There are a number of stories that occasionally receive comments and inquiries on posts from back in the day. This past few weeks, readers reached out related to the 2017 post “San Francisco’s Hidden Water Tanks” (Hidden Hydrology, 12.15.17), inquiring about a really cool hidden feature of the urban realm.
The post drew on a great article published at the time by CityLab/Bloomberg, “The Sublime Cisterns of San Francisco” (05.01.17), which explains the presence of brick circles located at numerous intersections around the downtown core of the city, such as the image below.
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Brick circles denote the location of old cisterns (via Bloomberg)
These reference the locations of underground cisterns, dating back to the 1850s, which were state-of-the-art in fire protection in the 19th and early 20th centuries. These cisterns were distributed around the downtown area and filled with water, which supplemented fire brigades and enabled them to pump water for fire-fighting prior to implementing pressurized water systems and fire hydrants. As noted in the Bloomberg article related to the need for new modern fire protection in cities:
“One of the ways officials responded to these blazes was to build cisterns. These subterranean vitrines were designed as a last-resort source of agua for firefighting. San Francisco’s 19th-century cistern system was reinforced with more, larger cisterns after the Earthquake of 1906, whose subsequent firestorm killed roughly 3,000 and left much of the city’s land looking like a blasted moon. To date there are 170 to 200 of the tanks stashed around town.”
Many of the remaining cisterns are intact below ground, revealing subterranean spaces unknown to those walking and driving above. Many are empty, but some are still used as emergency water sources today.
John Oram, aka the prolific Bay Area blogger Burrito Justice, dug deep into the cisterns as far back as 2011. Around 2016, when the original Bloomberg article was published, he created an interactive map (unfortunately no longer available) of their subterranean locations. The map represented the intersections where the cisterns were located, scaled by the capacity of the cistern below.
Another resource for these cisterns, which Oram used in his mapping project, was a 2014 project by Scott Kildall. As part of an art project called “Water Works,” Kildall focused on “…a 3D data visualization and mapping of the water infrastructure of San Francisco.” He also created an interactive map (now also unavailable) of the cisterns, and the project generated some interesting maps and art around the locations of key infrastructure, including cisterns, as seen below.
San Francisco Cisterns by Scott Kildall (via Scott Kildall)
For those interested in a deeper dive from these past sources, I recommend “What’s Underneath Those Brick Circles?” (Burrito Justice, 03.08.13), and “Cistern Mapping Project Reportback.” (Scott Kildall, 01.07.16). Although a seemingly hot topic in the mid-2010s, I only found a few scant more recent references to these cisterns. A good one worth listening to is part of a self-guided tour of these cisterns as part of the Exploratorium installation Buried History – Water Underground along with a link to a downloadable, printable map here.
I would appreciate any input from anyone in the Bay Area with up-to-date information or ongoing projects related to the cisterns.
Note: This post was originally posted on Substack on 01/31/25 and added to the Hidden Hydrology website on 04/22/25.
My first Substack publication, The Climate Landscape, explored various themes related to our changing climate and landscape architecture to examine nature-based solutions to climate change impacts. I recently decided to shelve that particular project and focus exclusively on writing about hidden hydrology; however, a few of those early essays were worth retaining here as they showed good overlap and connections between the two topics.
There is a direct connection between our cities’ buried and lost rivers and climate change. I touched on climate here previously in this post “Lost Rivers for Underground Energy. It took me some time to make a direct connection between my research on climate and lost waterways until more recently, and the revelation allowed me to weave together these two passions.
I’ve continued connecting the dots and trying to build a case for the importance of historical ecology and hidden hydrology in being the locus for solutions to contemporary issues, and not just focused on nostalgia. One aspect of this is looking first at causes and effects — looking back at the erasure of waterways from cities and demonstrating that the loss of ecological and hydrological systems exacerbates climate impacts such as urban heat, flooding, and sea level rise. I also looked forward to showing the patterns of historical hydrological systems that can act as frameworks for innovative climate solutions to provide adaptation and mitigation opportunities. The idea of “hydrological retro-futures” is the term I chose for this backward-forward process, which allows us to connect the historical ecology to the modern metropolis and tell these stories in an engaging, visual format.
One aspect of this project is visual. By using various graphical generative AI resources like DALL-E (see image below), I have been creating speculative images of hidden hydrology in the urban context, and exploring ways that revealing, restoring, and reconnecting with lost rivers can help us imagine the potential visual impacts that could be gained. I will share more in-depth on this project and some of the interesting graphics in a later post.
Hydrologic Retrofutures: Portland Series 1 (Generated in DALL-E via prompts Jason King)
The other aspect is research and case-study-based. Brainstorming a few key topics areas, I will continue to explore here, including:
MICROCLIMATE COOLINGThe daylighted streams will restore ecosystem services lost when buried, such as the presence of cooling surface water and vegetation that can aid in mitigating urban heat islands.
FLOOD STORAGE CAPACITYDaylighting streams and springs currently in pipes will increase the capacity of infrastructure systems and make them more effective for flood resilience.
SEA LEVEL RISEAreas of made-land in cities as a proxy for areas of flooding due to SLR and storm surge and ways to adapt these to absorb with more resilience
WATER HARVESTING TO SUPPORT URBAN BIODIVERSITYDiversion of water that would be piped into uses for support of landscape vegetation and urban greening
WATER USE FOR COOLING ENVIRONMENTSTapping into water from subsurface water pipes to help cool cities – use in pools, water features, misters, etc.
WATER FOR HEATING & COOLING BUILDINGSUsing water from buried sewer pipes for heating buildings
PALEO VALLEYSLooking at hidden ancient river valleys as sources for groundwater recharge and storage as new aquifers
By exploring these topics, I aim to gather feedback and generate a complete toolkit of solutions that can provide designers, planners, and policy-makers with options that work in multiple climates and scales and provide cascading benefits when implemented. I’d be interested to know of other topics and solution areas out there beyond this list, as well as any case studies, writings, or research on these topics.
Below are a handful of previous stories that cover some of these topics.
ANCIENT WATERWAYS FOR COOLING CITIES
A recent article in Fast Company outlines the idea of “How ancient waterways could be tapped to cool scorching cities”. The focus is on new scanning methods to reveal buried streams and ‘ancient waterways’ and how to see the hidden infrastructure and potentially repurpose the water for climate change adaptation strategies. The group leading this effort is Cool City, an offshoot of the Korean Pavilion as part of the 2021 Venice Biennale, with projects using mapping underway in both Naples and Seoul. The unique idea here is to use handheld 3D scanning technology to provide more detailed scans of systems and then to use the gathered data to inform decisions for climate.
