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Introduction
Published in Mark S. Reed, Lindsay C. Stringer, Land Degradation, Desertification and Climate Change, 2016
Mark S. Reed, Lindsay C. Stringer
Soil sealing is a problematic form of physical soil degradation and often occurs during the construction of infrastructure, when the soil is covered with materials like concrete, plastic, etc., which prevent water from percolating through the land surface. This type of degradation is particularly problematic in developed, urban areas. For example, in Europe, approximately nine per cent of the total land area is sealed with impermeable material, with countries such as Germany, Portugal, the Netherlands, Spain and Hungary having sealed more than 45 per cent of their urban soils (Scalenghe and Marsan, 2009). Sealing has important effects on the relationship between the land and the climate. Surface sealing alters the balance of energy transfers and temperature regulation processes, affecting soil biota. Sealed surfaces absorb the sun’s energy during the day and cool slowly at night. This can cause sealed surfaces to be up to 20 degrees warmer than unsealed surfaces. Sealing also affects water flows and gas diffusion, affecting the ability of the soil to act as a carbon sink and to filter air pollutants. This is an important and often overlooked consideration as the world’s urban population continues to grow, as it provides important feedbacks that affect the climate.
Impacts of land take and soil sealing on soil carbon
Published in Ciro Gardi, Urban Expansion, Land Cover and Soil Ecosystem Services, 2017
Land use and land cover change (LULCC) by urbanization and, in particular, the expansion of urban areas is increasingly affecting the terrestrial carbon (C) stock as the global urban land cover is projected to increase by an area the size of South Africa until 2030 (Seto et al., 2012). Currently, larger than previously thought areas in Europe are already covered by settlement structures including cities, villages, and groups of houses along rivers, roads, and rail tracks or spread into the arable countryside (Figure 10.1). The processes of land take or land consumption interconnected with urban expansion can be defined as an increase of settlement areas over time (European Commission Staff Working Document, 2012). Land take includes the development of scattered settlements in rural areas, the expansion of urban areas around an urban nucleus (including urban sprawl), and the conversion of land within an urban area (densification). By conversion of open into built-up areas, some part of the land take will result in soil sealing by buildings, roads, and parking lots because gardens, urban parks and other green spaces are not covered by an impervious surface (European Commission Staff Working Document, 2012). Otherwise, land take can also be defined as the increase of artificial surfaces (e.g., housing areas; green urban areas; industrial, commercial and transport units; road and rail networks) over time (European Commission, DG Environment, 2011). Soil sealing means the permanent covering of an area of land and its soil by completely or partly impermeable artificial material (e.g., asphalt, concrete), for example, through buildings and roads (European Commission Staff Working Document, 2012). Soil sealing causes the loss of soil and some of its biological functions including C sequestration and loss of biodiversity, either directly or indirectly, due to fragmentation of the landscape (European Commission, DG Environment, 2011).
Characteristics of the urban heat island effect, in the coastal city of Patras, Greece
Published in International Journal of Sustainable Energy, 2022
Athanassios Giannopoulos, Yannis G. Caouris, Manolis Souliotis, Mattheos Santamouris
The development of higher ambient temperatures in cities compared to the surrounding rural and suburban areas is known as Urban Heat Island (UHI) phenomenon or effect, which is responsible for many human discomfort circumstances and increased energy consumption (Souza, Postigo, and Oliveira 2009). The most encountered heat island types could be considered those which occur in the air, at surfaces and in the ground beneath (Oke 1995). The present work deals with the investigation of near-ground ambient air UHI, which hereafter will be referred as UHI for convenience. Extensive research during the past decades proved that urban climates and heat islands are diverse and related to various features, some of them are local and others universal. Bouyer et al. (2015), Santamouris (2016) and Li et al. (2019) summarise the causes of UHI as: less evapotranspiration, because of soil sealing; solar energy absorption, due to lower albedo; less nocturnal infrared radiative loss, due to the building density; less convection, because of reduced air velocity, caused by higher urban surface roughness; higher anthropogenic loads, partly due to air conditioner rejects. It is obvious that these interactions are complex by their own. It is clear that the urban design demands, and principles are affecting all the above. Urban development is, by definition, increasing soil sealing. Albedo of the traditional building materials is low. Densities are desirable and related to development feasibility. Constructions and buildings usually produce a rough urban surface (Moon et al. 2018).
Land degradation and metropolitan expansion in a peri-urban environment
Published in Geomatics, Natural Hazards and Risk, 2021
Vito Imbrenda, Giovanni Quaranta, Rosanna Salvia, Gianluca Egidi, Luca Salvati, Marcela Prokopovà, Rosa Coluzzi, Maria Lanfredi
The centre gravity of this issue is certainly the land, i.e., the ‘place’ where different soil uses compete and that is the most impacted by urban growth (Portnov and Safriel 2004). The obvious example is an impact of peri-urban land use change implying trade-off between maintaining local agriculture and economic and social benefits of urbanization (Dolley et al. 2020). Urban expansion results in increasing pressures on natural resources, on agricultural land and causes degradation of ecosystem services as cities expand (Dolley et al. 2020; Parnell 2016; Seto et al. 2017). Among the most influential drivers of disturbance, urbanization, especially when its pace is rapid, represents an important anthropogenic process affecting worldwide peri-urban areas (Telesca et al. 2009; Zambon et al. 2017; Abubakar et al. 2020; Alipbeki et al. 2020). In most parts of Europe, urbanization, urban sprawl and growing demand for land cause increasing soil sealing (Prokop et al. 2011; Barbero-Sierra et al. 2013; Gardi et al. 2015; Cuadrado-Ciuraneta et al. 2017; Delfanti et al. 2016), soil degradation (Colantoni et al. 2015; Erisman et al. 2016), decreasing performance of natural functions such as biomass production, water storage and filtering or soil quality regulation (Gardi et al. 2015). It is also associated with other negative aspects such as loss of habitats and land fragmentation and water/air pollution (Erisman et al. 2016), reduced evapotranspiration (Carlson and Arthur 2000), increased overland flow and streamflow (Fletcher et al. 2013; Miller et al. 2014) and considerable precipitation changes associated with ‘heat island’ effect (Kalnay and Cai 2003). These changes contribute to food security threat (Ceccarelli et al. 2014; Glaesner et al. 2014) because it decreases productivity and tends to occur on the most fertile soils (Nizeyimana et al. 2001). These pressures are further intensified by climate change (Foley et al. 2005; Chapin et al. 2010).