IMPLEMENTING URBAN RAINWATER MANAGEMENT SYSTEMS: Between policy and practice in Berlin

Presentation at the 1st European Green Urban Infrastructure Conference, Vienna, Nov. 2015

by Natàlia García Soler

Abstract

Berlin’s experience in rainwater management since the 1980s is analyzed. The evolution of policy and planning instruments, and implemented projects is assessed and contrasted, focusing on shifting institutional arrangements.

Despite the multiple benefits of sus-tainable urban rainwater management and the variety of technical and instru-mental options to support its imple-mentation (from green roofs, retention ponds, infiltration trenches, permeable pavements to collection and use), these practices seem to be generally re-stricted to isolated model projects. This paper presents preliminary findings from UrbanRain, a research project funded by the Swedish Research Foun-dation (Formas), examining the chal-lenges and opportunities for main-streaming rainwater harvesting in three European cities. We review the evolu-tion of rainwater management practices in Berlin over the last 35 years. For that, we map and typify implemented pro-jects (according to targeted problems, envisaged solutions, how, when and where implemented and stakeholders involved), and assess policy and plan-ning instruments applied, paying special attention to changing institutional ar-rangements. This retrospective analysis points at connections between the evo-lution of instruments and projects. For example, while in the 1980s large, pub-lic pilot projects predominated; smaller private projects have increased since the 2000s. Tools like, targeted funding, split wastewater tariffs, tender re-quirements or discharge prohibition appear to be crucial behind this devel-opment. The paper concludes by syn-thesizing the findings of this analysis and depicting what implications they have for mainstreaming rainwater man-agement in the future. 

1. Introduction

Urban green assets benefit the urban climate and water cycle by enabling natural regulating phenomena of infiltration, evapotranspiration and retention. Because of that, the implementation of green solutions is closely linked to sustainably managing urban rain- and stormwater. Despite the multiple benefits of sustainable rainwater (RW) management and the wide variety of technical and instrumental options available to support its implementation (e.g. green roofs, green yards, infiltration trenches, permeable pavements, artificial or wetlands), these practices seem to be generally restricted to isolated model projects. Aware of that, the main goal of UrbanRain, a research project funded by the Swedish Research Foundation (Formas), is to figure out the challenges and opportunities for mainstreaming sustainable RW management in three European cities, Stockholm, Barcelona and Berlin.

Berlin has an early and very long experience on implementing green technologies to manage RW. However, abundant interventions have focused and still focus on conventional grey infrastructure to handle some of the problems related to urban water management in the city. An example of that is the Program 2020, launched in 1998 and expected to be completed by 2020, seeking an increase of the storage capacity of the combined sewer system to reduce or totally avoid combined sewer overflows (CSOs), one of the main challenges in the city to fulfil the surface water quality requirements of the Water Framework Directive (WFD) (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, n.d. a; Sieker 2013). This example illustrates that, even though Berlin is considered a front-runner in supporting the development and implementation of urban green assets in general and in doing so to manage RW and stormwater, in practice conventional and alternative solutions/ measures coexist.

According to Geyler et al. (2013, p.24) instruments and institutional regulations greatly influence the development of RW management. Similarly, Winz (2007) states that institutional support, for example in form of regulation or incentives, is fundamental for alternative RW management practices to succeed and consolidate. Concentrating on regulatory instruments and taking as example water saving ordinances in Catalonia, Domènech et al. (2014) highlight the centrality of these instruments to foster and consolidate RW collection and use practices.  It can be therefore inferred that policy instruments greatly influence the action conditions and the kind of technical solutions that are preferred and implemented; in that way, instruments  may contribute, or not, to the introduction, consolidation and widespread of non-conventional RW management solutions.

Based on this argument and the UrbanRain Project’s goals, the evolution of RW management practices in Berlin has been reviewed by assessing policy and planning instruments and implemented projects in the last 35 years. This paper presents preliminary findings from this research in form of a quantitative database compiling 108 instruments and 272 RW management projects executed from 1980 to 2015. This retrospective review has two main goals; provide overview background information for further analysis and a sound basis for the selection of the case studies, which will follow in the next research stage. In doing so, special attention is paid to changing institutional arrangements and type of executed projects. 

The results of this analysis are presented in the following paragraphs. They provide very valuable background information for assessing mainstreaming processes in the city as well as factors influencing them. However, they should not be seen as definite and complete but as interim and evolving results. Section 2 briefly depicts the applied methodology, Section 3 presents insights on the intermediate results, which are subsequently discussed in Section 4. 

 

2. Methodology

As previously stated, the retrospective review on RW management practices in Berlin, and the resulting database were motivated by the long experience and abundant examples in Berlin, as well as a lack of overview on them.

To make this exercise feasible, given the existing limitations and the inherent complexity and broadness of the topic, a simplified online research method was chosen and carried out during approximately one year. The author is aware of the existence of complementary tools, e.g. geo-informatics, and of the limitations of the used methodology. Thus it cannot be stated that the database reflects a definite and complete state of the art, but it contributes approaching it by providing a good overview on the existing tools and projects, as well as their temporal evolution.

The 35 years timeframe (1980-2015) was set in connection to an initial hypothesis related to the role that the German re-unification might have played in the mainstreaming process of sustainable RW management solutions. Because of that, it was considered appropriate to set the beginning of the timeframe back to the 1980s. It is important to underline that projects and instruments in phases prior to implementation, i.e. discussion, development and planning, have been excluded (in other words, the database contains them if they started getting implemented in 2015 or before).

How RW is managed in the city is influenced by the policy and planning instruments framing it and the implemented projects that bring it into practice, which in turn interact and affect what solutions are implemented how, where and by whom. Consequently, both, instruments and projects, are contained in the prepared database to help analyzing to which extent and in what form sustainable RW management practices mainstream in Berlin. Due to the transversal and multi-level character of urban RW management, projects and instruments connected to several decision-making levels (EU, Federal, State, District) and sectors (grouped in environmental protection, urban planning and development, water management and “others”) are included.

Planning and policy instruments are understood here as public supporting tools in form of legal pieces, planning tools, financial incentives (direct and indirect), strategic and informative documents, etc. relevant for Berlin. This comprehends for example, the Federal Wastewater Charges Law, the Building Code for Berlin, Berlin’s Urban Development Plan- Climate, EFER Funding, Ecological Construction Pilot Projects Program, 100-Yards-Contest (“100-Höfe-Wettbewerb”), German Guidelines for Roof Greening for Municipalities, Berlin’s Environmental Atlas, Neighborhood Concept Green Moabit, among others. Research projects working on related fields have not been included. All instruments are registered just once, implying that e.g. landscape plans are just recorded in the year 1990 (when they were established as tool for whole Berlin) instead of every time they are issued; legal pieces in the year of their last re-formulation (German: “Neufassung”) and comprehensive revision; technical standards are not included individually but as a “pack” in the year the first was issued, and for ecological development plans of the rivers passing through the city, the year in which their development process started was taken into account, instead of their completion (some are still in development).

The implemented projects included range from very big, well-known and paradigmatic projects to single-building, private measures. Including this broad spectrum is considered very important, since this reflects the “profile” of existing systems in Berlin and may enable identifying if and how they changed through the years. Bearing that in mind, it is fundamental to clarify what these projects are. For the purpose of the database it was considered suitable to dismiss projects considered “conventional”, e.g. those consisting on underground retention basins, and to focus on “alternative” practices instead. These are defined as built interventions adding value to RW by retaining, infiltrating, evaporating, collecting or/and using it, instead of directing it directly to the canalization or water body. That comprehends e.g. green roofs, façades, yards, swales and trenches, permeable pavements, retention ponds, artificial wetlands, collection cisterns and RW use facilities.

