The consumption of land by construction leads to a loss of soil functions with permanently negative effects on the efficacy of the natural balance. Soils have a large variety of functions which need to be protected: they provide habitats for plants and animals, they store and filter the groundwater, they act as buffers against pollutants, they are the foundation for agriculture and for healthy living, and they are an archive of natural and cultural history. These fundamental functions of the soil must be secured by adequately taking the needs of soil protection into account when planning for the future.
Soil is increasingly gaining importance in societal and ecopolitical matters, especially in view of its adaptation triggered by climate change, the carbon and water storage capacity of the soil and biodiversity. This has led to the introduction of measures and regulations at national level to reduce new land consumption and impervious soil coverage as well as a need for sustainable land management in cities and municipalities.
In 2002, the Federal Government already formulated the goal of reducing new land consumption to 30 ha per day by 2020 (BMUV 2021). This goal was not met, however.
With the German Sustainable Development Strategy 2016, the Federal Government postponed the 2020 goal of 30 hectares to “under 30 hectares per day” by the year 2030 (indicator of sustainability target 11.1a, Federal Statistical Office 2018). In the updated Federal Government’s Sustainable Development Strategy 2021, the aim is to establish a closed-loop land-use regime by 2050, meaning that, in net terms, no additional land shall be developed for the purposes of settlement or transport (Federal Government (ed.) 2020; Federal Statistical Office (Destatis) (ed.) 2021a).
“Germany’s mean, measured across the four years between 2018 and 2021, indicates that the settlement and traffic area increased by an average of about 55 hectares per day. The indicator has thus slightly risen compared to that of the preceding years (54 hectares per day between 2017 and 2020).” (translated from Federal Statistical Office (Destatis) (ed.) 2023a, 2023b, 2023c). Efforts to address this trend shall involve setting ambitious targets and implementing measures on both international and national scales. The global Sustainable Development Goal 15 by the United Nations, along with Germany’s corresponding Sustainability Strategy, emphasise the crucial role of protecting and sustainably utilising soil resources, with degradation neutrality as a central objective (United Nations, 2015; Federal Government (ed.), 2021).
The difference between new land consumption (or land consumption) and impervious soil coverage: the term ‘new land consumption’ refers to the net increase in settlement and traffic areas. The indicator ‘increase in settlement and traffic area’ applies to natural areas that have been converted into settlement or traffic areas. It may therefore also include pervious spaces, such as urban parks, courtyards, greenery along roads, cemeteries, and allotment gardens. Particularly in urban areas this indicator is often not enough to determine the actual condition of the soil and assess the sustainable management of this resource. The impervious area of a city may increase even if land consumption remains the same, such as through inner development and structural redensification. Therefore, information on impervious soil coverage generally offers a more detailed insight into the condition of the soil across the city (LABO, 2020).
Impervious soil coverage (“sealing”) is one of the 16 core indicators by which sustainable development in the State of Berlin is measured (Amt für Statistik Berlin-Brandenburg 2021). This indicator sparked a process in the State of Berlin, aiming to sustainably integrate soil, a limited resource, into the complex interplay of construction and planning processes, based on regulatory options. This process further seeks to strengthen the protection and restoration of valuable soil functions.The goal of the Senate Department for Urban Mobility, Transport, Climate Action and the Environment and the Senate Department for Urban Development, Building and Housing is therefore to provide instruments for an active, practice-oriented land management system. These make it easier, in particular, for the soil protection authorities to perform their tasks as public authorities, e.g. in the context of urban development planning, and of competently integrating aspects of soil-protection in the environmental impact assessment process.
One problem that appears regularly in planning practice is that the impervious covers required for developing an area can hardly be offset in material terms. In principle, the best compensation would involve the removal of the impervious cover (de-sealing) of another area. However, due to the restrictions of availability of most land for such measures, it is difficult to find areas in Berlin where the impervious cover may actually be removed. It is then not possible, using the Environmental Impact Assessment, to implement such measures, due to the lack of any adequate available land. Proposals for the removal of impervious coverage usually have a chance to be realised if areas with the potential of having their impervious cover removed are already known, have been checked for suitability, and are listed in the register.
An initial step was the compilation of Environmental Atlas Map “Planning Advice for Soil Protection”, an important planning instrument for soil protection assessment. The weighing of the various functions and sensitivities of the Berlin soils permitted a differentiated evaluation of urban development planning. For example, in the case of soils which, from a soil protection viewpoint, were classed as particularly valuable, the search for alternative sites for relevant development planning projects was recommended.
The project “Potential for the Removal of Impervious Coverage in Berlin”:/sen/uvk/umwelt/bodenschutz-und-altlasten/vorsorgender-bodenschutz/vorsorgender-bodenschutz-nichtstofflich/entsiegelungspotenziale/ (only available in German) was initiated to improve the availability of areas for impervious coverage removal as a second step. The goal of the project is to identify and evaluate land which could potentially have its impervious cover permanently removed in the foreseeable future. To the extent possible, the efficacy of the soil is to be restored, and habitats valuable from a conservationist point of view are to be developed for plants and animals. In addition, the aim is to support a geographical decoupling of the sites of impairment and those of restoration by means of a city-wide survey and a uniform system for the evaluation of the recorded areas. In individual cases, the instrument of impact mitigation regulation (according to construction law and conservation law) may be considered an option here. The recorded areas generally represent available land that may be used to offset human intervention in the soil or the permanent loss of soil functions. They also indicate land suitable for impervious coverage removal measures within the framework of funding measures.
In the context of the project phases since 2010, a survey has been conducted in all Berlin boroughs, all four Berlin forestry agencies, and among private owners. The most recent update was carried out between October 2023 and November 2023. The data obtained during this survey process has been compiled in a centrally managed database. In the continuous progress of the Berlin programme dedicated to removing impervious covers, the upcoming goal is to consolidate existing records regarding areas potentially suitable for this purpose. This includes exploring participatory approaches to uncover previously unrecognised potential, engaging various stakeholders within the city.
In order to continue to support the implementation of removal measures, a tool to derive simplified cost approaches for the expected dismantling costs has been prepared (an Excel input file simplifies the cost estimate for an impervious coverage removal measure). Based on the review of the literature, proposals for a guide to action have been developed. They address technical and qualitative standards for the regeneration of soil functions following the process of removing impervious covers (all documents only available in German). Additionally, regular newsletters provide updates on current events concerning the removal of impervious soil coverage. In 2021, documentation on successful removal measures was released, outlining the project process, financing and the involvement of the Spandau borough office (SenUVK 2021; please refer to Potential for the Removal of Impervious Soil Coverage (Soil De-Sealing) – Berlin.de (available only in German) for access to the newsletter and documentation). Another report on a current project is scheduled for publication in 2024, documenting the removal measures undertaken at the former Marienfelde borough nursery site.