3D scanning of “Casa dell’Acqua” Municipality of Volla (via Cool City)
There’s merit to this as a way of approaching climate change through the use of these buried systems, both as a resource for water for irrigation and a passive cooling system and as a way to increase pipe capacity by removing underground streams through daylighting which frees up vital volume for additional stormwater management.
Mapping these has been done for many years, either as a GIS exercise with overlays of historical maps on current conditions and subsequent field verification or looking at current sewer and water and combined systems. This provides a good working system network to understand this hidden potential but not forgotten water in the city. Still, Cool City is taking it to the next level, as mentioned in the article, quoting a project collaborator, Nick De Pace, a professor of architecture and landscape architecture at the Rhode Island School of Design:
“Buried streams and old waterways are not totally lost to time. Many cities have maps showing where a former creek has been shunted into an underground tunnel to make way for aboveground urban development, for example. But De Pace says many of these maps are imprecise, and the new digital scanning and mapping of the Cool City project can bring much more actionable detail to buried streams, aqueducts, and springs. By using this water to irrigate green roofs, parks, and other urban vegetation, cities can counterbalance their heat-trapping hardscapes.”
A low-resolution snapshot of the scan below shows how compelling this composite imagery may be, showing the spaces above and below. Does it aid in climate planning, maybe? They mention that it can be used for irrigation, for more green spaces to mitigate urban heat islands, and for having more water on the surface to reduce heat and provide more cooling. Additionally, the mix of green and blue infrastructure systems can tap into the buried water to help adapt to climate change impacts.
Composite scan of subsurface conditions (via Fast Company)
I wonder, however, how feasible it will be to scan much of the sub-surface infrastructure as proposed above by Cool City, as it’s a mixed bag of small and large pipes and some more expansive and cavernous sewers, depending on the location and the era in which they were implemented. It’s a question to me if it is helpful to have 3D versions of these systems, or is mapping or modeling adequate to see the potential system components and flows and determine how it can be ‘tapped’ to become a tool to fight climate change?
3D scanning is an excellent visualization tool, as it is often difficult to imagine what lies beneath, which is less compelling than a line on a map. As mentioned in the article, understanding the available water resources more clearly is half the battle. The next part is how to operationalize this water for climate strategies. I am interested in seeing more from Cool City, how the technology works, and what solutions come up for using hidden hydrology for climate solutions.
While tying flooding to historically buried waterways isn’t novel, this is a unique idea, using mapping to overlay the Home Owners’ Loan Corporation (HOLC) maps showing redlining categories, which are well-documented spatial histories of racial and socioeconomic discrimination. The researchers used these factors (buried streams and redlining grade) as two of the criteria for flood risk along with proximity to coastal zones and intensity of vegetative cover.
The article is a deep dive, so I will skim on the surface with a bit on the methodology and findings, which are engaging and would be replicable anywhere using similar criteria. The mapping processes, including mapping and DEMs, were interesting. The inference of buried water bodies and flood risk has been borne out in recent events. The authors explain the connections between mapping and current flood risk:
“Although the actual stream channel or wetland surface were buried and built upon, high resolution elevation models (e.g., LiDAR) can be used to reveal the remnants of distinct depressions from these structures, such as meandering stream valleys, in heavily urbanized landscapes. The authors assume that, although no longer occupied by active streams or wetlands, residential homes built on buried stream valleys will experience an elevated probability of flood risk not included in floodplain maps, but also that the process of burial and removal were influenced by income and race embedded in some of the racist housing policies of the 1930s and 1940s.”
Figure from article: “An example of a river in Southwest Detroit identified by the first United States Geological Survey (USGS) topographic map from 1905 (top left), the existing buried stream valley, as evidence from LiDAR data from 2020 (elevation units in feet above sea level), that is capped with residential development (top right), and the intense First Street Foundation Flood Factor risk of parcels near the ghost river (bottom).”
The flood risk data came from First Street Foundation’s Flood Factor, which would be good to explore in more detail. As described, the flood risk of parcels is rated 1 to 10 based on the chance of flooding in a time interval. There were also additional criteria, as mentioned, with coastal proximity, using available data, and vegetation density using Normalized Difference Vegetation Index (NDVI) data to describe the level of vegetation—more on both of these in the article, along with all the analyses.
A figure from the article showing flood risks by type of area “associated with inland, coastal zone, ghost streams, and ghost wetlands within redlined neighborhoods.”
The results reinforce other narratives of disproportionate risk tied to redlining districts that had more marginalized populations. The level of parcels at risk in zones C and D from the HOLC maps, although the amount of burial varied with the presence of most buried streams in HOLC Grade A & B and more buried wetlands in HOLC Grades C & D. As the authors mention:
“Flood risk is disproportionately distributed, caused in part by outlawed, racist housing policies. Understanding where risk is highest can help identify optimum locations for adaptation measures to minimize flood damage in these neighborhoods.”
This does bring up why mapping these streams is important, and the connections to climate change, although not overt, are implied as changes in precipitation and storm intensity make flood risks more frequent and more damaging. As the authors conclude (with a nice reference to hidden hydrology (citation please), the “…role of redlining in present day flood risk applies to cities throughout the United States, as does the importance of mapping ghost streams and wetlands to inform residents of the role “hidden hydrology” may play in increasing flood risk.”
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SAVING SWAMPS TO SAVE OURSELVES
It was a treat to read one of my favorite authors, Annie Proulx (Swamps can protect against climate change if we only let them, New Yorker – 06.27.22), discussing wetlands and their potential for climate change protection. She includes tales of killer herons, stolen rafts, and evocative ideas on our complex relationship with swamps, noting that “Many modern Americans do not like swamps, herons or no herons, and experience discomfort, irritation, bewilderment, and frustration when coaxed or forced into one…”
Swamps were not always reviled or out of favor, as Proulx recounts, in particular the views of Henry David Thoreau, on the subject:
“Thoreau has been called the patron saint of swamps, because in them he found the deepest kind of beauty and interest. He wrote of his fondness for swamps throughout his life, most feelingly in his essay “Walking”: “Yes, though you may think me perverse, if it were proposed to me to dwell in the neighborhood of the most beautiful garden that ever human art contrived, or else of a Dismal Swamp, I should certainly decide for the swamp.”
The connection to hidden hydrology lies in the massive loss of wetlands and the subsequent loss of function to reduce carbon and the numerous ecosystem services beyond that are provided by wetlands in filtering and mediating water in our landscapes. Development in the US meant filling wetlands for farmland, pasture, and eventually cities. The swamps often were a barrier to progress and Proulx notes:
“Across the country, the ongoing stories of vile adventures in the muck made it clear to military, government, and citizenry that something had to be done about the swamps so universally detested. Everywhere there were horrendous mixtures of fen, bog, swamp, river, pond, lake, and human frustration. This was a country of rich, absorbent wetlands that increasingly no one wanted.”
