Rainfall Trends and Extremes in Saudi Arabia in Recent Decades

Abstract

The observed records of recent decades show increased economic damage associated with flash flooding in different regions of Saudi Arabia. An increase in extreme rainfall events may cause severe repercussions for the socio-economic sectors of the country. The present study investigated the observed rainfall trends and associated extremes over Saudi Arabia for the 42-year period of 1978–2019. It measured the contribution of extreme events to the total rainfall and calculated the changes to mean and extreme rainfall events over five different climate regions of Saudi Arabia. Rainfall indices were constructed by estimating the extreme characteristics associated with daily rainfall frequency and intensity. The analysis reveals that the annual rainfall is decreasing (5.89 mm decade−1, significant at the 90% level) over Saudi Arabia for the entire analysis period, while it increased in the most recent decade. On a monthly scale, the most significant increase (5.44 mm decade−1) is observed in November and the largest decrease (1.20 mm decade−1) in January. The frequency of intense rainfall events is increasing for the majority of stations over Saudi Arabia, while the frequency of weak events is decreasing. More extreme rainfall events are occurring in the northwest, east, and southwest regions of Saudi Arabia. A daily rainfall of ≥ 26 mm is identified as the threshold for an extreme event. It is found that the contribution of extreme events to the total rainfall amount varies from region to region and season to season. The most considerable contribution (up to 56%) is found in the southern region in June. Regionally, significant contribution comes from the coastal region, where extreme events contribute, on average, 47% of the total rainfall each month from October to February, with the largest (53%) in November. For the entire country, extreme rainfall contributes most (52%) in November and least (20%) in July, while contributions from different stations are in the 8–50% range of the total rainfall.

Application of Normalized Difference Vegetation Index (NDVI) for the Detection of Extreme Precipitation Change

“…In addition, it is known that NDVI is frequently influenced by changing precipitation patterns [56]. In this paper, the contribution of precipitation amounts of extreme precipitation events to annual total precipitation is smaller than the results of Almazroui (2020) [57] and Almazroui and Saeed (2020) [58]. This phenomenon can be associated with the wide distribution of typical subtropical monsoon climate in the MLR-YR.…”

The role of ecosystem transpiration in creating alternate moisture regimes by influencing atmospheric moisture convergence

“…Interestingly, relationship (5) established for local hourly rainfall for a specific study area in the Amazon region (Baudena et al, 2021) encompasses characteristic precipitation rates over a broad range of spatial and temporal scales, from annual precipitation in deserts (Almazroui, 2020) and semi-arid zones (Zhang et al, 2022), boreal (Smirnova et al, 2017), temperate (Beudert et al, 2018) and tropical (Makarieva et al, 2013) forests, to hurricane (Makarieva et al, 2017) and flood-causing (Kreienkamp et al, 2021) rainfall (Fig. 5a).…”

The Influence of the Madden–Julian Oscillation on the Wet Season Rainfall over Saudi Arabia

“…Using this station rainfall dataset, the frequency of wet season rainfall events was calculated during the period 1985-2021. The frequency of extreme rainfall events was also calculated using the methodology adopted by Almazroui (2020). Extreme rainfall events are defined as those with daily rainfall ≥ 26 mm.…”

“…The vulnerability of arid and semi-arid regions to flash floods has been shown to be equal to that of areas with heavy rainfall events (Zipser et al 2006;Haggag end El-Badry 2013;Tippett et al 2015). For example, in January 2005 and 2011, and in November 2009, Saudi Arabia experienced heavy rainstorms and flash flood events which caused massive loss to infrastructure and human casualties (Almazroui 2020;De Vries et al 2016;Yesubabu et al 2016). Therefore, it is pertinent to understand the intraseasonal variability of Saudi Arabian wet season rainfall, which may be modulated by the Madden-Julian oscillation (MJO).…”