Thursday, April 30, 2015

Stationarity Is Dead

By Kathleen Sayce

When civil engineers, architects and planners design buildings, roads, bridges, levees, dams, drainage canals and other structures, they use the principle of stationarity to decide how high, how strong, how wind resistant, this structure has to be to withstand a typical 50-year, 100-year, 500-year or 1000-year event.

All construction balances on a line between built 'strong enough' and 'over-built too much' to keep the cost as low as possible. The stationarity principle has historically ensured that the structure will last for its planned life, which may be anywhere from twenty years to several hundred years.

To settle on the event standards to design to, professionals refer back to applicable weather metrics and disaster occurrence histories, including high and low temperatures, rainfall, stream flows, floods, snow falls, wind storms, tornadoes, droughts, and earthquakes.

A recent rain burst in the west Willapa Hills overloaded a culvert on Peter's Creek that runs under Highway 4 near Naselle. In the background you can see flagging on the washout edges; the highway pavement is at the very top of the image. Photo by Kathleen Sayce.

One of the reasons modern cultures measure weather events is to provide metrics for infrastructure and building designers, planners and insurance agents. Building codes also emerged, to set minimum standards that ensure a building will not flood, catch fire or blow down during normal events, and will stay in good condition for its design life.

Several years ago a national science magazine ran an editorial which stated that the concept of stationarity was dead [I did not think of this title, I borrowed it from that article]. The authors are engineers, who explained that when a river community had three thousand-year flood events in five years, it was time to redefine a one-thousand-year event. That it was past time to reevaluate appropriate event standards with a new, broader measure of caution. Five percent (higher, wider, stronger) might not be enough anymore. Twenty-five percent might be better, or in some instances, fifty percent. [1 February 2008, P.D.C Milly et al, access via]

This washout on Peter's Creek occurred when blockage in the culvert due to debris coincided with a rain burst. Water built up behind the highway levee and pushed through, washing out the soil and road surface above the old culvert. Photo by Kathleen Sayce. 

Change goes on around us all the time, both in our culture and in the natural world. In the past three decades, local air temperature measurements changed. Plant growing zones are defined by winter low temperatures, and have been shifting steadily warmer for many locations. Fifty years ago, the South Coast of Washington was defined as a region 7 growing area, with winter low temperatures between 0 and 10° F. Today this same geographic area is considered zone 8, with lows between 10 and 20 °F. Similar changes have happened for many areas.

Along with warming winter temperatures, we’ve seen higher summer temperatures. In 2012, in just one hot spell, over one thousand high temperature records were broken in the Midwest. Many locations set new records day after day, until the heat wave finally quit. New records for consecutive days over 100 °F were also set.

If you are an engineer working on cooling systems, you have to design for increased cooling capacity. Otherwise, the cooling system will never work properly. Ditto on insulation and heating standards, stormwater, and roof snow loads.

The Astoria-Megler Bridge was designed in the 1960s. At the time, the design standards based on then-current stationarity guidelines looked pretty good. But now, knowing about local earthquakes and tsunamis, with ships four to five times larger and ten times heavier, with longer, heavier commercial trucks, and heavier passenger vehicles, the bridge is woefully under-designed. A new bridge in this location today would be designed to a new standard.

No one thinks this bridge is in eminent danger of collapse––that is not the point. The point is that data about traffic loads, weather extremes, wind loading, and seismic events has changed. The degree of uncertainty about event severity that can be expected has also changed. Stationarity has changed.

For a house, this means more insulation, stronger framing, a tougher roof, a higher foundation or a location on higher ground. For a road crossing a river, it may mean a larger culvert or stronger, higher bridge, along with higher road levels and deeper ditches to each side. For a stormwater system, it means more capacity.

Last winter, a rain burst in the west Willapa Hills flooded South Bend, overloaded culverts that drained west to the bay from there south to Naselle, and blew out a culvert on Peter's Creek in Naselle, taking out a section of Highway 4. Part of the flooding was due to blockages in culverts, and part to culverts that were faced with water flows well beyond their design capacity.

The new box culvert on Peter's Creek will look much like this one––a box culvert under Highway 101 that drains Chinook Marsh to Baker's Bay. This is a small bridge, and the new one is being designed now. Note where the dirty concrete begins; this is how high the water gets in this culvert on a regular basis. Photo by Kathleen Sayce

The culvert that formerly ran under Highway 4 will be replaced with an open box culvert, which means that there will now be a small bridge where there once was a corrugated pipe. Engineers are designing it now. In South Bend, storm drains were cleaned out, and their capacity will probably be reviewed.

A change in stationarity means, when constructing anything––a road, a culvert or bridge, a home, or other structures––it's time to let go of thinking that we know what might happen based on the past, and design instead for the next increment stronger, windier, colder, hotter, wetter, to be appropriate for that structure and location. The problem with our time is that the weather is not what it used to be, and our old stationarity standards need to be reset.

Thursday, April 2, 2015

Ocean Acidification on the South Coast: Nature at Bat

March 23, 2015, ran in early April, 2015

Understanding ocean acidification is not simple, because the process of acidification is not simple. Neither is the rest of nature simple. Nature is more complex that we can imagine. We can over-harvest, mine, bomb, poison, pave and otherwise mess up this great world, do our very best to destroy the ecology that supports our lives, and yet, nature bats last.

