In-channel modifications

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• Groundwater recharge dams are built in a streambed, and designed to collect stream runoff water in a surface water reservoir upstream of the dam. To provide recharge to groundwater, either the surface water reservoir upstream of the dam serves as a percolation pond, or water is released through pipes to infiltrate in the downstream riverbed.
• Subsurface dams refer to structures designed to contain underground flow, from a natural aquifer or from an artificial one, built with an impermeable barrier. It creates an area of groundwater storage upstream of the dam, raising the water table.
• Sand storage dams are constructed above ground in an ephemeral river bed. During periods of high flow, sand and gravel accumulates against the dam. Runoff water can easily infiltrate these highly permeable soil deposits, creating an artificial aquifer upstream of the dam.
• Mini-earthen check dams and permeable rock dams are gullies and ravines are transformed into small streams at the base of hills and divide the agricultural and non-agricultural land in to various segments. These streams are converted into series of mini water reservoirs by constructing check dams.
• Channel spreading techniques increase the wetted area and infiltration rate. Widening, leveling, scarifying and dredging of streambeds are all examples of this technology. Using "L"-shaped levees, the pattern of the surface flow in the river channel is changed, slowing the rate of river flow and increasing the channel length to provide more time for infiltration. i>Stream flow augmentation is a special case, which involves application of recharge water to a stream channel near the head of its drainage area to re-establish or increase infiltration through the stream bed. It is considered a recharge alternative in areas where streams fed by groundwater have ceased to flow of have become dry in their upper reaches.

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