Plant Competition

28 December 2015

Cody Zilberberg, Jay Angerer, Lori Metz, and Jimmy Williams are working to introduce both interspecies plant competition and selective grazing into APEX. They are using modules for plant competition based on the ALMANAC model and the selective grazing component of PHYGROW. This development will allow APEX to realistically simulate grazing by and weight gain of cattle, sheep, and goats, as well as calving and weaning dates, rotational grazing, and methane emissions. For more information contact Dr. Williams (


21 December 2015

Kate Behrman and Mari-Vaughn Johnson are working with Jimmy Williams to develop an improved wetland component for APEX. It is based on the denitrification subroutine developed by Cesar Izaurralde. Contact Dr. Behrman ( for more information.


14 December 2015

Kyung Hwa Cho is interested in fecal bacteria dynamics in surface waters. Since existing watershed models have limitation in simulating seasonal variability of fecal bacteria, he has developed new bacteria subroutines for SWAT to improve its prediction accuracy. He is testing the new modules with observations from different sites. For more information contact Dr. Cho (

New Landscape Contaminant Modeling System

7 December 2015

The US Army Corps of Engineers is developing a new landscape-scale contaminant modeling system to identify and simulate the fate of sediment, nutrients, and chemical contaminants over large spatial and temporal scales. The system uses:

  • SWAT to simulate overland and small stream flows of water, sediment, nutrients and agricultural pesticides
  • ATTIC (Advanced Tool for Tracking Industrial Chemicals) to identify commercial sources of specific chemicals of interest
  • CSM (Contaminant Simulation Module) to simulate the transformation of contaminants in large streams
  • NSM (Nutrient Simulation Module) to simulate algae, C, O, N, and P dynamics in large streams
  • HEC-RAS (River Analysis System) to simulate flows and sediment transport in large streams.

The system is being tested in the Calleguas Creek Watershed in California. For more information contact Dr. Billy Johnson (

Massive EPIC Analysis for the UK

30 November 2015

Robin Taylor is working with researchers at the University of Durham (UK) to use EPIC to conduct a massive factorial simulation experiment to determine if crop rotations can be used to reduce runoff, erosion, and nutrient losses from farm fields in the UK. The study involves 18 crops in 941 crop rotations grown on two sites, four slopes, eight soils, and 169 fertilizer combinations.  The USDA-ARS computer cluster is being used, allowing 150 simultaneous runs to be executed simultaneously. To date, approximately 14 million runs have been completed, and about 8 million runs remain. For more information, contact Dr. Taylor (

Rice Paddies

23 November 2015

A group of SWAT developers, including Drs. Balaji Narasimhan (, Phil Gassman (, Jaehak Jeong (, Tasuku Kato (, recently met in Tokyo to discuss and plan improvements in simulation of rice paddy irrigation, hydrology, and water quality by SWAT and APEX. For more information contact these scientists.

Short-Term Weather Forecasts

16 November 2015

Hydrologic and agricultural management models can use short-term (1-8 days) weather forecasts in SWAT format to help farmers and water authorities manage their resources.  Zach Easton (, Andrew Sommerlot ( and Daniel Fuka are developing a tool based on the NCDC/NOAA Global Forecast System to allow SWAT to project hydrology up to eight days in the future. For more information contact Dr. Easton or Dr. Fuka.

Weather Data to Simulate Climate Change Scenarios

9 November 2015

Zach Easton ( and Daniel Fuka (, are developing a tool that allows users to generate daily IPCC CMIP-5 climate change data interpolated to the precise locations of historical meteorological stations. For more information contact Dr. Easton.

Greenhouse Gas Emissions

2 November 2015

Terrestrial ecosystems can be important sources of greenhouse gas emissions (CO2, NH4, NO2), and their magnitude can be affected by land management. Zach Easton (, Moges Berbero ( and Daniel Fuka ( are developing algorithms to simulate these emissions in SWAT. Cesar Izaurralde ( is developing similar algorithms for inclusion in EPIC and APEX. For more information contact Dr. Easton or Dr. Izaurralde. 

Global SWAT Inputs

26 October 2015

As part of a US National Science Foundation B-Cube project, Zach Easton ( and Daniel Fuka ( are developing a data “brokering” system to provide ARC SWAT users with a number of global land use, digital elevation, soils, and daily weather data bases in SWAT input formats. For more information contact Dr. Easton.