Rice Irrigation Systems for Tailwater Management (6/7)
J.E. Hill, S.C. Scardaci, S.R. Roberts, J. Tiedeman, J.F. Williams
Float Valve Rice Boxes
To improve the conventional system replace the conventional rice weir boxes with a "smart box." A smart box operates on the same principle as a toilet tank or a horse trough valve. It consists of a float valve, mounted downstream end of a pipe that passes through a levee to connect adjacent rice basins. The float valve allows only enough water to pass through the pipe to maintain the desired water depth on the downstream side. An entire series of basins can be self-regulating, with respect to water depth, as long as inflow is not limiting.
| Figure 8. Close-up of a "smart-box" between 2 levees. |
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 The plastic container or float of a smart box is adjusted so that it opens and closes a vertically hinged butterfly valve (fig. 8). When the water in the downstream basin is low, the plastic container floats downward and opens the flapgate, allowing water into the basin. When the water depth reaches the set level (adjustable by adding or removing water from the hollow plastic float) the container floats upward, closing the valve: water cannot enter the basin. As long as a source of water is available to the topmost basin, the series of basins is self-regulating. Each basin takes in water as needed, and shuts off when the desired water depth is reached, thereby eliminating the day-to-day management associated with traditional flashboard weirs. Once smart boxes are properly adjusted, no spill from them should occur from the bottommost basin.
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