What is Blue Infrastructure Worth? The Value of Lakes Around an Expanding Megacity
In and around cities, lakes take up important roles as places of recreation, but also by providing resources and other kinds of benefits. How do local people in Bangalore perceive different kinds of such ‘blue infrastructure’ in their city? And which factors influence their perceptions? A new place-based social-ecological study provides some answers.
Facing phenomena like rapid urbanization, environmental degradation and biodiversity loss, it becomes all the more relevant to place a spotlight on cities’ green and blue infrastructures as tools to mitigate some of the negative impacts of these processes in urban ecosystems.
Bangalore’s indigenous infrastructure
In rapidly expanding megacities, semi-natural habitats take up an especially relevant role for regulating urban climate, maintaining biodiversity and improving quality of life. In urban planning and research, these spaces are described under the umbrella term ‘ecological infrastructures’ — with ‘green infrastructure’ as a designation for networks of parks and other kinds of greenspaces, and ‘blue infrastructure’ meaning all kinds of water bodies.
Especially in the Global South, urban water bodies face severe sustainability challenges, such as drought, flooding, and shortage of clean water. At the same time, they have great potential to foster biodiversity and other ecosystem services such as climate regulation, air cooling, water storage, flood prevention, water purification, growth of particular crops, and business opportunities.
While today’s urban planning knows many progressive water management options, the idea of capitalizing on hydrological structures to sustain human existence is a very ancient one:
There are many time-tested indigenous land and water management systems across the world that have the potential to inform contemporary ecological infrastructure development.
The South-Indian city of Bangalore, which has experienced a long process of city development from a so-called ‘city of lakes’ or ‘garden city to the bustling IT hub of today, is still shaped by an extensive network of freshwater reservoirs for water supply. Bengaluru city is surrounded by many villages in an urban-rural gradient; in the past decades, rapid urbanization has led to rural, transitional, and urban lifestyles existing side by side.
Nowadays, Greater Bengaluru has more than 200 lakes, many of which are only seasonally filled with water and have been actively maintained by local communities in the past. The lakes used to be so important to villages that many of them were named after their lakes: They formed the ground for drinking water, agricultural irrigation, groundwater recharge, fishing, fodder collection, livestock grazing, and cultural activities.
A people-based perspective is key to revealing people’s present perceptions, values, challenges and options of diverse beneficiaries.
Findings: Places, people and perceptions
Together with various international colleagues, our group members Tobias Plieninger, Pramila Thapa, and Mariotorralbav have performed a survey among 536 residents along two rural-urban gradients in Bangalore, India, asking about individual perceptions of provisioning, regulating and cultural ecosystem services (ES)* from traditional water-filled and (permanently or seasonally) dry lakes, as well as about associated challenges and management options. They did so mostly through the ‘photo elicitation’ method, showing people certain photos and asking for demographic information and perceptions in an accompanying questionnaire.
Their findings told a lot on the value of lakes in and around megacities:
Especially when compared to their small surfaces, traditional lakes are of disproportionally high societal importance in Bangalore. They provide a multitude of ecosystem services* that strongly benefit people.
1. Along all gradients, the regulating and cultural services were standing out, meaning that benefits such as aesthetic values, habitat maintenance, and climate regulation were most important to local infrastructure users. However, compared to earlier times, the lakes appear to have lost some of their formerly relevant functions, i.e. the provision of food and fodder, in much of the study area. Apart from their benefits, lakes have some negative contributions (disservices) that did also matter to respondents, but to a much lower degree.
2. Urbanization thus plays a strong role in changing local people’s relationship with different kinds of lakes: While both water-filled and dry lakes proved important to local communities, the services they provide differ, also depending on the level of urbanisation (i.e. the lakes’ setting, from rural and peri-urban to urban).
- Especially in rural areas, dry lakes are reported to offer key regulating ES, like protection against natural hazards, and even some provisioning services, such as extraction of silt and sand.
- For all other services, water-filled lakes’ capacities were reported to be much higher — particularly for cultural and regulating ES, and particularly in more urban spaces. Thus, restoring some permanently dry lakes to their former water-filled state may be useful for a stronger capitalization on ecosystem services.
3. Sociodemographic factors have some effect on ES assessments. In and around Bangalore, different social groups share similar views of ES from lakes. However,
- women perceive less benefits from lakes than men, particularly regarding cultural and provisioning services; and
- the importance of the more abstract and “biological” regulating services is more intensively perceived by those with a higher education level.
- Marginalized groups (in terms of caste membership or religion) appear more reliant on provisioning ecosystem services for basic subsistence, and may therefore particularly suffer from the general trend of encroachment and conversion of dried-up lakes. In our study area, ‘traditional’ users have often been side-lined when community-based management of lakes was replaced by state management in urbanisation processes.
4. Regarding challenges, people largely agreed with previous scientific studies, mentioning physical alterations, deposition of pollutants, or spread of invasive plant and animal species. For many of the widely appreciated regulating and cultural services (e.g., flood regulation, aesthetic values), actual physical access is not that important anymore: Few people showed concern about decreasing access to lakes.
5. The local community demanded management options that departed substantially from those commonly proposed in the literature and by neighbourhood lake groups: Instead of promoting local agency or community management, many respondents expressed support for conventional measures, such as sewage treatment plants or — most often — fencing, which has been harshly criticised by environmental justice scholars.
Conclusion: Challenges and pathways to environmental stewardship
The changing relations of people to lakes must be seen in the context of larger socio-economic and cultural transformations brought about by urbanisation (e.g. occupational changes, decreasing dependence on local ecosystems). These transformations also present challenges to fostering stewardship of traditional blue infrastructure.
Complex social-ecological strategies for improving ecosystem services supply from lakes that go beyond ‘easy’ solutions — such as fencing — are needed. These, however, require better communication strategies.
People living near lakes have local knowledge and clear ideas for lake improvement, but are less vocal on how these can be implemented institutionally. Promoting cultural attachment of people to lakes — for instance, through cultural activities — may generally facilitate greater sense of local ownership over blue infrastructure. For polluted lakes, special clean-up and awareness-raising strategies are recommended.
Even dry lakes’ contributions to blue infrastructure networks should be recognised in spatial planning, as these supply crucial provisioning services but are at risk of being encroached and converted to other land uses.
All in all, traditional lakes should become keystone structures of blue and green infrastructure development for sustainable urbanisation in the Global South — maintaining and restoring them should be prioritized over establishing new waterbodies.
Full study: T. Plieninger, P. Thapa, D. Bhaskar, H. Nagendra, M. Torralba, B.M. Zoderer. 2022. “Disentangling ecosystem services perceptions from blue infrastructure around a rapidly expanding megacity”. Landscape and Urban Planning 222, 104399.
*With its ecosystem service (ES) framework, the Millennium Ecosystem Assessment has paved the way to an adequate understanding of the direct and indirect contributions of ecosystems to human survival and quality of life. Provisioning, regulating and cultural ecosystem services are impacting human wellbeing. Importance of and access to such ecosystem services, however, differ substantially across beneficiary groups and are subject to strong inequalities.
