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 (firstname.lastname@example.org) and Daniel Fuka (email@example.com) 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.
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 (firstname.lastname@example.org) 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.
5 October 2015
Use of SWAT for simulation of urban watersheds is increasing. Dr. Jaehak Jeong (email@example.com) has developed algorithms to simulate the effectiveness of several conservation practices used to control water flows and improve water quality in urban areas. These can be used with both daily and sub-daily applications, and they will soon be incorporated into the SWAT Conservation Practices Tool. Contact Dr. Jeong or Dr. R. Srinivasan (firstname.lastname@example.org) for more information.
28 September 2015
An interface designed to help SWAT users develop scenarios involving soil and water conservation practices is under development. The tool will soon be available on the SWAT website and will allow users easily to add combinations of conservation practices to selected SWAT subbasins and HRUs in order to assess their conservation benefits by subbasin or the whole watershed. Both agricultural and urban conservation practices are included in the tool kit. Contact Dr. R. Srinivasan (email@example.com) for more information.
21 September 2015
QSWAT, a QGIS Interface for SWAT has been developed by Dr. Chris George and made available with documentation and example datasets (developed by Dr. Yihun Dile) on the SWAT website. This free and open-source software will be used extensively in SWAT training, especially in developing countries where use of commercial GIS software is cost-prohibitive. For more information, see the SWAT website or contact Dr. George or Dr. Srinivasan (firstname.lastname@example.org).
14 September 2015
Worldwide CFSR daily climate data since 1979 have been available in SWAT input format on the SWAT website since November 2014 and have already provided almost 30,000 downloads. A similar interpolated version of the CFSR data base is available from Zach Easton and Daniel Fuka at Virginia Tech, from which data have already been downloaded more than 40,000 times. A number of studies have demonstrated the utility of this global daily data base for SWAT applications; however, biases in rainfall estimates have been discovered for several regions. Recent experience shows that the utility of these databases can be increased by application of a bias correction tools that are available on the SWAT and Virginia Tech websites. Contact Dr. Srinivasan (email@example.com), Dr. Easton (firstname.lastname@example.org), or Daniel Fuka (email@example.com) for more information.
7 September 2015
A new SWAT manual is under development to support the roll-out of SWAT+. It will contain chapters on all the major component processes simulated by SWAT+ written by expert SWAT users from around the world. In addition, it will include chapters on model sensitivity analysis, calibration, and evaluation. Selected datasets and exercises will also be provided to be used in academic and professional courses. The theoretical and sensitivity/calibration/evaluation components will be provided in both hard-copy and electronic formats, and example datasets and exercises will be available on line to facilitate updates. For more information contact Drs. R. Srinivasan (firstname.lastname@example.org) or Jeff Arnold (Jeff.Arnold@ars.usda.gov).
31 August 2015
A new modular version of SWAT, SWAT+, is under development! The new version will have a much-improved modular design and input file structure to facilitate addition of new and improved algorithms and subroutines. The simplified structure will be easier for users and developers to understand, and it should stimulate exchange of algorithms with other models. The new SWAT code and associated software should be available on the SWAT website before the 2016 International SWAT Conference in Beijing.
There will be a special session at the upcoming Purdue Conference, Oct. 14-16, covering the new SWAT code, input/output file structure, test datasets and a developers’ interface.
For more information contact Dr. Jeff Arnold (Jeff.Arnold@ars.usda.gov).
24 August 2015
JAVA Forge has been selected for SWAT version control. The site will include all SWAT revisions, notes, and the code for each model version. It can be obtained at: javaforge.com/svn/swatmodel. Any SWAT user can become a Java Forge member, create a login, and contact Nancy Sammons (email@example.com) for access to the SWAT site
17 August 2015
Because of SWATlite’s simplified input requirements and speed of execution, it is being used to simulate subbasin hydrology and soil erosion for the entire world. Preliminary runs for the major continents have already been executed, and the project can serve as a foundation for more complex analyses using the complete full SWAT model. Contact Dr. Srinivasan (firstname.lastname@example.org) for more information.
- Land use: available at 30 m and larger grids.
- Digital elevation: USGS, 1 km resolution.
- Daily weather: generated from CFSR.
- Soils: FAO, 1:1 million.