1. INTRODUCTION. 1 The consortium of the GNOUWP Master plan is composed by the participating firms and institutes:

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2 New Orleans after Katrina: Building America s Water City David Waggonner, Nanco Dolman, Derek Hoeferlin, Han Meyer, Pieter Schengenga, Sabien Thomaes, Jaap van den Bout, Jaap van der Salm, Chris van der Zwet ABSTRACT After the catastrophe caused by hurricane Katrina in 2005, New Orleans architects and engineers started a process to develop an integrated and comprehensive urban water management plan. During five years, a group of American and Dutch designers, engineers, planners and scientists worked together to develop a new approach for the water management system in the metropolitan area. The plan proposes a water management system which is different from the pre-katrina system in two ways. First, instead of a continuing soil-subsidence, the new water system will result in a stabilization of soil- and groundwater levels. Second, instead of separating urban districts and downgrading public spaces, the new water system will contribute to new spatial quality and coherence of the urban fabric. The plan shows that innovative water management strategies not only improve the protection against flooding, but they also create new perspectives for the spatial, social and economic future of the delta city. The most innovative aspect of the plan is the way how hydraulic engineering, spatial design and governance are related to each other from the regional to the neighbourhood scale. 2

3 1. INTRODUCTION This paper is a description and analysis of a design intervention in the New Orleans metropolitan region, which aims to combine a new water management strategy with a reorganization of the urban fabric, aiming not only safety and water sensitivity in urban areas, but also an improvement of the quality of the spatial structure of the metropolitan region. The proposal for the design intervention has been presented in the Greater New Orleans Urban Water Plan (Waggonner&Ball Architects, 2013), in this paper abbreviated as GNO Urban Water Plan. The proposal is the result of a consortium of American and Dutch firms in architecture, urban design, landscape architecture and engineering, assigned and financed by the Greater New Orleans Inc. in It is based upon a long process of preparing workshops, known as the Dutch Dialogues workshops. The Dutch Dialogues were initiated by the New Orleans based firm Waggonner&Ball Architects, supported by the Royal Embassy of the Netherlands and the American Planning Association (Meyer, Morris, Waggonner, 2009). The importance of this process is the comprehensiveness of a GNO Urban Water Plan which aims also to improve the quality of the metropolitan spatial structure. It is true that the aim for such a comprehensive approach is not unique. Everywhere in the world, from Canada to Australia and from the Netherlands to Vietnam, initiatives have been undertaken to combine or integrate spatial planning, urban design and hydraulic engineering. Results have been discussed at many international conferences and published in many journal-papers and books. (see for instance Kuitert 2008; Prominski 2012). However, a clear method of a design strategy, which is relevant as well at the scale of metropolitan region as at the scale of neighbourhoods, streets and individual parcels, and which can deal with complex governance structures, is lacking. When we see overviews of different approaches and experiments to combine spatial planning, urban design and hydraulic engineering (see for instance Feyen et al. 2008), we can distinguish two categories: one is focusing on the physical design of neighbourhoods, streets, blocks; the other is focusing on the larger, regional scale and has a more abstract character, represented by general schemes. A clear link between both levels is lacking, but it is exactly what is necessary in an urbanized delta area like the Greater New Orleans metropolitan area. The main reason why we consider the work for this GNO Urban Water Plan as innovative, is because it is an attempt to organize a closer collaboration among design and engineering, scientific knowledge and governance at different scales. The result is not only a concrete plan which is relevant for the case of New Orleans, but also a method which is relevant for many other delta cities. This method was not defined and available in advance, but has been developed by trial and error during 1 The consortium of the GNOUWP Master plan is composed by the participating firms and institutes: Waggonner+Ball Architects, Arcadis, Deltares, Royal HaskoningDHV, City of Rotterdam, City of Amsterdam, H+N+S Landscape Architects, Bosch Slabbers Landscape Architects, Robbert de Koning Landscape Architect, Palmbout Urban Landscapes, Manning Architects, Dana Brown & Associates Landscape Architects, Future Proof, CDM Smith, Nelson Engineers, Dewberry, GCR, KBR, Eustis Engineering, Geosyntec consulting, Sherwood Design Engineers, Delft University of Technology, Tulane University, LSU Coastal Sustainability Studio, Bright Moments. 3

