Geohazards and Geomorphological Setting in Poznań Urban Area, Poland

Abstract

This paper presents the results of geohazards mapping and evaluation their role in the modifying of the urban landscape in Poznań, Poland. Information on geohazards specific to an urban lowland area (river floods, flash floods, mass movement, wind erosion) because of increasing climate change was compiled into a geomorphological map. The most spatially widespread geohazards in Poznań include: (a) on moraine hills/uplands: mass movement, wind erosion, and flash floods (4.9% of the city area); (b) on outwash plains: mass movement and flash floods (8.6% of the city area); (c) on fluvial landforms: mass movement and river floods (9.8% of the city area); (d) within plains of various origin: flash floods (7.6% of the city area). Mass movement affecting short but numerous (and locally steep) slopes, and flash floods are the most widespread geohazards (16 and 14%, of Poznań's area, respectively). Extensive urbanisation especially the expansion of impervious surfaces increases the high risk of flash floods.

Urban Geomorphology Methods and Applications as a Guideline for Understanding the City Environment

“…It is evident in [88,89], describing and mapping anthropogenic landforms in the municipality of João Pessoa (Brazil), similar to the Italian ones, and in [90] (Vienna, VA , USA), using multitemporal topographic data (stereo aerial and ortho-imagery) for anthropogenic erosion and accumulation detection. Numerous other examples are available from Poland [91][92][93][94][95][96]. The proposal again, and in almost all cities around the world of the same landforms, offers the possibility of applying the Italian approach to cities of recent evolution or sprawling ones.…”

Flood Perception from Local Perspective of Rural Community vs. Geomorphological Control of Fluvial Processes in Large Alluvial Valley (the Middle Vistula River, Poland)

“…Similar traces of levee breaches (crevasse splays) formed during the previous catastrophic floods [65,66] cannot be found in the upper reaches of the Vistula River. Nevertheless, the remnant landform of crevasse splay from the 2010 levee breach still exists in the Lower Vistula River [29,45] and appears to have remained almost unchanged since its deposition during the 2010 flood. We perceive such a landform as a natural flood mark which additionally denotes a levee breach location and permits us to envision the geomorphological aspect of the overbank flow.…”

“…The flood collective memory is usually not very long [24], especially in areas where the riverscape was transformed into a cityscape [25], but the floodplain remains a flood-prone area, even if it was embanked and became densely populated [26][27][28][29]. The landscape of rural areas mostly enables easier identification of flood remnants than in the case of urban areas.…”

Nature-Based Solution Integration to Enhance Urban Geomorphological Mapping: A Methodological Approach

“…Academic studies of urban geomorphology and geoheritage have incorporated considerations of climate change into their research [94,133,143]. However, it is essential to recognize that rapid urbanization is a significant factor that directly contributes to climate change [144].…”