How Much Rain Would End The Drought In North America?

How Much Rain Would End the Drought?

What's the best way to get people to stop watering their lawns? Why aren't we investing in desalination? Will we ever get used to the idea of drinking our own (recycled) pee? And most importantly, when will this drought be over? You had a lot of questions about water, so we turned to two experts to get us all some answers.

Hadley and Peter Arnold work on water issues as executive directors of the Arid Lands Institute in Burbank, California. They also have an incredibly smart proposal to turn urban water grids into low-cost, localised systems which could capture and store water at the neighbourhood level.

How much would it have to rain for the drought to be considered "over"?

Hadley: There are lots of ways to answer that question. Droughts are temporary and one definition is returning to "average" or "normal" perception rates. Another is to say droughts are the new normal. Another might be to wrap our heads around what would be involved to replenish what we have overdrawn during the last few years.

As of August 2014, California had lost 63 trillion gallons of groundwater in one 18-month period of drought — a combination of no replenishment from surface water, increased evapotranspiration rates, and increased groundwater pumping by users without water in their rivers or their wells. A 63 trillion gallon groundwater loss was measurable by satellites in the form of a 1/2" drop in the elevation of the Sierra Nevadas. Fun back of envelope facts: This is the equivalent of enough water at current usage rates to supply every person in the City of LA for 240 years.

(That 63 trillion gallon figure is for January 2013 to August 2014 — not the whole drought — about half of it. I don't know the figures for the first half and I don't know if they can be extrapolated from the second half; it's probably not 1:1.)

In a couple of rainy days last December, when we all rejoiced over rain here in LA, we received approximately 10 trillion gallons of precipitation in 10 days, statewide (including snowpack at 10 inch of snow for every 1 inch of rain). Of course, not all of that water makes it back into the groundwater table — due to our not-so-clever design of the built environment, for example, a lot of it in the cities sheets off to the ocean, but a lot of it makes it into the ground around the rest of the non-urbanised state.

How Much Rain Would End the Drought?

The warmer-than-average ocean temperatures off the coast of South America are predicting a probable El Niño this winter

So: If we look only at the 63 trillion gallon loss over 18 months, then a 10-trillion gallon estimated gain is — at least at the order of magnitude level — consistent with an estimate that it would take approximately six storm systems like the one in December to occur to bring us out of drought.

If we wanted to account for losses in the first stages of drought, maybe to be safe one could guess that evaportranspiration and groundwater pumping rates were not quite as severe in the first 18 months as they were in the second — maybe we lost 20 or 30 trillion gallons? — so maybe a total of 30 + 63 trillion? Maybe we need eight or nine of these storms, not six?

Will El Niño 2015-2016 bring us eight or nine of those ten-day storm cycles? I doubt it, but maybe, and we will begin to chip away.

The mantra of climate impact on Western hydrology: wet will be wetter, dry will be drier; there will be longer, more severe drought periods punctuated by more intensive precipitation events. So there's a chance.

The real question is: What will we do with all that water running down LA's streets?

I recently read that as many as one-third of all businesses and homes in California don't have meters, can this really be true?

Hadley: Metering is a huge issue — metering groundwater withdrawals within agricultrual areas like the Central Valley especially. This is what the data coming out of the GRACE satellite studies is telling us — we are withdrawing beyond "safe yield" in response to not having sufficient surface water; but don't have the feedback mechanisms to monitor/discipline our own pace/use.

California seems bent on using command and control methods for limiting water use, instead of pricing. Why not establish a basic level of water required and then progressively hike the price as you use more? Even billionaires don't want a water bill in the $US100,000-a-month range, do they?

Peter: LADWP already has tiered pricing for potable water consumption — we'd love to see it applied more broadly across the state. It's a likely next step (and more effective one) after across-the-board percentage reductions.

Why not expand reverse osmosis water treatment plants across the Pacific Ocean and pump it where needed? I have not done any research so this may be an ignorant question, but one I think a lot of people would have.

Hadley: Not sure how easy it is or isn't; but here's my take. Like desalination, reverse osmosis is energy intensive. And the scale you are talking about is still in the future. We can't really afford either — the energy and carbon intensiveness of our water systems is problematic already (warming the atmosphere to reallocate a hydrologic cycle got us into this mess) and conservation, recycling, and design of smart localised systems are not contingent on massive amounts of R+D, capital, and time to make them happen. Time is of the essence at this point.

Something else that we are committed to as central to water solutions is the visibility of water systems: providing centralised, remote, largely invisible, unknowable projects administered by remote management elites leaves us with an impoverished citizenry — less capable, less cognisant, less aware and responsive to the demands and limits of their time/place. We think designing for energy, designing for time, and designing for visibility and accessibility are a huge part of the solution.

Reclaimed wastewater is a huge potential source of water in arid areas. The two huge roadblocks are cost of treatment and public perception. Which of these will be easier to overcome?

Hadley: The yuck factor is a big impediment. Have you seen Jack Black's segment in Last Call at the Oasis? Worth watching; also worth remembering that all water is recycled water (its a closed system). West Basin in Orange County, California — Nat Geo did a great story on it, so did the NY Times — has done a fantastic job — treating wastewater to a very high grade of "designer water" and instead of putting it into peoples faucets, sending it to aquifers. When it's withdrawn later from the ground, people see it as "groundwater." Its been re-"naturalized" in their minds — the yuck factor is gone. We'll get there.

