With El Niño now gone, Californians now move onto the strong possibility of a La Niña – “the positive phase of the El Niño Southern Oscillation and is associated with cooler than average sea surface temperatures in the central and eastern tropical Pacific Ocean” – a weather system which will likely exacerbate drought conditions as temperatures climb and humidity drops across the state. Let us hope the Sierra Nevada snowpack can hold out as long as possible…
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As Southern California continues to grapple with drought (following the gradual deflation of hope for relief from this year’s non-El Niño event), as a landscape architect, I find myself thinking again about additional measures we can implement locally to preserve and protect resources which are vital to sustaining a healthy and viable environment: protecting important and iconic trees (many now plagued by secondary pest infestations), enacting soil conservation to combat losses due to lack of vegetated covers, and putting a moratorium on tapping already dwindling water tables from pumping.
Furthermore, a continuing drought can possibly be indicative of global warming trends – temperature extremes, deviations from precipitation pattern norms, storms with more energy – which, paradoxically, force us to prepare for droughts’ extreme opposites: street flooding, siltation and erosion of streams, and excessive pollution entering our water bodies.
As a society, I feel that many environmental issues reflect our convenient and pervasive view of the environment as being ‘out there’ – isolated and disjointed elements…problems separate from us, rather than the environment as an integrated, living system of plants, soils, microbes, hydrology, and animals, that include us. A shift in understanding our part and participation in the environment as a functioning system is critical to our success in addressing these complex issues, and includes looking to the environmental systems themselves for answers.
I often think the most successful landscape designs mimic nature. Within the water use reduction forum – while local and state-mandated measures have provided significant gains – I believe the implementation of more green streets as an addition to and component of our urban infrastructure system can greatly assist in conserving water and other important resources while mitigating potential global warming issues, such as increased flooding. A system of linked stormwater ‘best management practices’ that capture, clean and store water, Green Streets minimize environmental impacts locally the larger environment as well.
In addition to being effective, many of these systems are an extension of relatively simple natural systems: rain barrels, rain gardens, vegetated swales, permeable pavers, native and adaptive plant material tolerant of both drought and periodic flooding. Water can be stored for passive or pumped re-use, vegetated swales slow water and aid in soil retention; vegetated right-of-way infiltration areas can infiltrate water and filter impurities; infrastructure to underground infiltration galleries can hold water for slow dispersal to replenish adjoining water tables. Typically sized per municipal standards, many communities and urban centers around the country and world have and are installing green streets (or green infrastructure components) to address issues of flooding, pollution uptake, water conservation, and water infiltration as aging, engineered systems fail or can no long achieve results in line with changing needs.
Building Green Streets involves communities. From your neighbors’ rain barrel to the street’s vegetated infiltration swale, there is an exposure and visualization of both resource components and the linkage between them: water, soil, plants, animals. These components – which define and link the neighborhood – provide community building through resource preservation and declare a conscious movement away from car-based thinking to giving streets back to pedestrians: a green, community, synergistic, and living-system effect.
A few years ago I attended a California State Assembly hearing titled, “The Future of Stormwater: Capture, Store and Supply”, which was given by the Select Committee on Regional Approaches to Addressing the State’s Water Crisis. In addition to providing much of the groundwork for the passing of Proposition 1 (Water Quality, Supply, and Infrastructure Improvement Act of 2014), the hearing focused upon opportunities for stormwater to become a significant part of the Southern California water supply.
In the past decades policies and practices have changed to help capture and store stormwater, such as the AHBE Landscape Architecture projects described in Jennifer Salazar’s, “Under Construction.” Collectively, these efforts help to clean our rivers and oceans, while also capturing and storing stormwater. While these types of projects contribute to recharging of the underground aquifer, according to Council for Watershed Health’s Water Augmentation Study, increased stormwater capture could add an additional 384,000 acre feet of water to aquifers annually.
Improved watershed storage capacity is critical. If this turns out to be a wet El Niño cycle, we will be sending billions of gallons of water to our oceans, which will prevent flooding, but will not help recharge our state’s essential aquifers. Groundwater aquifers in the Southern California have the storage capacity, over 2 million additional acre-feet. And as Yiran observed in “10 Things You Should Know About El Niño,” California’s largest surface water reservoirs are located in Northern California.
Over the last decade, the issue of stormwater has transformed from a water quality problem to a water supply opportunity. And Proposition 1, with its $7.12 billion for state water supply infrastructure projects, will provide funding for more types of projects to “capture, store and supply”, if not in time for this El Niño cycle, then the next. More supply infrastructure projects will help California adapt to increasing the amount of water that can be stored during wet years for the dry years that will continue to challenge California.