As this occurred, there were impacts, but climate change, and sea level rise in particular, exacerbates flooding, and filled-in wetlands at the margins are poor habitats for the buildings or fields we placed on them that are now in danger of being washed away with more intense storms. There were impacts to landscapes and plantings that reduced habitat. Beyond biodiversity loss, humans will feel the overall loss of resilience more acutely. Still, it is hard to save or restore these landscapes, as Proulx notes in her story of the Black Swamp.
“One authority on water, William Mitsch, has suggested that if ten per cent of the old Black Swamp soils were allowed to become wetlands again they would cleanse the runoff, yet Ohioans remain powerfully anti-wetland. Even private efforts to restore small wetland areas are met with neighbors’ complaints about noisy frogs and fears of flooding.”
Related are mangroves, which are also summarily destroyed, taking with them the ability to reduce storm surges and protect coastal areas in places like the Everglades. As described: “Mangrove swamps have been called the earth’s most important ecosystem, because they form a bristling wall that stabilizes the land’s edge and protects shorelines from hurricanes and erosion, and because they are breeding grounds and protective nurseries for thousands of species, including barracuda, tarpon, snook, crabs, shrimp, and shellfish. They take the full brunt of most storms and hurricanes, and generally survive—but not always.”
Larger, more intense hurricanes can damage mangrove areas with salt or sediment intrusion, reducing their ability to regenerate and removing their support for biodiversity. While natural disasters are a risk, development still threatens these areas despite mounting evidence of their benefits.
“Although climate researchers see mangrove swamps as crucially important frontline defenses against rising seawater and as superior absorbers of CO2—they are five times more efficient than tropical forests—they are in big trouble, and mangrove removal is a constant threat.”
The conclusion for Proulx is to re-establish our love of the swamp, and connect the existential threat of climate change to our ways of life to the natural systems we destroy in the process. Protecting what is there in terms of wetlands and mangroves left standing is the first goal, as well as restoring and expanding these valuable ecosystems, all of which are possible, even necessary as adaptation and mitigation strategies. Proulx ends with a call to action we can all heed:
“It is usual to think of the vast wetland losses as a tragedy, with hopeless conviction that the past cannot be retrieved. Tragic, indeed, and part of our climate-change anguish. But as we learn how valuable wetlands are in softening the shocks of the changing climate, and how eagerly the natural world responds to concerned care, perhaps we can shift the weight of wetland destruction from inevitable to “not on my watch.” Can we become Thoreauvian enough to see wetlands as desirable landscapes that protect the earth while refreshing our joy in existence? For conservationists the world over, finding this joy is central to having a life well lived.”
Note: This post was originally posted on Substack on 12/17/24 and added to the Hidden Hydrology website on 04/22/25.
The recent essay, “Daylighting a Brook in the Bronx” (Pioneer Works, 10.23.24), by Emily Raboteau, focuses on a high-profile stream daylighting project from a resident’s perspective. The project to daylight Tibbetts Brook has been ongoing for many years. For some quick background, Tibbetts Brook originates north of New York City in Yonkers, where it flows from Tibbetts Brook Park, heading south into the Bronx and reemerging above ground in Van Cortlandt Park. It then flows underground the remainder of the way south through the city, as demonstrated on the graphic below, showing the original course of the now-buried waterway and its eventual connection into the last leg of the Harlem River before draining into the Hudson.
Illustration of Tibbetts Brook’s original course in the Bronx – via Pioneer Works
Raboteau, a resident of the Bronx, outlines the project from a personal and experiential perspective, joining some of the local advocates from the Tibbetts Advisory Group and the Parks Department and others working on the daylighting project and highlighting some of the site-based artworks focused around the brook. The positives of the project are notable, as she mentions early on in the essay:
“Daylighting will abate combined sewage overflow, extend greenspace, absorb heat, and relieve chronic flooding in our area’s janky, archaic drainage system, in an act of climate mitigation and as a community effort to solve a mess caused by old crimes.”
I’m not planning on spending too much time recounting her specific words, which I strongly encourage you to take the time to read. I wanted to extract my reflections on a couple of critical themes she highlighted in her essay.
Perfection and Imperfection in Daylighting Projects
The challenges of these projects are myriad, and while striving for a solution that solves all the problems, trade-offs must often be made. She mentions a couple of issues, including the high cost, resistance from the MTA, and the need to underground the creek under rail lines in some industrialized portions. Additionally, gentrification could arise by ‘cleaning up’ marginal spaces during the daylighting project. On one hand, revitalization could improve the area and attract new residents and economic activity. Conversely, the improvements could incentivize new developments and rising costs, displacing long-time residents. Another issue she brings up is the potential lack of good access from some of the adjacent neighborhoods, creating questions of ultimately who will benefit and the overall environmental justice issues at heart in any project like this. As she notes:
“I had so many ethical questions without easy answers. It felt uncouth to ask them of a dream thirty years in the making…. Could it ever be pleasant here? Difficult to picture. Even with the brook resurrected, there would still be the sound of the road.
I wondered: how else might the park change the neighborhood? Will it invite gentrification? Will it grow too expensive to live here? Despite the ecological and economic benefits, will anyone suffer? Can daylighting outpace inundation, or will it be rendered moot by water tables that rise with the sea? If flooding catastrophes continue, what then? Would government funds be better spent moving the most disadvantaged among us out of the watershed to higher ground? Has anyone asked for the brook’s consent? Whose help is sanctioned when it comes to healing the land, and whose is rebuked?
The intersecting concerns and challenges are common in similar projects, no less complicated by threading daylighting through a dense urban center. Patience, openness, and creativity are vital, but the lack of these often results in projects never seeing the light of day. Compromises cannot come at the cost of marginalized communities. Yet, the short-sightedness of attempting to achieve “perfect” restoration in the form of all-or-nothing solutions is equally as damaging to attain nothing. The ability to see multiple solutions that can celebrate, reveal, and restore function requires looking beyond the ecological and including pointing a lens at the cultural context of these projects, balancing imperfection with appropriateness.
Cultural Restoration
The potential of restoration lies beyond the technical aspects and helps us fill the gaps left in implementing imperfect solutions. Raboteau mentions some of the work of artists around the brook, much of it done under the banner of the “Rescuing Tibbets Brook” project as part of the Mary Miss-led project, City as Living Laboratory. Works mentioned include Visions of Tibbetts Brook, Tibbetts Estuary Tapestry, and Estuary Tattoos, all focusing on artistic and community works around the creek restoration.
Other cultural works are mentioned in the essay. Dennis RedMoon Darkeem‘s upcoming work and the planned daylighting project use harvested mugwort, an invasive species growing near the creek in Van Cortlandt Park, and weaving it into large textiles to act as sound barriers along the course of the stream corridor. She goes into more detail about two other artists. Noel Hefele and his Daylighting Tibbetts en Plein Air paintings (see below), and The Buried Brook, an augmented reality installation by Kamala Sankaram that uses a phone app to trace “the sonic geography of the buried Tibbetts Brook.”
Numerous documents and reports on the proposed $133 million project to daylight the brook can be discovered online, touching on many technical challenges. The real story is about grounding the technical with the human dimensions while highlighting the more prominent themes of hidden hydrology. Overall, the result of these cultural explorations to complement the hydrological and ecological, to Raboteau, can be revelatory:
“I appreciate how initiatives like these offer an expansive response to catastrophe, a way to gather, and even a sense of hope. It’s not just the architecture of the daylighting project that interests me, the restitching at the scale of infrastructure, or the civic muscle behind the job, but the metaphysics of the exhumation. Daylighting feels like a cause for ceremony, a chance to pay respect to the body of the ghost river that flows unseen under our feet. Better yet, to imagine the perspective of the brook.”
Both ideas above are inherent in the conceptual potential of what can be accomplished when we think beyond just daylighting as a functional pursuit. First, we must move beyond unrealistic ideas of “perfect” and strive to achieve real projects that inevitably fall short of all that can be accomplished but succeed in not collapsing under the weight of being overly idealistic. Second, to achieve the first, we must continue to explore and expand our ways of engaging with lost rivers and buried creeks beyond. These include the incorporation of a continuum of solutions from the artistic to the ecological.
The recollection of the creek can be expressed metaphorically through art and soundscapes, which provide additional layers of meaning and context to the project’s more functional hydrological and ecological goals. This shows how daylighting projects, while aiming for restoration of function, are not really about attempts at pure ecological restoration but a mix of green infrastructure and ecological design aimed at multiple goals like access to nature for humans and other species, reconnecting communities, and achieving climate-positive design, among many other potentialities.
The potential of these solutions highlighted by Raboteau:
“Daylighting feels like a cause for ceremony, a chance to pay respect to the body of the ghost river that flows unseen under our feet.”
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CONTEXTUAL CODA
Tibbetts Brook has been a topic of interest in my thinking on Hidden Hydrology for some time. I first discussed the Brook in an article on Steve Duncan, a ‘drainer’ type of urban explorer focusing on underground and buried creeks and rivers. He has explored and photographed urban creeks around the globe, but focused on many New York City creeks, including Tibbetts Brook, as I wrote about in a post, “NYC: Watercourses to Undercity” (Hidden Hydrology, 12.28.17).
Tibbetts Brook was the subject of the article “Why New York Is Unearthing a Brook It Buried a Century Ago” (NY Times, 12.6.21), which discusses the project goals and objectives in detail. “The city plans to unearth the brook — an engineering feat known as “daylighting” — at a cost of more than $130 million, because burying it in the sewer system has worsened the city’s flooding problems as a warming planet experiences more frequent and intense storms.”
The re-interest in the Tibbets project and connections to climate-related flooding came about as a reckoning of post-hurricane Ida solutions, which included more ‘spongy’ green infrastructure, hardening critical infrastructure, and methods to “unclog drains and widen pipes.” I’ve written about Eric Sanderson’s work of historical ecology and mapping hidden waterways in his Mannahatta and the broader Welikia Projects. He writes a powerful post-Ida opinion piece, “Let Water Go Where It Wants to Go” (NY Times, 9.28.21), where he connects the impacts of Hurricanes Sandy and Ida to areas where waterways were buried, shorelines filled, and wetlands paved over.
“Water demands a place to go. That means making room for streams and wetlands, beaches and salt marshes. It means solving human-caused problems with nature-based solutions. These include removing urban impediments to let streams flow once again, a process known as daylighting; restoring wetlands and planting trees. It also means using the collective power of our community — expressed through tax dollars — to help people move to safer places.”
Overlay of flooding locations (28th Street subway station) in New York City and the location of former wetlands (The National Archives via NY Times)
In my reflection on this article by Sanderson, these connections between hidden hydrology and climate are of keen interest, so this led me to investigate in more detail one of the significant benefits espoused by those advocating daylighting Tibbetts Brook — which was alluded to by Raboteau — the ability to make cities more resilient to climate change by removing base flow water from buried pipes, or captured streams, through daylighting, and freeing up that water to handle extreme rainfall events and reduce flooding. As noted in the NY Times article:
“Though out of sight, the brook pumps about 2.2 billion gallons of freshwater a year into the same underground pipes that carry household sewage and rainwater runoff to wastewater treatment plants. It takes up precious capacity in the outdated sewer system and contributes to combined sewer overflows that are discharged into nearby waterways.”
To learn more about this concept, I wrote on “Captured Streams” (Hidden Hydrology, 12.11.21), taking a deeper dive into the broader idea and its applications globally, drawing on a paper by Adam Broadhead and others, which makes the case that the encasement of freshwater streams in urban sewers is a widespread issue, significantly increases wastewater treatment costs by needlessly treating clean water and the various economic, social, and environmental benefits of diversion. The team included case studies from Zurich, highlighting efforts by the Swiss city to pioneer the idea of urban daylighting to remove base flow.
A diagram of the process, similar to the process envisioned at Tibbetts Brook, from the paper is below.
Diagram of buried stream separation from sewers in Zurich (via Broadhead et al.)
The Tibbetts Brook project aims to be a model case study in this form of separation. While the result will fulfill the goals to reduce flooding, create more resilience, and provide additional positive environmental benefits, the more significant questions Raboteau asks in her essay are vital to allow us to envision the bigger picture and redefine what counts as success: Who is included at the table in planning and design and how are those voices given appropriate weight? Who ultimately benefits? Who has access when the project is complete?
Give the essay a read, and let me know your comments.
Note: This post was originally posted on Substack on 11/30/24 and added to the Hidden Hydrology website on 04/22/25.
I was combing through the writings on my original Hidden Hydrology blog, with the idea of bringing in some of the ‘best of’ content still relevant today. This 2018 post, “Underground Energy For London” was worth reconsidering, focusing on a report that identified a significant potential latent in hidden hydrological systems, to provide heat and cut carbon emissions through tapping into underground lost rivers. The specifics came from a group called 10:10 Climate Action, who focused on using London’s now-buried rivers as a source of power, asking the question:
“But what if we could use them to power our city once again? Through the magic of heat pumps, London’s lost rivers could provide low cost, low carbon heating and cooling to the buildings above. They could help us solve the big challenge of decarbonising heat. There’s huge potential for London’s lost rivers to provide clean, efficient and reliable heating for the city – tackling climate change and air pollution. And of course the same technology can be used in other underground waterways like sewers in towns and cities across the country.”.
