We have developed a novel siphon-infiltration trench system to mange water and sediment budgets in riparian systems. We have demonstrated in the laboratory and developed a numerical model showing the three hydrologically-distinct flow regimes in a infiltrating siphon system: 1) infiltrating flow at low-flow rates, 2) cycling outflow at intermediate-flow rates, and 3) constant outflow at high-flow rates. These flow regimes are dependent upon infiltration gallery design, soil hydraulic conductivity, and rainfall intensity. Part of the water entering the infiltration trench infiltrates into the soil, while part of the incoming water is periodically flushed out by the nonliner flow behavior of the siphon. The coupled behavior of the infiltration trench and siphon results in the system being self-cleaning. Stormwater or overland flow can be captured and injected into a modified infiltration gallery attached to a siphon and emplaced adjacent to a stream or arroyo bank. This injected soil water can be used for streamside vegetation, surface-water treatment, riparian restoration, bank stabilization or other purpose. The design is simple, low-cost and self-cleaning. ANTICIPATED RESULTS & POTENTIAL COMMERCIAL APPLICATIONS OF RESEARCH Few cost-effective tools exist for controlling runoff or for improving riparian systems. In addition, improvement of surface-water quality is now an environmental priority. American agriculture, in particular, is facing increasing public and regulatory pressure to reduce nonpoint source pollution from fields and rangeland and runoff from livestock operations. By infiltrating runoff, water can be stored and treated in riparian zone soils leading to better water quality and increased water availability. The measured and modeled characteristics show potential for use in improving surface water quality, maintaining stream base flows, establishing riparian vegetation, and reducing bank erosion and downstream sedimentation.