As previously mentioned, the methodology applied has some limitations, mainly the differing, unequal accessibility and quality of information available online and in brochure format depending on the type of project and instrument. Even though these issues affect both, instruments are generally well documented. Hence, the impact these limitations have on the information about projects is supposed to be more relevant, possibly incurring some bias in their assessment. Generally, public, or public-related, and large (public or private) projects with high profile are better documented online than private, small-scale ones. Similarly, more recent projects are more often detectable online than older ones. Thus, it is to be assumed that there are more systems installed at private and commercial sites, than included in the database. An example of this limitation, and potential bias, are the over 1,600 greening projects financed by the State Funding Program for Greening measures (“Hofbegrünungsprogramm”) running from 1983 to 1995 (cf. Reichmann, 2009). However, since no disclosed information could be found on all of them, they are not included in the database as singular projects. When interpreting the results, it is very important to bear that in mind.
For statistical purposes, the years in which instruments and projects were launched and constructed are grouped in 5-year terms, with the exception of the first group “till 1990”, to avoid fragmenting data too much, and the last “2015”. In other words, the category “1990-1994” includes initiatives that started between January 1990 and December 1994.

 

3. Database results

3.1. Findings on policy and planning instruments

At the moment, 108 instruments with a connection to RW management in Berlin, issued between 1980 and 2015, could be identified and are included in the database. To facilitate their statistical assessment, they have been grouped in sectors and levels of decision-making, as well as in the type of instrument.  In terms of sectors, fields of action, the following categories have been established: water management (incl. drinking water, surface water, wastewater and groundwater if applicable), environmental protection (focus on nature protection, pollution, habitat protection- biodiversity, environmental impact and relief), urban planning and development (incl. landscape planning and housing) or “others” (incl. climate change (CC), technical standards and investment in education facilities). Concerning the levels of decision making, EU, Germany, Berlin and its districts have been considered. Additionally, the instruments are typified in “require”, “promote” and “inform”, taking as a reference the proposed classification by Ansel (2011, p. 21). The “require” category includes generally and administratively binding instruments like laws, tender requirements, technical standards and planning instruments, e.g. urban land use and development plans, landscape program, ecological development plans for rivers passing Berlin. “Promote” instruments comprise tools incentivizing certain behaviours and practices, generally through direct and indirect subsidies and funding, or the direct execution of certain practices by public authorities, e.g. “International Architecture Exhibition”, urban development funding programs, “public” landscape interventions, “public” pilot projects, split wastewater tariff, greening contest-prize, etc. “Inform” instruments, instead, are those providing information (e.g. Berlin’s Umweltatlas and FIS Broker) or reporting on specific issues and topics, as well as on “best” practices to communicate and provide knowledge and raise awareness. For some instruments, it was not clear if they are administratively binding or not (e.g. Berlin’s Landscape Strategy) and were attributed the category ”inform”.

In regards of the temporal distribution of all instruments identified, approx. 26% were launched between 2005 and 2009, 19% in 1990-1994, 17% between 2010 and 2014, 16% in 2000-2004, 11% between 1995 and 1999, 7% till 1989 and 4% during 2015. In terms of sector of decision making, about 44% of the instruments are related to urban planning and development, 32% to water management, 18% to environmental protection and 6% to others. Coherent with the fields of action and distribution of competencies, the degree to which the different decision-making levels got involved (reflected by % of instruments resulting from them) also varies. 58% of the instruments resulted from the State Berlin, 20% from the German Federal level, 16% from the EU and 6% from the Districts. However, it is not possible yet to determine how instruments from one level influence or motivate those from the others, if and which chain effects existed and to which extent resources from one level enabled  instruments from others (e.g. EU funding in State funding programs). Concerning their typology, approximately 46% of the compiled instruments belong to the category “require”, 36% to “inform” and 18% to “promote”. Here it is necessary to mention that the data presented here does not reflect the efficacy or impact of the instruments, but their amount or relative presence (% out of total registered instruments). Thus, based on this information it cannot be inferred how effective each type of instrument, sector or level of decision making has been in supporting the implementation of sustainable RW management practices in Berlin.

As depicted in 1 no significant breaks can be identified in the issuing of supporting instruments. The predominance of “require” instruments is observed through the years, with the exception of the last 5 years (since 2010), in which “inform” instruments are the most abundant. As stated above chain effects can be identified. For instance, “require” instruments from EU encourage “require” Federal instruments and this in turn “require” or “inform” instruments at State level. In addition to that, instruments, especially “require”, are often released in combination with complementary ones of other types, especially “inform”. How this combination of supporting instruments is carried out and functions in practice is of great interest for the research project and will be further assessed in forthcoming research stages.

Changes in the field of action to which the instruments are related are assumed to point at alterations in the political agenda and priorities, which in turn are influenced by many other factors that could not be assessed here (e.g. experienced events, social values, personal interests and time until elections, etc.). Based on the information illustrated in 2, the “priorities” of action in Berlin seem to have evolved from urban planning and development, predominant instruments in the 80s and 90s, to the growing importance of water issues from 1995 onwards and “booming” from 2000 to 2010 and environmental protection concerns becoming more significant from 2000 on. The abundance of instruments on CC in the category “others” may explain why it gained presence in the last years. 

Fig.1 Temporal distribution of policy and planning instruments according to their sector; Source: Author

Connections between decision-making levels and the type of instruments, as well as with the sectors have been identified. Consequently, a relationship between the type of instrument and sector of action was assumed and corroborated, as shown in 3. These interlinkages and the extent to which levels are involved may depend on the way how competencies are distributed and which influencing mechanisms are at each level’s hand. In other words, bearing in mind the fact that urban planning and development is a local competency (framed by and complying with State and Federal principles) and the particularity of Berlin being a City-State, it is not surprising that all identified instruments at the district level belong to the urban planning and development sector. Similarly, environmental protection and water management instruments are predominant at the EU level. 

 

Fig.2 Relationship between level of decision making and sector; Source: Author

In terms of the link between the sector and the type of instrument used, “require” instruments distinctively dominate environmental protection and water management. This can be explained by the fact that in these fields of action guaranteeing “minimum” negative effects on the environment via binding regulations and legal pieces is mainly sought. The plurality and diversity of instruments on urban planning and development is reflected in 4, since all types of instrument are present to similar extents. As depicted in the same figure, the field of action “others” is mostly managed with “inform” instruments by now, these correspond to CC-focused instruments, currently being rather approached through publishing strategic, informing and awareness raising brochures and documents.

 

Fig.  Relationship between sectors and type of policy and planning instrument; Source: Author

As previously mentioned, these insights on the instruments’ characteristics and evolution trends deliver a quantitative reflection of the existing supporting instruments, and do not reflect on their efficacy and impact. Promote instruments, for example, have shown a rather weak presence based on the quantitative analysis, yet in practice, some of them seem to have a central role in supporting the mainstreaming of RW management practices in Berlin, e.g. split tariff, Environmental Relief Program (Umweltentlastungsprogramm, UEP I and II) or Federal funding for urban development programs (e.g. urban renewal, sanitation and development, quarter management, urban renewal West and East, Active City- Active Centers, etc.). Similarly, the actual influencing capacity of the decision-making levels can difficultly be reflected by this data since many of the instruments are recorded once instead of every time they are applied (see Section 2.). For instance, districts can intervene every time land use and landscape plans are developed and altered, building permits are issued or development and construction contracts are signed but all these mechanisms are recorded once in the database. Likewise, the importance of EU “promote” instruments in form of funding is underrepresented because they are not included as singular instruments (e.g. Horizon 2020, LIFE program, European Regional Development Funds (ERDF), etc.), but often in other State and District instruments like UEP.
In parallel to these tools supporting “alternative” green solutions, instruments promoting “conventional” grey systems, like the RW cleaning basins program in the 80s and the still on-going canal rehabilitation program, Program 2020 are still cornerstones of the RW management in Berlin. The Program 2020 aims at expanding the storage capacity of the combined sewer in the city centre via underground retention basins and automatic devices seeking to reduce, or avoid, CSOs, and has an approximate cost of 140 million € (cf. Rehfeld-Klein, 2011). Thus, there is a coexistence of policy and planning instruments encouraging differing technical solutions. Grey solutions for detaining RW in the canalization are carried out in parallel to the launching of information materials on and funding for greening and unsealing of urban spaces, and the split wastewater tariff. In fact, the WFD, one of the instruments considered crucial for the widespread sustainable water management in Europe, appears to motivate the implementation of rather big, conventional solutions in Berlin, since together with the river development plans, the priority is to act on combined sewer system area (to reduce CSOs) and the main measures carried out there are conventional underground retention basins, giving measures to retrofit areas in separate sewer system an add-on character (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, n.d. a).

The instrument database and its analysis provide a very valuable overview and reflection on the instruments applied in Berlin since the 80s to frame and influence the implementation of green RW management solutions. However, conclusions must be drawn with caution.

 

3.2. Findings on implemented projects

272 projects implemented in Berlin between 1980 and 2015 have been identified via online research. For internal research purposes, they have been divided in “green infrastructure” and “blue infrastructure” projects, even though they were not necessarily conceived as an infrastructure in a narrow sense, but as “disconnected” systems. The main difference between these two groups is that “green infrastructure” did not include a water management component. In other words, there was no explicit link to RW management in its goals, or no other system component focusing on it (e.g. no infiltration trench, in case of greened yard). Contrarily, the “blue infrastructure” projects may include greening measures, but count with others more explicitly focusing on RW (e.g. unsealing is combined with RW retention and infiltration facilities). This differentiation is sensitive and could become problematic, especially given the unbalances in the available information on the different projects, yet coherent and necessary with the methodology for internal case selection. Based on the clarified differentiation, approximately 57% of the included projects belong to the category “Green infrastructure” and about 43% to “Blue”.
When interpreting the database results it is important to bear in mind that the actual amount of especially “green infrastructure” might be considerably underestimated. An example of that are the 1,643 projects, corresponding to 740,000m2 greened yards and façades and 65,000m2 greened roofs throughout the city, which were financed between 1983 and 1995 by the State Funding Program for Greening measures (cf. Reichmann, 2009). Or the projects supported by instruments like “100-Yards-Contest”, “Contest Green Yards – Good Climate” and “Spandau Action Green Thumbs”. These projects could only be included fragmentarily due to data availability. To complement that shortcoming and provide a more exhaustive picture of greening issues in the city, information on Berlin’s sealing degree and green/open spaces has been collected and is presented in the following paragraphs.

In 2011, the sealing degree of Berlin’s surface was 32.8% (total surface calculation including water bodies and streets). Here it is important to underline that permeable pavements are considered in this statistic as sealed surfaces (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, 2012a). This sealing degree is approx. 0.9% higher than in 2005 (31.9%) and took mostly place in form of “unbuilt sealed area” (defined as sealed surface without buildings, e.g. roadways, parking lots, paved paths, etc.). This percentage cannot be compared to previous data because they were acquired and calculated using different methods. However, a possible reduction of sealing degree in the city since the 90s is considered very unlikely (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, 2012a). Currently, 83.1ha are registered in the cadastre as “unsealing potential” area, dismissing 1062.4ha classified as “diffuse unsealing potential” because of inaccurate quantification opportunities (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, 2015a).

Green and open spaces are categorized according to the following uses: forests (17.3% of whole Berlin’s area are forest), grassland (1.3%), arable land (2.5%), brownfields (3.6%) and tree nurseries and horticulture businesses (0.4%), these green space uses are mostly located outskirts, while small garden areas (3.8%) are closer to the city center but still out of the “Berlin Ringbahn”, parks- green facilities (5%), city square/ boulevard (0.1%) and cemeteries (1.3%) are present all over the city (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, 2011). According to the data of 31st of December 2014, public green spaces occupy a 12.9% of the total city area (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, 2014a).

Green and unsealed spaces are unevenly distributed throughout the city in terms of their type and of their area. However, it can generally be inferred that central districts like Mitte and Friedrichshain-Kreuzberg have the highest proportion of sealed and built surface (around 80% of their area), while in periphery, e.g. in Treptow-Köpenick, Pankow and Spandau, this proportion ranges between 35-50%. The size of the green and open spaces increases the further they are away from the city center. Periphery districts, very rich in forest and with extensive park areas, e.g. Treptow-Köpenick (approx. 9000 green hectares in total), Spandau (almost 4000ha), Steglitz-Zehlendorf (close to 4000ha) have the largest total green areas in the city. Interestingly, the center-close district of Charlottenburg-Wilmersdorf has significantly larger green areas (about 2600ha), than periphery ones like Marzahn-Hellersdorf (about 1600ha) or Tempelhof-Schöneberg (approx. 1200ha). This can be explained by the fact that more than half of its green area corresponds to the Grunewald forest in the West. The most central districts, Mitte and Friedrichsain-Kreuzberg, have the least green surface (about 700ha and 200ha respectively) and more than half of it are parks/green areas. (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, 2011). As expected, the proximity to the densely built city center generally relates to less green spaces; yet, Mitte has larger green areas than Friedrichshain, despite being the center of the city.  Therefore other variables like image, priorities-interests, actors involved and urban development history of Berlin, among others, should be considered to explain the uneven distribution of green spaces.

The spatial distribution of the identified projects is also of interest for this research, since it may point at possible factors influencing the implementation and spread of alternative RW management practices. The following map, 5, shows this distribution across the districts expressed in percentage of “green” or “blue” projects out of the total, implemented in each district. For instance, the green 13% in district Mitte means that 13% of all cataloged projects are “green” projects which are implemented in this district. The blue, 4% similarly refer to the share of blue projects in this district from the overall amount of projects. Projects without data on their location or executed in several districts (e.g. 20 main green paths, green tram tracks) are not included in the map but were accounted for in the calculation of these percentages.

Fig.1  Spatial distribution of projects; Source: Author based on a map from Berlintipps.net

As it can be seen, no clear trends in the projects’ distribution can be identified, yet a light inclination towards Eastern city districts can be recognized. This, however, does not necessarily mean that these districts are frontrunners in these matters since, according to Nickel et al. (2014, p.413), the water autarchy of West Berlin during the division of the city was a very significant motivator of decentralized RW, stormwater management and green assets protection.

Additionally, the map reveals certain prevalence of “green” projects in the city centre and of “blue” projects tending to the outskirts. This is shown by the marked numbers in circles (highest percentages of each type of projects). These slight tendencies in the projects’ distribution may be explained by manifold factors, for example, financial resources available in the districts, actors involved, proximity to water protection areas, population profile, amount of new developed or renewed buildings and settlements, available space (given the distinction between “green” and “blue” projects, it could be assumed that water-related technical systems like infiltration trenches or gravel filters, may be space intense and consequently complicated to implement in very dense areas like the city center), historical issues etc. Nonetheless, at this stage of research and based on the collected information the following factors appear to have (had) a great influence on the process.

