Thresholds of Exchange

PROJECT STATEMENT

Venice is a very popular tourist attraction , a major cultural center in the Renaissance which is famed as “City of Water ” and “The Floating City.” However, Venice is suffering from flood because of frequently increasing sea level and sinking sea floor. To protect Venice from the menace of flooding, the ideas of THRESHOLD -EXCHANGE -ABUNDANCE are introduced . The major concept of this solution is to close the lagoon and transform part of the sea into freshwater rivers . Also , to maintain the native ecosystem of the freshwater & sea water habitats, many things were exchanged and transferred between both sides, including fresh and saltwater, organisms and materials, ships, tidal and wind energy. Also , an abundance of freshwater resources and energy were created by this way.

PROJECT NARRATIVE

BACKGROUND & HISTORY

Venice, an island city, remains a major Italian port in the northern Adriatic Sea and is one of the world ’s oldest tourist attractions and cultural centers. However, Venice has seen its worst flooding in 2019 since 1966, when the city was hit by tides of up to 194 centimeters and 80 % of the city was flooded resulting in hundreds of millions of economic loss in euro. Furthermore, flooding happens more frequently than before. Extreme flooding that used to occur in Venice once every 100 years is expected to recur every six years by 2050. This could become far more common by 2100, recurring every five months. The flood in Venice is mainly caused by seabed sinking, sea level rising, and high tide.

DESIGN INTENT

This project aims to provide a permanent solution for the flooding problem in Venice while minimizing the impact to the ecosystem at the same time. To solve the flooding problem, enclosing the lagoon with dams and transforming part of it into sea freshwater river are crucial parts for the solution. At the same time, many things would be exchanged between the Adriatic Sea and closed lagoon such as fresh & saltwater, ships, fish, plankton, nutrients and sediments, all for conserving a sustainable native ecosystem.

STRATEGIES

THRESHOLD

This part is comprised of isolating the lagoon and transforming it into freshwater since salt-marshes are essential to marine ecosystem by providing shelter and food for various species of organisms and they have a function to resist flood by trapping and stabilizing sediments in the marshes. Most of the salt-marshes areas are reserved to reduce the impact on native ecosystem by proposed solution. Venice island would be situated in the center of the lagoon with seabed which is much deeper than the surrounding flat salt-marshes, isolated by barriers.

EXCHANGE

1.) WATER EXCHANGE – Tidal barrages and pumping station

With tidal barrages, salt -water, sediments, plankton, and nutrients could transfer from the Adriatic Sea to the Closed Lagoon. At the same time, pumping stations produce excess fresh-water in the opposite direction.

2.) ENERGY EXCHANGE – Tidal barrages, wind turbines and pumping station

Tidal barrages and wind turbines are constructed to generate electricity ,which can power up pumping stations for transferring water between the lagoon and the Adriatic Sea.

3.) SHIPS EXCHANGE – Ship lifts

Ship-lifts are constructed to transfer ships across the dams as there is a large difference in water level between the lagoon and the sea . Considering the effects of maritime activities on ecology and the scenery, routes in Lido Inlet were canceled. Small size ships for tourists go through Malamocco Inlet while larger vessels for tourist and industry go through Chioggia Inlet.

4.) FISH EXCHANGE – Fish migration river

The fish-migration-river allows diadromous fish to migrate between the Adriatic Sea and the closed lagoon while the long channel inside preventing salt water from entering the freshwater basin. In this way, some migratory fish species could keep their route between the closed lagoon and the Adriatic Sea.

ABUNDANCE

Large quantities of fresh water bodies are created by closing lagoon for drinking, industrial & agricultural activities ,as well as fish-farming. Furthermore, electricity is generated by tidal barrages and wind turbines, which can supply to Venice.

PHASES

There are three phases of barriers with different height in accordance to the rising sea level. In the worst scenario forecasted by NOAA (National Oceanic and Atmospheric Administration), the height of sea level and high tide will be 360cm, 760cm, 1050cm to 2100, 2200, 2300 respectively. All three phases have similar construction plans like barriers, tidal barrages, wind turbines, pumping stations, ship lifts and fish-migration-rivers. At the same time, there are brackish marshes and wetlands between different phases of barriers which could filter saltwater , weaken tides and provide shelter and food resource for ecosystem. Through three phases of barriers, salt -water would be filtered into freshwater and supply to the lagoon, which can be used as drinking water for local dwellers, as well as supporting farming used as drinking water for local dwellers, as well as supporting farming, farm-fishing and industrial activities.

CONCLUSION

By isolating the lagoon with barriers and dams, Venice is protected from high tides and sea level rising in both short and long term. At the same time, this solution offers a sustainable strategy that reduces the impact of marine ecosystem by exchanging water bodies, organisms and materials in between both sides. In addition, an abundance of fresh water and electricity are generated to supply Venice.

Research Background
Venice suffers from frequent floods due to increasing sea level and sinking sea floor. The proposed solution is to isolate the lagoon and make part of it into a freshwater system. In the worst-case scenario, most of Venice would be flooded in 2040.

Abundance in Resources
Currently, the MOSE project is used to protect Venice by raising gates to temporarily isolate the lagoon with limitations and negative impacts like the height constraints, electric energy consumption, and erosion. The proposed solution offers better benefits than MOSE with less drawbacks.

Precedent Analysis
There are several relevant cases (realized or proposed) that use barriers to isolate a river or sea.

Managing Exchange
After isolating the lagoon from the outer sea, whether it would hold all of the precipitation and flow from mainland watershed should be taken into consideration. The largest amount of rainfall is in June at about two hundred million cubic meters of precipitation. However, the closed lagoon could only hold one hundred million cubic meters.

Managing Exchange
The solution is meandering river flows to increase water flow length and adding reservoirs to keep excess precipitation.

Threshold
Salt-marshes are essential to marine ecosystem by providing shelter and food for various species. They can also help resist flooding by trapping and stabilizing sediments. Most of the salt-marshes are preserved to enhance the effectiveness of the proposed solution.

Threshold
The elevations of the north and south areas of Venice are lower than 3.6m in 2100. Agricultural land and wetlands are situated in there and could be flooded to give the sea more room to manage at higher sea levels.

Water Exchange
With tidal barrages, salt-water, sediments, plankton, and nutrients could transfer from the Adriatic Sea to the Closed Lagoon. At the same time, pumping stations remove excessing freshwater to the opposite side.

Energy Exchange
Tidal barrages and wind turbines generate electricity to supply power for pumping stations. These stations are responsible for transferring water between the lagoon and the Adriatic Sea.

Ship Exchange
Ship-lifts are constructed to transfer ships across the dam. Ship routes in Lido Inlet were canceled. Small size ships for tourists would go through Malamocco Inlet, while larger vessels for tourist and industries go through Chioggia Inlet.

Fish Exchange
The fish-migration-river allows diadromous fish to migrate between the Adriatic Sea and the closed lagoon, while the long channel inside prevents salt water from entering the freshwater basin. Thus, some migratory fish species could keep their route between both sides.