Assessment of modern hydro‐meteorological hazards in a big city – identification for Warsaw

Abstract

Continuous urban development significantly transforms the ecosystem in a big city. The increasing frequency of heat waves and their influence on the rise in mortality in big cities suggest that the thermal hazard (long‐term occurrence of high air temperature) is one of the key climatic hazards of present times. The global temperature rise, reinforced in urbanized areas by the anthropogenic heat flux, leads to intensified convection processes and increased precipitation, especially torrential rain. One of the most important hydrological hazards in a big conurbation is the urban flood hazard. In this paper the identified climatic hazards occurring in a big city are analysed: the thermal hazard and the urban flood hazard. The areas currently exposed to thermal and urban flood hazards in Warsaw are identified and assessed in terms of the hazard level. The results obtained are verified with the data from meteorological measuring stations (the thermal hazard) and from the Fire Department interventions connected with rainfall and flooding (the urban flood hazard). A map of hydro‐meteorological hazards was created by combining thermal hazard and urban flood hazard maps. The approach combining the exposure to thermal and urban flood hazards, presented in this study, uses widely accessible spatial data and can be applied to any location. It can also play a significant role in assessing the adaptation of urban areas to climate change and be an important source of information on the current exposure to hydro‐meteorological hazards as well as their possible increase.

Variability of the Boundary Layer Over an Urban Continental Site Based on 10 Years of Active Remote Sensing Observations in Warsaw

“…These effects can be seen on the scale of the annual cycle (Figure 9). The extreme summer heat wave was observed over Europe during July 2015 and resembled exceptionally high values for the two following months [82][83][84]. A European heat wave event was also reported for September 2016 [11].…”

“…Moreover, the global temperature rise, reinforced in urbanized areas by the anthropogenic heat flux, leads to an intensified convection process and increased precipitation (especially torrential rain), causing thermal and hydrological hazards in large conurbations. The areas currently exposed to thermal and urban flood hazards in Warsaw were identified and assessed in the recent work of [83].…”

Severe storms as an example of a natural hazard in the urban area – case studies of the area of Warsaw, Poland

“…An important feature of Warsaw's climate is that an urban heat island (UHI) is formed. Case studies show that the differences in air temperature between the centre of Warsaw and the surrounding non-urban area can reach 10°C and higher (Wawer 1995(Wawer , 1997Błażejczyk et al 2014a;Żmudzka 2019). An important factor that favours the formation of UHI is wind speed (Błażejczyk et al 2014b).…”

“…It depends on the street layout, the presence of squares, green areas, and so on. In addition, there is a high potential for urban flash floods (Majewski 2002;Mejia & Moglen 2010;Żmudzka et al 2019). Therefore, the study of meteorological conditions in relation to urban areas is one of the most important issues of modern climatology.…”

Urban geomorphology of the Vistula River valley in Warsaw

“…The city is located on the banks of the Vistula River (Main Map), where the inundation hazard on the floodplain is constant, as well as a risk of erosion and deposition that may come from overbank flow during flooding. Unfortunately, such geomorphological implications are often overlooked in the urban environment (Falkowski, Bujakowski, et al, 2017;Kasprzak & Traczyk, 2014;Mansur et al, 2018;Martins et al, 2019;Miller et al, 2020;Żmudzka et al, 2019). The Vistula River valley covers ca.…”