---
title: the resilience a place already has is alive
canonical_url: https://ensurance.app/guide/the-resilience-a-place-already-has-is-alive
markdown_url: https://ensurance.app/guide/the-resilience-a-place-already-has-is-alive.md
subtitle: "the floodplain, the marsh, the canopy and the soil are infrastructure. kept in condition, they can repair themselves"
category: ecosystem-services
---

# the resilience a place already has is alive

*the floodplain, the marsh, the canopy and the soil are infrastructure. kept in condition, they can repair themselves*

**Resilient infrastructure** is infrastructure that keeps working through a shock, such as a flood, a storm surge, a heat wave or a fire, and recovers. Engineers usually mean built works: levees, pumps, culverts, treatment plants. Much of what does that work for a place, though, was never built: floodplains, marshes, forests, tree canopy and soil.

Upstream, a floodplain spreads high water across open land before it reaches the bridge. On the coast, a salt marsh takes some of the force out of a surge. In town, the trees cool the block. The floodplain and the marsh do that work whether or not anyone pays for them. [**Ensurance**](/manual/ensurance?from=guide) is how the people who depend on them can pay for their keeping. It is not the floodplain, and it does not stop a storm.

:::johnson
**the resilience a place already has is mostly alive.**

Much of it has no one assigned to keep it, and it works only while it is kept.

[what natural infrastructure actually is →](/guide/what-natural-infrastructure-actually-is?from=guide)
:::

## the capital plan often leaves out the marsh

A pump was bought; a marsh was inherited. A pump station comes with a price, a design capacity and a replacement date, so it lands on a ledger. A marsh usually has a landowner, but often no one whose job is its condition, so it can sit outside the capital plan even where it does part of the same job. ([Natural](/guide/what-natural-infrastructure-actually-is?from=guide) and [living infrastructure](/guide/what-living-infrastructure-actually-is?from=guide) have their own definitions.)

The World Bank and the World Resources Institute (WRI) wrote in 2019 that "in many circumstances," combining "green infrastructure" with gray "can enhance system performance." They added the engineer's condition: green infrastructure "must be as rigorously evaluated and carefully designed as gray projects."

## what the living systems do for a place

| living system | the job it does | one figure, and what it covers |
|---|---|---|
| **Floodplain** | Spreads and carries high water past towns | California's Yolo Bypass, an engineered floodway fed by weirs, "conveys 80 percent of the system's floodwaters" south of the Fremont Weir. Scope: the flood-control system, not all river flow (California Department of Water Resources, 2010) |
| **Inland wetland** | Stores floodwater and lets it go slowly | "A one-acre wetland can typically store about three-acre feet of water, or one million gallons." Scope: a typical figure (US Environmental Protection Agency, EPA), not any one site |
| **Coastal salt marsh** | Lowers flood heights and losses behind it across most of the area studied | Properties behind a marsh save 16% in flood losses a year on average, against those where marshes were lost. Scope: Ocean County, New Jersey, modeled (Narayan et al., 2017). The wider Sandy study found wetlands raised flood heights in 20% of the region |
| **Mangroves** | Reduce waves and surge on tropical coasts | Flood protection "exceeding $US 65 billion per year". Scope: a global model (Menéndez et al., 2020) |
| **Coral reefs** | Break waves offshore | Without reefs, annual expected flood damages would double; Indonesia, the Philippines, Malaysia, Mexico and Cuba gain most, each more than $400 million a year. Scope: a global model (Beck et al., 2018) |
| **Forested watershed** | Keeps drinking water clean at the source | New York City's Catskill and Delaware supply is "the largest unfiltered water supply in the United States." Scope: one system (National Academies, 2020) |
| **Urban tree canopy** | Cools streets in summer | Daytime cooling was greatest above 40% canopy cover, at about city-block scale, and limited at night. Scope: Madison, Wisconsin, in summer (Ziter et al., 2019) |
| **Beaver-dammed stream** | Holds up through wildfire as a refuge | Beaver-dammed corridors were "relatively unaffected": greenness fell 3.05 times as much in comparable corridors without beaver. Greenness rebounded the next year either way. Scope: five western US wildfires, by satellite (Fairfax and Whittle, 2020) |
| **Soil** | Holds water for plants | 1% more soil organic carbon adds about 1.16 mm of available water per 100 mm of soil, "very small" in the authors' words. Scope: a meta-analysis of 60 studies (Minasny and McBratney, 2018). USDA's Natural Resources Conservation Service gives 20,000 gallons per acre for 1% more organic matter, a different measure and far higher |

The best-known figure, Narayan and colleagues' **$625 million** in direct flood damages avoided by wetlands across the northeastern US during Hurricane Sandy, carries the study's own caveats: "a little over 1%" of Sandy's flood damage, varying "considerably between zip-codes," and higher flood heights in 20% of the region. These are modeled direct damages, not insured losses.

