Uncertainty of Intensity-Duration-Frequency Curves Due to Adoption or Otherwise of the Temperature Climate Variable in Rainfall Disaggregation

Abstract

Most areas around the world lack fine rainfall records which are needed to derive Intensity-Duration-Frequency (IDF) curves, and those that are available are in the form of daily data. Thus, the disaggregation of rainfall data from coarse to fine temporal resolution may offer a solution to that problem. Most of the previous studies have adopted only historical rainfall data as the predictor to disaggregate daily rainfall data to hourly resolution, while only a few studies have adopted other historical climate variables besides rainfall for such a purpose. Therefore, this study adopts and assesses the performance of two methods of rainfall disaggregation one uses for historical temperature and rainfall variables while the other uses only historical rainfall data for disaggregation. The two methods are applied to disaggregate the current observed and projected modeled daily rainfall data to an hourly scale for a small urban area in the United Kingdom. Then, the IDF curves for the current and future climates are derived for each case of disaggregation and compared. After which, the uncertainties associated with the difference between the two cases are assessed. The constructed IDF curves (for the two cases of disaggregation) agree in the sense that they both show that there is a big difference between the current and future climates for all durations and frequencies. However, the uncertainty related to the difference between the results of the constructed IDF curves (for the two cases of disaggregation) for each climate is considerable, especially for short durations and long return periods. In addition, the projected and current rainfall values based on disaggregation case which adopts historical temperature and rainfall variables were higher than the corresponding projections and current values based on only rainfall data for the disaggregation.

Spatiotemporal Variability of Current and Future Sub‐Daily Rainfall in Japan Using State‐Of‐The‐Art High‐Quality Data Sets

“…A significant number of studies have recently analyzed the global warming impacts on the sub‐daily extreme rainfall intensities (Fadhel et al., 2017, 2021; Hosseinzadehtalaei et al., 2020, 2021; Scoccimarro et al., 2015; Takhellambam et al., 2022a; Zhao et al., 2021), based on the commonly used regional and global climate models under RCP or SSP scenarios (main abbreviations and terminologies are listed in Table 1). However, these models are generally designed to simulate the climate conditions under certain external forcings (e.g., greenhouse gas emissions) rather than a specific degree of warming level at a given time (e.g., 1.5 and 2 K warming at the end of the 21st century under the Paris Agreement).…”

Methodology for IDF equation based on reduced pluviograph records

“…Thus, as a way of mitigating the effect of this phenomenon, reducing the losses generated by them, hydraulic-hydrological designs, such as collection systems, must consider the maximum flow. This is a characteristic of hydrological verification specific to the site under study to ensure the minimum requirements of security, durability and efficiency of the system (Fadhel et al, 2017;Fadhel et al, 2021).…”