4 the design and planning process itself and during many discussions with different stakeholders in the Greater New Orleans metropolitan area. In this paper we want to clarify this statement and to explain the method of combining scientific research, hydraulic engineering and urban and landscape design. This explanation starts in the next section, which describes the reasons and background of the GNO Urban Water Plan, including the social and economic goals lagging behind. Subsequently the existing relation between problems concerning urban form, water management and governancde will be explained. In case of changing the water system, it is almost impossible to ignore the effects on urban form and the governance conditions. Special attention will be paid to the water system itself and the proposals to change it, followed by a section which will show the way how the new water management principles can be used to reorganize urban form. An important issue to address is the relation with the complex governance structures of the Greater New Orleans metropolitan area. These structures seemed to be an obstacle for an efficient planning and design process. This section argues that the design-process itself plays a role as a generator of the development of a new governance culture. 2. THE NEED FOR A NEW WATER SYSTEM: MORE THAN SAFETY The effects of hurricane Katrina, which hit the City of New Orleans in August 2005, were disastrous: a large part of the city flooded, almost two-thousand people died, tens of thousands were evacuated and many did not return. Since 2005, the US Army Corps of Engineers spent 14.5 billion US dollars to improve the flood walls around the city substantially. Not only broken flood walls have been repaired, but also new storm surge barriers have been constructed. New Orleans is recovering, and safety first is an important basic condition for this recovery. According to numbers from the Department of Commerce, the city's GDP of 2010 was almost $9 billion higher than it was in 2005, unadjusted for inflation. However there are still reasons for concern. The large fields of empty plots in several city districts still remind us that the number of residents before Katrina used to be larger. The U.S. Census Bureau counted 369,250 residents in the City of New Orleans in 2012, which is still only 75% of the 2000 population of 484,674. The Greater New Orleans metropolitan area counts 1,191,089 residents in 2012, which is 90 percent of its 2000 population of 1,316,510. The decline of population did not start with Katrina. In the last fifty years, while most southern cities gained population, New Orleans declined, having reached its peak population of 627,525 in The Greater New Orleans Data Community Center mentions that the regional economy is largely reliant on legacy industries in decline. The three largest economic driver industries tourism, oil and gas, and shipping and logistics shed tens of thousands of jobs between 1980 and New Orleans has a 23.2 percent poverty rate - one of America s poorest cities. 4

5 To develop a sustainable future for New Orleans, something more should happen than repairing the flood walls. In this respect, a fundamental reconsideration of the position of New Orleans as a delta city is necessary. Already long before Katrina, the need for a reorientation of New Orleans to the physical conditions of the delta has been addressed by several authors (Lewis 1976; Hallowell 2001; Kelman 2003; Colton 2000, 2005). During the 19 th and early 20 th century New Orleans used to have a reputation of an exemplary American city, celebrating the values of the new unified federal state, thanks to the special character of its water-oriented public spaces (Upton 2008). The influence of the delta on the city s culture, especially on the famous culinary culture and the lively music industry, has been celebrated widely (Campanella 2010). During the 20 th century, the meaning of the position of the city in the swampy delta became dominated by danger and discomfort. This negative image of living in the delta does not contribute to bend the mentioned economic decline of the city. The question is how New Orleans can develop a new relationship with its delta condition, which can contribute to create a new spatial, economic and social perspective for the city. New Orleans has a complicated relationship with the conditions of the delta. Hurricanes are not the only problem for the city. New Orleans is an extremely wet city in many respects. The city is situated in the centre of the swamps of the Mississippi river delta, sandwiched between the Mississippi river and Lake Pontchartrain (Figure 1). The Mississippi river discharges huge amounts of water, with an average of 16,000 m3 per second and peaks of 48,000 m3/sec (Walker 1994). Lake Pontchartrain is linked to the Gulf of Mexico; it was especially from this side that New Orleans was flooded during Katrina. A large part of the urbanized area of Greater New Orleans is situated in drained swamps, provided with an extensive hydraulic system of pumps, drainage pipes and outfall canals. The continuous drainage caused subsidence in large parts of the city below mean sea level. Average annual rainfall in New Orleans is 1592 mm, which is for instance more than two times the annual rainfall in the Netherlands. During the twentieth century, annual precipitation increased by about 20% (Burkett et al., 2001). Rainstorms resulting in 100 to 200 mm storm water during several hours and in flooding of the deepest parts of the city are no exception. The frequent floods of the city and the heavy infrastructures for drainage have a large impact on the social life and relations in the city. The districts which are flooded most frequently and most seriously are the districts with the lowest average income, highest unemployment rates and highest concentrations of African and Hispanic Americans (Campanella 2006; Zedlewski,Turner 2006; Fussel 2007). Moreover, parts of the drainage system, like the elevated and walled outfall canals, function as walls between neighbourhoods, isolating and separating these neighbourhoods from each other. Around the city, the vast areas of wetlands are the product of the sediments transported by the Mississippi river. These wetlands used to protect the city against the immediate power of the hurricanes. However the channeling, embanking and damming of the Mississippi river system resulted in a drastic reduction of the supply of sediments and fresh water to the wetlands, which are declining rapidly and losing their function as a buffer between the open sea and the city (Gramling 2012). In this complicated context, the repair and extension of the existing flood wall structures will make the city a bit safer against hurricanes on the short term, but it will not result in a fundamental revision of the way how the city deals with its delta condition on the long term. While large parts of the city are still suffering from the disastrous effects of Katrina, the plea to combine a reconstruction policy with a new water management approach became louder (Campanella 2006, 2010). 5

