211112_PROJECT ABSTRACT_03

 

GEO-INFRA-PORT           (Project Abstract) 211112              Ashkan Sadeghi. Dip 16

Key words: local economy, salt marshes, accretion, erosion, tide, storm buffer, soft infrastructure, hard infrastructure, transit system, transportation, city core, morphology, drainage, irrigation, flood, sewage collection, environmental feedback, hydrodynamic, ecosystem,

THESIS

The project aims to design an ecological port city that would accept a rapid market growth of Shanghai with the production of local economy that could impact international markets. Dongtan is the site of the project on the island of Chongming in Shanghai.

There are two major conditions that challenge the proposal: SOne is the geological feature of salt marshes and the tidal flats in which the island accreting by processes of sedimentation. Thus, the new infrastructure must adapt itself to such mechanisms to harvest the eco-system and turn into a productive field. Secondly, there is the issue of transport infrastructure that all current systems have a direct negative feedback on nature. Therefore, the project proposes multilayer, three dimensional transport systems as a core of the port city that not only copes with mobility and transit system but also serves a potential economy boost for agriculture and local material production.

HYPOTHESIS

The project starts by studying the water management infrastructure and by understanding how such complex interrelationships function in different scales of mudflat conditions. In parallel, transportation in different magnitude of function will be studied to explore their impact on the city and transit port infrastructure.

DESIGN METHODOLOGY

SOFT VERSUS HARD INFRASTRUCTURE

The project explores the relationship between “soft” versus “hard” infrastructure. Here economy is described as “soft” and water management as “hard” infrastructure.

Creation of dykes, canals, drainage, irrigation, sewage collections, flood control systems and coastal managements are the key water management infrastructures which embrace the foundations of the project. On the other hand, concentration of local agricultural and fishery production systems as a way of developing special economic zone will have a great impact on self-sustainability of the city-port and its trading markets. Therefore, in this case, hard will sustain soft infrastructure and vice versa and the relationship between geological infrastructure and man-made infrastructure becomes a complex mechanism where one gives a positive feedback for developing the other.

PHYSICAL AND MORPHOLOGICAL CHARACTERISTICS OF THE SITE

The long-term development of mudflat–salt marsh ecosystems is determined by the interaction between hydrodynamic conditions and sediment. High hydrodynamic energy either from waves or current velocity and the lack of sediment will generally cause mudflat–salt marsh ecosystems to reduce in size due to erosion; whereas high sediment availability combined with low hydrodynamic energy will most likely result in vertical accretion or lateral extension. Given the abundant sediment supply carried by the Yangtze River, Chongming Dongtan was formed by sedimentation, and has been expanding into the East China Sea with a speed of 200m~300m per year in the past decades. Therefore, acceleration and deceleration of these mechanisms can drive the desired platform for future design criteria.

ENVIRONMENTAL HABITATION

Tidal wetlands, intertidal flats and marshes play an important role in the functioning of estuarine ecosystems; Channels, shoals and tidal flats represent a wide range of habitats for many different organisms. They are often highly productive and represent an important feeding ground for bird populations and a nursery for fish and seals. By use of dikes and irrigation system as an interface, the project consequently, maximises the land ratio for such habitation.

SPATIO-TEMPORAL EVOLUTION OF TIDAL WETLANDS

Tidal landscapes are colonised by denser vegetation that result in channels, which are formed with a higher channel drainage density. Hence this demonstrates that feedbacks between vegetation, flow and landform have an important control on landscape evolution. The project mechanises these feedbacks by use of efficient drainage control systems to maximise quality of soil for vegetation.

LAND RECLAIMATION AND METHODOLOGY

In the Yangtze estuary land claim of large intertidal areas still continues in recent years. This relatively shows how morphological evolution responds to reclamation of tidal wetlands. In order to reclaim land for new alternative architectural production, there are two fundamental acts has to be made towards its succession. First is an efficient wet-land engineering solution and second is the adaptation of government system and law enforcement. To be continuing…

(Fractal geometry applies to investigate the modification and evolution in tidal creek formation before and after the reclamations.)

ENERGY

Energy consumption of the project will be minimised with designing zero-energy infrastructure. Energy will be generated by solar panels, wind turbines and bio-fuels. These wetlands also serve as storm buffers that absorb wave energy and rising tidal waters during storms, therefore, wave energy converter could potentially generate part of the energy requirement.

MATERIAL CONSTRUCTION METHODOLOGY

One of the major environmental concerns is the pollution of estuarine sediments with chemical contaminants. A wide variety of organic compounds and metals are discharged into estuaries from industrial, agricultural, and urban sources. In this case metal extraction from sediment can provide a great opportunity to produce material system for construction.

 

 

APPENDIX

Chongming Island located at the Changjiang River(Yangtze River) mouth, China, is the largest estuarine alluvial island in the world. It is a very rapidly growing island due to the sedimentation provided by the Changjiang River (Yang, 1999). The river transports 4.68 × 108 t of sediment into the East China Sea per year. About half of the sediment settles in the area of the river mouth (Chen et al. 1985). Consequently, the intertidal marsh on the southeast side of Chongming Island expands at a rate of 100–150m per year, forming about 5 km2 new marsh area every year. In addition to these natural environmental changes, the island is also drastically changed by extensive local human practices. Over 500km2 of intertidal marsh flats has been reclaimed by constructing dikes since 1956 by the Shanghai government.

The multi-temporal Landsat data were found very useful for monitoring and mapping the tidal flat accretion and erosion processes. Three main conclusions were made so far: 1) The area of tidal flat > 0m level did not increase so fast after the large scale reclamations as expected. On the contrary, in some years, the shoreline even retracted because of the great runoff induced by river floods. 2) the proportion of high tidal marsh to the total intertidal area has decreased as a result of the reclamations. This can lead to enhanced exposure of the dikes to waves and currents. 3) The reclamation also broke the balance of tidal creeks which showed a decrease in the fractal dimension. The new system of tidal creeks is tending to a new balance after the reclamation. The information extracted from the remote sensing data may lead to a better understanding of coastal processes and help for planning land protection and reclamation work in Dongtan, Chongming Island.

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