The headlines declared that Cape Town was on the brink of disaster. A drought in the Western Cape province of South Africa that began in 2015 resulted in severe water shortages in the region, most notably City of Cape Town. The situation became critical in 2017 when the clock on city’s water dashboard counted down ominously to Day Zero—the day the drought-stricken city was expected to eventually run out of water. By March of 2018, the city had reduced its daily water usage by more than half. That combined with good rains in the winter meant disaster averted, and by June 2018 dam levels had increased to 43% of capacity. Now, Day Zero appears to have been put off indefinitely, but the question remains: Could a Cape Town situation happen here in California?
Dr. Jay Famiglietti is a hydrologist, a professor, and director of the Global Institute of Water Security and the University of Saskatchewan, where he holds that Canada 150 Research Chair in Hydrology and Remote Sensing. Previously, he worked at NASA’s Jet Propulsion Lab and University Irvine. Dr. Famiglietti is a regular advisor to state and federal governments about water availability and water security issues. At the Urban Water Institute’s fall conference held in San Diego in August of 2018, Dr. Famiglietti addressed the possibility of whether San Diego, Los Angeles, San Francisco, or agricultural regions could face a Day 0 in the future.
Dr. Famiglietti began by pointing out that in a sense we’ve already have, as during the worst part of the drought, East Porterville and a few other communities ran out of water. And he noted that Cape Town is really experiencing rapid climate change, perhaps at a rate that’s faster than water managers and the population can really keep up with; the pace at which humanity is responding to climate change is being outpaced by the surprisingly the fast changes being experienced in some regions.
Cape Town is located on the border between the dry areas and the wet areas in the southern hemisphere, which has been shifting because of climate change; this is similar to California’s position in the northern hemisphere, he said.
“Climate change is happening, the rainfall patterns are changing, and they have had a colossal drought that’s gone on for three years, possibly related to climate change,” Dr. Famiglietti said. “The expectation is that droughts will be more persistent and punctuated by more intense rainfall, similar to what’s expected in California.”
Cape Town relies on six reservoirs for its water supply, which going into the winter in the southern hemisphere (which is summertime in the Northern hemisphere), the reservoirs were at about 21% of capacity. The six reservoirs are not very big, which is a key issue, because if a city is dependent on small reservoirs, it can be a problem, he said. The city’s population has grown over the last few years, and there’s tremendous income inequality which means that usually the first people to take a hit in terms of water availability are the poorest, he noted.
It’s not as if Cape Town didn’t have plenty of warning that the water problem could become serious, Dr. Famiglietti said. A 1990 newspaper article covered a study that focused on the potential effects on water availability and water management in South Africa, and nobody listened. As a result, Cape Town was pretty slow to respond to the realities of climate change.
“There was really a denial of the situation up until about a year ago when we started hearing about Day 0,” he said. “There’s always politics; we’re never going to get away from that because building infrastructure is expensive, so politics over the need to build more reservoirs, and the perceived constraints on the economy were a major obstacle.”
There were some shutdowns of water to the small, poor communities, which is not uncommon in Cape Town. Less well publicized and something quite common is that there is a strong, social reluctance to act until people need to. “We see it here in California,” he said. “It’s super hard for people to change their behavior unless they absolutely have to.”
Eventually, mandatory conservation actions were taken with citizens cut down to 50 liters per day, or about 12 gallons per person, per day. Homeowners who used too much water had water saving devices installed by the water police, and there was public shaming with publications of names of water overusers (something Dr. Famiglietti acknowledged he was not comfortable with).
The concept of Day 0 was that when storage in the reservoirs reaches about 13-13.5%, then all the taps would be shut off. Residents could collect 25 liters per day at 200 different collection points in the city. Dr. Famiglietti noted that the warnings did work; residents were able to reduce water use by 50% relative to three years prior.
Once Cape Town entered the rainy season and the rain did come, there was a sense of relief; Day 0 has been pushed off into 2019 and now might never happen. If they don’t get rain, the concept may come back. Officials are now considering actions such as desalination, sewage recycling, building more reservoirs, and changes in pricing.
In California, groundwater supply is essential to resilience, but Cape Town has relied entirely on surface water, so if Cape Town is going to start using the groundwater, then groundwater and surface water need to be managed together, he said. “It’s time for people to start to get together and think about how to solve these issues jointly because it’s in everyone’s mutual interest,” he said.
Dr. Famiglietti then turned to discuss California, presenting a figure from the NASA Gravity Recovery and Climate Experiment (or GRACE), a satellite that can measure and track storage changes of all the snow, surface water, soil moisture, and groundwater. GRACE takes monthly measurements, tracking changes in the water around the globe. He acknowledged that it’s a pretty coarse resolution and can’t really provide site-specific information, but it can help us understand what is happening in California and around the world.
“Here’s the conundrum,” said Dr. Famiglietti. “We look at our reservoirs and the reservoirs are in good shape, but reservoirs don’t actually store that much water. Most of our water is actually in groundwater, and we’re hitting that groundwater pretty hard. It’s natural to look at a reservoir and see that it’s empty and be really concerned; there’s a great visual. But when the reservoirs are full, we lose the public’s attention.”
But while California reservoirs are in good shape, the prediction for Lake Mead is bleak, with the level nearing the critical line which is when the water levels fall below the intake level and hydropower capabilities cease, Dr. Famiglietti said. “We’re pretty close, and there’s a downward trend there, so when we back up and look at the big picture, there’s cause for concern.”
He presented a time series from the GRACE satellite looking at total water storage changes in the Sacramento, San Joaquin and Tulare basins. He noted that it’s not the total amount of storage, this is just the change. “There are ups and downs from the climate oscillations, but there’s a trend there,” he said. “And there’s the reliance on groundwater during periods of drought. In California, we tend to use about 2/3rds groundwater, 1/3rd surface water during drought periods.”
