Watershed Assessment and Modeling

Watershed assessment and modeling tries to determine what are the sources and factors that affect delivery of critical pollutants in a watershed. Geographical Information System (GIS) land use/land cover research often plays a critical role in such watershed assessment and modeling efforts. Research through CSREES and the Land Grant System explores new tools, methods, and models that can help decision makers make better watershed management decisions.

Research pertaining to "Watershed Assessment and Modeling" can be broken into the following categories (linked further down on this page):
GIS Land Use/Land Cover Research
New Watershed Assessment Methods and Models
Evaluation of Watershed Sinks
Highlighting Partner Activities

GIS Land Use/Land Cover Research
Examining the different types of land use and land cover within a watershed can reveal important information about potential sources of contamination to its water bodies. GIS-based tools, being developed at Land Grant Universities and with CSREES funding, help to determine land use composition for a given geographical area and identify those water resources at the highest risk from agricultural or other human activities. Other research is being conducted to determine the impact of various types of cover on water quality.

Accomplishments:
Research has shown the amount of impervious surface in a watershed to be a reliable indicator of the impacts of development on water resources. The Impervious Surface Analysis Tool (ISAT) is an ArcView extension developed through a partnership between the University of Connecticut (UCONN) Nonpoint Education for Municipal Officials (NEMO) and the National Oceanic and Atmospheric Administrations’s Coastal Services Center (NOAA/CSC). It is used to calculate the percentage of impervious surface area of user-selected geographic areas (e.g., watersheds, municipalities, subdivisions) and incorporates land cover change scenarios to examine how these changes influence impervious surfaces. ISAT is helping communities minimize impervious surface as a result of land use change therefore protecting watershed health and water quality. The UCONN Geospatial Technology Program (GTP) developed population density-related impervious surface coefficients in 2002, and used them along with ISAT to generate accurate impervious surface estimates for 244 watersheds.

At North Carolina State University, studies on the infiltration rate of permeable pavements are being conducted. The focus of these studies is to determine infiltration rates and the amount of runoff reduction associated with permeable pavement use, as well as the impact of permeable pavement on water quality.

New Watershed Assessment Methods and Models
Watershed assessment methods and models are continuously improving with the help of new technology and research completed at Land Grant Universities and with CSREES funding. These models can be incorporated into tools that predict watershed responses to various types of land use, human impacts, and management practices. Once developed, these new tools can often be made accessible to their target audiences on the Internet. This provides decision makers with a wealth of research-based information to help them manage watersheds and improve water quality.

Evaluation of Watershed Assessment Models:
A regional effort in the CSREES Southern Region is developing and evaluating TMDL planning and assessment tools and processes . The goals of the project are to: develop, improve and evaluate watershed models and other approaches for TMDL development and implementation; assess potential economic benefits and costs and equity issues associated with TMDL implementation at the watershed and individual landowner scale; and assess the potential ecological benefits and implications of TMDL implementation at the watershed level.

Evaluating Pollution Risks of Different Land Uses:
MANAGE is a watershed assessment tool, developed by the University of Rhode Island NEMO , that uses computer-generated maps to evaluate pollution risks of land use and landscape features. MANAGE evaluates the cumulative effects of current land use, future development and pollution management practices on water resources. MANAGE has been tested and successfully applied in several Rhode Island communities. In these communities, MANAGE results have led to actions that protect local water resources, such as strengthening groundwater protection regulations, managing on-site wastewater systems, controlling land disturbance and expanding public education on resource protection.

University of Arkansas researchers are developing models that predict the vulnerability of ground water to nitrate and pesticides from agricultural runoff in the Mississippi Delta region. The models are based on Neural Networks, Fuzzy Logic, Neuro-fuzzy and Geostatistics, and GIS will be used to generate vulnerability maps from the models. The results of the research will be shared via the Internet with various stakeholders including policy makers and partners at local, state and federal agencies.

A watershed-scale model for the entire Connecticut River is being developed at the University of Massachusetts using GIS analysis and the Soil and Water Assessment Tool (SWAT). The objective of the model is to evaluate the effects of land use and development practices and policies on water quality and ecological integrity. Model development is still in progress, though preliminary results of the analysis can be used to identify sensitive areas of the Connecticut River Watershed that impact water quality, helping to identify vulnerable areas in need of protection.

