In the Flemish Periphery of Brussels, Brook Valleys Are Enlisted in Numerous Spatial Plans As Blue-Green Links

Deep but natural profile of the reopened Beekstraat. Photo VLM Blue-green IN THE FLEMISH PERIPHERY OF BRUSSELS, BROOK VALLEYS ARE ENLISTED IN NUMEROUS SPATIAL PLANS AS BLUE-GREEN LINKS. 12 | BLUE-GREEN FINGERS IN THE FLEMISH PERIPHERY > URBAN LANDSCAPES Water plays a vital role in spatial planning and development. Waterways which help to shape an area with their green structure are often referred to by planners as ‘blue- green fingers’. In built-up areas, creating such fingers often comes down to re-opening waterways. The collaboration with technical experts is crucial to turn the blue-green links drawn on the plan into reality. In doing so, it is better not to be overly strict in drawing boundaries between the initial conceptual design and the ‘technical design’. This article discusses two cases in the Flemish Periphery around Brussels – the Woluwe Valley and the Wezembeek brook – which illustrate how the relationship between concept and technique can influence the success of such operations. in the Flemish Periphery of the Brussels Agglomeration MAARTEN SPER, JEROEN REYNIERS, INGRID BEERENS [ FLEMISH LAND AGENCY (VLM), PROJECT DESIGN DEPARTMENT ] 1 2 Blue-green fingers in the Flemish Periphery The Flemish Land Agency (Vlaamse Land- maatschappij - VLM) has been working on a land-use planning project in the Flemish Periph- ery for several years. The VLM’s remit is largely complementary to the designation process of the ‘Flemish Strategic Area around Brussels’ (VSGB). The VLM acts in support of the VSGB’s open space policy by developing land in-situ. It is from this perspective that this article elaborates on the importance of blue-green links in the Flemish Periphery of the Brussels agglomeration, with focus on the Woluwe Valley. In the Flemish Periphery, brook valleys are 1 The Woluwe as a green S in the municipal 2 Wezembeek-Oppem municipal structure plan: structure plan of Machelen developing a ‘soft axis’ along the Wezembeek Valley enlisted in numerous spatial plans as blue-green links. The plans of the Flemish Strategic Area around Brussels, for instance, assign a key role to the Zenne, Woluwe, Maalbeek brook, Zuunbeek brook, etc. For instance, they provide: as structure-defining brook valleys. ■ water storage and water retention (blue) Municipal structure plans are examples at a different level. ■ ecological added value (green) In Machelen, for example, the plan includes a ‘green S’ around ■ a public network with parks, cycle paths and walkways. | 13 the Woluwe and in Wezembeek-Oppem plans refer to the soft They also raise the quality of the residential and working envi- axis that is made up by the Wezembeek brook. (Fig. 1, 2) ronment by: Such ‘fingers’ are capable of delivering a major contribution to ■ connecting residential centres the quality of the living environment. The multifunctional aspect ■ regulating the city climate through the supply of colder air of a blue-green network is paramount in urban and suburban ■ enhancing the image and appeal of the region. areas. Just as with the open spaces in suburban areas, their added The dense infrastructure and buildings which typify the value is found in a combination of various ‘ecosystem services’ (sub)urban area make it difficult in many ways — not to men- affecting a large target public. tion, extremely expensive — to re-open waterways. During the FIRST PUBLISHED IN > RUIMTE 29 - MARCH 2016 01 water 3 3 VLM planning vision for open space 4 in the Woluwe basin in the Flemish 01 water 01. buffer for bottleneck Region (VLM, 2010). The black lines show 01. buffer for bottleneck the locations where a watercourse Om bovenstrooms meer ruimte should ideally be reopened. the geven aan het water kunnen flessenhalsenOm bovenstrooms en eerder meer begravenruimte 4 Instruments and principles for the kanalenthe geven omgevormd aan het worden water totkunnen buffer (SecchiVigano/Ecorem 2012) Woluwe Valley bijflessenhalsen sterke regenvallen. en eerder begraven kanalen omgevormd worden tot buffer 02. infiltration zones (wadi) bij sterke regenvallen. 02. infiltration zones (wadi) Lokale wateropslag in gedecentrali- seerde systemen om infiltratie en purificatieLokale wateropslag te invergema gedecentrali-kkelijken. voornamelijkseerde systemen in zonesom infiltratiemet hoge en permeabiliteit.purificatie te vergemakkelijken. voornamelijk in zones met hoge 03. reopening of buried streams permeabiliteit. 140 03. reopening of buried streams 140 Opportuniteit om de kwailteit van de publieke ruimtes te verhogen door de beekjesOpportuniteit te heropenen. om de kwailteit van de walking links. Sadly, town planning publieke ruimtes te verhogen door de beekjes te heropenen. can do little about such situations, especially if the watercourse is still invisible. 