By guest blogger Erik Ohlsen and Permaculture Artisans
The heavy rains in California this winter, coming on the heels of years of drought, highlight the need to rectify our relationship to water, both as individual land stewards and communities alike.
Home-scale solutions can make immediate impacts on our ability to address both drought and flood problems while also contributing to the health and well being of nearby streams and fish. But perhaps more important to address is a shift in our perspective in terms of how we see and approach water management on our landscapes in context of our local watersheds and our place in them.
A sensible relationship with water is a key factor that has been missing from the management of our landscapes over the last 100+ years. The development industry has thought of water as a negative that needed to be drained away lest it destroy our structures and cause flooding.
We need to think about water within the context of runoff
Since we have built towns and cities with a “drain away” design, we have created our own drought. If we examine the amount of stormwater which drains away from buildings, roads and farmlands, we’d be shocked by the volume of water we cause to flow away from where we need it most – water that, as it runs off, actually increases the risk of flooding.
Managing stormwater in ways that maximize its infiltration potential within our landscapes is the key to all of this. Putting it into perspective, the Winter of 2014-15 in Sonoma County, saw approximately 20 inches of rain, or roughly half the average rain we get in a “normal” year. But 20 inches is still a lot of water! One inch of rain over 1 acre is approximately 27,000 gallons of water! One inch on 1,000 ft.² of roof yields approximately 620 gallons. In a 20-inch year, 12,400 gallons of water falls on a 1000 ft.² roof, and we still have millions of gallons flowing through our rural, suburban and urban communities. We can use this water!
Water needs to be the first element designed into a landscape
By integrating water into all our developments and all future planning, human and ecological systems can thrive.
The best place to put water is into the soil, which has a phenomenal capacity to store it. Think of soil as a water “battery.” It can hold an incredible charge. We just need to charge it up safely. We do this by “slowing, spreading, sinking, and saving” the water that falls and runs on our landscape.
We can immediately implement solutions that will store literally millions of gallons of water per year. You can do it too!
Water-Catchment and Flood-Mitigation Planning
Whether planning for a new development, or as is more often the case, mitigating and re-designing existing landscapes, here is a step-by-step process for designing water-catchment and flood-mitigation plans for your property.
1) Assess your drainage needs – Identify areas where you need to drain water away. Water can damage houses, roads, pathways and other built structures, which all need good drainage.
2) Design your storage system – Decide if catchment is right for you and identify the best locations for tanks, ponds or cisterns. Once drainage and storage locations are identified, they become the basis for your entire water management plan.
3) Develop a water infiltration plan – Identify opportunities to allow water to sink into the soil. Think of the side of roads and pathways, in landscapes, farmlands, pastures, forests, parks, and other areas where there is no danger to structures. Usually there are more places to let water infiltrate than we realize. This can help to recharge groundwater while also protecting nearby creeks from erosion sediment that can have a negative impact on fish populations.
4) Be smart about your design – Be purposeful when planning infiltration systems in the landscape or on the farm. The best ideas are usually those that integrate other needs like food production. Strategically locating elements where they can serve more than one function and work in symbiotic relationship with other elements will cut energy use and raise yields. For instance, a privacy screen can also act as a water infiltration system if it is planted on top of a rain garden. If you use edible plants, you now have an edible water-harvesting privacy screen that yields a variety of food and serves several functions. Successful design needs to adapt to the constraints of your soil, climate, topography and context in your greater hydrological ecosystem.
Water infiltration techniques that manage water across landscapes – often called “earthworks” – offer a variety of ways to shape and grade the soil to fulfill multiple functions and uses. Whether it’s contour swales, rain gardens, or terraces, the appropriate technique needs to reflect the ultimate goals and design of the space to achieve good function, stability, safety, environmental health and aesthetics.
Harvesting water is vital, but we have to design for flood protection too
A big source of flooding is the enormous amount of manageable stormwater running off of landscapes, houses, roadways, and agricultural soils. This quickly inundates low-lying land because it has nowhere to infiltrate. With no water being absorbed in the upper reaches of the watershed, an enormous volume of water floods into our creeks and rivers.
We need to turn our built environments and our agricultural lands into water-catchment, water-absorbing systems.With an ecological design approach, we can actually drought-proof our communities and reduce the threat of devastating floods at the same time.
Water is the basis for life. So let us ensure that the waters of our planet run free and clear for all living things. If we want a viable future for our children and grandchildren and security for ourselves in the here-and-now, we must fundamentally change our relationship to water.