Carrying Capacity: What it Is and its Impact on Sustainability

The sustainability of cities is not only intrinsically related to short-term resilience to major catastrophes, but also to long-term resilience to adapt and transform as a result of evolutionary lessons from social, economic, cultural and environmental changes. The sustainable development of urban systems is based on the degree of their adaptability and transformation to systemic changes.

One of the key factors to be taken into account for territorial sustainability is carrying capacity.  In a city, this refers to the maximum number of people, vehicles, infrastructure and services that a city can sustainably support without compromising the quality of life of its inhabitants or the functionality of urban systems.

It is determined by taking into account various factors, such as the availability of natural resources (water, energy, soil), the capacity of transport and infrastructure systems (streets, roads, public transport, water and sanitation networks), the capacity of public services (education, health, security), the capacity to absorb waste and emissions, and the capacity for adaptation and resilience in the face of natural disasters or unforeseen events.

Cities must therefore be aware of this carrying capacity and the associated concept of panarchy. According to Gunderson, Lance and C. S. Holding, "panarchy is a conceptual framework that explains the dual, and seemingly contradictory, characteristics of all complex systems: stability and change."  

It is the study of how economic growth and human development depend on ecosystems and institutions, and how they interact. This conceptual framework allows us to analyze the evolution of cities from the complexity of systems and their adaptation in a global, regional and local framework.

The basic concepts of panarchy are: i) change is neither continuous and gradual, nor continuously chaotic; ii) different scale levels concentrate resources and potential differently; iii) ecosystems do not have a single equilibrium, but multiple equilibria are common; iv) ecosystems have stabilizing and destabilizing processes; and v) management systems must take into account these dynamic characteristics of ecosystems and be flexible.

These concepts are not just abstractions, they are possibilities to implement measures at the city level. And as can be seen, the degree of sustainability varies from city to city.

The Seven Most Sustainable Cities (Cities in Motion Index 2022 Report. IESE) and reasons:

1) London, for its human capital, international profile, urban planning and governance.

2) New York's economy is its greatest strength, but the city also excels in the areas of mobility and transportation, urban planning, human capital and international profile. 

3) Paris ranked well in its international profile, mobility and transportation, and human capital.

4) Tokyo has a strong economy, international profile, governance and technology. 

5) Berlin is a balanced city, performing well on many dimensions, especially its governance, urban planning, and human capital. 

6) Washington, D.C., is strong in human capital, technology, governance and urban planning.

7) Singapore's technology and international profile are its most outstanding areas.

In Mexico, how did Tequila manage its carrying capacity in the pandemic?

One of the most pressing issues for residents and tourists pre-pandemic had been overtourism. That is to say, the overloading of historic centers, museums, tourist products, and restaurants — everything that makes the coexistence and enjoyment of a city. Both in terms of cars and people, cities and especially historic centers have a maximum load capacity.

In addition, in the pandemic, that load had been diminished. If before there was no distance to keep, later the distance was 2 meters, so even if there were fewer people, the carrying capacity was saturated before.

One of the advantages of cities that have real-time information is the possibility of: i) sizing the problem; ii) preventing; iii) managing; and iv) resolving with one objective: that the carrying capacity is not exceeded with healthy distancing.

In Tequila, through information technology, it was possible to have data that made it possible to: 1) analyze pedestrian and vehicular traffic; 2) make traffic projections; 3) generate real-time and preventive alerts; 4) use cameras to detect people and the direction in which they were headed; and 5) cars in motion through control traffic lights.

What was the dimension of the problem:

1. The capacity of the historic center of Tequila was: 1,500 vehicles/hour and 2,016 people/hour.

2. The capacity of the historic center of Tequila with healthy distancing was: 1,008 people/hour.

3. The estimated unmanaged overload on weekends in cars was 62% to 248%.

How was it managed?

- The ascent and descent of tourists was prohibited at the entrances to Tequila.

- Satellite parking lots were established.

- Real-time road decisions were made based on the results of the big data information system and cameras.

- Communication campaigns were carried out by the city council to convey prevention measures.

- Capacity in restaurants, cafes and bars was restricted by 50%.

- Tactical urban planning was used to achieve deconcentration.

- A sanitary filter for collective transport was established.

What was achieved? 

- Zero vehicle saturation.

- Staying within the preventive limit, and that tourists and residents maintained a healthy distance.

- Management of alerts received.

In short, respecting the carrying capacity of the destination. 

Therefore, it is in the hands of the destinations to manage their carrying capacity, which an Intelligent Tourist Destination can do. On its way to intelligence, Tequila was able to combine technological intelligence with non-technological intelligence in such a way to mitigate problems, a way to be smart and sustainable.

Destinations are systems and we must "listen" to them; the city gives signals that make it sustainable and since the city is a public good, it must be managed in complexity, not in linearity.