The first one is connected to the fact that Berlin counts with two different sewer systems, the combined sewer system (waste and rainwater are lead to and by the same canal) found in the city center (within the Berlin Ringbahn) and 1900km long (in Mitte district, Prenzlauer Berg in Pankow; Friedrichshain-Kreuzberg district, in Schöneberg, part of Tempelhof-Schöneberg; in some parts of Neukölln and of Wilmersdorf – in Westend, Charlottenburg-Wilmersdorf district; as well as Spandauer Altstadt, in Spandau). And the separate sewer system (with two separate canals, one for rainwater and one for wastewater) 4300km long and found in all the other parts of the city. (cf. ISU, 2012). Even though it is not possible to precisely determine how many projects are located in each sewer system, the collected data, as depicted in the map, shows the above mentioned tendency of “blue” projects being found rather in areas with separate sewer system (out of the “Berlin Ringbahn” and periphery) while “green” ones are mostly in combined sewer system (city center). How significant this relationship might be, in which direction and why is to be assessed in depth in forthcoming research stages.

Secondly, the challenges faced and opportunities for action in the city center greatly differ from those in the periphery. In the inner city concerns related to the high sealing degree are prevalent, like urban heat island effect, as well as, increasing groundwater level, wet cellars and CSOs. CSOs are mainly being handled by underground expansions of the storage capacity of the canalization, here categorized as “conventional solutions”, are well known and considered as “predictable/reliable” solutions (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, n.d. a; Rehfeld-Klein, 2011). Problems with increasing groundwater levels and wet cellars in some parts of the city rather discourage technical measures like infiltration or detention of RW (cf. Sieker, 1998; Moss, 2011), and urban heat islands are being mostly approached by greening measures seeking their cooling effect and improvement of living conditions (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, 2011, 2012b, 2013 and 2014b). These aspects might help comprehend which type of projects are distributed throughout the city districts. However they are not sufficient to soundly clarify it. A deep discussion on the reasons is considered out of this paper’s scope but shall be part of next research steps.

In terms of their temporal distribution, a 25% of all identified projects started in 2010-2014, 23% 2005-2009, 11% 1990-1994 and 2000-2004, 8% 1995-1999 and 2% until 1989. This clearly points at an increase of projects being implemented in the last 10 years, it could be biased as consequence of the online-based research, since more recent projects are more likely documented in this format. However, since the available information already reflects that the implementation of projects did not suffer any significant breaks, it is assumed that, in spite of the drawbacks, the acknowledged trends are valid and it might be inferable that RW management projects using green solutions gained, or at least kept, importance through time.

Having underlined this general information, the following paragraphs assess how the projects evolved in the last 35 years in terms of their size1 and type of building/ site2 they are located in. In terms of size, no distinct predominance has been identified. Approximately 37% of the projects are small and 35% large, and on 28% no data was available. Instead when looking at the type of building/site they are located in it is easy to notice that projects at public space/ service clearly predominate representing 52% of all projects, followed by those at residential sites (32%) and commercial (12%) (4% without data). Since public-based projects are better documented online, it is to expect that projects at commercial and residential sites are underestimated in the presented numbers. The category “public space/service” includes public spaces (e.g. streets, squares, Administration buildings) and public services referring to educational, social and health facilities (e.g. schools, hospitals, Kindergarten). The importance of these two sub-types among “Blue” and “Green” projects diverges. While for “Blue” it is balanced with approx. 50% in each. In the case of “Green”, 73% correspond to public spaces and 27% to public service facilities, indicating that “public green projects” mostly refer to greening/ unsealing projects in public spaces.

Pic. Blue residential projects, left side small, right side large; Author: Natàlia García Soler

By assessing how these parameters changed over time, interesting findings come across. In terms of size (6), a slight trend towards growing numbers of small “green” and “blue” projects can be found. Large greening projects in 1990-1994 greatly correspond to urban development and renewal areas. The number of large greening projects tends to decrease with exception of 2010-2014, between these years several big landscape interventions and new (re-)development areas were officially declared and carried out. The number of small “green” projects, mostly in form of greened yards or roofs increases, according to the database, but it is important to remember that between 1983 and 1995 over 1600 greening projects were executed funded by the Funding Program for Greening measures which are only partially accounted for. In terms of “blue” projects, large ones before 1995 were new developed settlements and those between 2000 and 2014 mostly gravel filters (close to water bodies) as well as renewed or newly built large properties (business headquarters, schools, etc.). Between 2005 and 2009, the number of large “blue” projects remains stable but the number of small ones grows significantly and this difference even increases for the following phase (2010-2014). Lacking data on the timeframe of execution affects more significantly “green” projects than “blue” ones, probably due to the sources of information used to identify them (often planning consultants and architects websites, which have a limited amount of information with open access online).

Fig.  Relationship between type of site/building and size of project; Source: Author

Looking at the temporal evolution of the projects based on the type of site they are in (7), it can be noticed that “public space/service blue” projects are present throughout the 35 years, increasing and maintaining their amount in the last 15 years, years in which the amount of projects at commercial and residential sites grow significantly. Instead, “public space/ service green” projects were abundant in 1990-1999, 2005-2009 and 2010-2014, while the number of “residential green” projects grows since 2000 remarkably and steadily, and “commercial green” projects increased noticeably in 2005-2009, but less projects were found for the following years. In relation to “green” projects at commercial and residential sites it is considered very challenging to find projects implemented in earlier considered timeframe with the applied methodology.

Fig.  Temporal distribution of projects according to type of site/building; Source: Author

Based on the obtained data on the projects’ categorization and their temporal evolution, it was assumed that both parameters, type of site/building and size, were related. This relationship is graphically captured in 8.

Fig.  Relationship between type of site/building and size of project; Source: Author

About 30% of the public space/services projects correspond to “large green” projects (expansive greening in frame of urban renewal and development projects), while “small green” ones account for only about 9%. Contrary, “blue” projects at public spaces/services are about 19% large and 17% small (here new settlement developments, gravel filters, renewal of public facilities’ parcels and single buildings seem to be almost balanced). It can be cautiously inferred that projects at public spaces/services sites or buildings tended to be larger in scale. At commercial sites and buildings, “small green” projects, around 30%, and “large blue” projects predominate with approximately 27%. This diverging observation could be explained by the fact that, very often, “blue” projects were executed in the frame of a new construction, renovation or expansion of company’s site and buildings, in many occasions being obliged to limit their RW discharge into the canalization  and/or having lots of available space (e.g. parking lots, roofs, pathways, etc.). Thus, several technical solutions are frequently implemented in combination (e.g. greening, unsealing, infiltration trenches, RW collection, etc.). On the other side, “green” projects mostly consisted of roof greening, which not always entails a large area. Furthermore, approximately 18% of projects in commercial sites/buildings are “small blue”, generally in form of RW collection and use. Concerning residential sites/ buildings, the majority of projects implemented correspond to “green” projects (about 70%, incl. n.d.), very few in large dimensions (e.g. private residential sites with green roofs or yards) and approx. 36% “small” ones. Here the group of projects with no data on their size is very significant (32%) and hinders further conclusions. “Blue” projects are rather marginal (30% in total, incl. n.d.) and among them about 13% are small, and 10% large.

