Modification of quality control weighting to enhance rain gauge assessment and rainfall data reliability

Reliable, standardized, accurate, and continuous hydrological data are essential to ensure effective planning and management of water resources. However, the current quality control method stipulated in the Circular Letter of the Directorate General of Water Resources No. 10/SE/D/2021 shows weaknesses in the weighting of criteria in Stage 1 (QC1), which does not adequately reflect field conditions. The existing weights are Instrument Performance (0.558), Environmental Condition (0.054), and Observer (0.388). Application of QC1 at the Situ Cisanti rainfall station produced a score of 2.518 (Good). Field surveys indicated good instrument performance and reliable observers, but the station was surrounded by tall trees that obscured rainfall, a factor not well represented due to the minimal weight of environmental conditions. To address this, revised weights are proposed: Instrument Performance (0.493), Environmental Condition (0.196), and Observer (0.311), with a sub-criterion adjustment for Rain Gauge Selection (0.530). These adjustments account for consistency and expected evaluation outcomes. The revised weighting provides a more representative assessment and can serve as input for revising Circular Letter No. 10/SE/D/2021. Implementing this improved quality control model is expected to enhance the reliability of hydrological data and support more effective, standardized data management policies.