In harvesting rainwater, the overwhelming majority of the attention is focused on active rainwater collection systems - that is systems with tanks and pumps. Passive rainwater catchment is too often overlooked, and yet, a very impactful and important practice.
Passive rainwater collection is the art of slowing down rainwater and letting it infiltrate locally rather than channeling it too quickly running off the land. It promotes healing of the land and treats rainwater as an asset rather than a problem. It has been practiced for centuries; however, with the advent of deep wells and cheap electricity to drive big pumps, it has all but been forgotten.
However, with droughts, significantly larger storm events and the new emphasis on building green; it maybe getting a second life. But even today many doubt the connection between rainwater, surface water, and underground water. In looking around at how we live, there seems to be no understanding in our "modern" urban planning that the connection between stormwater (i.e. rain that becomes stormwater in rain events, than running into streams too quickly and not having a chance to recharge the aquifier) - and groundwater is strong and direct.
An extremely well made DVD by The Cuenca Los Ojos Foundation highlights this connection and how it can actually heal the land if properly managed. The foundation works to preserve and restore the biodiversity of the borderland region between the United States and Mexico through land protection, habitat restoration and wildlife reintrodion.
In this land that gets more sun than water. With a topography that varies dramatically; going down slope from mountain crests at 9,000 feet, pine trees give way to oaks; mesquite and grasslands give way to mixed desert shrub. During the monsoon, water gushes out of the mountains and courses through the flatlands, bringing the washes to life.
For the past eighty years, the rainwater and overflow from an artesian well have drained off the cienega, causing serious erosion at the edges of the fields. Now these areas have been plugged and are creating shallow pools in their place. With each succeeding year the level of the streambed rises as silt is deposited behind the gabions. When the level becomes even with the lowest bank the flood waters flows over the cienega as they did in the past, but has left behind precious silt and seeds to create a new micro-ecosystem where none existed before. In order words, passive rainwater harvesting has helped to bring this wild and desolate area back to life.
This beautiful 30-minute movie, is great for all ages, and depicts the changing of the land with the introduction of passive rainwater catchment, not in decades, but in just a few years. It is a powerful and awe inspiring visual testament to the art of passive rainwater harvesting.
The property is dotted with ancient small rock walls crossing old streambeds. Some of these stacked rocks, probably dating back to 900 AD, show that passive rainwater catchment had been part of the managing water on the property for centuries. Since the property was purchased and has now been turned into a foundation, over 20,000 of these structures have been built. Turning a great wasteland back into a mecca of wildlife and plants. The film also documents the creation of a half mile berm to slow down rushing rainwater from three mountain drainage areas, bringing back to life streams that had been dry for years.
This marvelous movie ($15 including shipping!) is a wonderful piece for anyone interested in educating themselves or others on the truly amazing power of passive rainwater management. Buy two and give one to the local library.