Mapiam Punpim Puttaraksa, Sakulnurak Sikarin, Methaprayun Monton, Makmee Choowit, Marjang Nat
Department of Water Resources Engineering, Faculty of Engineering, Kasetsart University, P.O. Box 1032, Bangkok 10900, Thailand E-mail:
Water Sci Technol. 2023 Mar;87(5):1259-1272. doi: 10.2166/wst.2023.056.
Weather radar is a form of alternative indirect rainfall measurement for use in mitigating flash flood hazards. It is a challenging task to obtain accurate radar rainfall data without integration with automatic rain gauge networks. This paper investigated transformation equations to convert the calibrated daily Z-R relationship to the sub-hourly scale and proposed optional schemes for downscaling the daily bias adjustment factor into 15 min resolution scale to produce a high-resolution radar rainfall product for flash flood modelling. Radar reflectivity data from three radar stations in Thailand and their corresponding daily gauge rainfall data were used in the analysis. Two bias adjustment schemes (DMFB and DS_DMFB), accounting for the temporal variation, and one spatiotemporal scheme (SPTB_IDS) were used to generate three corresponding rainfall datasets for the unified river basin simulator (URBS) model to simulate flood hydrographs in the Tubma basin, Thailand. The results showed that combining the proposed 15-min Z-R scaling equation and the SPTB_IDS produced the most reliable radar rainfall amount leading to an increase in the accuracy of flood modelling with the lowest uncertainty. This indicated that the temporal downscaling solution together with spatial interpolation technique for sub-hourly radar rainfall assessment could benefit flash flood simulation in a data-scarce basin.
天气雷达是一种用于减轻山洪灾害的间接降雨测量替代形式。在不与自动雨量计网络集成的情况下获取准确的雷达降雨数据是一项具有挑战性的任务。本文研究了将校准后的日Z-R关系转换为亚小时尺度的转换方程，并提出了将日偏差调整因子降尺度到15分钟分辨率尺度的可选方案，以生成用于山洪建模的高分辨率雷达降雨产品。分析中使用了泰国三个雷达站的雷达反射率数据及其相应的日雨量计降雨数据。两种考虑时间变化的偏差调整方案（DMFB和DS_DMFB）以及一种时空方案（SPTB_IDS）被用于为统一流域模拟器（URBS）模型生成三个相应的降雨数据集，以模拟泰国图马河流域的洪水过程线。结果表明，将所提出的15分钟Z-R尺度方程与SPTB_IDS相结合产生了最可靠的雷达降雨量，从而提高了洪水建模的准确性且不确定性最低。这表明，用于亚小时雷达降雨评估的时间降尺度解决方案与空间插值技术相结合，可使数据稀缺流域的山洪模拟受益。