02 equipped landscape Sometimes the watercourse runs 02 equipped landscape01. public transport pool fairly deep, which requires extra 01. public transport pool De implementatie van een nieuw space to be able to offer added value publiek transport systeem laat de in terms of landscape and experi- creatieDe implementatie van een denser van geëquipeerdeen nieuw land-publiek transport systeem laat de ential value. Yet, as in any urban- schapcreatie rond van trameen endenser metro geëquipeerdhaltes. II.2. strategischeland- ruimtes en acties ised region, extra space is severely 02. potential schap rond tram en metro haltes. limited. Moreover, the complexity II.2. strategische ruimtes en acties 02. potential Verbinding tussen bestaande parken of watercourse structures makes en instrumentenpotentiële sites voor en voorzieningen principes re-opening a stream so difficult that omVerbinding monofunctionele tussen bestaande industriële parken en logistiekeen instrumentenpotentiële zones sites meer voor en tevoorzieningen principes vermengen urbanisation wave that came after the 1950s, natural hardly anybody is prepared to even metom verschillendemonofunctionele stedelijke industriële activiteiten. en logistieke zones meer te vermengen structures were ignored, waterways were culverted attempt it. 03 infrastructures met verschillende stedelijke activiteiten. over and valleys were filled in. In addition, it is not Re-opening a watercourse not 03 infrastructures01. buffer alongside infrastructure Het bestaande groene systeem kan just pure water that flows through this underground only demands a due understanding onderling verbonden worden aan de 01. buffer alongside infrastructure handHet bestaande van landschapsoplossingen groene systeem langs kan infrastructure, as separating effluent and rainwater is of the course itself, it also requires infrastructurenonderling verbonden en door worden zo een aan buffer de complex as well as costly. As long as the hydrological knowledge of the sewers connected tehand creëren van landschapsoplossingen voor nieuwe activiteiten langs eninfrastructuren groene actieve en door gebieden zo een bufferzoals system remains invisible it is ignored in area develop- to it. The complexity of the water purificatiete creëren van voor water nieuwe en lucht. activiteiten ment and conversion, with all the consequences this system in densely built-up areas and en groene actieve gebieden zoals 02. logistics parks purificatie van water en lucht. entails. However, waiting for separation or treatment the fragmentation of administrative 02. logistics parks De grote infrastructuren die de programmes in the long term is not an option. powers means that the right infor- monofunctionele zones bedienen A specific feature of the Woluwe area are the mation is not always available. kunnenDe grote worden infrastructuren ingezet als diegroene de verbindendemonofunctionele elementen zones die bedienenook een ‘moerriolen’ (large collectors that carry off rainwater, The intensity of construction vermengingkunnen worden van activiteiteningezet als toelaten. groene groundwater and effluent), which were installed after and infrastructure projects makes verbindende elementen die ook een 03. narrowing street profile vermenging van activiteiten toelaten. the Second World War to collect water in the flood- it sometimes difficult for various 141 03. narrowing street profile In de toekomst kunnen sommige 141 sensitive Woluwe region. But while the dimensions of parties to keep up-to-date with each straatprofielen worden gereducerd these collectors have long ceased being adequate to other’s plans and to discover po- zodatIn de er toekomsteen nieuw kunnen type publieke sommige en groenestraatprofielen ruimte ontstaat worden die eengereducerd specifiek prevent floods, they do divert a large portion of the tential win-win situations in doing karakterzodat er krijgteen doornieuw publiek type publieketransport. en spring and rainwater from the original waterways. so. The storage capacity of a new groene ruimte ontstaat die een specifiek karakter krijgt door publiek transport. This means natural flood areas are completely cut off open watercourse for instance could from the brook water, leaving them unavailable during make an expensive planned buffer heavy rainfall. basin superfluous, but to do so, all 04 patches Lack of visibility means that many project developers stakeholders need to be fully au fait 04 patches 01. densification of uses Om de bestaande kleine patches will not invest much energy in an open watercourse. with these plans... The fact that the in stand te houden kan het gebruik 14 | 01. densification of uses vanOm hetde groenbestaande ingevuld kleine worden patches met Often they do not even realise a watercourse is pre- Woluwe area is intersected

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