Tallgrass prairie once occupied 67.6 million hectares in the North American Midwest but less than 0.1% remains today. Consisting of more than 2200 ha, Neal Smith National Wildlife Refuge (NSNWR) was established by the US Fish and Wildlife Service in the 5217 ha Walnut Creek watershed in Jasper...

A watershed based model, the Soil and Water Assessment Tool (SWAT), along with transfer coefficients is used to assess alternative principles of allocating nutrient load reduction in the Raccoon River watershed in central Iowa. Four principles are examined for their cost-effectiveness and...

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...