Having lived in Saudi Arabia, a land both dry and full of excess, I can't fathom how California, a place nowhere near as wealthy, can waste water with such abandon. It rained once every two to three years where I lived, and promptly flooded the place, but during the rest of the time our water was from minimally reliable springs or very expensive, oil-powered desalination plants. Is California seriously thinking desalination is salvation?

Peter: Your point is a good one. Lots of people want to know why California isn't just solving this with de-sal. We've grown accustomed to technology as our salvation. De-sal will be part of a portfolio but it's not the total solution. Peter Gleick of the Pacific Institute wrote a great article on why Australia invested in de-sal and then idled many of the plants; Israel is often held up as an example, but their circumstances included massive conservation, rainwater capture, and 75% recycling before de-sal (and energy security) fully integrated into their portfolio. We have a long way to go with the low-hanging fruit of conservation, recycling and storm/rainwater capture before turning to energy/carbon intensive de-sal as the "solution."

If it were legal everywhere to do it, how much water could be saved by people capturing and using rooftop rainwater runoff for gardening and such?

Peter: If we combined conservation, water recycling, and harvesting stormwater runoff, we could meet as much as 82% of LA's current water needs. In the San Fernando Valley, we believe we could capture enough stormwater to meet approximately 500,000 people's needs for a year in an "average rain" year.

Is storm drain capture really feasible? Especially considering the issue with runoff and pollution in storm drain water?

Peter: It's definitely feasible and it's already got a massive push behind it: LADWP recently released its Stormwater Capture Master Plan. Its focus is to capture stormwater in a small number of large-scale infrastructures dotting the city; and to incentivise permeable surfaces wherever possible. This plan has many stakeholders and was years in the making; feasibility has been a big part of the process. Stormwater is recognised widely as a resource for cities in drylands diversifying their portofolios.

How Much Rain Would End the Drought?

LADWP's plan to capture stormwater and treat on a larger scale

That said, our approach differs in its scale and granularity. We are proposing to complement large stormwater capture facilities with thousands of small, low-cost neighbourhood scale interventions. Also, importantly, our recommendations for permeability are tied to very specific geographic locations — where is permeability really to LA's advantage (giving consideration to soil suitability and the presence of serious contaminants?) and where would infiltration actually undermine or compound LA's existing groundwater contamination challenges. Infiltrate everywhere is, in our view, to be avoided.

For supply: Stormwater has to be captured and detained before it enters the existing stormwater system (which requires a small scale distributed approach). For flood threat: intensive rain events beyond the capacity of capture and store, so we need to keep the existing storm systems to handle flood threats.

So yes: feasibility. And beyond feasibility: optimization.

Gov. Jerry Brown called for a 25% reduction in water use, however in Rancho Santa Fe, a "rich/high income community", water use went up by 9%. Should rich people limit the amount of water they use, even if they can afford tons of it?

Hadley: Across the board percentage reductions are necessary, overdue, and not particularly effective. 25% of the Peninsula's lawn-watering water budget is not the same as 25% of Pacoima's lawn-watering budget. Tiered pricing will help reach not percentage decreases but absolute decreases. And we think its not unrealistic to expect the R-word (rationing) at some point in the not-too-distant future.

The point is whether it's fair to ask a renter in a parched low-income neighbourhood where irrigation water may be putting supplementary food on the table to cut 25% from an already low water budget, while asking huge estate-owners to cut back on watering their golf-course sized lawns by the same percentage? It won't be long before we are moving past percentage reductions and looking at equitable gallon-per-person targets, incentivizing staying within those allotments and/or penalising going beyond them.

What can you tell us about privately controlled water banks? Are they having any impact on our current drought?

Hadley: I know little to nothing about private water banks but the concept gives me the willies. The idea of water controlled by or for wealth is — for me — incompatible with the public interest, incompatible with water as a human right, incompatible with a central credo of the West: agua es vida, water is life. We are familiar, however, with a form of water banking in rural New Mexico that takes place in the context of water collaboratives — -democratically managed, cooperatively owned and managed water districts. We'd love to see how small scale water banking systems might be applied to networked neighbourhood watershed districts in urban centres — but it will take retooled governance and metering technologies as well as a retooled built environment and informed citizenry.

I was wondering if there's one place in the world you think is really succeeding at dealing with drought and water scarcity — a city or country you look to as a model.

Hadley: Australia's Millennial Drought (2000-2010) really opened its eyes and made it a leader. They are now leaders in water-sensitive urban design — capturing rainwater and stormwater at as many scales as possible. When some Aussies came to a conference we hosted in 2012 and travelled a bit in the Southwest beforehand, they came back to LA shocked that we aren't water-catchers. Where are your rain barrels? Andy Lipkis, founder of TreePeople, tells a story about Aussies: they used to say, G'day. Now they ask, How's your tank?

As a Southern California resident looking to get a home, can I stay here, or should I look for a home in another state?

Peter: I'll tell you what I'd tell myself: stay. This is an exciting time and it requires us to cope and innovate. Look for a home, and adapt (with) it. Plenty of studies would say there's enough water here — we just don't use or manage it appropriately. The design of our homes and our neighbourhoods can play a role in adjusting that: How to get a lot more — more value, pleasure, nutrition, hygiene, industry, habitat — by using a lot less — less water, less energy. Find your home and let yourself put down roots knowing that those roots have to look and operate like they belong in a drylands — robust and hardy and part of a larger ecology, not transplanted from some greener pasture — and you'll do just fine.

Picture: AP Photo/Chris Carlson

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