6 The most important problem, which frustrated the development of a new approach, was the fragmentation of knowledge, design and governance of the spatial system and the hydraulic system of the metropolitan area in many different institutes. The New Orleans metropolitan region is lacking a comprehensive approach, based on understanding the complexity of the relation of the city with the delta (Whelan 2009). These considerations were the reason for a group of New Orleans citizens to organize an impulse which might lead to a new fusion of knowledge, design and governance. The aim was a fundamental revision of the policy concerning the reconstruction of the urban fabric of the city in relation with the water management system. This impulse was organized by bringing together a wide group of specialists with a background from design and engineering, scientific knowledge and governance from the Netherlands and the United States. The organization of a series of pressure-cooker designsessions with this group, entitled Dutch Dialogues, created the possibility for experiments concerning a new approach to the reconstruction of New Orleans (Meyer, Morris, Waggonner, 2009). 6

7 The Dutch Diaologues workshops were organized from 2008 to 2011 with Dutch and American participants: specialists in hydraulic engineering, subsurface and ground water systems, architecture, urban design, landscape architecture. Every workshop finished with a presentation to and debate with a large and diverse group of stakeholders neighbourhood representatives, politicians, the Louisiana US senator, the mayor of New Orleans, representatives of water boards and levee boards, public works departments, and others. The first result of these three years was that the idea of a possibility to generate another approach to water management in relation to urban development became alive in the public debate. The second result was that the federal government provided a budget to develop a master-plan for a new water-management strategy for the Greater New Orleans area. The assignment for the design of this master-plan was given to a consortium headed by Waggonner&Ball Architects and composed by a number of partners from the Dutch Dialogues workshops. The work of the consortium resulted in the Greater New Orleans Urban Water Plan (Waggonner&Ball Architects et al., 2013). 3. URBAN FORM, FLOOD CONTROL AND GOVERNANCE 3.1 Urban form in relation to topography and flood control More than two and a half centuries ago, the city of New Orleans settled on the broad riverbanks of America s largest river (Lewis 1976; Campanella 2010). Over time, the French trading post evolved into an urbanized region that stretches from the high and dry natural levees of the Mississippi far into the former swamps and marshes of South-Louisiana. Urban patterns in New Orleans are strongly related to the city s soils, hydrology and topography. The key to understanding the urban structure of the city lies in the relation with the deltaic landscape where it is built upon, and in the historic changes of this relationship. The morphology of the urban landscape is determined by the natural levees of the Mississippi and the vast expanse of Lake Pontchartrain that is connected with the Gulf of Mexico. In between, there is marshland stretching from the foot of the natural levee as far as the shores of the lake. This marshland is divided more or less parallel to the river by the modest ridge of a former tributary of the Mississippi: the Gentilly and Metairie ridges. An old creek of Lake Pontchartrain, Bayou St. John, with its natural levees at right angles to the banks of the lake and the Gentilly ridge, cuts through the marshland. The Bayou offered the shortest route from the lake to the Mississippi and provided the first settlement with a shortcut across water to the Gulf of Mexico. The spatial structure and appearance of present-day New Orleans are characterised by a series of grids that have been rolled out over the underlying landscape (Figure 2). First of all there is the French grid-iron pattern of the 18 th century colonial city on the riverbank, fronting the Mississippi. Then the reclamation grids of the plantations that settled along the high and dry banks of the meandering river. Urban expansion based on these radial gridiron patterns resulted in the lush and spacious Victorian-style Garden City. This city on the natural levee discharged its rainwater and sewage water traditionally to the swamp below. 7

8 In the 19 th century the expansion of the city gradually brought about the grid-shaped reclamation of the backswamp, which accelerated after the introduction of woodscrew steampumps in 1915 (Colten 2005). The water level in the swamps and marshes as far as the Gentilly ridge was lowered by means of a hydraulic infrastructure of water pumps and large concrete aboveground and underground flood control channels. The water was pumped over the ridge and via newly constructed channels discharged in Lake Pontchartrain. Finally, in the 20 th century, the city of New Orleans grew into what we know today as the Greater New Orleans Region. The landscape between Lake Pontchartrain and the Mississippi was reclaimed and subdivided by means of a new generation of grid-shaped patterns. The post-ww II developments created an extensive suburban landscape in the former swamps. From then on the city was no longer situated solely on the river but also had a front on Lake Pontchartrain. Floodwalls surrounding the metropolitan area created the image of New Orleans as a fortress in the delta (see also Camapanella in this issue; Meyer, Nijhuis 2013). In order to drain the newly built subdivisions like Gentilly, Lakeview and Pontchartrain the system of flood control channels was expanded. Since then this hydraulic system not only drained the 18 th and 19 th century parts of the city along the Mississippi, but also the polder city along the Lake. 8

9 As a result of this occupation process the city can be roughly divided into two grid zones: one along the river and one along the lake. Between them, the Gentilly ridge and the remnants of the original expanse of marshes are situated (figure 3). In this remaining zone between the polder-gridirons along Lake Pontchartrain and the meandering gridirons on top of and alongside the natural levee, traffic infrastructures have put down roots. This zone of railroads and highways functions as an internal periphery in the city and forms a serious breach in the spatial structure of the city. Within the two major gridiron zones, seven different parts of the city can be distinguished, each with its own spatial features, with specific street types and patterns of parcelling. (figure 4) A system of sewers and outfall canals is superimposed onto them, outfall canals sometimes coinciding with the boundaries between two parts of the city and sometimes transecting one of them. (figure 5). 9

10 Because of land-subsidence, the outfall canals are situated in elevated beds and provided with high concrete flood walls in order to be able to deal with high water levels. As a result, neighbourhoods are separated from each other by these walled canals. The hydraulic infrastructure cleaves the city structure into isolated fragments. 10

11 3.2 A uniform hydraulic system in a differentiated city The problem of New Orleans is the uniformity of its hydraulic infrastructure which is not able to take into account the differentiated territory and morphology of the city. Rainwater runs off from the neighborhoods along the Mississippi levee back-slope and Gentilly ridge towards the isolated lowlying bowls in between, burdening them with even more storm water (Figure 6). The drainage system cannot handle extreme rainfall events, resulting in frequent nuisance and substantial economic damage. The GNO Urban Water Plan estimates eight billion dollars economic damage caused by storm water flooding during the next fifty years. Furthermore a century of deep drainage has caused the peat soils to dry out and the land to subside up to 8ft (2,5m), a process that continues today and leads to damaging underground infrastructures and buildings. The former peat wetlands, originally at approximately sea level, now resemble a bath tub ; a city below sea level surrounded by higher elevated waters, increasing its vulnerability to storm on the surrounding water. Subsidence causes water to stagnate locally, and has made discharge increasingly difficult in the low laying areas. Exactly these neighborhoods suffered most from Katrina s floodwaters in 2005, and still represent the main urban renewal challenge today. Communities have been working hard to rebuild their city, but there are still many abandoned properties in what were once thriving middle class suburbs. The quality and appearance of many of the homes is questionable at most, and the public spaces are uninviting. 11

12 3.3 The complexity of governance in Greater New Orleans The governance structure in the Greater New Orleans metropolitan area is generally considered as very weak (Brand, Seidman 2007). This weakness is related with the fragmentation of different governance structures at different scales, in different territories and in different disciplinary sectors. Concerning the fragmentation at different scales it is important to mention the different policies and responsibilities of the federal state (especially the US Army Corps of Engineers), the State of Louisiana, the Greater New Orleans metropolitan area and the parishes. The US Army Corps of Engineers (USACE) has the responsibility to control America s most important waterways like the Mississippi river for navigation. A second task of the USACE is the building of flood defense structures. The USACE deals with a general risk standard of a 1:100 chance of flooding also for the Greater New Orleans region. Compared with the Netherlands, where a 1: is used for the urbanized western part of the country, the American standard is very low. Moreover, the USACE is famous in showing little sensitivity concerning taking into account local circumstances (O Neill 2006). Discussions with this institute on the integration of flood defense structures in the urban fabric were considered as impossible. The USACE is responsible for the construction of the levee system; maintenance and control is the responsibility of local levee boards which hardly have any means for this task. The relatively low risk standard, combined with the lack of means for maintenance of the levees, are the main cause of the collapsing levees during Katrina. For the future, this conditions has not changed essentially. At the level of the State of Louisiana, initiatives have been taken to recover the wetlands of the Mississippi river delta (Coastal Protection and Restoration Authority of Louisiana, 2012). However this means a difficult process of negotiations with the USACE, because wetland restoration is dependent from repair of former affluent rivers by digging holes in the Mississippi river levees. The Greater New Orleans Region is a rather weak administrative collaboration of seven different municipalities, which are called parishes : The City of New Orleans, Jefferson, Plaquemines, St. Bernard, St, Tammany, St. Charles and St. John the Baptist. Each parish has a different administrative organization and a different organization of water management. In the Parish of New Orleans itself an independent Water Board is responsible for the drainage of the city; Jefferson Parish has a Public Works Department which is, next to other tasks, responsible for the drainage of the territory. Communication among the organizations responsible for water management is rare. Another complicating factor for a comprehensive planning process is the fragmentation of administrative bodies with different sectorial responsibilities, such as housing, urban planning, traffic planning, water management, flood defense. The Greater New Orleans region counts many authorities for these domains, with many different goals, policies, regulations, often conflicting with each other. 12

13 4. TOWARDS A NEW WATER SYSTEM 4.1 Spatial analysis: basins and sub-basin boundaries The development of a new water system requires a thorough knowledge of the surface and subsurface conditions of the urban territory. This knowledge was only partially present at the responsible institutions in New Orleans. Extra data collection and field research delivered knowledge that the composition of the soils of the urban territory is rather complex and differentiated (Stuurman 2008). With this knowledge it was possible to draw sections and maps of the city which showed a patchwork of different basins and sub-basins, each with specific subsidence characteristics and with a specific capacity to absorb storm water. With the knowledge of the absorption capacity of the sub-basins and insight in the capacity of the pumps and pipes it became possible to make an integral analysis of the city s water system, which is necessary as a basis for modeling the problems and to test possible solutions. In the analysis of the new GNO Urban Water Plan the planning area is divided in four storm water basins: Jefferson Basin, Orleans Basin, Orleans East Basin and St. Bernard Basin. In these four storm water basins more than fourty sub-basins can be considered. The basin and sub-basin boundaries in maps 1 are based on a combination of: - Hydrologic boundaries, based on the height of the land, elevation, natural water sheds and runoff water, as well as the composition of the urban soil and subsurface; - Hydraulic boundaries, based on discharge directions in pipes as well as closed en open canals storm water system; - Urban land use, based on the proportion of paved area which determines the speed and amount of rainwater runoff. Benchmark: 1-in-10 year rainfall In case of a certain storm, a certain amount of water cannot be handled by the existing hydraulic system and causes flooding. This amount of water can be considered the water assignment. The ambition for solving the water problem is a discussion of a balance between costs and benefits. The water assignment is not normative, but has to be appropriate by balancing the effectiveness of the investments in relation with the costs. The ambition of the GNOUWP is linked to a return period: T10; the capacity of the drainage system is designed on a 1:10 (a chance of once in ten years) rainfall situation (9 inch in 24 h). T25; roads must be accessible during a 1:25 rainfall situation. T100; the outside levee safety was dimensioned to a chance of overtopping of 1:100. Storm-water in streets occurs in New Orleans once or twice a year. Also the drainage system has a fixed capacity depending on good maintenance. Storm events are however very dynamic. Corresponding with the preferred drainage T10 capacity the GNOUWP requires a T10 storage capacity as well. 13