Since October of 2015 all of Southern California has been preparing for what the National Oceanic and Atmospheric Administration (NOAA) called an “El Niño, amongst the strongest on record.” Forecasts of torrential downpours, mudslides, and gail force winds caused every plucky young field correspondent to salivate with anticipation, and made every single 30-something a recipient of a waterproof flashlight for the holidays from concerned, out-of-state relatives. To date, Southern California is still roughly 2.5” shy of the norm for precipitation.
So what happened?
Well, let’s take a look at the recipe for a normal weather pattern:
First, you take the Earth, tilt it on an axis of about 23.0°, and set it spinning. Add a nice hot equator running through that HUGE patch of Pacific Ocean between the western coast of the Americas and the eastern coast of China and Australia. Toss in a heaping handful of the Coriolis effect, and top the whole thing off with a strong dash of trade winds.
So the equator heats up, the planet spins, heavy cold air from the poles gets sucked down to replace the light warm air around the Earth’s middle, and *POOF*, weather happens.
What also happens is you get a pile up of warm water off the coast of China. Literally a pile of water! The sea surface is normally about 1.5 feet higher and 45° F warmer in Indonesia than Ecuador.
During an El Niño year the trade winds become a little weaker, the deep ocean cold water isn’t being churned to the surface, and there is nothing to hold back all that warm water, so it starts to float back to the western side of the Pacific, bringing with it much needed rain for the coast of California.
All this month the AHBE Lab has offered insights about the causes and effects of El Niño, both in its global influences and to our local Los Angeles environment. Yiran Wang’s 10 Things You Should Know About El Niño is a great primer about the global seasonal phenomena, while Gary Lai’s piece, Feast or Famine: Epic Drought to Epic El Niño connects the historical meteorological antecedents with this year’s El Niño.
Now for something more material and concrete: three AHBE projects have been under construction during the recent El Niño storms. Each project is designed with different features and techniques to incorporate sustainable stormwater best management practices (BMP), and showcase solutions faced while working during an unusually wet season here in Southern California:
Monrovia Station Streetscape
As an adjacent project to the Monrovia Gold Line Station, this project was to “demonstrate the healthy relationship between public space and sustainability” (Design Criteria Manual draft – 12/2013), alongside to provide infrastructure for stormwater management. The 1.3 miles of sidewalk around the station neighborhood are constructed from permeable pavers above Silva Cells. Silva Cells are open-sided box frames engineered to keep soil available for street adjacent tree roots. Also, the street trees are planted in lowered curbside parkway swales that permit stormwater to flow into each planter directly from the street gutter using typical roadway grading. The storm water that flows into the parkways infiltrates into the ground, supporting native plants and street trees.
The biggest challenge faced during this season’s heavy rainstorms has been young, newly installed plants being washed away in the flow through parkways due to the intensity and length of the rainfall. Mitigation includes replacing washed out plants and temporarily blocking off the inlets from the street until the plants have stronger, more established roots. Though the Gold Line Station will not begin public operations until March 5, 2016, the streetscape has recently had its final landscape review.
Team members: Prime, IBI Design Group; Civil Engineer, CivilTec
Johnny Carson Park
A 17-acre public park in Burbank just north of the 210 Freeway, this project’s primary best management practice is the transformation of the Little Tujunga water channel that traverses the park from a concrete-lined creek into a destination water feature designed with an enhanced wildlife habitat, recreational access, and improved water quality.
During the storms, the concrete channel had been removed and had not yet been planted with restorative bank-stabilizing planting. This resulted in the erosion of the bottoms and sides of the exposed channel. Riparian stream bank plantings that are part of the design – such as brush mattresses – are being installed as quickly as is feasible in between storms to stabilize the creek sides. Brush mattresses are a living erosion control mat that is durable upon installation, and will increase in durability as it becomes rooted into the slopes of the stream. The park is scheduled to open in spring of 2016.
Team members: AHBE, Prime; California Watershed Engineering (CWE), Civil Engineers; Restoration Design Group, Stream Restoration
Torrance Storm Water Basins Enhancement Project
AHBE designers worked with the City of Torrance and civil engineers California Watershed Engineering (CWE) to cleanse and mitigate stormwater at 3 locations in the city.
The primary goal of the basins is to reduce exceedance of bacterial release into the Santa Monica Bay. The stormwater is retained, treated, and infiltrated into the ground, with excess released into the Santa Monica Bay. AHBE’s landscape design creates natural habitat, encouraging an increase of wildlife within the area. An outdoor classroom, positioned at the highest point of the area, provides an area to engage and educate local students as they learn about this stormwater treatment system and its benefits to the environment. The basins were opened to the public last autumn.
See the recent video Stormwater Basin Enhancement Program – Torrance CiriCABLE produced at the completion of the construction in September of 2015: