Water, the Common Element of Disaster

It isn't very scientific to string three events together and turn them into a natural law. However, recent so called "natural disasters" in the US should provoke architects, planners and engineers to ponder the issues and ask serious questions with increasing urgency.

Water the issue of the 21st Century, environmentally, economically
and socially

The three events are the ongoing catastrophic wildfires in central and in northern California, the recent flood that ravaged the small historic town of Ellicott City near Baltimore and the historic floods in Louisiana this week.

The nearly 6" of rain that fell on Ellicott City, the 25" of rain that fell on Louisiana in three days and explosiveness of the fire in San Bernadino County all were called "unheard of", "never seen before", "historic" or "a 1000 year event". By all accounts these were not just hyped up assessments of the moment, they are born out by the stats of the past. And they have another thing in common: They all have to do with water. In the case of California, it is the absence of water that resulted in the dry conditions that make these fires so hard to control, in the floods it isn't only the obviously extraordinary rainfall, stormwater management and settlment patterns play a major role as well.

The Big Sur fire when it was only 6 hours old on 7/22. Much of the area has been
devoured by flames by the fire that is still raging. (Photo: Philipsen)

For most it takes direct exposure to really feel affected or pay attention. These days it is hard to avoid exposure.

I happened to observe one of those canyon fires, the Sabaranes-Big Sur fire from a small plane just six hours after it started and it was already impressive especially as I had toured a similar canyon and mountain range in an offroad vehicle the day before and the heat and extraordinary dryness had made a deep impression on me. That was nearly four weeks ago on July 22. Today the fire is still burning and only 60% contained according to Cal Fire. It has burnt over 123 square miles and destroyed 57 homes. That is one and a half times the entire land area of the City of Baltimore.  An exceptional loss to the State parks such as beautiful Big Sur. But this fire is already old news. The headlines now belong to the Blue Cut Fire in San Bernardino County. It threatens over 82,000 people in 34,500 homes. The number of homes already destroyed in the just three days this fire has been burning is not yet known. The fire closed an Interstate, a health center, schools and a rail line and has grabbed attention because it is so close and around human settlements.

Ellicott City flood damage

Back home I witnessed  the 6" in two hours rainfall with my own eyes from the windows of a restaurant in downtown Baltimore. The view was just like some of the most impressive video footage taken in Ellicott City which had been taken from restaurant windows. In both cases it started with just a few inches of water rapidly flowing down the street and some cars braving the gushing water. On Baltimore's Charles Street the worst was that the water mounted the sidewalk curb. Then it receded. Main Street Ellicott City, by contrast, turned from a street with a few inches of water into a mountain stream with a raging torrent several feet deep. The torrent destroyed all the stores and restaurants on both sides of the street and many homes and businesses much further upstream.  Main Street has been closed ever since with emergency workers trying to shore up buildings, filling the gashes ripped deep into the sidewalks, fixing severed utilities. The street won't open again before mid September at the earliest and even then it is unlikely that commercial activity will happen there anytime soon. I also happened to be in South Germany in May of this year when a freak rain-storm wiped out the village of Braunsbach only some 60 miles away and killed two people.

The Louisiana flood has not even fully receded but the Red Cross has already declared that the damages are the worst since Hurricane Sandy. 12 people have died. 40,000 homes damaged, 30,000 people in shelters, big even by Louisiana standards, a state used to flooding. A huge flood area, a very different event form the one in Ellicott City. 80,000 people have already applied for disaster assistance. Yet, exceptional precipitation here, too, was compounded by the way the land had been developed.

California deep well irrigation

Armchair strategists will no doubt come up with all kinds of ideas what should be done to make communities more resilient. It isn't the intent of this article to join their ranks. There is no silver bullet that solves those three problems, nor can anybody say with any credibility that the three events are necessarily linked to a common cause such as climate change. Statistically they could be flukes and it could be just coincidence that they all happened in short order inside the United States even before the hurricane season has really fired up.

However, it is eerie, how much the events fit the description of what researchers, speaking about the consequences of climate change, have predicted or described as increasingly likely: namely extreme droughts in some areas and extreme precipitation in others.

In the report, ’Environmental Outlook to 2050’  from 2012, the OECD (Organisation for Economic Co-operation and Development), estimates that about 1.5 billion people today live in areas seriously affected by water scarcity. According to the report, the number will increase to almost 4 billion by 2050, which will trigger a global food crisis, if we do not change our course. (Source)

In fact, climate researchers and folks studying sustainability, resilience and appropriate human response to changing climates have long identified water as the dominant global issue, both its scarcity and its abundance. Not oil or rare earths but water! It is the very thing most of us still take for granted and use without much second thought. As long as we could drain or dam our rivers, dig ever deeper wells into our groundwater or send pipelines into arid zones to grow wine and alfalfa, engineering has been seen as the answer to whatever issue. Nowhere is this more obvious than in central California where intensive farming with high water need crops abut desert like conditions. One has to see this from an airplane or stand in front of those stark boundaries to onder, how does this work? The answers is: Deep wells. Sometimes thousands of feet deep, these well take water from ancient aquifers, water that is sometimes decades or hundreds of years old and do not replenish anywhere near the speed with which the water gets pump out. A ticking time bomb.
What we call extreme events like the three above makes clear is that the biggest change may not be needed in Washington but all across America:

Unlike the effects of a drought on streamflows, groundwater levels in wells may not reflect a shortage of rainfall for a year or more after a drought begins. Despite reduced availability, reliance upon groundwater often increases during drought throughincreased groundwater pumping to meet water demands. If water is pumped at a faster rate than an aquifer is recharged by precipitation or other sources, water levels can drop, resulting in decreased water availability and deterioration of groundwater quality.(USGS)

Codes and Regulations

The biggest challenge is probably not that codes and regulations stand in the way of producing even more things more cheaply. Instead it is this: Our built environment is designed around a pretty narrow range of conditions with codes reflecting the extremes that we have historically known to be pretty much what we have to expect. That is true for wind, rain, temperatures, snowfall and also for fire safety. Those codes take into account only small deviations from what generations have defined as normal.  That means structures and systems built to those standards cannot withstand any "new normal" that involves forces and conditions that fall outside the patterns of the past.

