Yield Equations for Bed-Mounted Infiltration Galleries

Infiltration galleries are constructed near surface waters to induce recharge for water supply and irrigation diversion projects. Technical guidance for the hydraulic design of bed-mounted infiltration galleries is limited. We review the gallery yield equation presented by Driscoll, which appears to be an ad hoc application of the Thiem equation. Driscoll's results provide a relatively crude approximation of the flow conditions within a typical gallery. New yield equations that better represent typical gallery flow geometries are then developed by complex analysis and presented as dimensionless design charts. Comparison with the new solution shows that the Driscoll equation provides conservative results, underestimating yield by factors of approximately two; Driscoll's equation should be used with caution. The new yield equations are modified using the method of fragments to include the effects of a filter layer at the stream bed and skin losses at the drain, extending their use and providing a more rational basis for analysis and design of bed-mounted infiltration galleries.