Unfortunately, the report, nor the group 10:10 Climate Action as far as I can tell, is no longer available online from the original source. I tracked down an online version, so you can download a copy here.
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The use of heat pumps is fairly common practice. Extracting heat from these now piped subterranean waterways, and using this heat for buildings and other uses is more novel, offering an potential alternative power option for London and other cities.
The concept had also already been implemented in some areas, including Borders College in Scotland, tapping into local wastewater, and the State Ministry Building in Stuttgart, Germany, which tapped into flow from the Nesenbach, a buried river adjacent to the site. A map extracted from the report (image below) shows a number of the potential sites in London, including The Effra, Stamford Brook, The Tyburn, and the Fleet, all of which have potential sites for the use of these technologies. Specific places include Buckingham Palace (mentioned in a few of the articles above), which would tap the Tyburn, Hammersmith Town Hall which flows above Stamford Brook, and other buildings like schools and site elements like heated swimming pools, which is currently being done in Paris.
The following video explains the idea in a specific location, showing an example of a London pub that sits atop an ancient subterranean water source, using this heat pump technology for its heating and cooling for beer and wine.
There are questions on the cost-benefit, and each of these systems would require some infrastructure to be viable, however, it’s pretty exciting to consider the potential of these systems to contribute to energy savings and reduction of carbon emissions. The potential for savings of energy is significant. The Times article noted: “A report from the Greater London Authority concluded that water-source heat pumps could meet 4.8 per cent of London’s heat demand, with sewer heat offering another 6.7 per cent.”
The idea of giving back some of their benefits to the city, even while still being buried underground, is also worth exploration. While the original report is over six years old, I think the idea is still one that seems worthy of revisiting around the globe, identifying projects that could utilize similar techniques, as we search for expanded tools to battle climate change and rising energy costs. I’d be interested to know if any readers know of other cities today using this for district or building scale systems, or projects that have explored this idea of tapping buried rivers in water and sewers for heating and cooling. Let me know if you have any that come to mind.
Note: This post was originally posted on Substack on 11/16/24 and added to the Hidden Hydrology website on 04/22/25.
I spotted this great project this week on LinkedIn and thought it worth sharing. The transformation of urban highways to waterways is an interesting subset of hidden hydrology worth exploring, with some great global examples we will discuss more in the future. This project traces the history of the Catharijnesingel, a canal removed to create an urban highway in Utrecht in the Netherlands, and more recently transformed from hardscape back to its original form as a canal. This provides a great case study on the benefits of public spaces around water, and the ability to restore lost public and ecological benefits through the restoration of waterways.
An overview can be found on the European Prize for Urban Public Space competition site, (Public Space) which recognizes “…all kinds of works to create, recover and improve public spaces in European cities.” The Catharijnesingel project was the winner of the competition in 2022.
For some background, the original Catharijnesingel was a canal that flowed around the defensive walls of the historic city. A park was originally built in the canal zone in the 19th century but was drained and paved over in the late 1960s to 1970s to create space for a major arterial roadway.
Work on the Catharijnesingel before burial (Public Space)
The before picture shows the Catharijnebaan, the roadway built atop the original canal. In 2002, citizens began to discuss the removal of the roadway and restoration of the canal to its original form.
Photo of the Catharijnebaan, the urban highway removed for restoration of the original canal (Public Space)
The transformation shows the restoration of the canal and revegetation of the banks. The description provides the context of reconnecting with public spaces in urban environments, and the ability to create new, safe, places to access nature and socialize. As noted in the project assessment, on the Public Space website:
“The Catharijnesingel adapts to this new situation by providing pedestrian paths and boat routes and enough space for outdoor recreation. The emphasis on the different microbiotopes of the green areas also makes a positive educational contribution to outdoor activities, where the changing face of nature can be contemplated while walking (or sailing) on the Catharijnesingel.”
The transformation provides access to the waterway for boating, paddleboarding, shady spots, and water access points along the banks, providing much-needed recreation spaces. The project was built in two phases, over 2015 and 2020 with a total restoration area spanning 1.1 kilometers of length.
There’s also a great video on the Public Space website with some additional historical background and imagery. The project designer, Utrecht-based OKRA Landschapsarchitecten refers to the higher goal of the project as a “…climate-adaptive backbone for the centre of Utrecht,“ and elaborates on the project goals and results:
“In the 20th century Catharijnesingel became Catharijnebaan: an unattractive urban highway dominated by asphalt and concrete. When offered the chance to revert that development, we took the opportunity to push the idea further to its full potential. As the water returned to the historic Canal area, it brought along a new natural park route right into one of the busiest areas in the Netherlands. The result was an urban landscape that was fully connected to the past, the present and the future.”
These transformations provide a great example of the power to right some of the previous wrongs in urban areas, creating adaptable, climate-friendly spaces. While the canal was never a natural waterway, the project shows that restoring artificial waterways can provide myriad benefits similar to creeks and urban rivers, providing important hydrologic, climate, and public space goals.
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Note: This post was originally posted on Substack on 05/29/24 and added to the Hidden Hydrology website on 04/23/25.
Throughout history, there are numerous theories about building the Great Pyramids of Giza along the Nile River in Egypt. One of the key questions has been the logistics of moving the massive stones, each weighing over two tons. 2.3 million of these blocks of limestone and granite were used to construct the structures, without the aid of modern machinery. Theories for how this was accomplished vary and include methods of transport over land via sleds and rollers, and construction on-site using ramps, and pulleys. Some even attribute these other-worldly feats more broadly to the work of aliens.
Water and the Nile have always been tied to these theories, with the idea that the blocks were floated on the river from distant quarries for use on-site for the Pyramid construction. The structures sit at a slightly higher elevation from the floodplain, some distance from the main channels of the Nile, thus there have been questions on how the stones were transported this last mile from the river to the site itself. The research questions used the tools of hidden hydrology to develop theories on lost channels instrumental to the construction. Two such theories are discussed below.
Conceptual diagram of Khufu Branch, with location of sediment cores (PNAS)
The researcher’s process involved looking at soil cores: “Seeking evidence of an ancient water route, the researchers drilled down into the desert near the Giza harbor site and along the Khufu Branch’s hypothesized route., where they collected five sediment cores.” Analysis of the samples included paleobotany to look at plant fragments and pollen, and matching these species with the presence or absence of water-adapted or dry plantings to determine if the areas were part of a historical water body. The results showed periods of inundation that matched the construction of the pyramids.
This wet period allowed standing water to persist, and the proximity of the Khufu branch provided the ability to extend the reach of the Nile, allowing the construction of smaller canals close to the area of the Giza plateau. The branch is theorized to have dried up around 600 B.C. and the channel moved further away from the site of the Great Pyramids.