14 Water assignment per sub-basin In order to gain insight in the scale of the problem, surveys have been conducted per sub-basin to calculate how much water the current drainage system can handle. Figure 7 shows the results per basin per 100 acre-feet. The difference between the basins result from factors such as differences in land use (proportion of pavement), the current drainage system and the amount of space available for water storage in the current situation Model parameters: delay, storage and drainage The new water system is based on the principles of delay, storage and drainage of the water. These principles have been included as major perimeters in the model calculations. Delay The delay category includes all imaginable measures that keep water out of the drainage system, either temporarily or permanently. These are largely small-scale measures that can be implemented throughout the city in a wide scale. They include porous pavements, wadis (deepened areas in the public space which can be flooded during rainstorms), rain gardens and roof gardens. A preliminary study has provided a good estimate of the potential space for water that these measures together should produce, and this figure was utilized in the calculation model. The variable in the model calculations is the degree to which the potential space for delaying water is actually utilized. 14

15 Storage Storage is the temporary holding of water after it has entered the drainage system. Storage measures include expanding the existing surface water area, the construction of new surface water bodies or the organization of separate storage areas. These measures are generally larger-scale than the measures geared towards delaying the water. The preliminary study examined the potential area available for water storage in the city. These areas are indicated on the map and were entered into the model calculations. The degree to which this potential area is actually utilized is another variable in the calculations. Drainage The optimization of the drainage system is another element of the proposals. This element has the greatest consequences for the New Orleans Metro Polder and Jefferson. The degree to which the ridge works as a system barrier is the variable used in the model calculations. 4.3 model calculations Scenarios A number of calculations have been performed. First, the principles were calculated separately. This was a theoretical exercise to gain a feeling for the degree to which these principles might contribute to solving the water issue. Next, a series of combined calculations was conducted which included all principles. These realistic scenarios can be considered as steps towards solutions in the short, middle and long terms. Effects and conclusions The individual principles alone cannot solve the water issue. Even doubling the pumping capacity would only result in a reduction of the water issue by 40%. Water storage would provide the largest contribution relative to the other two. Therefore, in practice a combination of delaying, storage and drainage would be needed to achieve the desired result. This would entail a gradual growth process in which the existing water system is expanded and optimized at all imaginable scale levels. On a map the results of the model calculations for the fourth scenario for the entire city are projected. In this scenario, the water is delayed on 50% of the built-up lots, on 20% of the vacant lots and on the street. In addition, 75% of the potential storage area is actually utilized as such. The discharge of the back-slope areas is entirely decoupled from the central bowl by means of a new drainage channel along Claiborne Avenue, which is a major US Interstate Highway running from east to west in the zone of the mentioned Gentilly Ridge (Figure 8). We should note that the calculation results shown in the maps are merely an approximation of the actual situation. Figure 8 shows the results of the different scenario s in the area most affected by flooding, the central bowl in the New Orleans Metro Polder. In the fourth scenario the water assignment is largely solved even in this part. Shallow flooding (less than half a foot) would still occur during extremely heavy rainfall (1-in10-year storms). But deeper flooding would be effectively dealt with. 15

