Drought or Deluge, Rainwater Harvesting is about Water Sustainability
As the historic California drought enters its 6th consecutive year, everybody wants to know… What’s up with California’s water supply, anyway, and what can we expect for 2017?
The much anticipated El Niño winter we experienced in 2016 brought only “near average” rains. This was not enough to replenish reservoirs and aquifers, which are overdrawn even in normal rainfall years.
But with the drought out of the news cycle and mandatory water use restrictions lifted, Californians slipped by nearly 10 percentage points in water conservation. We conserved only 18% from benchmark in August 2016, down from a laudable 27% conservation in August 2015. Now the state is considering bringing back mandatory restrictions for 2017.
What’s to Learn?
It turns out messaging is important, and Californians (because we are human) need continual reminders to keep pushing the envelope on water conservation.
Lots of people think rainwater harvesting is cool. But what does it take to get that rain barrel or greywater project to rise to the top of your priority list? It takes a sense of urgency!
Or better yet, it takes an understanding that rainwater harvesting is about so much more than water conservation. The California drought shouldn’t be the only thing motivating us. Rainwater harvesting is about sustainable on-site water management in a holistic sense – no matter what the climate is doing this day, month, or year.
Rainwater Harvesting is about Sustainability – not just Water Conservation
Whether it’s wet or dry, rainwater harvesting mitigates the impact that we’ve created with all the hardscape in our environment by helping water infiltrate into the ground like it would in nature. Earth is our largest water tank. If we all steward what we take out of the collective, we will be more resilient in the face of whatever the climate has in store.
With climate change on the radar (but too big for the average person to really digest), we all need to shift towards lifestyle measures that will help us live in balance with Earth’s capacity to meet our needs.
The Hydrologic Cycle – a refresher:
The hydrologic cycle is something you probably learned about in the 4th grade, but everybody can use a refresher. Water evaporates from Earth’s surface and condenses into clouds. Clouds create precipitation. Some of the water that falls infiltrates to recharge groundwater, and some runs off into rivers, lakes, and the ocean. From there the whole process starts over. This has been happening since the beginning of time. The part that many of us forget is that we have just as much water on the planet as we ever did… and we always will!
So What’s All the Fluster about the California Drought?
Even though the planet has as much water as ever, humans have drastically impacted the hydrologic cycle and how the water is distributed. We have built our environments to shed water off, rather than welcome it back into the ground where it belongs.
Here’s the thing: modern cultures create hardscape virtually everywhere we go. Hardscape is defined as any surface that water cannot penetrate. This includes roads, parking lots, and the roofs over our heads. Interestingly enough, lawns also qualify as hardscape, with dense roots preventing infiltration and, if sprayed or fertilized, lawns actually add more pollutants to the runoff that sheets off them.
The crux is that we’ve broken the infiltration link in the hydrologic cycle by laying down surfaces that water can’t get through. Moreover, all of this hardscape adds pollutant load to the increased volumes of runoff (think automotive chemicals, pesticides, etc.).
How Humans have Changed the “Nature” of Water
In a natural environment, roughly 50% of the rain that falls on the ground infiltrates. This serves to hydrate soils, recharge shallow and deep aquifers, and maintain base levels in rivers and streams. About 40% evaporates or evapotranspirates, and the remaining 10% becomes runoff.
Let’s compare that to developed environments like our towns and cities. In a developed landscape, only about 15% of rainfall infiltrates, and a whopping 55% becomes runoff.
Yikes! Let’s stop for a minute to really process this. We’ve virtually flipped nature on its head as far as the hydrologic cycle is concerned. Instead of allowing water to infiltrate and replenish the water table, we send it swiftly away. This runoff sheets off our expansive hardscapes, causing erosion along the way, and polluting our sensitive waterways. In dry climates this causes droughts to be much more pronounced. In wet climates, it makes stormwater loads unmanageable.
The Problem with Runoff
The extreme quantities of runoff generated in our urban and suburban environments have become one of the most pressing environmental issues of our time.
Also known as “nonpoint source pollution,” these amplified volumes of runoff pick up chemicals and nutrients and swiftly deliver those to our sensitive waterways. The increased runoff also causes streambanks to erode, stripping our waterways of their natural defenses. According to EPA, stormwater runoff is the single largest contributor to water pollution.
This is a good time to note that in nature, runoff is actually not the primary contributor to stream flows. In undeveloped environments, only 10% of precipitation enters waterways as runoff. The majority of water replenishes the water table, and groundwater is what maintains the base flows in our rivers and streams.
How does Rainwater Harvesting Help in ALL Climates?
Rainwater harvesting is the simplest direct way to mitigate the hardscape on your property – and it is essential your efforts to get back into sync with the environment – in any climate zone.
Harvesting rainwater helps take the peak off of storm loads, and makes water available during dry spells. Every drop we use from a rain tank is a drop we don’t take from our overdrawn collective water resources.
In dry climates, we’re focused on the water conservation side. In wet climates, rainwater harvesters are motivated by reducing stormwater impacts.
But in fact, people in all climates benefit from both sides of the coin. Even drought-ridden areas experience severe stormwater impacts when it does rain (if you’ve stuck with me through this whole article, you know exactly why: all the hardscape and parched earth prevents water from infiltrating). In wetter climate zones, shorter periods between rains mean users can more easily rely on collected rainwater as a primary irrigation source. Those of us who use rainwater in the garden help keep our soils hydrated, with excess seeping back into the ground where it belongs. This helps to mimic nature’s infiltration patterns, and also keeps soil biology active and healthy.
All this is to say, by harvesting rainwater, you are essentially mitigating some of the impact created by your roof.
Hint for Advanced Rainwater Harvesters:
Once you see how quickly your rain barrels fill, take the opportunity to bleed some of your water off into an infiltration basin during the dry times between storms. This will help get more water back into the ground, and free up capacity to collect more the next time it rains. You can also pump water into more accessible tanks to free up capacity to collect more. Click here to learn how!
Keep harvesting, folks – and you don’t have to wait for the next fear-based news piece on the California drought. Those who harvest rain enjoy the benefits of increased resilience and self-reliance, and healthy plants and soils.