Pic.  RW management system Wisch Engineering (Source: IKZ Haustechnik, 2012)

To sum up, despite the acknowledged methodological drawbacks of this database, the exercise provides very valuable information on the evolution of RW management projects in Berlin. First of all, it has been proved that there were no significant pauses in their implementation and that the number of executed projects in the last 15 years increased. And secondly, raising numbers of projects at commercial and residential sites were observed, probably in parallel to a general size reduction of projects implemented, with the exception of projects linked to new developments, renovation or expansion of commercial sites and public service facilities.

 

4. Findings on potential interlinkages between instruments and projects

The instruments’ efficacy and impact in supporting the mainstreaming of RW management practices in Berlin are to be analyzed in more detail in forthcoming research stages of the UrbanRain project, paying closer attention to other influencing factors. This section aims at briefly discussing potential linkages between the instruments and projects for sustainable RW management in Berlin as well as their evolution.

Literature highlights the influence of policy and planning instruments on the implementation of projects, to which extent they spread and how they consolidate as a valid alternative to conventional practices. For example, Schütze (2013, p. 383) states that “…regulations and government policies influence the process of adoption of decentralized RW management, harvesting and utilization systems”. According to Rauch et al. (2005, p.403), non-structural solutions (among others, policy and planning instruments) contribute generating, establishing and consolidating context conditions suitable for implementing structural decentralized solutions. Considering these arguments and the similar temporal distribution of instruments and projects included in the database, it could be assumed that instruments applied in Berlin generally have a notable influence on the RW management practices in the city and the projects implemented. Which instruments contributed and supported the implementation of non-conventional RW management systems the most and with what effect is not yet interpretable.

The variety of available policy and planning instruments, as well as their multi-level and multi-sectoral character have been reflected by the statistical data. The statistically acknowledged changes in the “weight” of the different decision-making sectors throughout the 35 years are assumed to point at changing policy agenda. However, the reasons why and how certain matters get in the political agenda are out of this paper’s scope. Concerns on fulfilling basic environmental standards, guaranteeing service provision and levelling off differences in the canalisation network between Western and Eastern Berlin were main concerns during the 1980s and 1990s (cf. Moss, 2000, 2011). At the same time, urban development and planning were central concerns in the city. Many of these challenges were often handled with grey and conventional solutions, but there was a certain openness and willingness to apply alternative solutions, echoed by instruments like “International Architecture Exhibition” (IBA, 1977-1987), State “Ecological Construction- Pilot Projects Programme” (1988-2001), “Federal Experimental Housing Program” and ecological requirements for social housing construction funding, which supported many large pilot projects (mostly residential settlements) embracing sustainable RW management practices and (re-)development of city areas including unsealing or greening measures. Since 2000 environmental aspects seem to gain importance at policy level and questions about the sustainability and suitability of traditional technical systems to cope with current and expected challenges raised. Parallelisms between this agenda development and evolution at international scale can be identified and are also underlined in e.g. Barbosa et al. (2012), Cettner et al. (2012 and 2014), Winz (2011), Agudelo-Vera (2011), Chocat et al. (2007).

Water quality concerns gained importance with the WFD coming into force in December 2000 and, as already mentioned, CSOs and other pollution sources became a central concern for the city (cf. Sieker 2013). To reduce or even avoid them, the program 2020 (1998 to 2020) was launched and should be complemented by retrofitting measures in areas with separate sewer system. Additionally, within the CC debate in the last years, the relevance of evapotranspiration to cope with increasing temperatures in urban areas, and the expected impacts of CC in Berlin (including strong precipitations and concentration of precipitation in fewer days) are extensively discussed and advocated for in many strategic documents, like StEP-Klima (2011) and the Landscape Strategy Berlin (2012). Special attention has been paid to inner city greening and unsealing measures. At the same time, green assets are currently valued in the urban context for enhancing living quality and city image. These priorities are also mirrored by changes in the supporting instruments and implemented greening projects in the city, even though similar “promoting schemes” for small scale greening and unsealing measures were identified in different stages, from the early 1980s until nowadays.

The centrality of policy documents in form of regulations and binding tools is widely recognized in the literature (cf. e.g. Lazarova et al. 2001; Krozer et al. 2010, Vallès et al. 2011; Li 2012, Petrucci et al. 2013, Moss 2001, Cettner et al. 2012, Wong 2007, Marsalek and Chocat 2002) and corroborated in the database by the predominance of “require” instruments. These set the base for other instruments and the frame for acting. For example, legal pieces like Berlin Water Law (Berliner Wassergesetz, reformulated in 2005), Federal Water Act (Wasserhaushaltgesetz, reformulated in 2009) and Federal Nature Protection Law (Bundesnaturschutzgesetz, reformulated in 2009) prioritize evaporating, retaining, using, and infiltrating RW close to the location of precipitation over its direct discharge into the canal. Furthermore, the fact that the State regulation on “exemption of rainwater” (NwFreiV) underlines the necessity and advisability of letting rainwater infiltrate onsite without requiring a permission, if it is not in drinking water protection areas, may favour the implementation of alternative ways to manage RW. Apart from these framing documents, based on the insights of this research, discharge limits issued by the water authority or districts, obligations included in land use plans and building permits (issued by districts) are some “require” tools with great potential for influencing and supporting the implementation of RW management practices, either by prohibiting RW discharge in the canalization, securing space for them in the development plans or including them as a prerequisite to obtain a building permission.

An often postulated supporter of greening and unsealing in Berlin is the Biotope Area Ratio, which counts with significant reputation at international level. Since 1994 this binding tool is contained in landscape program and to be included in district landscape plans (e.g. cf. Dolowitz et al. 2012; Nickel et al. 2014). In practice, however, it can be found in rather few Landscape Plans, by June 2015 it was included in 15 out of 44 consolidated plans and in 10 plans with ongoing establishment (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, 2015b), supporting greening and unsealing measures to a limited extent.

The mandatory ecological requirements for social housing (since 1990), architectural tenders (1992) and public and publicly financed buildings (1994) are attempts to push forward and spread these elements in new developed and renewed housing. However, water and greening are only some of the includable components. Thus, it is not possible to know which ecological aspects have been/are prioritized and implemented (e.g. architects, constructors and developers can chose what ecological measures and elements they include).

In 1, the example of the headquarters of Wisch Engineering is provided. The project was finalized in 2010, executed in frame of the company’s expansion and required by the discharge limitation issued by the water authority. As a consequence a RW management concept had to be developed to handle RW from approx. 12,000m2 of roof area and 1650m2 of asphalted surface. To do that vegetated troughs for enabling infiltration have been installed, “cleaning” the water before collecting it in two underground cisterns (each 96m3) and using it for toilette flushing and fire water, after having prepared it accordingly. A maximum of 50m3 of RW are allowed to infiltrate on the property annually. (cf. IKZ Haustechnik 2012, Rockstroh 2012)

“Promote” instruments are considered central management instrument in the literature, especially in form of subsidies (cf. e.g. van de Meene et al., 2011; Colebatch, 2006; Marsalek and Chocat, 2002; Geyler et al. 2013; Roy et al. 2008). Based on the amount of identified instruments of this kind, it is concluded that “promote” instruments are more rarely used for RW management in Berlin. However, in terms of impact, many of them seem to have major influence in the expansion of RW management practices. For example, the wastewater split tariff, a financial instrument based on indirect subsidies in form of discounts and exemptions in RW tariff if RW management measures are implemented, was introduced in 2000 as a consequence of a decision of the Administrative Court. In the same year the Administrative Court required a separated bill for RW drainage because it corresponded to more than 15% of the total wastewater treatment and drainage expenses (cf. Grundeigentum- Verlag, 2000). This tool is postulated as a main motivator for implementing RW management practices. However, while discussing this type of instrument, Schütze (2013) states that fee savings through the installation of RW management systems is mostly considered a convincing argument by those having lots of space or consuming lots of water (if RW is used) or being very environmentally aware. Thus, it might be possible that the split tariff is not necessarily leading owners of small properties to implement RW management systems, but those with larger parcels.

