Impact of Urbanization on the Simulation of Extreme Rainfall in the City of Jeddah, Saudi Arabia

Abstract

The city of Jeddah, Saudi Arabia, is characterized by a hot and arid desert climate. On occasion, however, extreme precipitation events have led to flooding that caused extensive damage to human life and infrastructure. This study investigates the effect of incorporating an urban canopy model and urban land cover when simulating severe weather events over Jeddah using the Weather Research and Forecasting (WRF) Model at a convective-permitting scale (1.5-km resolution). Two experiments were conducted for 10 heavy rainfall events associated with the dominant large-scale patterns favoring convection over Jeddah: (i) an ''urban'' experiment that included the urban canopy model and modern-day land cover and (ii) a ''desert'' experiment that replaced the city area with its presettlement, natural land cover. The results suggest that urbanization plays an important role in modifying rainfall around city area. The urban experiment enhances the amount of rainfall by 26% on average over the Jeddah city area relative to the desert experiment in these extreme events. The changes in model-simulated precipitation are primarily tied to a nocturnal heat-island effect that modifies the planetary boundary layer and atmospheric instability of the convective events.

Urban‐induced modifications to the diurnal cycle of rainfall over a tropical city

“…The evidence of urban rainfall modification is confirmed also in arid/semi‐arid cities (e.g. Li et al ., 2020a; Luong et al ., 2020). Also, some studies argue the reverse effect: urbanisation that reduces local precipitation (e.g.…”

Analysis of Outdoor Thermal Discomfort Over the Kingdom of Saudi Arabia

“…In the Kingdom of Saudi Arabia (KSA), changes in weather patterns and a sharp increase in extreme weather events are among the most significant drivers of social vulnerability, considerably threatening the living conditions of humans (Abdul Salam et al., 2014). Rapid growth in urbanization during recent decades and the consequent increase in impermeable surfaces of urban infrastructure surfaces have significantly changed urban ecosystems, substantially impacting the quality of life of urban residents (e.g., Du et al., 2019; Luong et al., 2020; Ren et al., 2008; van Hove, 2015; Warburton et al., 2012; Zhong et al., 2015). The ability of urban dwellers to adapt to varying thermal environments largely depends on the external meteorological conditions.…”

Retrospective Sub-Seasonal Forecasts of Extreme Precipitation Events In The Arabian Peninsula Using Convective-Permitting Modeling

“…Flash ooding occurs when heavy precipitation falls on dry soils with low soil-in ltration capacity (Al Saud 2010; Almazroui, 2011), lling ephemeral stream channels (called wadis in the Middle East) within a matter of minutes (Haggag and El-Badry 2013; Deng et al 2015). In recent decades, the AP has experienced rapid socioeconomic development, expansion of urbanization and agricultural activities, and high population growth (Luong et al 2020b;Hoteit et al 2021). Episodic extreme precipitation events and ash ooding have increased concurrently, causing hundreds of casualties and infrastructural damages costing more than one billion U.S. dollars Climatologically, most precipitation in the AP occurs during the cool season from November to April.…”

“…CPMs have been widely applied in weather forecasting (e.g., Clark et al 2016) and climate projection (e.g., Prein et al 2015, Kendon et al 2017. Included in the CPM literature are some studies simulating extreme weather events over the AP (e.g., Deng et al 2015; Dasari et al 2017;Luong et al 2020b) and incorporation of data assimilation (Viswanadhapalli et al 2016) to improve short-range forecasts, which inform the methodological approaches in this work. With respect to convective precipitation, CPMs add substantial value in determining the amount, timing, and storm structure of convective precipitation (e.g., Prein et al 2015;Ban et al 2014;Kendon et al 2012).…”