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[[Image:riverbed hand dug well.png|right]]
[[Image:RiverbedHandDugWell.jpg|thumb|right|350px200px| Hand-dug wells situated in riverbeds must be equipped with a well-head to prevent the well shaft being filled with sand during floods such as this hydro-dynamic well-head used in Sudan. It is shaped as a wedge to break the force of floods. © E. Nissen-Petersen, Kenya.]]
These are shallow wells which draw water from a natural or man-made aquifer specifically within a riverbed. The simplest version of these is a shallow hole dug every season in a riverbed which gets flooded with every flood event. Other versions allow the water to be accessed all year round through [[Handpumps]] or [[Small and efficient motor pumps]]. A bucket and rope can be used but risk of contamination increases. In such a case, household water treatment should be advocated.
===Suitable conditions===
* Wells need to be sited in riverbeds that are dry for part of the year, allowing construction to take place.
* There should be water remaining in the riverbed throughout the dry season.
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! width="50%" style="background:#efefef;" | Advantages
! style="background:#ffdeadf0f8ff;" | Disadvantages
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| valign="top" | - Taps water in riverbed rather than through riverbanks (if very defined aquifer where water is confined to riverbed) <br>
===Resilience to changes in the environment===
====Drought====
'''Effects of drought''': Can dry up.
More information on managing drought: [[Resilient WASH systems in drought-prone areas]].
===Construction, operations and maintenance===[[Image:RiverbedWellWithHandpump.jpg|thumb|right|350px200px| Riverbed well with offset handpump. Eric Fewster, BushProof. <br> (Click image to zoom.)]][[Image:NewRiverbedWell.jpg|thumb|right|350px200px| New riverbed well. The new well's ''hydro dynamic'' design means it won't be washed away or destroyed by fast flowing rivers during the rainy season. These wells provide cleaner, fresher water, and are safer than climbing into unprotected holes. They are time saving too as traditional wells have to be re-dug each dry season. Photo: Jane Beesley.]]
'''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.
The use of porous concrete in part of the section of the well shaft which is underwater can help increase flow velocity into the well. Porous concrete is made using a of 1 : 1 : 4 (cement : sand : aggregate) and can be used for curved blocks or also for a central portion of any pre-cast concrete ring. Also perforated pointed steel pipes can be driven horizontally into the aquifer using a jack – this can also increase flow velocity into the well.
==Costs== ==Field experiences== ==Manuals, videos, and links===
* [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDwQFjAA&url=http%3A%2F%2Fwww.waterforaridland.com%2FBooks%2FBook3%2520water%2520from%2520dry%2520riverbedspdf.pdf&ei=FyCGT8H-BK_YiQLG89DADw&usg=AFQjCNFLQVx1iso2008fkzuXgEsFbVPbGA&sig2=RO5ls6wQeRCQKrTLDC4zwA Water from dry riverbeds]. Advises how to survey a river and much more. Danish International Development Assistance (Danida).
* [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=28&ved=0CG8QFjAHOBQ&url=http%3A%2F%2Fwww.bvsde.paho.org%2Ftexcom%2Fdesastres%2Foxfihdwe.pdf&ei=pSeGT_evJqKiiQLgkfnvDw&usg=AFQjCNEBJyUS8eIPtEa6X6RajICMYNm_vw&sig2=_ikbSJRiaWbfPnvFAqCbPQ Hand-dug well equipment]. Covering well auger survey, well digging, dewatering and desludging kits. Oxfam Water Supply Scheme for Emergencies.
===Acknowledgements===
* CARE Nederland, Desk Study: [[Resilient WASH systems in drought-prone areas]] October 2010.