16 The fourth scenario solves the water assignment and still provides some space for expanding opportunities for delaying, storage and drainage in the future. This provides an adaptability for a future of unpredictable climate developments. The water assignment regards the city as a whole, and touches on all levels: large structures, through neighborhoods and streets, down to the private lot. That makes water a real urban planning assignment. The design on the system level shows how solving the water assignment can combined with improving urban structures en enlarging the unique characters of the basins and sub basins in the city. The challenge on a lower scale level is the design of a healthy and balanced water system, which really works in wet and dry periods and which forms the ideal foundation for a healthy urban ecosystem. 5. THE DESIGN STRATEGY The integration of the GNO Urban Water Plan and urban design projects covers different scale levels and time spans. In many places the elements of the drainage network cut its way through the gridiron structure of the residential areas. This network of traffic and water infrastructure divides and separates residential areas and commercial zones in isolated parts of the city that turn their backs to this infrastructure. In the slipstream of the new water management approach, the fault lines can be used and organised differently. Floodwalls will be removed, flood control channels will become green canals, the higher situated areas will be planted with trees for infiltration and shade, underground 16

17 outfall canals will be converted into water parks. The existing fault zones in the urban design structure will be transformed into meaningful connective and value-generating spaces. All together the GNOUWP aims to develop a new orientation of the city to the delta, focusing on three elements: the city edges, the metropolitan backbone and the public space. The analysis of the water system concerning basins and sub-basins delivered the possibility to link the strategy concerning the hydraulic system with a strategy of urban design. The hydraulic distinction between basin and sub-basins coincided with the spatial analysis which makes a distinction between the regional scale, the seven different districts, the sub-basins, finally the neighbourhoods, bocks and individual plots. This discovery created the possibility to organize a clear relationship among hydraulic engineering, urban design and governance-structures, as expressed in figure 9. Discussions between hydraulic engineers, urban designers and landscape architects could be related clearly to the different scales in this scheme. Also debates between the design-team and the many different New Orleans goverance-institutions were clarified with this scheme. 5.1 Regional scale: City edges and metropolitan backbone The transformation of the drainage and traffic networks into meaningful and connective networks of long lines improves accessibility of the edges of the urbanised area. These interventions open up the 17

18 prospect of upgrading the edges of the city. Beaches and ecological banks will be situated near the lake. The marshes within the flood barrier will be restored and made accessible to the public. The riverbanks, the lakefront and the edge of the marshes, each in its own way, can mature into highquality public city edges (Figure 10a and 10b). These edges not only make the embedment of the city in the landscape visible and tangible but also contribute to the quality of life in New Orleans through their recreational use. An important part of the new framework is the new backbone of the metropolitan region. Currently, the northerly polders and the southerly Mississippi ridge are separated by a water management fault zone. This is where large-scale infrastructures and industrial estates have nestled in the course of time. The area forms a fragmented peripheral zone between the north and south. The new GNO Urban Water Plan appoints this zone as an important water storage area which contributes to control the ground water level and can collect strom water during heavy rain storms. With this intervention it is possible to transform the whole zone into a blue-green park system, a central and connective zone where water structures can be combined with new developments like urban parks and other public or semi-public facilities (Figure 11a and 11b). Parks are proposed on the higher parts for infiltration and open expanse of water for retention are proposed in the lowest parts. This major route to downtown New Orleans can be provided with a new light rail connection, utilising the disused tracks. From the airport (by the marshlands in the west) as far as the French Quarter (by the Mississippi) new development sites will be made accessible and lined up. The downtown Superdome constitutes the final piece in this changing image of the city. Instead of getting lost amidst highway junctions and industrial plots, it will occupy the head end of the future park strip. The existing peripheral zone (between polder and backslope) will become the new central backbone of the metropolitan region, combining the new GNO Urban Water Plan with space for parks, public transport, new urban developments and special housing types. 18

19 5.2 District scale and neighbourhood scale: a typology of urban fabrics and public space Section 3 showed that the metropolitan area can be divided into seven distinctive types of urban fabrics. These distictive urban fabrics correspond with different soil-conditions, and by that with different conditions concerning ground water levels and concerning absorption and storage capacity of stormwater. The result is that each type offers specific opportunities for optimising the way of delaying, storing and draining stormwater. These area-specific opportunities for water management at a small scale offer just as many opportunities to strengthen the specific spatial features of the different types of urban fabric (Figure 12a and 12b). Within the seven distinguishable parts of the city, the street network, the landscape and the water management system are more closely interwoven. Polders will get open canals. Green boulevards will be planted with more emphasis. Watercourses will be dug up again. The many vacant plots can be, depending on the building density and the land use per section, allocated for water and planting or, to the contrary, for being built up again. Various pilot projects for the seven parts will function as test-sites, were the effectiviness of the new GNO Urban Water Plan can be monitored and improved. As far as the seven distinguishable urban areas are concerned, this approach results in a specific toolbox geared to each fabric, with sets of generic guidelines for public spaces and lots. 19

