News

Bacteria

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 (khcho@unist.ac.kr).

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 (Billy.E.Johnson@erdc.dren.mil).

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 (rtaylor@brc.tamus.edu).

Rice Paddies

23 November 2015

A group of SWAT developers, including Drs. Balaji Narasimhan (nbalaji.iitm@gmail.com), Phil Gassman (pwgassma@iastate.edu), Jaehak Jeong (jjeong@brc.tamus.edu), Tasuku Kato (taskkato@cc.tuat.ac.jp), 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 (zeaston@vt.edu), Andrew Sommerlot (andrewrs@vt.edu) 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 (zeaston@vt.edu) and Daniel Fuka (drfuka@vt.edu), 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 (zeaston@vt.edu), Moges Berbero (bwmoges@vt.edu) and Daniel Fuka (drfuka@vt.edu) are developing algorithms to simulate these emissions in SWAT. Cesar Izaurralde (cizaurra@umd.edu) 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 (zeaston@vt.edu) and Daniel Fuka (drfuka@vt.edu) 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.

Dynamic Soils Data

19 October 2015

In most landscapes soil depth and other properties vary with landscape position. This can lead to over- and under-estimation of properties that control hydrology and plant growth. This is an especially serious problem in soil data bases like FAO in which soil map units are large. To address this problem Zach Easton (zeaston@vt.edu) and Daniel Fuka (drfuka@vt.edu) have developed a tool to adjust SWAT soil parameters (depth, saturated conductivity, available water content, sand, silt, clay, and organic matter) for landscape position. These adjusted soil parameters are then output in SWAT input format at the scale of the base DEM of the SWAT model. The tool will soon be available by contacting Dr. Easton.

Tropical Vegetation

12 October 2015

Early versions of SWAT did a poor job of simulating the leaf area dynamics of perennial tropical vegetation like forests and savannas in which drought rather than cold temperatures triggers annual leaf senescence and the onset of the rainy season stimulates their regrowth. For his work in Brazil, Michael Strauch (michael.strauch@ufz.de) developed algorithms to address this issue. It requires the user to input the beginning and ending months of the transition period at the end of the dry season when plant growth is expected to resume, as well as the soil moisture content that triggers regrowth. Functioning only at latitudes between 20ºN and 20ºS, the algorithm causes leaf area index to fluctuate realistically between the minimum and maximum LAI of the vegetation type. This improvement has recently been incorporated into SWAT2012 and SWAT+. For more information contact Dr. Strauch.