Dr. Famiglietti then presented a picture showing cumulative groundwater level data from both the USGS and GRACE; he noted that the dark blue background represents the wet periods, the brown background represents the dry periods; and the lighter colors are moderately wet and moderately dry.
“It’s a long-term depletion trend that’s been going on for a century,” he said. “There’s a little recovery during wet periods and a big drop during dry periods. So the hope is that SGMA will help us slow this rate of depletion and maybe lessen the slope. I’m not sure we could ever make it horizontal or increase at the statewide levels, but those are things to think about.”
This groundwater depletion has resulted inland subsidence in the Central Valley. Dr. Famiglietti presented a slide from Tom Farr at NASA, showing the subsidence that occurred from 2015 to 2017, noting that the brighter colors mean more subsidence.
“It has slowed relative to 2014; in 2014, there were some issues that were dropping as much as a one meter per year,” he said. “The maximum rates here are half a meter per year. So subsidence has slowed a little bit … even a little recovery in 2017.”
Nationwide, the lower half of the country is getting drier, including the Central Valley and the High Plains aquifers which are big food producing regions, he said. Globally, many of the hot spots correspond to groundwater depletion from the world’s major aquifer systems which is putting our food security at risk.
Is Cape Town a wake-up call for cities around the world? Dr. Famiglietti said it is very, very difficult to plan for a water crisis during a water crisis. “There’s a knee-jerk reaction,” he said. “Politicians want to build something, but sometimes it’s not the best thing to do. Australia and the desal plants are a good example of how they were all built but really not used very much.”
There is a strong social behavioral side to this, and we need to understand how to change people’s behavior. “Common sense doesn’t always work,” he said. “There’s emotion, there’s comfort – there’s a lot that goes into it. If anything, Cape Town has shown that managing a water crisis requires a thorough understanding of the social side, the political side, as well as the environmental, biological, and physical sides.”
“As we think about the rest of the world, not just California, the time to start thinking about these plans is now, or we will see more Day 0s popping up in major cities around the world,” he continued. “To underscore my overall view of Cape Town, it wasn’t just a water situation; it was a management, political, and social situation and an infrastructure situation. I think they were caught off-guard, so we don’t want be caught off-guard here in California. I think our water management is fantastic, but it’s not just California. There’s other states in the union and there are a lot hot spots on the map.”
QUESTIONS AND ANSWERS
Question: How much of what you’ve seen in the Central Valley and in Cape Town can you say is related to climate change?
Dr. Famiglietti: “It’s hard to say that in any one location and at any one time whether something is climate change or not, but when you look at the frequency of what’s happening, there are changes in frequency of what’s happening, and it’s unlikely that some of these things would be happening without climate change. That said, I go back to this global map and there is a very big climate change component to this map. When you look across the high latitudes, those are mostly blue, they are getting wetter, and across the tropics, they are mostly blue, they are getting wetter, and in between is getting drier; that’s been predicted by the climate change models for the end of the 21st century and we’re seeing it now. It’s exacerbated in those dry areas where they are pumping groundwater because it’s dry and there’s less rainfall, so it’s exacerbating and accelerating the dry periods. Globally, very strong climate change indications.”
Question: How do you communicate science on the highest policy levels?
Dr. Famiglietti: “I use a hands-on approach, I just go and visit directly. I don’t go and ask for money, just go to inform. As you build relationships over time, you find out who are the water interested people and you build relationships, and we’ve been able to keep those going. The difficulty is in the in-between level, the level of the water managers, because the stuff we’re doing is very sciencey, not particular useful in water management. It can inform big picture water management, but it’s not like we can take it and make a decision here in San Diego. So if there’s a tricky layer, it’s at the layer of water managers because then at the grassroots public, the media is really behind this stuff so it works as a real amplifier to get the message out.”
Question: Are you seeing droughts, and forest fires in the other Mediterranean climates, and what is the effect on global food security?
Dr. Famiglietti: “Yes, I’m seeing the impact on drought and fire, certainly Eastern Europe, around the Ural and Caspian Sea, South America, across the Middle East … so we’re seeing increased persistence of drought, and when it does rain, it’s pretty intense. Food security is speculative at this point, but we did a study in 2015 that showed, if you look at that global map … we talk about 37 of the world’s major aquifers, and most of those red spots sit on top, over half of the world’s major aquifers that support irrigation, those are the world’s food producing regions and so we’re reaching a point here when you drive through the Valley, there’s a lot of fallowed land now, and there’s a lot more nut trees, a lot less diversity of crops, and we’ll see how it plays out around the world, but one thing is for sure is that the groundwater is disappearing and being depleted in 21 of the 37 major aquifers.”
Question: Instead of responding to drought by conserving, shouldn’t be building? There are so many other things involved in water problem then just looking at water rationing as the answer. Shouldn’t we be creating more sources of water?
Dr. Famiglietti: “There are different ways to approach the problem. There is the supply side and there is the demand side. One of the reasons why I default to the demand side is that it’s cheap and it’s easier to get people on board. On the supply side, our capacity to do sewage recycling is basically limited by our population, and while I think the San Diego plant is great, there are issues. The issues are the ones that are well-known; it’s expensive, it’s energy intensive, and I don’t think we have a long-term solution for how to handle brines. Think about the California Coast; if we add a desal plant every 20 kilometers, that’s an awful lot of discharge. I haven’t seen any discussions about the impact of that, so until we have the answers to those questions, I think that we are quite safe and conservatively thinking about conserving before developing new supplies.”