Quality Index-Driven Radar Mosaicking and Machine Learning for Enhanced Rainfall Estimation in the Chao Phraya River Basin and Its Tributaries in Thailand
摘要
This research presents an innovative method for producing radar rainfall mosaics in the Chao Phraya River Basin, Thailand, using the integration of data from various C-band weather radars operated by the Thai Meteorological Department (TMD). The approach employs open-source Python tools and integrates a novel quality index (QI) that merges cumulative beam blockage (CBB) and pulse volume to mitigate terrain-induced inaccuracies in radar calculations. A thorough 20-fold cross-validation guaranteed robustness under diverse rainfall situations, evaluating five separate bias correction methods utilizing ground truth data from the Hydro-Informatics Institute (HII) precipitation gauge network. The optimized random forest (RF) regressor exhibited exceptional performance, improving radar-gauge correlation at 111 of 169 HII stations, with a success rate of 65.74% and a median enhancement of 35.34%. Findings indicated a consistent underestimation in highland locations (bias ratios < 0.8) and an overestimation in lowland areas (bias ratios > 1.2). Although the RF model sustains bias ratios between 0.85 and 1.15 across all terrains, there remains a persistent underestimating in northern basins, indicating potential for further enhancement. This study’s open-access source code enables the research community and relevant stakeholders to modify the methodology for monitoring severe atmospheric disasters, storms, and hydrological hazards. This capability offers a substantial opportunity for TMD and other agencies to improve disaster preparedness and water resource management in Thailand.