Multi-Objective Validation of the Runoff Formation Model in the High-Mountain River Basin of the Central Caucasus

This study demonstrates the effectiveness of a multi-objective validation approach for a distributed hydrological model in a high mountain river basin. Focusing on the Baksan River Basin in the Central Caucasus, where snow and glacier melt play a crucial role in runoff formation, we applied the ECOMAG model, which has proven its reliability in high-altitude hydrology. To enhance the validation accuracy, we integrated diverse data sources, including observed river discharge, MODISderived snow cover, stable isotope hydrograph separation, glacier mass balance observations, and glacial runoff simulations from the A-Melt model. The results confirm the high performance of the model across multiple hydrological components. The simulated and observed discharge values showed strong agreement, with the Nash-Sutcliffe efficiency exceeding 0.8 for both the calibration and validation periods. The model successfully captured seasonal snow cover variations, achieving an R² of 0.85 when compared with the MODIS data. Isotopic hydrograph separation further validated the accuracy of the simulated meltwater and rainfall contributions to runoff. Although glacier ablation simulations showed some deviations, particularly for the Djankuat Glacier, these findings highlight opportunities for refining glacial process representation. Overall, this study confirms the robustness and applicability of multi-objective validation for hydrological modeling in complex mountainous regions. The integration of multiple observational datasets significantly enhances the reliability of modeling results, providing valuable insights into water resource management, climate impact assessments, and sustainable development in glacier-fed river basins.