Rainwater Catchment from a High Tunnel for Irrigation Use
High tunnels, also referred to as “hoop houses,” are simple, plastic-covered, passive solar-heated structures in which crops are grown in the ground. High tunnels resemble greenhouses, but are less expensive to construct and maintain. Fruit and vegetable growers use them to extend the growing season and intensify production in cold climates. The advantages of growing crops in high tunnels rather than in fields are:
- Extended seasons
- Weather protection
- Labor efficiency
- Environmental control
- Reduced incidence of plant diseases
- Improved quality
- Increased revenue per square foot
High tunnel production is considerably different from field production. More detailed attention is required on water and nutrient management, temperature control, crop selection, and continuous production strategies. The covered area in a high tunnel creates a desertlike environment so irrigation is required. Also, since every square foot offers profit potential, high tunnel production requires additional attention to appropriate drainage around the structure. The expanse of a high tunnel yields a large volume of water with every measurable rainfall. Approximately 900 gallons of water Rainwater Catchment from a High Tunnel for Irrigation Use will flow from the roof of a 30' by 96' high tunnel with a half-inch rain event. Unless the high tunnel site is elevated from the surrounding area and/or has drainage tiles installed around the perimeter, water accumulates and creates puddles around the sides of the high tunnel. This can create erosion problems as well as saturated soil on the inside edge of the high tunnel.
Described in this publication is a system to catch, store, and reuse the rainwater for irrigation in the high tunnel. The amount of water collected from periodic rain events often can be enough to irrigate and sustain a high tunnel for a few days to weeks. However, the water supply is not consistent and should not be the only water source for high tunnel crops. The ideal time to install a gutter system is at the time of construction because excess plastic from the cover can be utilized and support boards can be installed efficiently. However, gutters can be retrofitted on existing high tunnels.