Rainout Shelters: Some Basic Principles of Design and Operation

Rainout shelters are designed to protect a certain area of land against receiving precipitations so that an experimentally controlled drought stress can be imposed on that area. Many types of rainout shelters were designed and used, with better or lesser results. This is not a comprehensive review of this system but a concise discussion of the most important issues in designing, constructing and operating rainout shelters.

There are two main designs: (1) static and (2) movable. Within the moveable design there are automatic/motorized and manual versions. The automatic version is signaled to move over the protected plot by a rain sensor and an electric drive system. The manual version is moved either by manually switching the drive on ("manually driven") or by manually pushing it ("manually pushed") over the protected plot. The 'manually pushed' must by lightweight and hence it is cheaper and can cover a limited land area. The automatic version is becoming less popular because of reliability problems and cost. Hence, many automatic types become 'manually driven' after the first failure of the automatic system. The earlier automatic shelters were designed without any consideration for light transmission because they were not expected to remain over the protected plot for a long time..

The manual version is moved from its parking spot onto the protected plot whenever a rain is expected and not when the rain begins. It is moved into the parking space whenever rain is expected to cease completely. Good weather forecasting service is therefore important. If forecasting is unreliable, better have the shelter over the protected plot more time than expected. Therefore, the shelter construction must allow sufficient light inside as well as some ventilation.

The direction of the protected plot and the parking place of the shelter should be designed so that the parked shelter will not shade the plot in the morning or the evening and that the direction of the wind would not allow rain to blow under the shelter. The shelter parking place cannot be used for growing experimental plots.