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Riverbed jetted and driven wells

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{{Language-box|english_link= Riverbed jetted and driven wells | french_link= Coming soon | spanish_link= Coming soon | hindi_link= Coming soon | malayalam_link= Coming soon | tamil_link= Coming soon | korean_link= Coming soon | chinese_link=河床喷射井与管井 | indonesian_link= Coming soon | japanese_link= Coming soon }}[[Image:riverbed jetted and driven wells.png|right|80px]][[Image:dry riverbed well.jpg|thumb|right|300px200px|Halima Bidu collects water from a deep earth well on a dry river bed. Photo: Siegfried Modola/Shoot the Earth/[http://www.actionaid.org/2011/08/why-drought-about-power-not-rain ActionAid]]][[Image:JettedDrivenWellPoint.jpg|thumb|right|370px200px|Jetted / driven well point. Photo: WEDC © Ken Chatterton.]]__NOTOC__<small-title />

This category includes short small diameter cylindrical screens (slotted or perforated pipes) that are inserted into unconsolidated sediments using water pressure or physical force, usually vertically or obliquely. Digging is not needed in this case.

===Suitable conditions===

Due to pumping requirements, it is best to site these wells:

* Within 30 metres of the pump location.

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! width="50%" style="background:#efefef;" | Advantages

! style="background:#ffdeadf0f8ff;" | Disadvantages

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| valign="top" | - Speed and low cost of construction <br>

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 ===Construction, operations and maintenance===

The screens and pipework should be ideally 1.5 metres minimum from the riverbed surface. This is so that:

* There is at least a minimum of infiltration that occurs from surface water during the wet season when the river is flooded.

* During the jetting process, water emerges from the end of the jetting pipe and flows upwards to ground level. If the flow of water stops (e.g. water runs out, or to change a pipe), in most circumstances the sand around the jetting pipe/screen will collapse, after which it is impossible to re-start the flow of water to the surface. However, in some cases the hole will remain open – only in these cases can you add another pipe and continue jetting, but otherwise the depth you can install the screen is dependent on the length of jetting that can be done in one go without stopping the pump.

* Digging a large pit to the water table is advantageous since:

# In collapsing sands, you can jet to the base of the pit, after which you can glue extra pipes onto the screen to reach ground levelso level, so that a deeper well is achieved.

# The chance of losing the water column is minimized due to less pressure head that the water must overcome in order to flow to the surface. With higher pressure heads (i.e. more distance from water level in ground to ground level), the water is more likely to choose the path of least resistance, which at some point will be to go into the aquifer rather than come to the surface. In such a case where you lose the water column in collapsing sands, the well will be finished at that depth.

* A screen can have a ball valve at the end – in this case, the jetting pipe and screen are made from the same piece. Alternatively the screen can be separate from the jetting pipe, where the jetting pipe creates the hole and then is removed once the screen is installed to required depth. If a screen with valve is chosen, care should be taken if installing handpumps as the ball valve has a tendency to open over time letting in sand.

Extracting water can be done with handpump or mechanical pump. Handpump cylinder will need to physically be able to fit inside the screen that has been installed.

==Costs== =Manuals, videos and links=Field experiences==* [http://www.indiawaterportal.org/articles/well-revival-effort-sees-many-other-benefits Well revival effort sees many other benefits] A community drive to revive wells in Mokhla talab near Udaipur results in water security for longer periods of time as well as making leaders out of women.==Manuals* [http://www.indiawaterportal.org/articles/experiments-community-wells Experiments with 'community wells'] Mobilized farmers in Dhule, videosMaharashtra, show how communities can use groundwater as a common resource in an organised and links==collective manner.

===Acknowledgements===* CARE Nederland, ''Desk Study : [[Resilient WASH systems in drought -prone areas.'' ]] October 2010.

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