Urbanising Deltas: A Special Challenge

Urbanising deltas belong to the most promising regions of the world, considering their large concentrations of population, their role in the world’s ecosystems and their significance to the world’s economy. At the same time, these regions are dealing with extreme vulnerability and face multiple threats. The combination of intensification of urban and economic land use, the related disappearance of the deltas’ capacity to resist natural hazards and climate change are resulting in an increase of deadly diseases, poverty and substantial economic losses. To ensure a sustainable future in deltas, new strategies are necessary to improve the living conditions for all people in delta regions and to decrease their risk level. The big challenge is how to combine the benefits of deltas while improving their resilience.

Delta regions are magnets for ecology, economy and urbanization 
Deltas are the areas where rivers flow into seas or oceans; these territories are the products of the dynamic forces of seas, rivers and the climate. The complex, interactive processes of river discharges, sea waves, tidal currents, sediment transport and deposits, wind, temperature and vegetation are the driving forces of land formation. There are many different types of deltas, but they all have in common the fact that they contain the richest ecosystems of the world, with the largest amount of ecosystem services. The gradual transitions between land and water and between salt and fresh water are the biotopes and nurseries of many species that are crucial for the ecological balance of the world’s rivers and oceans.

Next to the ecological value in terms of biological productivity and diversity, these ecosystems have significant economic value via ecosystem services such as coastal protection, maintenance of fisheries and wildlife, erosion control, water catchment and purification, carbon sequestration, nutrient cycling, tourism, recreation, education and research.

Deltas offer excellent conditions for economic development and urbanization. Historically, deltas played an important role as birthplaces of urban settlements because of their position at the crossroads and trans-shipment point of international trade and due to the fertility of alluvial plains and the estuarine and coastal waters, which make deltas extremely attractive for agriculture and fishing. At present, deltas are magnets for urbanization and economic development. In 2050, 650 million people will live in delta and coastal urban regions. In many nations, delta and coastal regions are the engines of the national economies with the highest contributions to national GDP.

Deltas are places of increasing flood risk, water scarcity, ecological and economic damage
However, the processes of urbanization and economic development generate a growing risk for flooding resulting in increasing numbers of victims, severe economic damage and ecological downgrading. It is a misunderstanding to think that the increasing vulnerability of delta regions is the result of climate change. Of course, climate change has an influence on delta regions. But the main reason for the increased flood risk is the intervention of humans.

The greater concentration and densification of urban land use has resulted in the disappearance of natural land-water transitions, which are important as buffers in times of high-water levels and natural disasters. Increasing flood risk is a consequence of this disappearance of delta territories’ natural resilience capacity and is reinforced by sea level rise caused by climate change.

Land subsidence as a result of intense drainage and groundwater extraction increases the vulnerability of urbanized as well as rural areas, often dropping below mean sea level. Between 1980 and 2013, the global direct economic losses due to floods exceeded $1 trillion (2013 values), and more than 220,000 people lost their lives. It is expected that populations vulnerable to flooding by storm surges will multiply tenfold or more over the 21st century and this will affect an estimated 100 million people each year. Floods in urbanizing deltas have disastrous impacts on the economy as well as on the ecology of entire countries. As a consequence of flooding, local and national economic activities are disrupted for a long time, leading to a substantial decrease in GDP. The 2015 World Economic Forum (WEF) Risks Report has put the impact of Water Crises as the number one global risk.

There is a high risk of flooding, heat stress, water shortages and poor air quality, resulting in increasing amounts of socio-economic impacts, huge economic losses, increasing amounts of lives at risk and severe ecological down-grading or impacts on natural capital. Worldwide the impact of climate change, if modification does not take place, is expected to grow to US$ 500 billion or US$ 1 trillion a year by 2050 (World Bank, 2013).

Because of increasing flood risk and flood hazards, mass migration to deltas and coastal areas can quickly reverse, which is already the case in some areas. Floods in New Orleans (2005) and east Japan (2011) resulted in the departure of many people who never returned.

Towards new perspectives for urbanizing deltas
The challenge is how to combine sustainable economic utilization of delta regions with a substantial improvement in the quality of life for all social groups through interventions for decreasing risks and repairing the resilience capacity of delta territories.