There’s some predictability: If we pump greenhouse-warming gases into the atmosphere, the atmosphere will warm up. We are doing this. It is warming. Those gases are absorbed by water all over the world, because the balance of gases in the atmosphere is reflected by the balance of absorbed gases in the water. It’s a slow process, because there is a lot of water, which can hold a lot of carbonic acid and heat. That slow time lag between absorption and response has tricked many into thinking that what we do doesn’t matter to the global ecology.

Then there are down-welling and up-welling areas. There are areas of the oceans where cold salty water accumulates and drops down into the depths. Called ‘down-welling’ areas, these occur in the north Pacific, north Atlantic, south Indian Ocean and around Antarctica. Bottom flowing currents move the cold, salty water across the seafloor towards continents, where this water rises to the surface, called ‘upwellings’. There are upwelling areas all around the world. Some run all the time, others only with winds from certain directions. In the Pacific Northwest, upwelling usually occurs when winds are from the northwest in sunny, dry weather.

Upwelling in action:  Fog forms over cold water, comes ashore over the beaches, and dissipates over warmer land. On the horizon, blue water indicates the water there is warmer, not upwelled. This aerial is looking north over Ft Stevens across the Columbia Entrance to Cape Disappointment.  Photo by Kathleen Sayce
A summer day with active upwelling here on the South Coast is foggy with northwest winds. It’s sunny inland, it might even be sunny on Willapa Bay, but on the ocean beach it’s foggy. The fog is created when cold, old, very salty ocean water comes to the surface and cools the air. Onshore winds push the cold air onshore one, two, five, ten or twenty miles.

In the water, something more complex is going on when the acidic upwelled water reaches the surface. This water is typically thirty to fifty years old, and can be much older. It’s very salty. It’s high in some nutrients, and low in oxygen. As upwelled water rises to the surface, nutrients are taken up by phytoplankton that live only as deep as sunlight can penetrate into the water––usually less than fifty feet. Phytoplankton grow quickly in summer, tiny single-celled plants that can divide several times a day under good conditions. Those old nutrients are food for the phytoplankton.

Zooplankton can’t keep pace with the growth of plants. Not all phytoplankton cells are eaten, and when the excess cells die, they fall to the seafloor and decompose. This strips oxygen from the water column and seafloor, killing those animals that need oxygen to survive. Their bodies also decompose. More oxygen is tied up in each new wave of decomposition, forming a dead zone of low to no oxygen that expands as summer progresses.

A large dead zones appears each summer along the Pacific Northwest Coast; this year it persisted through winter. It typically extends from south Vancouver Island to northern California. Affected animals include crab, clams, fish, zooplankton, and more. Some fungi and bacteria thrive in low oxygen conditions, and they flourish in this dead zone, growing into huge carpets of mixed species––all thriving on no oxygen and high nutrients.

The second complexity is that this water is more acidic than it was a few hundred or even a few thousand years ago. Remember, what goes into the atmosphere is absorbed into water. With increasing amounts of carbon dioxide in the atmosphere, then in the water there is more and more carbonic acid, increasing the acidity of seawater.

The third complexity is that this cold, old upwelled water is low in calcium, and the local rivers are also low in calcium. For mollusks, calcium is essential to form shells. It also goes into solution (dissolves) easily in more acidic water, and as we have learned in the past ten years, more acidic water is not good for oysters and other bivalve larvae.

There’s always a weak point, a stage in a life cycle when each organism is most vulnerable to what appear to be tiny insignificant changes. For shellfish, this is as larvae, as they undertake the change from the free-swimming form to the shelled form, prior to settling down to become adults. At this stage, oysters and other bivalves grow their proto-shells. But in more and more acidic water, larvae can’t maintain shells, because the calcium dissolves out as fast as shell forms. The larvae linger for days to weeks, trying to make the change. Eventually they die.

But wait, you say, isn’t there deep, cold, low acid water off Hawaii? Hasn’t at least one oyster grower got a hatchery there, safe from the upwelled water? Yes. But oysters are not dominant species of food webs in the oceans of the world. Coccolithophores are a key animal, tiny calcium-shelled zooplankton that eat phytoplankton, and in turn are eaten by larger zooplankton and fish, which are eaten by larger fish, and on up the food web. Take coccolithophores out, and oceanic food webs aren’t just on a diet, they collapse. Fish populations go down; larger fish, birds and mammals that live on them are impacted too. Fishing fleets. Tribes. Food processors. Sport fishers. Oceanside restaurants selling fish and chips. Anyone who eats, catches, processes, and sells saltwater fish is affected.

So there you have it, a quick look at the complexity of ocean water chemistry, and the complexity of the ocean food web, and a hint at the coming changes in ocean ecology. There’s nature, standing near the plate, swinging the bat to warm up. She’s thinking about what she’ll do this time. She might bunt, and take out some nearshore ecosystems in a few key areas. Leave some other spots alone. Or swing for the fence, and crash major cocolith’ populations, along with sardines, anchovy and herring. If that happens, tuna, salmon, and other major fish populations go too, as these fishes are their key food sources. We simply don’t know what nature’s going to do in response to our plays, this time, or next time. We will have all the innings we can manage to stay in the game, but nature bats last.