Surface Flow Overestimation with CN vs. Low Precipitation with Green–Ampt in SWAT
Saba Shaghaghi
Hello,
When I use the CN method, I get an overestimation of surface flow. However, when I switch to the Green–Ampt method, the precipitation shown in the SWAT “Hydrology” section appears to be too low, which causes the surface flow to be nearly zero.
For the Green–Ampt method, I converted my weather data to hourly format, but after running the model, I still notice that the precipitation is reported as very low. Additionally, in my textinout folder there is no output.sub file, and the pcp.cli file only lists station names without including the subbasins.
Thanks for your assistance,
Best regards,
Saba
Saba Shaghaghi
Hello everyone,
I’m following up on my previous question. Could someone please help me understand where I can find which subbasins are receiving specific amounts of precipitation from my dataset?
When I use the CN method, I get an overestimation of surface flow. However, when I switch to the Green–Ampt method, the precipitation shown in the SWAT “Hydrology” section appears to be too low, which causes the surface flow to be nearly zero. For the Green–Ampt method, I converted my weather data to hourly format, but after running the model, I still notice that the precipitation is reported as very low.
Additionally, in my textinout folder there is no output.sub file, and the pcp.cli file only lists station names without including the subbasins.
Thank you for your time and assistance.
Best regards,
Saba
Natalja C.
Saba Shaghaghi
Hello Natalja,
Thank you for your response. Yes, both I changed my weather data to hourly-based format and also updated the time step to hourly in the advanced options before running the model. However, in the SWAT check, I noticed that the precipitation value is very low (46), and the simulated outlet flow discharge is also near zero.
In contrast, when I switch the method to the CN approach, the precipitation value becomes reasonable (1288), but the model produces a large overestimation of flow and runoff compared to my observed data. I have attached both result files for your reference.
Additionally, I would like to check how much precipitation each of my subbasins receives from my weather data. In my pcp.cli file, only the station names are listed, and the subbasins are not included, as shown in the attached file.
Best regards,
Saba
Saba Shaghaghi
Hi Natalja,
I wanted to follow up on my earlier questions. I’d really appreciate it if you could let me know how to fix this problem and what I need to do.
Thank you so much!
Best,
Saba