The interactive APEX (i_APEX) is a user friendly interface for the physical process and environmental fate model, Agricultural Policy/Environmental eXtender (APEX) (Williams et al., 2006, 2008; Williams and Izaurralde, 2006; Gassman et al., 2010). I_APEX is programmed in C++ and performs automatic...

A tool for managing large numbers of APEX runs, handling data input and output. Program Components: • ACCESS Database: Contains input tables used by i_APEX to construct APEX runs and output tables to organize APEX output. • Graphical User Interface: Allows for single runs and ranges...

In this paper, we discuss the importance of developing integrated assessment models to support the design and implementation of policies to address water quality problems associated with agricultural pollution. We describe a new modeling system, LUMINATE, which links land use decisions made at...

The purpose of this review and analysis is to provide a basic understanding of the issues related to worldwide hypoxic zones and the range of economic questions sorely in need of answers. We begin by describing the causes and extent of hypoxic zones worldwide, followed by a review of the...

The development of the field-scale Erosion Productivity Impact Calculator (EPIC) model was initiated in 1981 to support assessments of soil erosion impacts on soil productivity for soil, climate, and cropping conditions representative of a broad spectrum of U.S. agricultural production regions....

An integrated modeling system has been constructed for the Upper North Bosque River Watershed (UNBRW) in Erath and Hamilton Counties, Texas, to simulate the movement of nutrients from dairy waste disposal fields. The authors describe the environmental component of that modeling system, focusing...

This study investigates the implications of treating different environmental benefits as the primary target of policy design. We focus on two scenarios, estimating for both of them in-stream sediment, nutrient loadings, and carbon sequestration. In the first, we assess the impact of a program...

The effectiveness of conservation practices depends on their placement on the fields within the watershed. Cost-effective placement of these practices for maximum water quality benefits on each field requires comparing a very large number of possible land-use scenarios. To address this problem,...

The Raccoon River Watershed (RRW) in West-Central Iowa has been recognized as exporting some of the highest nitrate-nitrogen loadings in the United States and is a major source of sediment and other nutrient loadings. An integrated modeling framework has been constructed for the RRW that...

The size, scale, and number of subwatersheds can affect a watershed modeling process and subsequent results. The objective of this study was to determine the appropriate level of subwatershed division for simulating sediment yield. The Soil and Water Assessment Tool (SWAT) model with a...