Rendering of the Khufu Branch of the Nile (Alex Boersma/Proceedings of the National Academy of Sciences/NY Times)
Ahramat Branch
Several current articles (Cosmos,BBC) have reignited this dialog around these theories of the use of waterways for transporting building stones. They all refer to research from a May 2024 paper entitled, “The Egyptian pyramid chain was built along the now abandoned Ahramat Nile Branch.” (Nature Communications Earth & Environment, 05.16.24). The research team offers new theories about investigating the hidden hydrology to unlock these ancient mysteries. As noted in the article the team makes a similar assertion to the previous work on the Khufu Branch, however, they consider the hydrology differently as a parallel side channel they refer to as the Ahramat Branch. From their abstract:
“Many of the pyramids, dating to the Old and Middle Kingdoms, have causeways that lead to the branch and terminate with Valley Temples which may have acted as river harbors along it in the past. We suggest that The Ahramat Branch played a role in the monuments’ construction and that it was simultaneously active and used as a transportation waterway for workmen and building materials to the pyramids’ sites.”
The map below shows the route of the Ahrama Branch, which was situated on the western edge of the floodplain closer to the location of the Pyramids. In this case, the proximity extended the length of the Pyramid complex, including those to the south near Memphis. The study offers the opportunity for new information, protection of cultural sites, and outline areas to protect from urban development.
The ancient Ahramat Branch. (Eman Ghoneim et al./The Conversation)
The research team discusses the project directly in an article: “We mapped a lost branch of the Nile River – which may be the key to a longstanding mystery of the pyramids.” (The Conversation, 05.16.24). They discuss the methodology of using satellite images, digital elevation models, historical maps, and other sources to identify the traces of the waterway. As they note, there are ‘causeways’ that look to connect at the points of the major construction areas, which were used as “docks” for loading and unloading materials and for workers moving up and down the river.
The idea of understanding the historical hydrological elements of the river provides a unique approach, noted by the team:
“This research shows that a multidisciplinary approach to river science is needed to gain a better understanding of dynamic river landscapes. If we want to understand and protect the rivers we have today – and the environmentally and culturally significant sites to which they are inextricably tied – we need a greater appreciation of the interconnected factors that affect rivers and how they can be managed.”
3D view of the former Ahramat Branch in the Nile floodplain adjacent to the Great Pyramids of Giza. (Nature)
Similar to the Khufu branch, there are theories about what eventually happened to the Ahramat Branch. These include the gradual migration of the channel, tectonic shifts that changed the floodplain drainage, or accumulation of sand filling up the channel, concurrent with other desertification processes at work. The climatic shifts could also have led to more arid conditions and dissipation of the side channel due to lower flows.
Check out the articles and papers for much more detail. I appreciate these larger-scale investigations of hidden hydrology, especially when they intersect with the complexity of ancient constructions, providing hints of how water was instrumental in these monumental endeavors. It shifts the attention away from the typical urban focus of hidden hydrology, which concentrates on the burial and piping of streams in cities, positioning the investigations of hydrology through bigger contexts and longer timescales. And, it’s a pretty cool way to solve a mystery.
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Note: This post was originally posted on Substack on 05/21/24 and added to the Hidden Hydrology website on 04/23/25.
Milan once boasted a robust system of canals, similar to the well-known waterscapes of Venice. Lacking a large river in the urban area, the canals in Milan were developed in the 12th to the 17th centuries to provide water access and connections that were not part of the original city. The area in the southwest quarter of the city is known as the Navigli district, and today “…remains one of the last true connections the Milanese have with water. The Grand Canal (Naviglio Grande) itself dates back to 1177, making it one of the oldest navigable canals in Europe. Today, it’s packed with bars, cafes, restaurants, art galleries and boutiques; in non-lockdown times, it’s a lively meeting spot or a place for a gentle passeggiata stroll by the water.”
Much of the canal system was buried as part of the modernization of the city, but the system still exists, a few areas see daylight, but most are now underground in pipes. A recent paper by Carlien Donkor, Agenee Bavuso Marone, and Allegra Aprea, “Unveiling Milan’s Navigli and Underground Water Heritage through Integrated Urban (Water) Design.” (Blue Papers, 2024, Vol. 3, No. 1) discusses the Navigli through the lenses of climate adaptation, and water resource management, with a goal to “reclaim Milan’s identity as a “city of water” through a deliberate design methodology informed by the city’s history.”
“Snowfall in the Navigli, Milan” January 1852 (Image source: Angelo Inganni / Blue Papers)
The authors provide additional context for the historical canal and lock system, urban water power dynamics, and how these features had served functional purposes in the original historic city, like draining the marshy landscape mitigating flooding. They also discuss how these can restore the ‘water heritage’, and ways these systems can aid in addressing the contemporary urban issues facing Milan. The system map of Milan provides a hint at some of the main components. Some background, from the authors:
“The Navigli were dug as early as 1179 for defensive purposes, as private irrigation channels, and later as lines of trade and business, and became a part of everyday Milanese life (Aprea et al. 2018). In the past, these artificial rivers were the only source of running water for domestic use; for instance there were many old washing houses along the Navigli like the one in Vicolo dei Lavandai (Ministry of Tourism n.d.). They were even used to transport materials to the Duomo (Milan’s main cathedral) during construction (Tyson 2021; Global Site Plans n.d.). The Navigli system reached its peak during the Renaissance, when Leonardo da Vinci worked on the improvement and expansion of the canals (Tramonti 2014).”
Historical image of canals in Milan (Civico Archivio Fotografico/BBC)
The canals were filled early in the 20th century, many turned into roadways as cars and trains replaced boats for transportation. Like many other cities, the authors note: “…the canals were perceived as sources of disease and odor, and as health and hygiene needs of the growing city became alarming the initiative to conceal them were desirable.”
Incoronata Lock is a remnant of the canal system still visible (Joey Tyson/BBC)
The current system that is the result of this transformation has disconnected residents from the water, changing the nature of the city and diminishing the historical role the Navigli. There have been proposals for reopening the canals and daylighting some of the buried waterways, which are ongoing, however, the authors expand the notion to include a broader spectrum of opportunities to tap the historical legacy of the “city of water” as part of a modern water system. As noted: “By looking into the past and present water infrastructure, surface and underground, technological solutions for collecting, absorbing, filtering and purifying rainwater, formed part of this landscape project.”
This system diagram in the article takes some unpacking, but shows a master plan diagram “showing the hydraulic continuity of the project to the Fossa Interna as well as the three Navigli.” This included incorporating green infrastructure solutions (or in the parlance of some European areas “sustainable drainage systems” or SUDS), which have multiple benefits like restoration of biodiversity, reduced urban temperatures, and amenities.
Waterland master plan (Carlien Donkor, Agnese Bavuso Marone and Allegra Aprea, 2018/Blue Papers).
