Reinventing the Dutch Delta: Complexity and Conflicts

Abstract

Delta areas have been extremely attractive for urbanisation and economic development throughout history because of the fertility of the land and the strategic position for shipping networks. Moreover, nowadays the most rapid processes of urbanization occur in delta-areas [46].Urbanized deltas can be considered as areas with a double complexity: they have to deal with the complexity of the delta, as the meeting point of rivers and sea, and with the complexity of urban patterns, as a condition and result of economic, cultural and social life. Since the 1990s, delta-areas are facing new challenges related to this double complexity. Climate-change, rising sea-level and increasing peak-discharges of rivers force planners to reconsider flood-defence strategies. At the same time, globalisation and neo-liberalism created new conditions for urbanization processes. The vulnerable position of urbanized deltas has become clear with the disastrous effects of hurricane Katrina in the Mississippi-delta in 2005. In search of sustainable strategies, authorities and planners of different delta-areas are looking to the Netherlands as a benchmark, which seemed to deal with the double complexity in a successful and sustainable way. However, instead of considering the Netherlands as an example which can be copied in other urbanized deltas, it is important to understand the Dutch delta as a result of two specific conditions: first, the specific condition of the natural dynamics of the delta itself, and second, the coincidence of the Dutch delta with the territory of the Dutch nation-state. Moreover, fundamental discussions and reconsiderations are taking place concerning future policies and strategies for flood-defence, water-management and urban development in the Netherlands. Instead of the adage ‘fighting against the water’, a new adage ‘working with nature’ is arising. This change is not only important for future safety and urban development in the Netherlands itself, but might be relevant for other urbanized deltas as well. KEY-WORDS hydraulic engineering, urban design, land of cities, nation-state, metropolitan water-landscapes, cross-disciplinary approach 1 This article has been first published in Built Environment VOL 35 NO 4. THE NATURAL FORM OF THE DELTA A delta can be defined as the area where two different systems river and sea both with important influences on the morphology of the land, meet and influence each other. Processes of sedimentation, alluvium deposits and land-loss are contingent upon which system, the river or the sea, dominates. The Dutch delta is a sea-dominated delta, as a result of the meeting of a number of relatively small and medium-size rivers (Rhine, Meuse and Scheldt) and a coastal area with strong tidal currents and tidal differences, as well as formidable south-west winds and ocean currents. The importance of these special conditions is clear when we compare the Dutch delta with a river-dominated delta like the Mississippi-delta, which has a very different topography. In many respects, the Mississippi river represents a multiple of the river Rhine: in length, depth discharges, etcetera. However, the most astonishing contrast between these two rivers concerns sediment-transport: the Mississippi carries 400 times more sediment than the Rhine and deposits, each year, roughly 170 million tons of sediment in the Gulf of Mexico. Length 6,275 km 1,320 km Depth average New Orleans: 60 m Arnhem: 8 m Discharge average 16,000 m3/sec 2000 (summer) m3/sec Discharge – extreme 48,000 m3/sec 12,000 m3/sec Sediment transport 170 million ton/yr 0.4 million ton/yr