The importance of other “promote” instruments like the International Architecture Exhibition (IBA) and “Ecological construction- Pilot projects Programme” has been previously mentioned, since they were very important given the priorities in early 1990s and were accompanied by numerous informative material, becoming a potential learning source for further developing, testing and raising awareness on the technologies. In 2 some of the ecological elements of the settlement at Weinmeisterhornweg are to be seen. On the left, a pathway next to the small biotope used as infiltration swale and on the right green spaces also used as such. Apart from these elements, the settlement counts with a compact structure, green roofs and low sealing degree of open spaces to enable infiltration. An infiltration pond was also developed and thanks to all these measures no connection to the RW canalisation was needed. The settlement is 1ha big and was developed between 1992 and 1994 according to the ecological requirements for social housing construction and with support from the “Ecological construction- Pilot project Programme”. (cf. Senatsverwaltung für Stadtentwicklung und Umwelt, n.d. b) 

Pic.  RW management system Weinmeisterhornweg settlement (Source: GSW/IBUS GmbH, n.d.)

In terms of building-based greening measures, it is assumed, that funding provided between 1983 and 1995 (run 1983-1990 separately in both parts of the city, and from 1990 onwards citywide) greatly contributed to disseminate this kind of measures (cf. Reichmann 2009). No analogous city-wide tool has been yet released since 1995. Indeed, a new program is currently (October 2015) under discussion in the State Parliament. Some similar programs, with smaller scope are implemented at district level, e.g. since 1999 “100-Höfe-Wettbewerb” providing direct subsidies (up to 600€), since 2011 the “Spandau Aktion Grüner Daumen” and from 2001 to 2011, the city-wide “contest program” “Wettbewerb Grüne Höfe-Gutes Klima”. These initiatives encourage private owners and tenants, through direct subsidies of differing amount, to green and unseal part of their “properties”. 3 shows the transformation of a yard, before and after the greening measures carried out by the tenants (or owners) and partially funded in the frame of the “Spandau Aktion Grüner Daumen”.

Pic.  Greened yard, Spandau (Source: Wilhelmstadt-bewegt, n.d.)

The Environmental Relief Program I and II (Umweltentlastungsprogram), from 2000 to 2007 the first, and 2008 to 2015 the second, provided financing for renewal and new-development projects including environmental protection and technical innovation. Many schools and other social facilities benefitted from these direct subsidies. Additionally the Federal program Future Education and Care (Zukunft Bildung und Betreuung), from 2003 to 2009, also granted funding for education facilities including greening and RW management systems, among others, in the frame of renovations and new construction of their amenities. The UEPs’ successor program is the Berlins Program for Sustainable Development (Berliner Programm für Nachhaltige Entwicklung, BENE), running from 2014 until 2020, co-financed with EU resources (ERDF), which emphasizes on climate protection measures and environmental protection, leaving hardly any space to water aspects. “Promote” instruments have also remarkably held up the execution of large scale greening and unsealing measures, especially the financing from the Federal Urban Development Promotion (Städtebauförderung), in form of several urban development and renewal programs since the 1990s.
In one of these development areas, Biesdorf Süd, the Schmetterlingswiese (4) was developed between 2000 and 2005, biggest green space in the area (6600m2), designed as a rain retention basin filling in case of strong precipitation and being used as a playground when it is empty (cf. Senatsverwaltung für Stadtentwicklung, 2007, pp. 18-19)

Pic.  RW management system Schmetterlingswiese (Source: Archiv Baugrund/Alexander Krause, 2007)

As previously stated, the role of the EU as funding provider is not properly reflected by this exercise, because the abundant funding options with potential to finance RW management systems are not included in this database as singular instruments but partly when used for financing other programs (e.g. ERDF in UEP I and II). The growing importance of green assets within the EU is significant (mostly in form of “Inform” instruments, like communications, white papers, brochures, etc.) mostly with goal of increasing and protecting biodiversity and coping with CC. The EU seeks the integration of green assets in main policy fields but mainly encourages market based approach to support their implementation, focusing on developing marketable solutions. Since, based on its argumentation, public funds are limited and private sector could benefit from other positive effects of green assets like increasing value of area. Commission and European Investment Bank set the Natural Capital Financing Facility, financing natural capital projects generating revenues or saving costs for public and private entities, with 100-125 million € available till 2017. However, manifold funding options are available, ERDF, Cohesion Fund, LIFE +, as well as funding for research, and the financial framework for the period 2014-2020 contains expanded financing options for green asset projects (cf. European Commission, 2016).

A growing importance of non public projects for the last 15 years has been identified through the database. Analyzing interlinks between this evolution path and the supporting instruments applied may uncover altering governance arrangements behind the way how RW is expected to be managed in Berlin. Depending on the type of instrument used, the action supported is also different, e.g. while ecological requirements on social housing (since 1990), architectural tenders (1992) and public and publicly financed buildings (1994) force developers to incorporate ecological components to new constructions or renewals city wide and tries to persuade the public authorities to “lead by example”, funding for greening of yards and roofs in its diverse forms encourage directly owners and tenants to carry out the measures on their own.

The fact that often several, complementary, instruments have been released in combination has been pointed at in this paper. For example, informative brochure “New ways of dealing with rainwater” (2001) being published the same year that the State regulation on the exemption of rainwater was issued, one year after the split tariff was introduced, and being followed by the brochure “Measure catalogue to reduce water costs in public sector” (2002) recommending how to save costs by implementing water management systems, including rainwater, in public buildings; and a Federal publication depicting diverse options to manage RW (infiltration, use) with information about technical systems and options, economical and environmental aspects (2005). Many of these informative materials seek to raise citizens’ information and awareness, as well as their personal commitment and motivation to carry certain measures out, especially if these informative materials are published in temporal proximity to the release of “require” and/or “promote” instruments, since this may increase their effectiveness.

Thus, by implementing certain types of instruments in specific constellations in a way that they may reinforce each other, different actors and resources are supposed to be involved, to different extents in the implementation of RW management practices. With caution, and bearing in mind that public projects are present through the years, it could be inferred that a modest trend towards shifting responsibilities from public authorities to individuals might be identified in the execution of RW management in Berlin. Through enforced instruments, probably conditioned by other factors (e.g. public budget issues, among others), citizens in form of private companies or individuals are assuming “implementer” roles and public authorities “ruler and instigator” ones. All in all, however, it is necessary to recall that in case of matters perceived by the authorities as “urgent and serious” to fulfil legal standards and requisites, like CSOs in a combination of disadvantaging factors like (increasing groundwater table, over- and underused canalisation in some areas, etc.) authorities and water company still hold central functions of intervening and implementing themselves and tend to use well-known, conventional, engineering solutions. In other words, when “certainty” is required and major commitments/ duties are at risk, traditional top-down solutions are being preferred over non-conventional “bottom-up” ones, which are growing but to some extent seen as a complement instead of a mainstream solution.

