Comprehensive Hydroclimatic Evaluation (1901–2015), Regional Extremes, Seasonal Monsoon Dependency, and Next-Year Rainfall Forecasting using Linear Regression & Moving Average Models.
| Region / Zone ↑↓ | Historical Normal ↑↓ | Linear Regression Pred ↑↓ | Departure (%) ↑↓ | 5-Yr MA Pred ↑↓ | 10-Yr MA Pred ↑↓ | Trend ↑↓ | Slope (mm/yr) ↑↓ | R² Fit ↑↓ | Recommended Model | Action |
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The 1901–2015 dataset contains 4,116 records. Out of 49,392 monthly values, 70 missing entries (0.14%) were detected and imputed using the specific subdivision's long-term monthly mean. Seasonal aggregates (Winter: Jan-Feb, Pre-Monsoon: Mar-May, Monsoon: Jun-Sep, Post-Monsoon: Oct-Dec) and annual totals were mathematically recalculated to ensure exact additive consistency.
Trends were determined using Ordinary Least Squares (OLS) linear regression of annual precipitation against year (1901–2015). Regions with absolute slope |m| ≥ 0.5 mm/year were classified as Increasing or Decreasing, while those with |m| < 0.5 mm/year were classified as Stable climatological regimes.
Next-year (2016) forecasts were generated via three methodologies: (1) OLS Linear Regression, (2) 5-Year Moving Average (recent short-term mean), and (3) 10-Year Moving Average (decadal mean). Out-of-sample one-step-ahead backtesting was performed across the historical series to compute Root Mean Squared Error (RMSE) for each model, highlighting the empirical best performer.
District normals from district_wise_rainfall_normal.csv (641 districts across 35 States/UTs)
corroborate the sub-divisional
long-period averages (LPA), identifying intra-state microclimatic extremes (e.g., Cherrapunji/Mawsynram in
East Khasi Hills, Meghalaya vs Jaisalmer, Rajasthan).