The ability to use “historical analysis” as a way to create frameworks for modern water systems is highly aligned with the goals of this hidden hydrology project and the authors expand the notion beyond the technical to include the importance of culture in the water solutions.
“For older Milanese, water in Milan evokes a deep nostalgia for the disappeared aquatic city symbolized by the countless depictions in art of the Navigli. The Navigli brought water to the people and people to the water. In the same way, Waterland would do the same. While the call to reopen the canals is good, it should be noted that their water management function is for a different scale of city; this should be translated in a contemporary intervention.”
There is more in the article and references, so would appreciate hearing other’s reactions to the paper’s findings, and perhaps if applicable to other regions. Also mentioned earlier, some of the work is underway to daylight canals in Milan. Notably, a project called Riaprire I Navigli (Reopen the Canals) has a wealth of information on specific worth being done. It is worth a follow-up post for more info (and a good chance to work on my Italian), so stay tuned.
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Note: This post was originally posted on Substack on 05/13/24 and added to the Hidden Hydrology website on 04/23/25.
The idea of Detroit’s Ghost streams work bridges my two interests by connecting the dots of Hidden Hydrology and Climate Change, a topic that I will revisit often. The post discusses research in Detroit, Michigan, that connects buried streams and flood risks, using historical ecological information overlaid with redlining map data to show the potential negative impacts on historically marginalized communities.
The basis of the research is what are known as ‘redlining’ maps. For a little background, the Home Owners’ Loan Corporation (HOLC) was a government agency created to assess financial risk for mortgage lending for real estate. The tool was used to systematically institutionalize racist policies in cities around the United States by assessing areas inhabited by people of color, poor, and immigrants as much higher risk than those where rich, white residents lived. The process led to disproportionate investment in low-risk neighborhoods and marginalization in those deemed ‘hazardous’ or ‘high-risk’ zones, which ultimately created concentrated areas of poverty through a lack of economic opportunities. The redlining has become a shorthand for the inequity of communities, and mapping allows for looking at how these historical impacts persist in cities today.
The research overlays these maps with other data to extract how the legacy of racist home lending in the past has created more risk of impacts like flooding today. The goal of the study was “… to determine whether a history of waterway burial and/or redlining influenced the overall flood risk of communities today.” The data revealed that the burial of streams and wetlands did impact current risks in the historically marginalized communities. As Napieralski mentions in the podcast:
“Flood risk is very intricately linked to history, and by ignoring history we may be missing some clues that help us move forward.”
Rather than dwell on the negative, the authors mention the positive side of the analysis, noting that most communities have this data and that it can be useful in focusing on where best to employ solutions like green infrastructure or nature-based design solutions, saying: “If communities want to protect residents from flooding, it’s crucial for them to map and understand their “hidden hydrology.”
Buried But Not Dead
More in-depth exploration of the research is found in the journal article “Buried but not dead: The impact of stream and wetland loss on flood risk in redlined neighborhoods.” (City and Environment Interactions, January 2024). The study was authored by Napieralski along with Atreyi Guin, and Catherine Sulich, and their research outlines the mapping to overlay the Home Owners’ Loan Corporation (HOLC) maps showing redlining categories, using buried streams and redlining grades to estimate flood risk. The mapping processes were interesting, including the use of historical documents and Digital Elevation Models (DEMs) to infer buried water bodies and flood risk:
“Although the actual stream channel or wetland surface were buried and built upon, high resolution elevation models (e.g., LiDAR) can be used to reveal the remnants of distinct depressions from these structures, such as meandering stream valleys, in heavily urbanized landscapes. The authors assume that, although no longer occupied by active streams or wetlands, residential homes built on buried stream valleys will experience an elevated probability of flood risk not included in floodplain maps, but also that the process of burial and removal were influenced by income and race embedded in some of the racist housing policies of the 1930s and 1940s.”
Using data from First Street Foundation’s Flood Factor, the flood risk of parcels is rated 1 to 10 based on the chance of flooding in a time interval There were also additional criteria that were integrated into risks associated with different types of impact, sorted by HOLC grade. As the authors mention: “Flood risk is disproportionately distributed, caused in part by outlawed, racist housing policies. Understanding where risk is highest can help identify optimum locations for adaptation measures to minimize flood damage in these neighborhoods.”
Figure from the article, showing flood risks by type of area “associated with inland, coastal zone, ghost streams, and ghost wetlands within redlined neighborhoods.”
This does bring up why mapping these streams and wetlands is important. They provide a basis for analysis by using other data as cross-sectional overlays, unlocking connections between impacts that may, on the surface, be unseen. The connections of this work to climate change, of which flooding is a key impact, are clear, as changes in precipitation and storm intensity make flood risks more frequent and more damaging. The authors conclude the
“[The]…role of redlining in present-day flood risk applies to cities throughout the United States, as does the importance of mapping ghost streams and wetlands to inform residents of the role “hidden hydrology” may play in increasing flood risk.”
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Note: This post was originally posted on Substack on 05/08/24 and added to the Hidden Hydrology website on 04/23/25.
The Pacific Northwest has long been one of the innovation hubs for green infrastructure solutions. Portland, Seattle, and Vancouver have been leaders for over two decades in developing innovative options to manage stormwater in urban environments, creating decentralized solutions such as green streets, rain gardens, green roofs, and permeable pavings that have now become standard solutions and spread widely to regions.
In places with high rainfall, the initial drivers for these solutions were managing stormwater and reducing combined sewer overflows (CSOs) where rain and sewage mix in pipes, which, in extreme events, overflows into waterways creating pollution issues. The importance of green infrastructure has grown to include multifaceted outcomes, helping mitigate climate impacts by reducing flooding and providing shade to reduce urban heat, and providing ‘green’ solutions over ‘grey’, increasing habitat and helping minimize biodiversity loss.
Thinking strategically about where these solutions are built is key to success. Looking beyond site-specific and one-off strategies, the goal is to provide larger overarching frameworks for how these strategies are planned to work together to achieve holistic results, and ways to plan for these interventions. “How Rainways Could Restore ‘Raincouver’” (The Tyee, August 24, 2023) highlights some of the recent work in Vancouver. What they refer to as ‘Rainways’ are the green infrastructure interventions that have been proposed by City and community groups going back to 2012 built around water in the city and ways to discover and celebrate it.
St. George Rainway illustration (City of Vancouver, The Tyee)
The St. George Rainway is another precursor to some of the work. It was studied and determined that true creek daylighting would be a challenge, due to infrastructure and costs, however, there were other ways to functionally and metaphorically restore the essence of buried creeks through green infrastructure and art. Neighbors have implemented several interventions, including street murals that follow the meandering route of the old creek.