We propose to develop such strategies, which should become priorities:
1) The natural resiliency and adaptability of the deltas should be restored
It is necessary to revitalize ecosystem services and their capacity to contribute to the recovery of delta territories after disturbances. This revitalization must occur in many of the natural land-water transitions: beach and dune systems, salt marsh systems, coastal coral reefs and mangrove forest systems.

In the long term, ‘building with nature’ delivers the conditions for delta regions to adapt to climate change continuously, by using the formative power of nature as the strategy’s foundation.

Disappeared land-water transitions and related water systems need to be repaired and existing gradual land-water transitions need maintenance. For instance, the state of Louisiana plans to restore several river distributaries in the lower Mississippi River Delta by re-introducing sediment deposits in the delta wetlands. Processes of erosion of coastlines can be countered by new measures with the addition of new material, which can be integrated into the natural system.An example is the ‘sand engine’ on the Dutch coast: a man-made island of sand, which will be distributed along the coastline resulting in a structural enhancement of the shoreline. Because of the historically developed dependency of most urbanized deltas from ‘hard’ engineered solutions, mixed solutions should be taken into account of ‘soft/green’ and ‘hard’ engineering.

2) Towards an integrated approach
The processes of ongoing land subsidence should be stopped by rethinking drainage as the main policy to deal with storm-water management and to minimalize the industrial use of groundwater. The introduction of a new balance between retention, storage and discharge of storm-water is necessary in order to stabilize groundwater levels and stop ongoing land subsidence. This leads to the necessity to create more space for retention and storage of storm water in urban areas. Green- blue infrastructures are important elements of this strategy: spatial frameworks for combinations of long-term water and nature-sensitive urban environments with economic and social initiatives. These infrastructures and the process of their design have proved to play a key role in urban revitalization, economic development and community building. Successful examples of green-blue infrastructures can be found in Boston, Philadelphia, Singapore and Rotterdam.

3) Climate change and flood risk policy
Because of uncertainties concerning the exact effects of climate change on sea level rise and peak discharges of rivers, it is necessary to develop an adaptive and flexible approach that is able to accommodate future uncertainties.

An effective approach to enhance the resilience of urbanizing deltas has to focus on flood prevention taking into account the possibility of flooding.

Robust prevention measures will still be necessary in most delta areas. However, they should be combined with approaches that extend the resilience capacity of deltas by ‘building with nature’ as much as possible. Examples of this policy can be found in the Room for the River and Weak Spots Coast programmes in the Netherlands, in the proposals for restoring the wetlands of the Lower Mississippi River Delta and in the Rebuild-by-Design proposals for New York.

However, 100% prevention is not possible. It is recommended to take into account the possibility of flooding by spatial adaptation and disaster management.

Spatial adaptation means being prepared to moderate floods by special facilities in the built environment (buildings as well as public space), to limit the consequences of flooding as much as possible. Vital functions in the urban fabric such as facilities for energy supply, health care and public and private transport should be especially safeguarded from flooding.

Disaster management means being prepared for extreme floods with the availability of evacuation routes, accessible evacuation sites and trained first aid and emergency teams.

4) Sustainable port and industrial development means combining adaptation and mitigation
Urbanising deltas are not only victims of climate change but also contribute to climate change through their functions as important centres and transportation hubs of fossil fuel-based economies with large greenhouse gas emissions. The world’s largest centres of trans-shipping, storage and fossil fuel processing are situated in deltas; the economy of these delta regions is thus largely based on trans-shipping, storage, processing, financing, accountancy and insurance of fossil fuels.

The role of urbanizing deltas in the world’s economy and ecology can change in a radical way: from being the crucial hubs of the old fossil fuel-based economy, urbanizing deltas can become the engines of a new, clean energy-based and circular economy.

The reorganization of land use in urbanizing deltas should focus on the combination of adaptation and mitigation, by transitioning the regional economy from a fossil fuel-based economy to a clean energy-based economy that also generates space for sustainable land-water processes. New concepts and policies for the location and layout of ports and cargo transport to upriver destinations are a major priority. As an example, the Port of Rotterdam, in collaboration with the World Wildlife Fund, is developing a new concept in The Port of the Future. This concept will be implemented with local stakeholders and citizens, in order to contribute to the environmental and social resilience of the urbanizing delta. The concept is also being explored in Ghana.

