Clarification on Limitations in Using Observed Discharge for Calibration and Validation in Arjunanadhi Basin Study

[Sarangan K]

Hi there,

I am currently conducting a hydrological modelling study for my postgraduate thesis focusing exclusively on the Arjunanadhi sub-basin using the SWAT model. For my research, only long-term discharge data available correspond to a gauging station located downstream of a reservoir structure (from 1994-2024). As such, the observed discharge represents regulated releases from the dam rather than natural runoff from the Arjunanadhi catchment.

Furthermore, spatial analysis indicates that the gauging location may receive additional inflows from areas outside the Arjunanadhi basin boundary. Since my modelling domain is restricted only to the Arjunanadhi sub-basin, these adjacent-basin contributions are not represented in the model and may lead to discrepancies between simulated flows and observed discharge.

In view of these constraints, I kindly request guidance on the acceptability of using such observed discharge data for calibration and validation and on the most appropriate methodological practices to adopt. In particular, I seek advice on:

1. Whether calibration and validation against dam-regulated discharge influenced by unmodelled adjacent catchments is acceptable for academic research when upstream natural-flow stations are unavailable?
2. Whether explicit inclusion of reservoir operation modules is required in this case?
3. What limitations should be clearly documented in the methodology and discussion sections?
4. Any recommended strategies to minimize uncertainty arising from these factors.

I hereby attach the location of the stream gauge as jpg and the discharge values as csv files. Your advice will greatly assist me in ensuring transparency and scientific rigor in my thesis work.

Thank you very much for your time and kind support. Looking forward for your response.

 

Yours sincerely,
Deebendranath Sarangan K
Postgraduate Student
M.E Irrigation Water Management
Anna University, College of Engineering, Guindy, Chennai
+91 7010983406
20242...@student.annauniv.edu