## what living does that gray cannot, and the reverse

| | living infrastructure | gray infrastructure |
|---|---|---|
| **Repair** | Can regrow after damage, if the conditions that made it remain | Repaired by crews and budgets |
| **Rising water** | Some can build upward: intertidal oyster reefs in North Carolina "seem able to keep up with projected sea-level rise" (Rodriguez et al., 2014) | Stays the height it was built; raising it is a new project |
| **Several jobs** | Forests, floodplains and soils "can contribute to clean, reliable water supply and protect against floods and drought" (World Bank and WRI) | Dams and reservoirs, which the same report counts as gray, can serve several purposes too |
| **Capacity, as designed** | Varies by site and condition: measured mangrove surge reductions run 5 to 50 cm per km of width, and direct measurements in extreme events are limited | A stated design number from commissioning, such as the Fremont Weir's 343,000 cubic feet per second; a flood beyond the design event can exceed it |
| **Footprint** | Needs room: land the river is allowed to flood | Can fit a tight site: a floodwall, a pump station |
| **When neglected** | Can decline quietly and cross a threshold money cannot quickly reverse | Builds a maintenance backlog, and fails when loads exceed what it was built for |

The last row has its own post: [a pipe is a project, a canopy is a payroll](/guide/living-infrastructure-vs-gray?from=guide). The Yolo Bypass and the Fremont Weir sit in these tables on purpose: weirs let the water spill, and the floodplain carries it.

A marsh does not stop every surge, a forest does not stop every fire, and a record storm can exceed any buffer, living or built. Whether marshes keep pace with the sea is argued: one analysis found their vulnerability "tends to be overstated" (Kirwan et al., 2016), another found their elevation gain "constrained" (Saintilan et al., 2022). Marshes can keep up where soil-building feedbacks and room to migrate inland allow. Mangroves were very likely "unable to initiate sustained accretion" once relative sea-level rise exceeded 6.1 mm a year, a threshold the authors say is likely to be passed on tropical coastlines within 30 years under high-emissions scenarios (Saintilan et al., 2020).

## three places that put the ground to work

**New York's water.** A Watershed Protection Program lets the city meet water quality standards for its Catskill and Delaware supply, about 90% of average daily demand, with "only disinfection and occasional treatment of high turbidity caused by storms," and no filtration plant (National Academies, 2020). From 1997 to 2020, $2.5 billion was spent across the program, about $100 million a year. In the early 1990s the city estimated filtration at up to $6 billion to build and more than $300 million a year to run; an EPA-appointed panel said as little as half. The dollar years differ, so this is not a simple subtraction. Disinfection is the gray half.

**Room for the River, the Netherlands.** From 2006 to early 2019, the Dutch public works agency, Rijkswaterstaat, built measures at 34 locations on the IJssel, Waal, Lower Rhine and Lek for €2.3 billion, so the rivers can "safely discharge more water when river levels are high," improving safety for about 4 million people. At Nijmegen, the Waal dike was moved 350 m inland and a 3 km side channel was dug, lowering high river levels by 35 cm against a 27 cm target, at an estimated €351 million. There the dike was moved, not removed.

**Tulsa, after 1984.** The Memorial Day flood killed 14 people and caused $180 million in damages ($424 million in 2017 dollars), the city says. The Federal Emergency Management Agency (FEMA) describes the city's "voluntary buyouts and green space that doubles as stormwater detention." In 2022 FEMA gave Tulsa a Class 1 Community Rating System rating, its highest, and says residents "receive a 45% discount on their flood insurance policies." The rating covers more than the green space.

The International Union for Conservation of Nature (IUCN) defines [nature-based solutions](/guide/what-nature-based-solutions-actually-are?from=guide) (2016) as "actions to protect, sustainably manage and restore natural and modified ecosystems in ways that address societal challenges effectively and adaptively, to provide both human well-being and biodiversity benefits." Cities do it inside their limits too: [the city that drinks the storm](/guide/the-city-that-drinks-the-storm?from=guide).

## condition is the catch

The sources above measured systems that are there and working: a marsh against a marsh lost, coasts with reefs against coasts without. The work continues only while the system is kept. New York's filtration avoidance rests on a 1997 agreement and the filtration avoidance determinations that followed it. A living system pushed too far may not come back at all ([bounce back to what?](/guide/bounce-back-to-what?from=guide)).

So the question for a place is the condition of its living systems, who depends on them, and who pays for their keeping each year, beside the levee budget: the next post, [how to build resilience for a place](/guide/how-to-build-resilience-for-a-place?from=guide).