PHOTOS: HAN MEYER

5) Sustainable agriculture needs diversification
Deltas offer very fertile soils for agriculture. Their role as a main food supplier is under great pressure because of increasing urbanization and climate change impacts. A proper balance between agricultural, urban and industrial land is important. In many cases, uncontrolled urbanization leads to a dramatic loss of agricultural land as well as to mass vacancies of buildings and building sites.

Preventing a total urbanization of delta regions is also necessary for the maintenance or restoration of the absorption capacity of the delta territory during extreme weather conditions. Agricultural land can play a substantial role as part of a strategy to reinforce the flood-resilience capacity of the delta.

6) Social inclusiveness and community building integrated in spatial planning and design
The speed and scale of the current human migration to coastal and delta areas is unprecedented and creates a high risk for extreme social inequality. Marginalization and exclusion become realities for large groups of people. The consequences of increasing flood-risk especially affect the population with the lowest income, often recently arrived in the city and living in areas that were not previously urbanized, often because they are the most vulnerable areas of the deltas.

What makes the problem of the urban poor in delta areas special is the lack of risk awareness. Social inclusiveness should start with a strong policy to inform and communicate with the population concerning the increasing risks of the area.

Building sustainable and resilient urbanizing deltas means that strategies for flood prevention and ecological repair should be based on involvement of people living in the most vulnerable areas and lead to a higher quality of life for all social groups.

An inclusive delta approach would create conditions to make the ecosystem services of the delta areas beneficial for poverty alleviation. The Ecosystem Service for Poverty Alleviation in Deltas project is an example of this strategy.

Effective citizen engagement for the identification and prioritization of projects is necessary to ensure that actions are based on a shared vision and meet the needs of all citizens. The inclusion of civil society and the private sector in the implementation of activities means that there is likely to be greater ‘ownership’ of these interventions and that they will be maintained and protected more effectively, in part because the capacity of various factors will be strengthened to take proactive measures. If citizens perceive interventions as contributions to their wellbeing, they may be more likely to be directly involved in the implementation and maintenance of ecological and resilient projects, potentially generating cost savings.

7) Governance, financial means and capacity building
Making urbanizing deltas more resilient will mean financial expenses for new interventions and measurements. The expenses will be high in many cases, but the benefits will be much higher.

Effective prevention of flooding leads to reduction of costs for compensation of the damage, cleaning and reconstruction of flooded areas, as shown in several studies. 

Higher investments from private companies result in higher revenues for public taxes. The CPB Netherlands Bureau for Economic Policy Analysis calculated that the annual benefits of the Dutch Delta Works are four times more than the annual costs (annual write-off of investments and annual maintenance).

An effective and creative policy concerning financial issues should take the local circumstances very carefully into account. From this perspective, it is necessary to reconsider some of the programmes of global financing institutes like the World Bank and development banks, who sometimes use criteria and assessments that preclude funding for ‘building with nature’ solutions.

Smart combinations of flood prevention measures with other economic developments can substantially reduce the costs of flood prevention. New creative financing mechanisms need to be developed, for instance by introducing special ‘resilience tax’ systems for travelers, tourists and developers in delta regions. Urbanising deltas are extremely complex systems that are difficult to govern. The speed and scale of urban and economic growth often exceed the capacity of traditional public authorities. Cross-boundary coordination among national, regional and local authorities is necessary. Coordination among spatial planning, flood risk management and social and economic policies is essential to reach better global transfer and exchange of knowledge.

It is essential to facilitate data collection, modeling and real-time monitoring of deltas to strengthen the knowledge base. Delta citywide organizational capacity is needed (strategic, developmental competences and operational competences). The organization Delta Alliance has the ambition to contribute to this capacity-building in urbanizing delta regions.

(This paper would not have been possible without the contributions of Taneha Bacchin, Fransje Hooimeijer ad Steffen Nijhuis. Besides, 35 experts of deltas worldwide reviewed a first draft of the paper. We are very grateful to all of them.

The authors of this article wrote a plea for putting the theme of ‘urbanising deltas’ as a priority on the ‘New Urban Agenda’, to be defined at the UN Habitat III congress in Quito, November 2016. This article is a summary of this plea.)