Dear all,
I am using SWAT+ to model a catchment in the Pyrinees and after running the model, when I start to analyze the results, I get too low values of flow_out (0,0something m3/s, when the observed flow is 5 to 100m3/s) so my questions is:
How can I improve the output flow? Because with this difference, calibration won't be enough
Thank you all
Ana Ortiz I understand the challenges you are facing with the SWAT+ model outputs, particularly the issue of low flow values that do not align with the observed data. Your dedication to ensuring accurate results in your catchment modeling efforts is commendable. Drawing from my own experiences in hydrological modeling, I can suggest several steps that may help you address this discrepancy and enhance the accuracy of the output flow.
Firstly, it is crucial to meticulously review the input data utilized in the model. Ensure that the data, including precipitation, land use, soil properties, and topographical information, accurately represents the conditions of the Pyrenees catchment. Even minor discrepancies in the input data can significantly impact the reliability of the model outputs.
Furthermore, consider examining the parameters and configurations within the SWAT+ model itself. Adjusting parameters such as the curve number, hydraulic conductivity, and initial soil moisture content may lead to more realistic flow values. Additionally, fine-tuning the model's routing and channel parameters could aid in improving the representation of the flow dynamics within the catchment.
Moreover, conducting sensitivity analyses on the model parameters can provide valuable insights into the most influential factors affecting the flow outputs. This process will enable you to identify key parameters that require adjustments to better reflect the observed flow data.
Collaborating with fellow researchers and hydrological modeling experts who have experience with SWAT+ or similar models may also offer valuable perspectives and potential solutions to address the low flow values.
I encourage you to persist in your efforts to refine the SWAT+ model and ensure that the outputs closely match the observed flow data. By refining the model inputs, parameters, and configurations, you can improve the accuracy and reliability of the flow simulations, thereby facilitating a more robust calibration process.
Please feel free to reach out if you require further assistance or guidance. May your research endeavors yield meaningful and impactful insights for the Pyrenees catchment and beyond.
Dear Qamar,
Thank you for the response. I have discovered that not all the model has low outflows and that until a reservoir that I have almnost at the end of the watershed the model runs correctly.
Nevertheless, this reservoir does not have outflow so all the rivers that are below don´t neither. Do you, by any chance, know how could I input an outfow to the reservoir in SWAT+?Because I have a gauge just after the reservoir and I want to input those flow data.
Ana Ortiz Based on your description, it sounds like an outlet was not properly defined for that reservoir, causing flow to get 'stuck'. Not to worry, this can be easily addressed in SWAT+.
To define an outflow for a reservoir, you will want to use the .res modification file. Simply add a line like:
OUT_ID RES_NAME FLOW_CMD FLOW_COEF
Where:
RES_NAME is the name of your reservoir
FLOW_CMD should be set to 'measured'
FLOW_COEF can be set to 1
This will allow you to directly input observed flows at the gauge point immediately downstream. SWAT+ will use these measured values as the reservoir release rather than calculating it.
Please let me know if you need any other assistance getting the downstream flows properly routed past that reservoir. Proper implementation of reservoirs and dams is so important for watershed models - I'm glad we could resolve this issue. Wishing you all the best in your SWAT+ project!
Regards, #SWAT #Hydrology #WatershedModeling
Dear Qamar,
Thank you for your attention. What is the .res modification file? I have 6 .res files: hydrology.res; initial.res; nutrients.res; reservoir.res; sediment.res and weir.res
I can see that the release parameters are in reservoir.res, but these are controlled by the decision tables, in which I can not input release flows (or at least I did not find out how), I just can change the volume of water with which the reservoir uses the principal spillway or the emergency spillway. Nevertheless I do not have data for this.
Thank you again
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