## where ensurance fits

**Ensurance** tracks 19 flows that living systems provide. One is **Risk Resilience**, the work living systems do to lower the damage from floods, storms, fire and heat. It has its own account, [risk-resilience.ensurance](/risk-resilience.ensurance), where the people who depend on that work can see it. The account is not the marsh.

See how this applies to [governments](/solutions/governments?from=guide&topic=resilience), [utilities](/solutions/utilities?from=guide&topic=resilience), [infrastructure operators](/solutions/infrastructure-operators?from=guide&topic=resilience) or [insurers](/solutions/insurers?from=guide&topic=resilience).

## frequently asked questions

### what is resilient infrastructure?

Resilient infrastructure keeps working through a shock, such as a flood, storm, heat wave or fire, and recovers. It includes built works and living systems such as floodplains, wetlands, reefs and forests, which work only while kept in condition.

### is nature infrastructure?

For a place, yes. A protected watershed lets New York City leave its Catskill and Delaware supply, about 90% of average daily demand, unfiltered, and Tulsa's green space doubles as stormwater detention.

### does a marsh stop a storm surge?

Not on its own. Measured mangrove surge reductions run 5 to 50 cm per km of width. For Hurricane Sandy, wetlands avoided an estimated $625 million in direct flood damages across the northeastern US, "a little over 1%" of the total, an average of 11% across flooded zip codes, and they raised flood heights in 20% of the region. A large surge can exceed any buffer.

### can natural infrastructure replace a levee?

Sometimes, in part. The World Bank and WRI say combining green and gray "can enhance system performance" in many circumstances. At Nijmegen, the Dutch moved a dike 350 m inland and dug a side channel.

## sources

[Browder et al. (2019), *Integrating Green and Gray: Creating Next Generation Infrastructure*, World Bank and WRI](https://www.wri.org/research/integrating-green-and-gray-creating-next-generation-infrastructure) — "In many circumstances," combining green and gray "can enhance system performance"; forests, floodplains and soils "can contribute to clean, reliable water supply and protect against floods and drought"; green must be "as rigorously evaluated and carefully designed as gray projects"

[California Department of Water Resources (2010), fact sheet: Sacramento River Flood Control Project, weirs and flood relief structures](https://www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/california_waterfix/exhibits/docs/STCDA%20et%20al/scda_54.pdf) — The project spills floods through a system of weirs into basins "designed to contain flood waters and channel them downstream," farmed in dry weather; the Yolo Bypass conveys 80% of the system's floodwaters south of the Fremont Weir, whose design capacity is 343,000 cubic feet per second

[EPA, "Wetlands: Protecting Life and Property from Flooding"](https://www.epa.gov/sites/default/files/2021-01/documents/wetlands_protecting_life_and_property_from_flooding.pdf) — A one-acre wetland can typically store about three acre-feet of water, or one million gallons

[Narayan et al. (2017), "The Value of Coastal Wetlands for Flood Damage Reduction in the Northeastern USA," *Scientific Reports* 7:9463](https://www.ebi.ac.uk/europepmc/webservices/rest/PMC5579246/fullTextXML) — Wetlands avoided $625 million in direct flood damages during Sandy, a little over 1% of the total; 11% on average across 707 flooded zip codes; higher flood heights in 20% of the region; 16% average annual saving behind marshes in Ocean County, New Jersey

[Menéndez et al. (2020), "The Global Flood Protection Benefits of Mangroves," *Scientific Reports* 10:4404](https://doi.org/10.1038/s41598-020-61136-6) — More than $65 billion a year in flood protection; 15 million more people flooded each year without mangroves

[Beck et al. (2018), "The global flood protection savings provided by coral reefs," *Nature Communications* 9:2186](https://doi.org/10.1038/s41467-018-04568-z) — Annual expected flood damages would double without reefs; Indonesia, the Philippines, Malaysia, Mexico and Cuba each gain more than $400 million a year

[National Academies (2020), *Review of the New York City Watershed Protection Program*, report highlights](https://nap.nationalacademies.org/resource/25851/NYC%20Watershed%20-%204%20Pager.pdf) — Largest unfiltered supply in the US, about 90% of average daily demand; only disinfection and occasional turbidity treatment; $2.5 billion since 1997, about $100 million a year

[National Research Council (2000), *Watershed Management for Potable Water Supply: Assessing the New York City Strategy*, executive summary](https://www.nationalacademies.org/read/9677/chapter/3) — The city's estimate of up to $6 billion to build filtration and more than $300 million a year to run; an EPA-appointed panel said as little as half

[Ziter, Pedersen, Kucharik and Turner (2019), *PNAS* 116:7575–7580](https://doi.org/10.1073/pnas.1817561116) — Greatest daytime cooling above 40% canopy, at city-block scale; limited at night; Madison, Wisconsin

