ragarding crop managment problem in swat plus editor

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Anurag Yadava

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Oct 30, 2025, 10:19:27 AM (20 hours ago) Oct 30

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Dear Sir,

I am currently modeling a basin in SWAT+, and the model is running successfully. I am incorporating crop management practices for different cropping patterns—rice–wheat, soybean–wheat, and cotton–wheat (kharif–rabi)—across various HRUs. The model consists of approximately 25,000 HRUs.

Manual management operations have been applied for each crop, like the approach used in SWAT (via the .mgt file). For irrigation, I have utilized the four default irrigation options available in SWAT+, selecting the most appropriate one for each crop along with other relevant operations.

However, I have a few queries:

When an irrigation operation such as sprinkler irrigation is used, what source of water does the model assume by default?

I attempted to define water allocations under the Water Rights tab in the SWAT+ Editor, but the process is quite complex due to the large number of water sources (channels, reservoirs, and aquifers) in the model. Assigning sources individually to each HRU is extremely time-consuming, especially with more than 20,000 HRUs, as there is currently no option to select and assign sources to multiple HRUs or subbasins simultaneously.

Additionally, the model is providing reasonable crop yield outputs overall. However, in the rice–wheat pattern, while the simulated yield for rice is acceptable, the wheat yield is significantly lower. Interestingly, when rice is replaced with maize (with the same duration), the yields for both maize and wheat are acceptable. Similarly, acceptable results are obtained for the soybean–wheat and cotton–wheat systems.

Your guidance on addressing the irrigation source assignment and improving wheat yield simulation under the rice–wheat system would be greatly appreciated.