5. Conclusions

As shown and discussed in this paper, Berlin counts with plenty of project examples and supporting policy and planning instruments for sustainable management of RW through green solutions. However, their implementation and mainstreaming are not yet a complete success story. Potentials for further unsealing, greening and alternative decentralized RW management systems exist and are even cartographically captured by the Senate Administration in the StEP-Klima, where maps link the potential for these solutions around the city (to different extent) to current and expected climate-related challenges (cf. Senatsverwaltung für Stadtentwicklung, 2011, pp. 15-22). If and how these potentials will be exploited, or not, is an open question, and as underlined in this paper, it partially depends on how encouraging and supportive the policy and planning framework is.

This retrospective analysis and database have pointed and identified at certain connections between the evolution of supporting instruments and implemented projects managing RW in Berlin for the last 35 years, and contributed building up a base and background for understanding the evolution of such practices in the city and their potential mainstreaming. To draw sound conclusions on these issues, it is necessary to consider other influencing factors. Among others, political cycles, staff and organizational changes, budgeting, extreme events, actors involved, environmental performance of the systems, political priorities and interests, power relations, environmental limitations.

This research raised many questions that remained open. They are of great interest and will be object of further exploration in the upcoming analysis of the case studies within the UrbanRain Project. Such deep qualitative research offers great opportunities for examining contextual and case-specific influencing factors that may support or discourage the mainstreaming of sustainable RW management practices in Berlin, providing more conclusive insights on many of the aspects elucidated in this paper.

Notes

1. Size categorized in: large, small and not clear; based on the area of the projects in case of greening, and the drained, or supplied, area for water-related projects, in order to have the same measuring unit, m2. Large >5500m2, small< 5500m2, not clear= not found or unclear information.

2. Type of building/site categorized in: public/ public service, residential, commercial and no data; based on type/use of the site/building, not on the ownership, financing, etc. of the project, for this, available information online was insufficient.

 

References

Agudelo-Vera, Claudia M.; Mels, Adriaan R.; Keesman, Karel J.; and Rijnaarts, Huub, H.M (2011) Resource Management as a key factor for sustainable urban planning. Journal of Environmental Management, Vol. 92 Issue 10, October 2011, pp. 2295-2303
Ansel, Wolfgang- Deutscher Dachgärtner Verband e.V. (2011) Leitfaden Dachbegrünung für Kommunen -Nutzen, Fördermöglichkeiten, Praxisbeispiele-. Projekt -Nr. 28269-23 Abschlussbericht. Deutsche Bundesstiftung Umwelt. Available online at: https://www.dbu.de/media/29071409182171pn.pdf (last accessed 01-10-2015)
Barbosa, A.E.; Fernandes, J.N.; and David, L.M. (2012) Key Issues for Sustainable Urban Stormwater Management. Water Resources,  Dec 15, Vol. 46, No. 20, pp. 6787-6798
Archiv BauGrund/Alexander Krause (2007) Picture Schmetterlingswiese. Retrieved from: http://www.stadtentwicklung.berlin.de/bauen/entwicklungsgebiete/pdf/Bies... (p.19)
Cettner, A.; Ashley, R.; Viklander, M.; and Nilsson, K. (2012) Stormwater management and
urban planning: Lessons from 40 years of innovation. Journal of Environmental Planning and
Management, Vol. 56, Issue 6, pp.786-801
Cettner, Annicka; Ashley, Richard; Annelie Hedströma; and Viklander, Maria (2104) Sustainable development and urban stormwater practice. Urban Water Journal, Vol. 11, Issue 3, pp. 185-197
Chocat, B.; Ashley, R.; Marsalek, J.; Matos, M.R.; Rauch, W.; Schilling, W.; and Urbonas, B. (2007) Toward the sustainable management of urban stormwater. Indoor and Built Environment, June Vol. 16 No. 3, pp. 273-285
Colebatch, H.K. (2006) Governing the use of water: The institutional context. Desalination,
Vol. 187 Issues 1 -3, pp. 17-27
Dolowitz, D.; Keeley, M.; and Medearis, D. (2012) Stormwater management: can we learn from others. Policy Studies, Vol. 33, Issue 6, Special Issue:   Policy Transfer
Domènech, L.; March, H.; Vallès, M.; and Saurí, D. (2014) Learning processes during regime shifts: Empirical evidence from the diffusion of greywater recycling in Spain. Environmental Innovation and Societal Transitions. In Press
European Commission (2016) European Commission. Environment-Background on Green Infrastructure. Retrieved from: http://ec.europa.eu/environment/nature/ecosystems/background.htm (last accessed 17.01.2016)
Geyler, Stefan; Bedtke, Norman; and Gawel, Erik (2013). Nachhaltige Regenwasser-bewirtschaftung- Aktuelle Steuerungstendenzen im Siedlungsbestand. UFZ Discussion Papers, Department of Economics 3/2013
Grundeigentum- Verlag (2000) Grober Kalkulationsirrtum der Berliner Wasserbetriebe. In GE 11/2000, 696. 06.10.2000. Available online at: http://www.grundeigentum-verlag.de/?show=article&cat=01.07&id=26 (last accessed 18-09-2015)
GSW/IBUS GmbH (n.d.) Pictures Wohnungsbauvorhaben Weinmeisterhornweg . Retrieved from: http://www.stadtentwicklung.berlin.de/bauen/oekologisches_bauen/de/model... (last accessed 10-11-2015)

