Infrastructural Ecology: Embedding Resilience in Public Works

Parsing Resilience

Resilience refers to the capacity of a system to absorb and withstand disturbance and recover functionality. Much has been learned from studies of resilience and adaptive capacity in our planetary ecosystems. These self-organized communities of species manifest a range of useful reactive behaviors under stress. This commentary, by examining a number of innovative public works, explores how comparable resilience and adaptive strategies can be applied to human-constructed systems.

Biologists hypothesize that that the adaptive capacity of a system arises from the interactions of its component parts (Gunderson & Holling, 2002; Walker & Salt, 2006). Modularity among the parts ensures redundancy, while diversity, including different ways of performing the same function, enables a system to withstand a range of disturbances. Take our conventional municipal water supply systems, for instance, which are comprised of components, including reservoirs, aqueduct conveyance systems, filtration facilities, water mains, and pumps. The diversification of storage systems—from reservoirs to controlled lakes, reinjection of aquifers, to local cisterns for rainwater harvesting—may help compensate for extended dry seasons. At the same time, a modular series of water tunnels can provide delivery redundancy should one fail. While it might seem that diversification and modularity run counter to engineering notions of efficiency, it is also likely that an overemphasis on reductionism can reduce a system’s redundancy and flexibility and increase its vulnerability to shocks or perturbations.

Another attribute, its so-called “transformative” capacity, allows a system to transcend performance limitations. The alteration of underlying processes and introduction of new variables are additional pathways to resilience. Per our water system example, local reclamation, treatment, and strategic reuse of municipal wastewater can creatively extend the availability of that same initial resource. While the system’s functionality remains unchanged, its capacity is transformed. By closing a system loop, a once-through, linear urban water system becomes partially circular. In still other ways, resilience can also be increased by introducing resources from outside the system. In our supply scenario, as water stress conditions further shrink water availability, new sources must be procured beyond the watershed boundary. For those cities near the coast, for example, the incorporation of desalinated seawater into the system may be, increasingly, one option for augmenting the system externally.

For the purpose of this commentary, yet another distinctive attribute, “reciprocity,” is examined. Whereas diversity, modularity, and transformation promote resilience of a single system, reciprocity may also foster resilience in another system simultaneously. Recovered and appropriately treated wastewater, for instance, can amplify agricultural irrigation, increasing food production. Reciprocal coordination across different systems can secure mutual advantages and co-benefits. For infrastructure, such instances of interconnectedness and reciprocity transcend our conventional, industrial-era habits of segregating or “siloing,” single-purpose systems.

Defining Infrastructural Ecology

Infrastructural ecology, as defined here, constitutes a more holistic paradigm for public works. In practice, it strategically combines, collocates, or otherwise links certain workings of power, water, sanitation, transport, or even food systems. Such “hybridizing” of unrelated sector systems may produce efficiencies simply by sharing structure or space. Once conjoined, these otherwise unrelated sector systems may additionally achieve lower first- and/or operating costs.

Strategic alignment of different but compatible functions can also allow each to utilize the productive or distributive functions of another. Thus integrated, infrastructural systems can cascade (pass along or exchange) waste energy, water, or matter, such as recovered nutrients, for another’s reuse. Such symbiotic arrangements can cut pollution and greenhouse gas emissions, diminish waste, as well as reduce the demand for virgin resource inputs. Coupled in this manner, human-engineered critical systems effectively replicate the closed-loop, sharing logic and behavior of natural ecosystems. As applied here, the term infrastructural ecology encompasses these two different scenarios.

The examples that follow illustrate infrastructural ecologies that particularly focus on climate-forward strategies. Adapting infrastructure to the new norms of climate uncertainty requires approaches tailored to the type of asset, its particular vulnerability, while also emphasizing local resources and capacity. A number of innovative examples—from both industrialized and developing nations—illustrate the efficacy of such stratagems. Many of these projects have been implemented through collaborative, interdisciplinary leadership or an integrated set of policies. These exemplary projects and programs are organized in three groupings: (a) smart flooding solutions, (b) water-wise infrastructure innovations, and (c) macro-adaptation strategies to safeguard infrastructure and health in a warming climate.

Multifunctional Solutions to Flooding

Pope Francis, in his 2015 encyclical, “Laudato si” wrote that “climate change . . . represents one of the principle challenges facing humanity in our day. Its worst impact will probably be felt by developing countries in coming decades.” One of these, previously described, is Kuala Lumpur. Its rivers, swollen by intensified monsoons, tidal backflow and poor urban drainage have persistently flooded its financial and commercial hub, also the locus of severe vehicular congestion.

Here, the Malaysian Highway Authority and Irrigation and Drainage Department adroitly engineered a double-decker bypass tunnel and a temporary stormwater reservoir together in one project. Too costly as a standalone solution, the stormwater diversion project became economically feasible and less disruptive when conjoined with the tunnel. Moreover, because some of the construction costs were recouped through tolls, the bypass tunnel pays its own way (Kados & Kok, 2007).