20 6. THE DESIGN PROCESS AS A GENERATOR OF A NEW GOVERNANCE CULTURE The planning and design process - and especially the preparation of this process by the series of Dutch Dialogues workshops plays an important role in a transition to a new governance culture, which might lead to perspectives of realization of the goals of the GNO Urban Water Plan. The weak and fragmented governance structures in the Greater New Orleans region were already subject of serious discussions before Katrina (Brandt, Whelan 2004). Instead of starting a fundamental reorganization process of the formal administrative bodies, professionals and academics plead for the stimulation of a civic culture of informal and independent initiatives, which might contribute to a public debate on the future of the city and the region (Brandt, Whelan 2004; Whelan 2009). As a matter of fact, the Dutch Dialogues can be considered as such an initiative, which resulted in an increasing commitment of NGO s, business communities, neighbourhood communities, representatives of administrative and political bodies. The Dutch Dialogues workshops were organized outside the formal administrative and political organizations, but these organizations (as well as the diverse neighbourhood community groups) were invited for the presentations and discussions on the results of the design workshops. The designs themselves worked as a generator of public discussion and of developing a common language and vision on the future of the region. By repeating this process several times, the design proposals could be improved and finally show how different scales and sectorial aspects could be integrated in an comprehensive approach. This process has not ended yet; the future will show in what sense this approach will be implemented. Up to now, we can say that the design process of the Dutch Dialogues and the GNO Urban Water Plan are contributing to a change of the governance culture in the Greater New Orleans region in the sense that it created a new mutual relationship between formal institutions and more informal organizations and processes. 20

21 7. CONCLUSIONS: LESSONS LEARNED As argued in the introduction, a radical revision of the position of New Orleans as a delta city is necessary in order to develop a new perspective not only to create more safety against flooding, but also to contribute to the development of new spatial, economic and social perspectives for the city. The process of the Dutch Dialogues workshops and finally the GNO Urban Water Plan resulted in a comprehensive long term perspective for the spatial development and water management in the Greater New Orleans metropolitan area. This long term perspective means a radical break with the previous city planning and GNO Urban Water Plan, based on an extremely intensive drainage infrastructure and a total separation between urban planning and water management. Instead, the new GNO Urban Water Plan is based on the principle of delay - store - drain, which is only possible under the condition of a close collaboration among scientific knowledge, hydraulic engineering and urban and landscape design. The new aspect in this strategy is the focus on the small, medium and large scale. Taking its position as a delta city serious, New Orleans will develop a new relationship with the delta which influences the composition and meaning of local public spaces as well as the regional spatial structure on the long term. Concerning the developed method, especially two aspects are relevant for other urbanized delta regions. First, because of the extremely complex governance culture in the region, it seemed to be impossible to develop such a comprehensive and integrated policy, based on a vision with a broad public support. However by developing a design process outside the formal institutions, and starting the debate with these formal institutions, this informal process (the Dutch Dialogues workshops) resulted in a vision which is based on an increasing public support. This vision is a work-in-progress: the making of the vision is based on the mutual relationship between the expert-group of the consortium and the community groups, administrations and NGO s. With this achieved public support it became possible to organize a formal design and planning process, resulting in the GNO Urban Water Plan. Moreover, the design-process itself showed to be a driving force in a changing governance culture, which will be based on a mutual relationship between formal and informal processes. The design proposals played a role by delivering a common language which is not limited by administrative or territorial limitations. Second, the distinction among several levels of scale as well concerning the hydraulic system as concerning urban design as concerning governance, created the possibility to disentangle the complexity of all three domains and to organize clear relations among the three domains at the different scales. Finally, the GNO Urban Water Plan is not a blue print plan. Far from that. It delivers a large amount of tools and concepts, which will lead to clear results when they will be applied and elaborated in practice. This part of the story still should be developed. 21

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