High Tunnel Rain Collection
High Tunnels, otherwise known as hoop houses, are plastic-covered, solar-heated structures similar to greenhouses. Farmers use these high tunnels to protect their fruits and vegetables from cold temperatures, and extend their growing season. Iowa State University has come out with a high tunnel design to capture rain water for irrigation use. The design calls for gutters to be installed on the outside of the plastic frame, set at an angle to capture rain. At the end of the angled gutters, they have set up two water storage tanks with hoses attached to utilize the stored water for irrigation.
To prevent overflow, they came up with a simple, yet elegant solution: attach a plug to a floating vinyl ball. When the tank is at full capacity, the floating ball plugs the gutter, and redirects the excess water to an overflow gutter. Hoses running from the storage tanks are run through a filter, and then pumped to the plants. For extra environmental credit, Iowa State included a design for running these pumps with a battery charged with solar panels. In a temperate climate, their research shows that the design could gain up to half of the required water from this method. See the video of construction here.