDE reproduces known San Francisco (SF) Bay delta inflows from 1930-present with a Nash-Sutcliffe coefficient of 0.81 and is a useful method for hindcasting historical flows from 1858 - 1929, a period that predates direct measurement of delta discharge. I also recover and digitize ~80 years of Sacramento River daily water level data between 1849 and 1946, from which river discharge to SF Bay is estimated on a daily basis, after adjusting for changes to the river channel. This discharge combined with Net Delta Outflow Index estimates (1930 - 2011) and flow estimates from tidal data (1858 - 2011) provides a more accurate version of SF Bay historic daily inflows from 1849 - 2011. Next, the history of sediment transport and discharge into SF Bay from 1849-present is reevaluated using the daily discharge estimates. A non-stationary rating curve between river flow and sediment transport is developed, with net sedimentation observed during five bathymetric surveys that were used to constrain the total integrated sediment discharge. Results show that ~1600±320 million-tons of sediment have been delivered to SF Bay between 1850 and 2011. There has been an approximately 25 - 30% reduction of annual flow since the 19th century, along with decreased sediment supply. This has resulted in a ~60% reduction in annual sediment delivery to SF Bay. The annual hydrograph of inflow to SF Bay and the seasonality of sediment flux have changed considerably over time, due to both human alteration and climate change. Significant historic spring-melt peak floods have disappeared in the modern system and now peak flows mostly occur in winter. My flow estimation methods also confirm that the flood of January 1862 had the largest daily sediment load and the second largest daily discharge since 1849.

I hypothesized that vegetation and physical environmental characteristics would differ between the upper and lower extents of the annually flooded riparian zone on the John Day River, and that relationships between species and environmental variables would display differences between these two zones. Vegetation, environmental variables, and relationships between them were assessed for the entire annually flooded riparian zone, and for the proposed upper and lower zones. Data were collected from 60 one-square-meter quadrats: 30 in each the upper and lower zones. Sites were randomly selected and located so that flood duration was roughly equal at all sites within each zone. 34 plant species were encountered: 25 in the upper zone, 27 in the lower zone. Wetland obligate and facultative wetland species groups and eight individual species accounted for statistically different percentages ofquadrat cover between zones. ANOSIM analysis identified two statistically distinct vegetation communities between the two zones. Soil texture averaged 75.85% sand and 20.81% fines. Sand ranged between 36.69% and 95.55%. Fines ranged between 2.54% and 58.84%. A horizon depths and fine soil particle concentrations were greater in the upper zone. Coarser soils with more sand and gravel dominated the lower zone. All enviromnental variables studied, except pH, were highly variable throughout the study area. ANOSIM analysis results suggest that the upper and lower zones have distinct, statistically different physical environments from each other. Regression analyses relating species quadrat cover to physical environmental variables were performed for the total, upper, and lower riparian zones. Numerous differences were identified between the upper and lower riparian zones that the riparian scale analyses did not represent accurately. There were ten instances in which the zone scale analyses identified a relationship in either the upper or lower zone, while the corresponding riparian scale analysis failed to identify any relationship. The results of this study indicate that vegetation and the physical environment are statistically different between the upper and lower zones on this river, and that relationships between a given plant species and environmental variable can vary between zones. Future research and management efforts should consider and address the potential for such between-zone variation.