Researchers at the University of Puerto Rico are compiling a database to predict soil erosion in the Rio Grand de Arecibo Watershed. Data will be gathered using the Revised Universal Soil Loss Equation (RUSLE), and a management plan will be developed to minimize soil loss and subsequent siltation of the Dos Bocas reservoir. Through better-informed watershed management decisions, the project is expected to improve water quality in this reservoir, which provides drinking water to over 1.5 million people.

Researchers at the University of Arkansas are developing a decision support system that will link seasonal algal growth thresholds with land use practices in the watersheds of the Eucha Basin. The system integrates environmental and resource management elements to develop a risk-based strategy for water quality management in the Eucha Basin in Oklahoma and Arkansas.

Estimating Watershed Pollutant Loads:
A project at the University of Florida aims to estimate nitrogen distribution in the Santa Fe River Watershed, using a GIS-based geo-modeling approach. Site-specific measurements of nitrate will be upscaled to the entire Santa Fe River Watershed. A long-term goal of the project is to develop recommendations for potential BMP implementation in the Santa Fe Watershed to reduce nitrogen loads leaving the drainage basin.

Researchers at the University of Vermont are developing a watershed phosphorus model . The project combines Water Ecosystem Nutrient Dynamics (WEND) modeling with GIS knowledge to create a framework for estimating phosphorus losses in a watershed that can help regional planning and watershed management. The long-term goal of the project is to reduce phosphorus deposits in Lake Champlain.

Kansas State University has cooperated with the Cheney Lake Watershed organization to develop an Annualized Agricultural Non-Point Source (AnnANGPS) model to estimate expected soil and nutrient losses from an actual rainstorm as well as predict losses for the coming year in specific parts of the watershed. The model is intended to help the Watershed board direct their efforts and funding to the most vulnerable parts of the watershed.

A decision support tool, developed at Tufts University, addresses the issue of nutrient management in watersheds . The model integrates models of watershed nutrient loads and receiving water quality into a decision-oriented optimization framework. This will allow stakeholders to define and prioritize nutrient management objectives.

Evaluating Watershed Sinks
Riparian zones, transition zones between uplands and surface water, are important locations for groundwater nitrate removal, as well as the removal of other pollutants and sediments. Research at the Land Grant Universities and with CSREES funding is examining the roles these riparian zones and artificial or constructed wetlands on water quality functions at the watershed level.

Accomplishments and Examples:
Researchers at the University of Rhode Island (URI) Watershed Hydrology Laboratory determined landscape controls of riparian zone groundwater nitrate removal . These insights were translated into methods that can be adapted to available spatial databases and enhance our ability to target high value riparian zones for protection and restoration to improve or maintain water quality. The URI NEMO Program has incorporated these results into their programming with municipal officials and modeling efforts. Additional research at the Watershed Hydrology Laboratory is examining the effect watershed land use practices on the hydrology, soils, and groundwater nitrate removal function of riparian zones.

Iowa State University researchers have demonstrated that riparian buffers re-established on previously cropped or pastured land have tremendous potential to r emediate nonpoint source pollution in agricultural watersheds . Insights from this study are being used to improve buffer performance and placement within watersheds.

Highlighting Partner Activities
Partners of CSREES have been instrumental in watershed assessment and modeling research. These models have been widely used in watershed management and have been incorporated into many different decision support systems and management tools.

Accomplishments and Examples:
Developed by the U.S. Geological Survey, SPARROW is a method for regional interpretation of water-quality monitoring data. It relates in-stream water quality measurements to spatially referenced characteristics of watersheds, including contaminant sources and factors influencing terrestrial and stream support. The model estimates the origin and fate of pollutants in streams and quantifies the uncertainty related to these estimates.

Agricultural Non-Point Source (AGNPS) is a distributed parameter model developed by USDA Agricultural Research Service scientists and engineers. It predicts soil erosion and nutrient transport and loadings from agricultural watersheds for real or hypothetical storm events.

The TMDL Assessment Report issued by the National Research Council (NRC) assesses the scientific basis of the TMDL program. The report was requested by Congress following the issuance of updated TMDL regulations by the EPA in 2000. It represents the consensus opinion of the eight-member NRC committee involved in the TMDL assessment and supports a return to ambient-based water quality management while focusing on TMDL program goals.

Indicates work supported by the USDA-CSREES National Research Initiative Competitive Grants Program .

The intent of this page is not to catalogue all activities but rather to indicate the types of research in the CSREES Watershed Management theme across the U.S.