To their reciprocal advantage, the agencies’ dual purpose SMART (Stormwater Management and Road Tunnel) tunnel opened in 2003, operating three modes. In fair weather, both highway decks carry traffic beneath the city center. During moderate rainfall, stormwater flows through the lowest portion of the tunnel, sometimes, once traffic is partially curtailed, engulfing one of the decks. During floods, however, the tunnel is entirely evacuated. Floodwater fills the 9.7 km (6 mi) tunnel before draining to a holding area. The tunnel is washed down and desilted before reopening the motor way to vehicles.

Urban flooding has long vexed the city of Rotterdam. Vulnerable to both sea level rise on its western flank and overtopping rivers on its east, its traditional policy objectives relied on runoff attenuation measures—stormwater canals, green roofs, and other retention facilities. With increasingly heavier precipitation, water planners had to set a goal for implementing 900,000 m³ new attenuation capacity by 2050. This required a transformative, cross-sector approach. The new tactic combined urban flooding remedies with urban renewal; it distributes a series of multiple “water retention squares” within the inner-city fabric (de Graaf & van der Brugge, 2010). Designed in concert with local stakeholders, these pilot projects are located in deteriorated social housing neighborhoods. New multifunctioning plazas include one or more amenities—playgrounds, public squares, ball courts, and so on. These are designed to flexibly double as stormwater retention basins, reducing discharges to the sewer system (ESPACE, 2004). Elsewhere in Rotterdam (90% of which is below sea level) another double-purpose measure averts local flooding. Beneath the Museumpark, a subterranean 1,150-car parking garage provides 10,000 m³ of stormwater storage, retained until conditions allow its passage through to the sewer system (WaterWorld, 2010).

The restoration of mangroves in Viet Nam’s Red River delta represents another multipronged project in a flood-afflicted developing nation. Here the planning and supervising entity, Viet Nam Red Cross, with its staff and local community participation, reestablished more than 22,000 ha (54,363 acres) of depleted mangrove forests along a 100 km (62.1 mi) stretch of coast, directly benefiting more than 350,000 coastal inhabitants. Mangrove restoration reduced the cost of maintaining other constructed defenses, lessening the risk of damages estimated as high as US$15.0 million, almost double the US$8.8 million replanting effort. The new mangroves further support additional controlled shrimp farming and wood harvesting, augmenting local earnings. The value of carbon dioxide absorption under this integrated approach to infrastructure resilience has been estimated at US$281 million, at US$20 per metric ton (1.102 ton) of CO₂ (International Federation of Red Cross and Red Crescent Societies, 2015).

In the mid-90s, South Korea constructed a 12.7 km (7.9 mi) barrage across Gyeonggi Bay, creating Lake Sihwa. The seawall was originally designed to provide rising sea level flood protection for surrounding industrial estates and farmland, and to also reclaim 173 km² (67 sq mi) of land near the local metropolitan areas of three cities surrounding the lake. In addition, with rivers feeding the bay, the barrage was intended to create a 56.5 km² (22 sq mi) freshwater reservoir to address water shortages in the region. However, inflows from industrial activities and sewage from residential areas soon contaminated the basin (Young, Kyeong, & Byung, 2010). In 2004, a channel breaching the dike to allow for reintroduction of a seawater exchange of 60 billion tons annually through tidal circulation, restored ecological integrity to the basin (Bae et al., 2010).

This north-western coastal region of the Korean Peninsula, however, hosts some of the highest tides in the Yellow Sea, with a mean tidal range of 18 feet and a spring tidal range of 26 feet. The governmental authority, Korea Water Resources Corporation (K-Water), eyeing prospects for tidal energy along the coast, lit upon Sihwa lake as a means to reach CO₂ emissions reduction targets, while cleansing the polluted waters. It began construction of the Sihwa tidal power plant in the new channel to harness tidal energy (Cho, Lee, & Jeong, 2012). Completed in 2011, the Korean government-financed US$335 million plant, with its 10 submerged generating turbines, has a total power output capacity of 254 MW, based on inflows to the lake (Patel, 2015).

In addition to its power-producing and water-flushing services, this most multifunctional construction accommodated a four-lane highway atop the barrage between previously remote points. It also improved conditions for basin fisheries. With a wetland park integrated into a part of the barrage, today it offers intertidal zone sightseeing. As an exemplar project, it compounds public investment by serving as both an adaptation (resilient response) and mitigation (carbon-cutting) solution that serves South Korea’s escalating energy and water needs.

