What is the return period of intense rainfall events in the capital cities of the northeast region of Brazil?

Abstract

The northeast of Brazil is characterized by a semiarid climate, in which there is a considerable temporal and spatial variability in the distribution of rainfall. In this region, the occurrence of intense rainfall events (IREs) causes severe damage to the population, given that the rampant urbanization and land use processes make cities more susceptible to harmful consequences. Thus, the objective of this study is to estimate the period and the level of return of IREs in the capital cities of the northeast Brazil. For that end, observed data from weather stations of the National Institute of Meteorology for the period from 1988 to 2017 were used. We defined thresholds based on the excesses above the mean and inserted the data in the generalized Pareto distribution in order to obtain diagnostics of future estimates. Results showed that return periods were surpassed in seven of the nine capital cities in 2018. Furthermore, the estimates for IREs with a return period of 5, 10, and 100 years were higher if compared to the return period of 1 year. The results found in this study are extremely relevant for the understanding of the occurrence of these events and also serve as a tool for decision-making and the elaboration of policies aimed at minimizing the impacts of such events. K E Y W O R D S extreme value theory, generalized Pareto distribution, natural disasters

Intense Precipitation and Area of Risk: A Case Study of Mass Movement in the City of Natal, Brazil

“…Their analysis was performed using the return period for extreme events in the city of Natal, adopting extreme value distribution (EVD) models. In addition, the authors estimated that the probability of rainfall above 80 mm/day in the city in that month was 55.1% [33,34].…”

“…Events of intense precipitation during June in the eastern part of Northeast Brazil are quite frequent, since this month is considered the height of the rainy season in the region (April to July) [33,35,36]. Easterly Wave Disturbances are associated systems, since this is the period of greatest intensity [37][38][39], being responsible for 70% of the precipitation [40].…”

Environmental Disasters in Northeast Brazil: Hydrometeorological, Social and Sanitary Factors

“…However, the social and environmental conditions of the cities can also potentialize the occurrence of hydrometeorological disasters associated with excessive rainfall. In a study developed by Oliveira and Lima (2019) that analyzed the period of return of extreme events in the capital cities of NEB, the authors observed the occurrence of more frequent and more intense events in the wet season. However, these locations present a different behavior whether they are situated in the northern (São Luiz, Teresina, and Fortaleza) or coastal (Natal, João Pessoa, Recife, Maceió, Aracaju, and Salvador) portions of NEB.…”

“…Northeast Brazil (NEB) is characterized by the occurrence of extreme drought events (Moura and Shukla 1981;Groisman et al 2005;Marengo et al 2016;de Medeiros et al 2020). Annually, heavy rainfall events are also registered in the region (Calheiros et al 2006;Oliveira et al 2013b;Rodrigues et al 2020b;Oliveira and Lima 2019), usually concentrated in short periods of time as a result of the simultaneous interaction between topography, geographical location, surface characteristics, and the acting of different meteorological systems (Kayano et al 2009).…”

Meteorological droughts and water resources: Historical and future perspectives for Rio Grande do Norte state, Northeast Brazil

“…In addition to low water availability and increased demand for water, climate change projections and impacts are another worrisome factor in NEB (Oyama and Nobre, 2004). Studies suggest that extreme rainfall events will become increasingly frequent and intense in the region (IPCC, 2013; Oliveira and Lima, 2019; Spinoni et al ., 2019; Marengo et al ., 2020; Oliveira et al ., 2020) and temperature are predicted to increase above 3°C during the 21st century (IPCC, 2021). In this respect, the climate projections that dry spells events will become worst in the near‐ and long‐term future stand out, with decrease in water availability for irrigated agriculture and human use owing to reductions in precipitation and increases in evapotranspiration (Marengo and Bernasconi, 2015; Marengo et al ., 2017b).…”