Schools that worked for decades without air conditioning become too hot to learn, roofs that withstood snow for a century collapse, winds take down buildings that held up for many decades. Rains inundate places that never flooded before and extra fierce fires jump firelines that were sufficient to hold fire at bay before.

Aside from hurricane straps, flood doors in basements of flood prone houses and new snowdrift calculations for roof loads, there is little in the codes that truly reflects a new normal and would force at least new structures to be resilient. retrofitting of old structures for resiliency has happened mostly for earthquakes and is limited to California. It is possible, that similar retrofits will have to sweep many more regions of North America to tune buildings up for a new set of risks. Such cost would hit the country just when citizens and country are indebted like never before mostly for building and buying new stuff while what is on the ground crumbles.

New Risks

New extremes not only require that the maximum load or temperature assumptions have to be expanded, they modify the risks themselves and bring about a whole new set of dynamics and parameters. Ellicott City is a case in point. FEMA flood maps which show water levels based on historic flood measurements indicate that this small town is flood prone and stories of floods go back throughout its history. But those maps do not only not forecast the water levels to be expected in the future, they are defining a risk that has become quite different in a rapid extreme rainfall. 

In the past the main river at the edge of town swelled gradually and sometimes rapidly but floods always came from the river and inundated low lying areas with sometimes rapidly rising water. But extreme convective rain bursts that cause extraordinary downpours in a very short time frame changes everything: It is now not the flood rising from below but torrents from the hills above that pose the biggest risk. The extreme rainfall unleashes high-velocity high-volume water currents that comes tumbling down whichever path they can find: streets and pathways previously unknown to carry water. The high velocity and the sheer mass of the water have destructive energy that previous floods didn't have. As a result damage occurs way up from previously known flood levels and from dynamic forces of water and whatever objects water can carry. Just as debris becomes a projectile in a tornado, logs, cars and other objects took out building walls and storefronts in Ellicott City. Essential supports for the historic granite buildings that seemed indestructible were pushed out from under the buildings especially where main street made a curve and the water was redirected by buildings that now experienced "shore erosion" previously only seen in streams. 

Flood damage in the German small town of Braunsbach near Stuttgart

Similar flood events have happened in in Southern Germany in recent years, a place that had rarely seen tropical downpours in its previous history. Those catastrophes that cost lives and caused famage similar to the one in Ellicott City caused the State to prepare some new type of flood maps, different from the flood maps of old which show 100-year floodplains in river and streams valleys. The new maps are called Starkregen maps, the literal translation is "strong rain maps". They depict flooding from moving water not only when streams swell beyond their banks in low lying areas but flooding that occurs on the path to the low lying areas, the normally dry valleys or streets which have turned into waterways in those extreme downpours.

New risks require new thinking and totally new approaches. What is heard in Ellicott City today is what is echoed after every disaster: "We will rebuild because we are a resilient people". It won't be enough if the systems don't become more resilient as well.

Drought and fire

For years a drama of an even bigger dimension than the floods plays out in California, a drama previously only attributed to Africa or South America: the vicious cycle of droughts, floods and fires fueled by extreme temperatures. The absence of winter rains and usual precipitation patterns has left dead brush, dry grass and tinder dry trees as fuel for fires that can spread within minutes to uncontrollable size. The fires then leave the topsoils unprotected. They then will wash off in those sudden rain storms in the fall and winter that do little to relieve the drought conditions but cause the severe erosion that has shaped so much of the landscape we see today. That makes re-vegetation so much harder. Less vegetation and green will, in turn, reduce the chance for rain. This vicious cycle is known from Latin America and the depletion of rain forests. The regions around Sao Paulo, for example, have become so dry in 2014 and 2015 that hydro plants built only decades ago had to be turned off because of low river levels. The mega city itself had such low water pressure at times that the favelas and some high-rises didn't get a regular basis. Only the strong El Nino of 2016 has brought some immediate relief.

Sprawl in Orange County, CA (photo: Philipsen)

Sprawl

Sprawl makes things worse. In the case of Ellicott City hundreds of developments all over the watersheds of the small creeks Tiber and Hudson occurred on hilly terrain and originally wooded sites. This increased run-off dramatically, even at developments that followed Maryland's stringent stormwater management requirements, Once a rain event exceeds the required storm water retention requirements that are limited to the "100-year storm" the excess water simply goes overboard and spills unmitigated downhill. Of course depletion of tree cover exacerbates heat island effects which in turn contribute to convectional rain bursts.

Sprawl also plays a role in Louisiana not only making search and rescue harder but also directly contributing to so many houses being placed in harm's way.

 In California's San Bernadino fire thousands of homes are threatened in small settlements sprawling out from already sprawling Los Angeles due to lower land cost. Clearly, sprawl makes fire fighting a lot harder.  Often depending on  well and septic sprawl also directly threatens water as a resource with poor septic systems seeping into groundwater or streams, deep wells depleting aquifers and run off degrading local creeks and streams through sediment and erosion. Sprawl aslo affects the fragile arid ecosystem present in the hills north and southeast of LA.

Klaus Philipsen, FAIA

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