Resilient Responses to Water Insecurity

Along with the increased flooding along coasts, estuaries, and river banks, many other regions instead face the prospect of increased drought from meteorological shifts triggered by global warming. Water insecurity is compounded by urbanization, with developing nations’ increased demand for energy (40% more by 2030, Nelleman et al, 2009) and meat (50% by 2025, International Energy Agency, 2008) in their diets driving a 42% increase in demand for grain, doubling down on water use. Water insecurity threatens the web of energy and food. These interdependencies, or the “energy-water-,” or “energy-water-food nexus,” demand creative, integrated management across the sectors, as demonstrated by the following successful infrastructural initiatives.

From India, to Japan, the Netherlands, Israel, and Italy and more recently the United States, new solutions have emerged for the water-energy nexus that strategically combine distinctive but compatible functions. Floating solar photovoltaic (PV) systems, made up of ganged PV arrays, similar to ground-mounted PVs, are increasingly placed on water bodies. While these systems’ sizes and floatation methodologies vary, these floating arrays are more typically installed on man-made surfaces—from irrigation canals, to reservoirs, retention or wastewater storage ponds. To date, almost 100 MW of these double-acting systems have been installed globally (Holm, 2017).

India’s 10-MW electricity project sits atop 3.6 km (2.2 mi) of the Sardar Saraovar Namada Canal in Gujarat. By shading and cooling canal water, it reduces approximately 9,000 m³ (2.37 million gal.) annually in evaporative water loss to the arid heat. The panels are reciprocally cooled by the proximity of water’s thermal mass, extending their life span, and, according to one study, improving their performance by 10% or more (Wang, 2012). A system on a reservoir near Short Hills, New Jersey’s 135 kW Canoe Brook Water Treatment Plant, achieves comparable benefits, offsetting the plant’s carbon emissions, while also reducing unwanted algae growth on the reservoir.

Bogor City, Indonesia’s residents experience heavy monsoonal flooding. Still, given the excessive pollution of the rivers, they lack a safe water supply. The water deficit is exacerbated by disproportionate groundwater extraction and the soil compaction from dense urbanization that prevents groundwater recharge. A low-tech solution was developed here that at once solves these several problems. In backyards, parks, and urban marginal spaces, small vertical holes called “biopori” are hand-bored at frequent intervals by citizens to a depth of more than 3 ft. Organic waste is introduced deep into these columnar excavations, attracting earthworms that tunnel their way into the biopori to digest the waste. Their pathways increase soil porosity, allowing stormwater to infiltrate at almost a gallon per minute, replenishing the water table. A co-benefit of this small scale, decentralized solution is the production of useful fertilizer extracted as waste digestate from the biopori. The utilization of food waste in the biopori also reduces the amount of garbage strewn in the streets. Collectively, the biopori yield restored water tables, reduce flooding and polluting garbage, and increase food productivity. As a climate change adaptation, the nearby municipality of Bandar Lampung, along with other cities undertaking similar adaptation measure, has targeted the construction of more than 5 million biopori utilizing community labor (Saroso, 2014).

Until 2007, the City of Seoul, Korea, had relied solely upon water sourced from distant reservoirs, delivered at high cost. Given the region’s uneven (monsoonal) rainfall, water shortages were a municipal concern. Working closely with the City and in partnership with Seoul National University’s Rainwater Research Center, the developer of a major commercial/residential urban development installed a successful site-wide rainwater harvesting pilot program in 2007. It showed that 67% of the site’s annual rainfall could be captured, stored on site, cleaned, and reused to flush toilets, wash the development’s site, and irrigate its gardens (Mooyoung & Kim, 2007). Other rainwater was also set aside as reserve for firefighting. The occupants now receive significant savings in their water rates, while the developer received his investment payback in 8 years (Han & Kim, 2007). In 2008, the government enacted new ordinances requiring similar systems on all new public buildings and also provides subsidies for private systems.

A different multipronged and high-yield solution to water deficit entails the multiple use of the resource itself. Preindustrial societies’ practice of integrated water management—Cistercian monks’ wastewater reuse for tanneries and in grain milling, or the Sri Lankan dammed pond system, that cascaded and reused water from village to village—has long since been supplanted by segregated, once-through water systems. California’s Orange County Water District (OCWD), however, has skillfully learned to close the water loop to buffer against recurring droughts, aggravated by climate change. One hundred million gallons per day of the county’s treated and purified wastewater is reclaimed for reuse in multiple modes. First, it is used for groundwater reinjection to eventually replenish the OCWD’s aquifer. Second, by refilling the district’s groundwater basin, it prevents further land subsidence caused by groundwater overpumping. Added to near-coastal wells, it also forms a critical hydraulic barrier against seawater intrusion into the aquifer (Kemsley, 2008). When the systems’ US$142 million expansion is completed, almost no surplus wastewater will be discharged to the ocean. It is important to highlight the fact that OCWD’s system delivers the lowest cost of manufactured (recycled) water per drop for Southern California (Bilodeau & Sebourn, 2017).

