I am using data from the 2 Meteorological stations for SWAT input but the relative humidity, solar radiation and windspeed data is not given ? what should be the approach to make the ".Wgen" user table.
Why is the user table a requirement if we are inputting the data for the maximum number of years for which simulation is being carried out and the SWAT can generate the solar radiation, wind and humidity data by simulation?
Hello
just remember that SWAT use *.mdb files and all what you need is to modify your data to fit on these files. The Wgen file is just long-term statistics for your sites. if you have access to long-term meteo data you calculate these statistics for each of your stations at the study site. alternatively there is a global Wgen file just you need to understand the primary key or code to link the data with your stations. To generate the stations statistic try to download "pcpstat" or can be done in spreadsheet.
small advice, try to run the model on tutorial data, for any site, first before you use your own data and get any results and them modify the model step-by-step; I believe it is a psychological matter and also will check if the model installed correctly or not.
Cheers
Dear Saima,
Meteorological variables you mentioned such as relative humidity, solar radiation and wind speed data are used to calculate potential ET using Penman-Montheit method in the SWAT model. If you have already observed (min and max) temperature for your study, rather than simulate such variables using e.g. weather generator, you may use another PET calculation method e.g. Hargreaves that is temperature-based potential ET estimation. Numerous studies have been done to compare the model performances using PET estimation resulted from different methods. You can use these studies as a consideration when selecting method for PET estimation.
Good luck!
Dear Saima Nauman,
If you go to the weather data definition editor, you will find that there are two options available, under every meteorological data category (rainfall, temperature, humidity, solar radiation, wind speed). These options are: simulation and raingages. Raingages can be used if you have available meteorological data. Should you not have available data or have some missing data, simulation can be used.
Hope this helps. SWAT manual is very informative. Look it up!
Good luck with your research!
Kostas Kaffas
The easiest way is to use global weather data (https://globalweather.tamu.edu/) for wind, humidity, and solar radiations, if they are missing in observed data. If you choose Hargreaves method for PET then the relative impact of these variables gets lower. Only the statistics from global weather data can be used in .wgn along with the Hargreaves method.
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