『Summary
　This paper presents and implements a framework for modeling the impact of land use practices and protection alternatives on nitrate pollution of groundwater in agricultural watersheds. The framework alternatives on nitrate pollution of groundwater in agricultural watersheds. The framework utilizes the national land cover database (NLCD) of the United State Geological Survey (USGS) grid and a geographic information system (GIS) to account for the spatial distribution of on-ground nitrogen sources and corresponding loadings. The framework employs a soil nitrogen dynamic model to estimate nitrate leaching to groundwater. These estimate were used in developing a groundwater nitrate fate and transport model. The framework considers both point and non-point sources of nitrogen across different land use classes. The methodology was applied for the Sumas-Blaine aquifer of Washington State, US, where heavy dairy industry and berry plantations are concentrated. Simulations were carried out using a developed framework to evaluate the overall impacts of current land use practices and the efficiency of proposed protection alternatives on nitrate pollution in the aquifer.

Keywords: Nitrate; Groundwater; Agriculture; Land use; Contamination; Modeling; Management』

Introduction
Modeling framework
　Overall description
　On-ground nitrogen loadings
　Soil nitrogen dynamics
　Groundwater flow and nitrate fate and transport
Application of the modeling framework
　Description of the study area
　Nitrogen sources and loadings
　Soil nitrogen dynamics
　Groundwater flow model
　Nitrate fate and transport model
Calibration
　Calibration data
　Calibration parameters
　Calibration approach
　Calibration and verification assessment measures
　Calibration and verification results
Sensitivity analysis
Simulation of the protection alternatives
Capabilities and advantages
Summary and conclusions
References