A water-short world will inevitably rely upon seawater desalination, despite its energy intensity, high costs, and problem of saline waste contamination. An alternative, low-impact and bold solution, the Seawater Greenhouse is a newly proven technology currently deployed in the desert climates of Jordan, Australia, Qatar, and the United Arab Emirates. A nearly passive system, it relies on solar energy and seawater inputs. Designed to promote evaporative cooling and solar distillation in a single light-weight structure, the greenhouse yields high-quality crops and surplus fresh water as follows: First, oncoming seawater is evaporated upon entry, producing an ideal cool and humid condition inside the greenhouse, and reducing irrigation needs by 50%. Next, after further solar-induced evaporation occurs, the fresh water that condenses on cold seawater-filled pipes is collected (Patton & Davies, 2006). In Qatar, the 600 m² (6,500 sf.) pilot produces 75+ kg/m²/year (165 lb.) of cucumber and other high-value vegetable crops, along with useful minerals harvested from the waste brine. Other integrated enterprises under consideration include the production of algae in waste salt ponds for use as biofuel or fish food (Casey, 2014). This unique energy-water-food solution provides improved water and food security for near-coastal arid regions.

Transformative Adaptation and Mitigation Strategies at Scale

The previous multipurpose and intersectoral responses to climate instability—flood mitigation and promotion of water security—are examples of single project initiatives, individual solutions that nonetheless lend themselves to replication incrementally. In contrast, “transformational adaptations” are measures that are planned at a larger scale and/or intensity (Kates, Travis, & Wilbanks, 2012). Significantly, these adaptations respond to the collective vulnerabilities of multiple urban infrastructure systems in a warming world: excessive stormwater overwhelming wastewater systems and scouring roads and bridges, high temperatures melting pavement and causing transit rail buckling, heatwaves producing excessive water withdrawals and triggering electrical grid outages, and so on.

Municipal-level implementation of green infrastructure—cool and green roofs and, in particular, tree planting—should be considered a transformational measure due to the potential scale of application, one capable of producing a beneficial cooling effect across transport, water, Information and Communication Technology, sanitation, and energy systems. The urban forest delivers both relief from the urban heat island effect and carbon reduction, via both diminished air-conditioning demand and improved carbon storage. It is noteworthy, here again, that one measure achieves two net positive ends, mitigation and adaptation. It underscores the importance of building low-carbon, climate resilient infrastructure.

The City of Stuttgart was the forerunner in improving urban ventilation and cooling through protection and amplification of its greenspaces. Its hilly surrounding forests, vineyards, and agricultural areas refresh the air and produce thermal or “katabatic” winds that drop cool night air into the city. Guided by its 1992 “climate atlas,” more than 60% of the city remains green, 39% of which is well-protected. In addition, over three decades, the city has also subsidized more than 300,000 m² (3.2 million sq ft) of green roofs (Kazmierczak & Carter, 2010). Such climate-wise planning is becoming more widespread; for instance, Kobe, Japan, has developed its own climate atlas and policies that capture katabatic winds from its mountains and daytime breezes from the sea.

Tree conservation and planting activities directly shade pavements, ensure more porous ground cover, reduce air pollution, and provide essential evaporative cooling (evapotranspiration). Cooling through tree planting—coupled with cool paving and roofing, planted walls, vegetated bioswales or ditches—has a multiplicative effect. It not only diminishes heat stresses acting on a range of infrastructural assets, but it also improves urban drainage and water storage in the built landscape, adding further ecological and social resilience.

Rising temperatures across Australia have led city councils there to seriously address urban heat with shade. Perth’s 2016 Urban Forest Plan aims to increase canopy cover from 19% to 30%. In 2012, Melbourne targeted doubling tree canopy cover from 22% to 40% by 2040, by planting about 3,000 new trees every year, while Sydney has committed to doubling by 2030. India’s explosive urbanization has increased the net heat stored in cities. Today, it is swiftly moving forward with vegetation-induced cooling. India now sets aside 1% of highway development project cost for tree planting along highways, railway lines, rivers, and irrigation canals. Under this policy, 140,000 km (87,000 miles) of highways will be tree-lined (Imam & Banerjee, 2016). India’s Paris climate commitment allocated US$6.2 billion for reforesting 12% of its land area by 2050, much to be undertaken by its citizenry (Balachandran, 2016). Some 800,000 volunteers from the state of Uttar Pradesh planted 49.3 million tree saplings along roads, railways, and on public land in 1 day in 2016. The following year almost 1.5 million people in Madhya Pradesh planted 66.3 million trees in 12 hours. (Nace, 2017). Through these and other greening measures, India is protecting its investments in urban infrastructure, while improving public health, regional biodiversity, and gaining other quality of life improvements co-benefits.