To further visualize the potential benefits, the team here are some good before and after visuals on the site, transforming asphalt into rain gardens with pathways and plantings.
For a deep dive, the Rain City Strategy is a comprehensive document published in 2019 to celebrate water and address environmental and social challenges. The basis is green infrastructure in the city, using streets and public spaces, buildings and sites, and parks and beaches. The overall goals are water quality, resilience, and livability. This includes the management of stormwater to protect and increase water quality, facilitate infiltration, and become more adaptable to climate impacts by mitigating flooding. Beyond function, creating spaces that provide equitable access to nature and benefits to the community are inherent in solutions, assuring they aren’t just solving one problem but many.
The report includes references to the original buried and disappeared streams that existed before urbanization. These maps build on the work going back almost 50 years to research done by Sharon Proctor in her book ‘Vancouver’s Old Streams’, published in 1978 with a sweet hand-drawn version of the map below (read more about this in my 2016 post “Vancouver’s Secret Waterways”).
The execution of more formal St George Rainway design concepts is available from 2022, showing how the concepts are applied to the segments of St. George Street, with plans and sketches illuminating the proposed condition.
The holistic proposal of looking at the macro-level buried rivers as the genesis for these community interventions. The benefits of the designs are manifold, as noted in the project summary:
Reduce street flooding
Treat rainwater pollutants from roadways
Reduce combined sewer overflows into local waterways
Enhance climate resiliency
Increase biodiversity
Cool the neighbourhood during summer heat
CODA
It’s great to see this connection between hidden hydrology and innovative stormwater solutions take shape in such an intentional way. In the past, cities have looked at these buried stream routes in locating facilities and creating smaller sub-watersheds. For some background, in a presentation back in 2006 at the National ASLA conference, I did a presentation entitled “Neighborsheds for Green Infrastructure”, where I made a case for using the routing of buried streams as a framework to implement green infrastructure solutions in Portland, Oregon. I’ll dig up some of these ideas and repost them, as they may be worth revisiting, in the meantime, I mention it in part of my introductory “Ecological Inspirations” post at HH (see image below). Stay tuned for more on this.
Neighborshed Diagram from 2006 in Portland (Jason King)
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Note: This post was originally posted on Substack on 05/03/24 and added to the Hidden Hydrology website on 04/23/25.
Strong connections exist between hidden hydrology and the larger work of historical ecology, in terms of methodology and the work to piece together complete stories from fragments of disparate sources. Often the traces of historical waterways inform the larger ecological patterns of places to establish baseline conditions, and historic vegetation patterns, and begin to establish markers to document change. The overlay of indigenous occupation is an additional element, however, it is often hard to reconstruct due to a lack of physical documentation. Examples of projects successfully implementing this type of work are valuable case studies.
A recent article, “Tribal leaders and researchers have mapped the ancient ‘lost suburbs’ of Los Angeles” (Los Angeles Times, October 9, 2023) explores a successful process, highlighting work by groups using these techniques to study six village sites in the greater Los Angeles region. These “lost suburbs”, in this case, are the original settlements and villages within the LA Basin, where, as noted in the article, “…culture thrived here for thousands of years amid a landscape of oak and walnut woodlands riven with waterways teeming with steelhead trout and prowled by wolves and grizzly bears.”
Ancient routes and key village locations (LA Times)
Three tribes, the Chumash, Tataviam, and Kizh-Gabrieleño collaborated with diverse interdisciplinary academic researchers to piece together a tapestry of inhabitation, as noted in the LA Times article by one of the project leads, UCLA’s Travis Longcore: “We had to dig deep for evidence of the great society buried under our modern empire of terraced and graded slopes, rivers sheathed in concrete, industrial development, freeways and sprawl.”
These provide a trail of evidence to follow for appropriate ecological restoration and responses to climate change. Hidden hydrology is one essential key to the understanding of these ancient places. From the LA Times: “One map reveals the locations of streams, wetlands, vernal pools, and tidal flats that were buried or drastically altered to accommodate urban development.”
Comparison of development impacts on waterways (LA Times)
This is a part of the full historical ecology of the region discussed in the following section. Understanding the pre-colonization waterways allows for restoring places informed by an authentic indigenous history. As noted by Matt Vestuto, one of the collaborators from the Barbareno/Ventureno Band of Mission Indians:
“…the mapping project offers hope for a long overdue reappraisal of Native American history… Almost overnight, we were disenfranchised from the landscape — but our people are still here… now, the challenge is to restore the environment, and rebuild our nations.”
“Descriptions of the historical landscape patterns and function have led to a conclusion that this landscape and region cannot be understood without listening to the stories of Indigenous people who managed this land and thrived for thousands of years before the arrival of European settlers.”
A key part of the work is cartographic regressions, which include reconstruction of the topographic history and hydrological patterns using old maps, aerial photography, and other archival sources, like texts, drawings, place names, historical accounts, and archaeological work. The analyses look closely at trade networks, historical flora and fauna distributions, and their impact on habitat, and provide the blueprint for future restoration. As noted in the Executive Summary:
“This project is unique because a commonly shared, detailed map of the historical ecology—the flora, fauna, hydrology, and landforms, that evolved within Southern California’s Mediterranean climate over millennia and supported human populations for 9,000 years, has never been developed. Individually and cumulatively, the results of this research are vital resources to all regional and local planning efforts involving sustainability, habitat restoration, and preparing for climate change.”
Story Maps
An interactive Story Map is also worth checking out, providing a visual executive summary of the report. Focusing on the section related to Historical Water Features, the team traces stream routes in intervals, including 1896-1903 and 1924-1941, with the ability to compare, via slider, the two time periods as shown below, and highlights the radical change of regional hydrological patterns as the city developed.
The citywide mapping of vegetation types is directly related to these original historical waterways, and an interactive map, based on the Military Grid Reference System (MGRS), using a 1km grid, to provide map data in cells of potential natural vegetation (PNV). This is described in the Story Map as the “…vegetation that would develop in a particular ecological zone or environment, assuming the conditions of flora and fauna to be natural, if the action of man on the vegetation mantle stopped and in the absence of substantial alteration in present climatic conditions.”
Map of Hypothesized Potential Natural Vegetation of the Los Angeles Region (LALAH Story Map)
The connections between hidden hydrology, historical ecology, and indigenous occupation are more than just understanding the past. As the researchers point out, the ability to employ this data for solutions to loss of biodiversity, climate change impacts, and other challenges, while celebrating the cultural legacy of place, is key. There’s a wealth of information worth studying this model in more depth, to better understand the Los Angeles Basin ecology and hydrology and to refine and adapt this approach to other regions, specifically centering Indigenous stories as a key component in historical ecology work.
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Note: This post was originally posted on Substack on 05/01/24 and added to the Hidden Hydrology website on 04/23/25.
