Simulating rainfall IDF curve for flood warnings in the Ca Mau coastal area under the impacts of climate change

Truong An Dang

doi:10.1108/ijccsm-06-2020-0067

Abstract

Purpose The purpose of this study is to evaluate the rainfall intensities and their limits for durations from 0.25 to 8 h with return periods from 2 to 100 years for Ca Mau City in Vietnam. Design/methodology/approach First, the quality of the historical rainfall data series in 44 years (1975–2018) at Ca Mau station was assessed using the standard normal homogeneity test and the Pettitt test. Second, the appraised rainfall data series are used to establish the rainfall intensity-duration-frequency curve for the study area. Findings Based on the findings, a two-year return period, the extreme rainfall intensities (ERIs) ranged from 9.1 mm/h for 8 h rainstorms to 91.2 mm/h for 0.25 h. At a 100-year return period, the ERIs ranged from 18.4 mm/h for 8 h rainstorms to 185.8 mm/h for 0.25 h. The results also show that the narrowest uncertainty level between the lower and upper limits recorded 1.6 mm at 8 h for the two-year return period while the widest range is at 42.5 mm at 0.25 h for the 100-year return period. In general, the possibility of high-intensity rainfall values compared to the extreme rainfall intensities is approximately 2.0% at the 100-year return period. Originality/value The results of the rainfall IDF curves can provide useful information for policymakers to make the right decisions in controlling and minimizing flooding in the study area.

Highlights

Rainfall is considered as one of the main factors of the hydrological cycle, which is closely related to human activities, especially in the agricultural sector (Al Saji et al, 2015; Lee and Dang, 2020)
Intergovernmental Panel on Climate Change (2014) reported that the frequency and severity of flooding in the lowest terrain regions are exacerbated by high-intensity rainfall (HIR) events under the negative impacts of climate variability (ICV)
The objective of this study is, to establish rainfall IDF curves based on historical rainfall data series in 44 years (1975–2018) for durations 0.25, 0.5, 1, 2, 3, 4, 6 and 8 h with return periods of 2, 5, 10, 20, 30, 50 and 100 years to support the construction of infrastructures in Ca Mau Peninsula

Summary

Introduction

Rainfall is considered as one of the main factors of the hydrological cycle, which is closely related to human activities, especially in the agricultural sector (Al Saji et al, 2015; Lee and Dang, 2020). According to Wayal and Menon (2014), stormwater management and the design of traffic roads, as well as underground works able to withstand floods and HREs are commonly based on rainfall IDF curves They are often established using historical rainfall data series through the quality verification to evaluate rainfall intensity for a constructed rainstorm duration and its return period (Al-Baldawi and Alzuabidi, 2016; Dakheel, 2017). Al Hassoun (2011) evaluated rainfall intensity based on IDF curves through the Gumbel distribution for the Riyadh region from a 32-year rainfall data series They reported a good match for durations from 0.5 to 24 h with return periods from 2 to 100 years. A study on changing rainfall patterns across the Mekong Delta by Lee and Dang (2018) found that climate variability has affected the temporal and spatial distribution of rainfall patterns in three recent decades

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