[Fairfax and Whittle (2020), "Smokey the Beaver," *Ecological Applications* 30(8):e02225](https://doi.org/10.1002/eap.2225) — Beaver-dammed corridors "relatively unaffected" by wildfire; greenness fell 3.05 times as much without beaver across five western US fires; greenness rebounded the next year regardless of beaver

[Minasny and McBratney (2018), "Limited effect of organic matter on soil available water capacity," *European Journal of Soil Science* 69:39](https://doi.org/10.1111/ejss.12475) — An increase of 1.16 mm of available water per 100 mm of soil per 1% more organic carbon; "very small"

[Rodriguez et al. (2014), "Oyster reefs can outpace sea-level rise," *Nature Climate Change* 4:493](https://ideas.repec.org/a/nat/natcli/v4y2014i6d10.1038_nclimate2216.html) — Intertidal reefs in North Carolina "seem able to keep up with projected sea-level rise"

[Kirwan et al. (2016), "Overestimation of marsh vulnerability to sea level rise," *Nature Climate Change* 6:253](https://www.usgs.gov/publications/overestimation-marsh-vulnerability-sea-level-rise) — Marsh vulnerability "tends to be overstated"

[Saintilan et al. (2022), "Constraints on the adjustment of tidal marshes to accelerating sea level rise," *Science* 377:523](https://doi.org/10.1126/science.abo7872) — Marsh elevation gain is "constrained in relation to sea level rise"

[Saintilan et al. (2020), "Thresholds of mangrove survival under rapid sea level rise," *Science* 368:1118](https://doi.org/10.1126/science.aba2656) — Mangroves very likely "unable to initiate sustained accretion" above 6.1 mm a year of relative sea-level rise; threshold likely passed on tropical coastlines within 30 years under high emissions

[McIvor et al. (2012), *Storm Surge Reduction by Mangroves*, The Nature Conservancy and Wetlands International](https://www.conservationgateway.org/collections/ocean/storm-surge-reduction-mangroves/) — Measured surge reductions of 5 to 50 cm per km of mangrove width; direct measurements are limited

[Rijkswaterstaat, Room for the River](https://www.rijkswaterstaat.nl/en/projects/iconic-structures/room-for-the-river) — Work from 2006 to early 2019, €2.3 billion, 34 locations, about 4 million people

[Climate-ADAPT, "Room for the River Waal: protecting the city of Nijmegen"](https://climate-adapt.eea.europa.eu/en/metadata/case-studies/room-for-the-river-waal-2013-protecting-the-city-of-nijmegen) — Dike moved 350 m inland; 3 km side channel; 35 cm lower water levels against a 27 cm target; about €351 million

[City of Tulsa, flooding history](https://cityoftulsa.org/government/departments/water-and-sewer/flood-control/flooding-history/) — The 1984 flood: 14 killed, nearly 7,000 buildings damaged or destroyed, $180 million in damages ($424 million in 2017 dollars)

[FEMA, "Teamwork Approach to Outreach and Engagement Reduces Flood Risk"](https://fema.gov/ht/node/631725) — "Voluntary buyouts and green space that doubles as stormwater detention"; Class 1 Community Rating System rating in 2022; 45% flood insurance discount

[IUCN (2020), *Global Standard for Nature-based Solutions*](https://portals.iucn.org/library/sites/library/files/documents/2020-020-En.pdf) — The 2016 IUCN definition quoted above

[USDA Natural Resources Conservation Service, irrigation and water management](https://www.nrcs.usda.gov/getting-assistance/other-topics/organic/nrcs-assistance-for-organic-farmers/irrigation-and-water-management) — "A one percent increase in soil organic matter can help the soil retain an additional 20,000 gallons of water per acre"; a different measure from organic carbon, and disputed

## the series

1. [resilience means to leap back](/guide/resilience-means-to-leap-back?from=guide) — **Read first:** The word's root, its travels, and the question that changed in 1973
2. [bounce back to what?](/guide/bounce-back-to-what?from=guide) — A beam returns to its shape; a lake or a reef pushed too far becomes something else
3. [what makes a living system resilient](/guide/what-makes-a-living-system-resilient?from=guide) — Many kinds doing one job, spare capacity, connection and the slow things nobody watches
4. [the resilience a place already has is alive](/guide/the-resilience-a-place-already-has-is-alive?from=guide) — The floodplain, the marsh, the canopy and the soil as infrastructure
5. [how to build resilience for a place](/guide/how-to-build-resilience-for-a-place?from=guide) — Six steps, starting with the living systems a place already stands on
6. [no place is resilient alone](/guide/no-place-is-resilient-alone?from=guide) — Why the unit that works is the region, and every place in it