Identification precipitation threshold and resulting river discharge: an IDF-based approach in the Central Himalaya, Nepal

Abstract

A comprehensive understanding of the intricate relationship between precipitation threshold and extreme river discharge, especially in mountainous regions, is challenging yet crucial for effective mountain risk management. This study, conducted in the Himalayan region of Nepal, employs an innovative approach using Intensity-Duration-Frequency (IDF) curves to identify potential precipitation extremes relevant to extreme river discharges. Detailed analysis of historical hydrometeorological events and their impacts in Nepal was carried out to select a specific event for thorough examination. Additionally, the research evaluates satellite-based precipitation data and utilizes frequency analysis techniques such as Gumbel and Log Pearson Type III distributions, customized to the region’s unique conditions. Furthermore, the study evaluates Probable Maximum Precipitation (PMP) and Depth-Area-Duration (DAD) curves at various sub-basin levels. The findings underscore the significant role of 3-day consecutive precipitation over 1-day events in generating extreme river discharge within the basin. Notably, the study reveals discrepancies between PMP values derived from gauge-based and satellite-based data, emphasizing the necessity for proper bias correction of the satellite data. Despite its limitations, the research highlights the potential of high-resolution satellite data for disaggregating gauge observed daily precipitation and underscores its applicability to other Himalayan basins, offering valuable insights into precipitation-related extreme events and their implications for water resource management and disaster risk reduction.