Unveiling spring behaviour through copula-based inter-spring connectivity in the Central Himalaya

Area of Science:

• Hydrology
• Statistical Modeling
• Geosciences

Background:

• Himalayan springsheds face challenges in water resource management due to limited hydrological monitoring.
• Understanding inter-spring connectivity is vital for accurate discharge prediction.

Purpose of the Study:

• To evaluate elliptical and D-vine copula models for predicting spring discharge (S5) using data from other springs (S1-S4) and rainfall.
• To test if simpler models outperform complex ones in data-limited, strongly connected hydrological systems.

Main Methods:

• Utilized observed discharge data from four springs and concurrent rainfall.
• Applied elliptical copula models (Gaussian, t) and various D-vine structures.
• Assessed model performance using Root Mean Square Error (RMSE) and R-squared (R²).

Main Results:

• Elliptical copulas significantly outperformed D-vine models, with the best achieving RMSE ≈ 0.11 lpm and R² ≈ 0.76.
• Simplified, hydrologically coherent D-vine structures showed improved accuracy (R² ≈ 0.58-0.59) over complex ones.
• Strong inter-spring correlations support the use of symmetric dependence structures.

Conclusions:

• Symmetric dependence structures, like elliptical copulas, effectively represent groundwater-spring linkages in similar geological settings.
• Copula-based modeling provides efficient and powerful tools for discharge prediction in monitoring-limited Himalayan springsheds.
• This approach supports sustainable water resource management despite data constraints.