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[[Image:riverbed infiltration galleries icon.png|right]]
[[Image:OmoRiver.jpg|thumb|right|300px250px|The Omo River in Ethiopia, Africa. <br>Photo: [http://www.flickr.com/photos/neslab/6826784275/ Davide Comelli.]]]
Channels take water from a riverbed to a collector well in the riverbank. They are often screens (slotted or perforated pipes) that are inserted horizontally into a riverbed, but also infiltration galleries can be made from channels with graded gravel as long as sediments are not washed into the collector well. Where screens are used, the screen diameter tends to be larger than that used normally for jetted/driven wells.
'''General advice on cement''': A common cause of cracks in structures and linings (e.g. in tanks, dams, waterways, wells) is errors in mixing and applying the cement. First of all, it is important that only pure ingredients are used: clean water, clean sand, clean rocks. The materials have to be mixed very thoroughly. Secondly, the amount of water during mixing needs to minimal: the concrete or cement needs to be just workable, on the dry side even, and not fluid. Thirdly, it is essential that during curing the cement or concrete is kept moist at all times, for at least a week. Structures should be covered with plastic, large leaves or other materials during the curing period, and kept wet regularly.
[[Image:InfiltrationGalleryDiagram.jpg|thumb|right|300px250px|Infiltration gallery. <br> Drawing: © Ken Chatterton. In: Hussey, S.W. (2007) Water from sand rivers: guidelines for abstraction. WEDC, Loughborough University, UK.]][[Image:InfiltrationGalleryBuild.jpg|thumb|right|300px250px|Building an infiltration gallery. Infiltration Area: 1080 ft2 (100.3 m2). Cost - $9.33/foot2. Overseas supplier (AUS).]]
====How deep is the water table?====
Since the trees below must have their tap root in the water table, the depth of a water-table can be found by knowing the depth of the tree’s tap root. A rule of thumb states that the tap root of a tree has a depth equal to about 3⁄4 of the height of the tree. The height of a tree can be found by measuring the length of the shadow the tree is casting on the ground and comparing it with the length of the shadow of a stick 100 centimeters long. The two measurements should be taken in the sunshine of early morning or late afternoon when the shadows are longest. For example: If the stick’ shadow is 80 cm long, the ratio is: 80/100 = 0.8. If the tree’s shadow is 12 m long, then the tree is: 12 m x 5 / 4 = 15 m high and the tap root and water level is at: 15 m x 3⁄4 = 11.25 m depth.
[[File:WaterTableDepthChart.jpg|thumb|center|400px|Click on chart to zoom in.]]
====Other considerations====