IKZ Haustechnik (2012) Zweierlei Regenwasser – Regenwasserversickerung, -bevorratung und -nutzung im Industriebetrieb. Retrieved from: http://www.ikz.de/nc/ikz-haustechnik/artikel/article/zweierlei-regenwass.... (last accessed 18-11-2015)
Informationssystem Stadt und Umwelt  (ISU) der Senatsverwaltung für Stadtentwicklung und Umwelt (2012) Umweltatlas Berlin (Ausgabe 2012). Berlin: Senatsverwaltung für Stadtentwicklung und Umwelt – Kommunikation
Krozer, Yoram; Hophmayer, Sharon; van Meerendonk, Hans; Tijsma, Simon; and Vos, Eric (2010) Innovations in the water chain – Experiences in The Netherlands. Journal of Cleaner Production, vol. 16, pp.439-446
Lazarova, V.; Levine, B.; Sack, J.; Cirelli, G.; Jeffrey, P.; Muntau, H.; Salgot, M.; and Brissaud, F. (2001) Role of Water reuse for enhancing integrated water management in Europe and Mediterranean countries. Water Science and Technology, Vol.43, No. 10, pp. 25-33
Li, Congying (2012) Ecohydrology and good urban design for urban storm water-logging in Beijing, China. Ecohydrology and Hydrobiology, Vol.12, Issue 4, pp.287-300
Marsalek, J. and Chocat, B. (2002) International Report: Stormwater Management. Water Science Technology, Vol. 46, No. 6-7, pp.1-17
Moss, T. (2000) Unearthing Water Flows, Uncovering Social Relations: Introducing New Waste Water Technologies in Berlin, Journal of Urban Technology, Vol. 7, N.1, pp. 63-84 
Moss, T. (2001) Battle of the Systems? Changing styles of water recycling in Berlin. In: Guy, S., Marvin, S. and Moss, T. (eds.) Urban Infrastructure in Transition. Networks, Buildings and Plans. London: Earthscan, pp. 43-56
Moss, T. (2011) Planung technischer Infrastruktur für die Raumentwicklung: Ansprüche und Herausforderungen in Deutschland; in Tietz, Hans Peter, and Hühner, Tanja (eds.) Zukunftsfähige Infrastruktur und Raumentwicklung. Handlungserfordernisse für Ver- und Entsorgungssysteme
Nickel, D.; Schönfelder, W.; Medearis, D.; Dolowitz, D.P., Keeley, M.; and Shuster, W. (2014) German experience in managing stormwater with green infrastructure. Journal of Environmental Planning and Management, Vol. 57, No. 3, pp.403-423
Petrucci, Guido; Rioust, Emilie; Deroubaix, José-Frédéric; and Tassin, Bruno (2013) Do stormwater source control policies deliver the right hydrologic outcomes? Journal of Hydrology, Vol.485, 2 April 2013, pp.188-200
Rauch, W.; Seggelke, K.; Brown, R.; Krebs, P. (2005) Integrated Approaches in Urban Storm Drainage where do We Stand? Environmental Management Vol. 35, Issue 4, April 2005, pp. 396-409
Rehfeld-Klein, M. (2011) Mischwassersanierungskonzept für Berlin bis 2020 und danach? – Versuch eines Ausblicks. (Presentation)
Reichmann, B. (2009) Stadtökologische Modellvorhaben und Gebäudebegrünung. Tagungsband - Internationaler Gründach-Kongress 2009, pp. 135-144
Rockstroh, B. (2012) Industriebetrieb mit zweierlei Regenwasser. Verfahrenstechnik- Special Regenwasser, 11-12 / 2012. Available online at: http://www.wwt-online.de/sites/default/files/Rockstroh_Seite22-25.pdf (last accessed 04-10-2015)
Roy, A.H.; Wenger, S.J.; Fletcher, T.D.; Walsh, C.J.; Ladson, A.R.; Shuster, W.D.; Thruston, H.W.; and Brown, R.R. (2008) Impediments and solutions to sustainable, watershed-scale urban stormwater management: lessons from Australia and the United States. Environmental Management Aug, Vol. 42, No. 2, pp.344-459
Schütze, T. (2013) Rainwater harvesting and management- policy and regulations in Germany. Water Science & Technology: Water Supply 13.2, pp. 376-385
Senatsverwaltung für Stadtentwicklung (2007) Städtebaulicher Entwicklungsbereich. Biesdorf-Süd. Bilanz der Entwicklung. Available online at: http://www.stadtentwicklung.berlin.de/bauen/entwicklungsgebiete/pdf/Bies... (last accessed 08-10-2015)
Senatsverwaltung für Stadtentwicklung (2011) Stadtentwicklungsplan Klima. Urbane Lebensqualität im Klimawandel sichern. Berlin: Medialis. (Also available online at: http://www.stadtentwicklung.berlin.de/planen/stadtentwicklungsplanung/do...)
Senatsverwaltung für Stadtentwicklung und Umwelt (n.d. a) Europäische Wasserrahmenrichtlinie. .In Berlin. Maßnahmen. Retrieved from: http://www.stadtentwicklung.berlin.de/umwelt/wasser/eg-wrrl/de/inberlin/... (last accessed 29-09-2015)
Senatsverwaltung für Stadtentwicklung und Umwelt (n.d. b) Ökologisches Bauen- Abgeschlossene Projekte- Wohnungsbauvorhaben Weinmeisterhornweg. Retrieved from: http://www.stadtentwicklung.berlin.de/bauen/oekologisches_bauen/de/model... (last accessed: 02-10-2015)
Senatsverwaltung für Stadtentwicklung und Umwelt (2011) Umweltatlas. Flächennutzung- Grün- und Freiflächenbestand (Ausgabe 2011). Retrieved from: http://www.stadtentwicklung.berlin.de/umwelt/umweltatlas/id601.htm (last accessed 29-09-2015)
Senatsverwaltung für Stadtentwicklung und Umwelt (2012a) Umweltatlas. Boden-Versiegelung (Ausgabe 2012). Retrieved from: http://www.stadtentwicklung.berlin.de/umwelt/umweltatlas/ic102.htm (last accessed 29-09-2015)
Senatsverwaltung für Stadtentwicklung und Umwelt (2012b) Strategie Stadtlandschaft Berlin. Natürlich, Urban, Produktiv. Berlin: Senatsverwaltung für Stadtentwicklung und Umwelt
Senatsverwaltung für Stadtentwicklung und Umwelt (2013) Stadtentwicklungskonzept Berlin 2030. Statusbericht. Berlin: Senatsverwaltung für Stadtentwicklung und Umwelt.
Senatsverwaltung für Stadtentwicklung und Umwelt (2014a) Öffentliche Grün- und Erholungsanlagen. Daten und Fakten. Retrieved from: http://www.stadtentwicklung.berlin.de/umwelt/stadtgruen/gruenanlagen/de/... (last accessed 05-10-2015).
Senatsverwaltung für Stadtentwicklung und Umwelt (2014b) BerlinStrategie. Stadtentwicklungskonzept Berlin 2030 (Stand: April 2014). Berlin: Senatsverwaltung für Stadtentwicklung und Umwelt.
Senatsverwaltung für Stadtentwicklung und Umwelt (2015a) Umweltatlas. Boden- Entsiegelungspotenziale (Ausgabe 2015). Retrieved from: http://www.stadtentwicklung.berlin.de/umwelt/umweltatlas/i116.htm (last accessed 08-02-2016)
Senatsverwaltung für Stadtentwicklung und Umwelt (2015b) Landschaftsplan. Unterscheidung zwischen L-Plänen und BFF-L-Plänen. Available online at: http://www.stadtentwicklung.berlin.de/umwelt/landschaftsplanung/lplan/de... (last accessed 29-09-2015)
Sieker, F. (1998) On-site stormwater management as an alternative to conventional sewer systems: a new concept spreading in Germany. Water Science and Technology, Vol. 38, Issue 10, pp. 65–71

Sieker, F. (2013) Regenwasserbewirtschaftung in Deutschland – Bestandsaufnahme und Ausblick. GWF Wasser Abwasser, Vol. 154, No. 4, pp.474-484
Stahre, Peter (2002) Integrated planning of sustainable stormwater management in the city of Malmö, Sweden. In: Strecker, Eric W. and Huber, Wayne C. (eds.) Proceedings Global Solutions for Urban Drainage, pp. 1-14
Vallès, Maria; Domènech, Laia; and Saurí, David (2011) Estudi sobre l’aplicació de les ordenances municipals per a l’estalvi d’aigua a Catalunya. Xarxa de Ciutats i Pobles cap a la Sostenibilitat. May 2011. Available online at:
http://www.diba.cat/documents/553295/963215/estudi_final_ordenances_virt... (last accessed 07-11-2014)
Van de Meene, S.J.; Brown, R.R.; and Farrelly, M.A. (2011) Towards understanding governance for sustainable urban water management. Global Environmental Change, Vol. 21 Issue 2, August 2011, pp. 1117-1127
Wilhelmstadt-bewegt (n.d.) Hofbegrünungsinitiative - Aktion Grüner Daumen. Retrieved from: http://wilhelmstadt-bewegt.de/projekte/gruen-freiflaechen/gruene-hoefe (last accessed 18-11-2015)
Winz, Ines; Brierley, Gary, and Trowsdale, Sam (2011) Dominant perspectives and the shape of urban stormwater futures. Urban Water Journal Vol.8 Issue 6, pp. 337-349
Wong, Tony H.F. (2007) Water Sensitive Urban Design- the journey thus far. Environment Design Guide, August 2007 Des 11, pp. 1 -10
Yannopoulos, S.I.; Grivaki, G.; Giannopoulou, I.; Basbas, S.; and Oikonomou, E.K. (2013) Environmental impacts and best management of urban stormwater runoff: measures and legislative framework. Global NEST Journal, Vol.15 No 3, pp. 324-332