Analyse Land Use Maps
What is it?
Land use map analysis option processes series of land use maps and creates SWAT input files based on land use changes defined by the maps and corresponding change dates and time steps. This option is can only be used if the current SWAT model is the latest SWAT model created through interactive SWAT model creation method at SwaNET. When completed, this option introduces new HRUs in current subbasins, if needed, and creates land use update files that adjust the HRU ares within each subbasin based on the dates of land use change. Thus, user can incorporate multiple land use in a single simulation.How to use it:
Define Baseline
User need to first define the baseline- the date of the current land use map. It is assumed that all the other land use changes occur after this baseline date. Thus users need to build the initial SWAT model with the earliest land use map.Upload land use maps
Users can either upload own new land use maps or import the new land maps from DataNET, a global data visualization platform at the Magnet platform. Users don't need to upload upload any lookup table if the maps are either from Magnet platform or Cropland Data Layer (CDL) or National Land Cover Database (NLCD). If from other sources, please upload corresponding lookup table. A land use look up table looks as follows:Value,Landuse
1,CORN
2,COTP
3,RICE
4,GRSG
5,SOYB
6,SUNF
Please refer to Model Databases page at the Texas A&M University for more details.
Select Update Date and Type
Next, users need to select the date of new land use map. Users can select two types of changes: abrupt or yearly. Abrupt change assumes that the land use change occurs abruptly on the given date. Yearly change assumes that the change occurs gradually from previous date to the new date. For example, if an HRU area changes from 0% to 10% of the subbasin area in four years, the change is area is 2.5% over four years. Once selected, click "Add LU Info to Table". Repeat the process if there are multiple land use maps to be analyzed.Run Analysis
Once all the land use maps are uploaded, click "Create Map Based LU Updates" to run the analysis. Please remember, additional land use map analysis can be done at later times.Once the process is complete, SWAT input files are created and updates are applied at the approprite dates.
Please note that if the SWAT model is already calibrated, calibration parameters are not applied to the newly introduced HRUs. So, please use land use analysis tool prior to running SWAT model calibrations. .