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[[Image:94px-Icon_sanddam.png|right|80px]]
[[Image:Sand dam.JPG|thumb|right|200px|Sand dam construction in Kitui, Kenya. Photo: M. Hoogmoed.]]
'''Sand dams ''' are a simple, low cost and low maintenance, replicable rainwater harvesting technology. They provide a clean, local water supply for domestic and farming use and are suited to semi-arid areas of the world.
Regions with highly erratic rainfall often have rivers with temporary seasonal sandy bed streams. They only experience heavy water run-off for short periods of time after rain. During such periods of high flows, large quantities of sand are transported downstream. Some sand can get trapped on the upstream sides of rock outcroppings along the stream. The sand traps form natural water storing aquifers. Sand dam technology provides a means to reproduce this water collecting mechanism and to increase the size of existing aquifers.
Sand dam projects here have not only improved water availability, but benefited the community socially and economically. Locals are trained to participate in construction of the dam, maintenance, financial management, and also in natural resource management.
===Suitable conditions ===[[Image:Sand dam flood.JPG|thumb|right|200px|Sand dam during flooding. Photo: [http://www.rainfoundation.org/index.php?id=151 RAIN Foundation.]]]
Sand dams can be constructed and used for household, community and even municipal uses. There are examples of sand dams which are connected via infiltration galleries, off-take wells and pump stations into municipal piped water systems.
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<br> ===Resilience to changes in the environment===
====Drought====
'''Effects of drought''': Can dry up; Water yields low. <br>
Sand dams require careful maintenance, and immediate repair, as flooding causes hundreds of tons of water to fall over the dam wall and onto the spill-over apron. Flood water may also spill over and erode the wing walls and, perhaps, even over the riverbanks during heavy rains. When determining the dam and spillway height at the selected location, it is very important that the water level and flood line remain below the riverbanks after construction of the dam, or that flooding will not lead to problems up or downstream of the dam. If the flood level is higher than the riverbanks, construction of a dam is not advisable.
===Construction, operations and maintenance===
[[Image:Sand dam diagram.JPG|thumb|right|200px|Cross section of a sand dam.<br> Diagram: Netherlands Water Project. <br>Click image to see details.]]
[[Image:Sand dam trench.JPG|thumb|right|200px|People excavating a trench. Source: [http://www.sswm.info/category/implementation-tools/water-sources/hardware/precipitation-harvesting/sand-dams RAIN (n.y.)]]]
The lifespan depends on the materials used and expertise with which it is constructed and maintained. The dams in Kitui Kenya were built at a cost of US$7,500 and have a minimum lifespan of 50 years.
===Costs===
The construction of dams is largely carried out by the local community. Costs mainly relate to local availability of cement, masonry and professional supervision.
The cost to benefit ratio for the sand dam's first year of operation is 1:12.
===Field experiences===
In Kenya, it has been used with good outcome in the Kitui, Machakos and Samburu districts. Other countries with similar dry environments such as the U.S.A, Thailand, Ethiopia and Namibia also have used it in numerous and diverse forms.
Communities in this area depend on agriculture and livestock farming, which is very limited due to the unstable water supply. In 2007 several NGOs implemented 7 sand dams and 10 surface runoff tanks. This combination should provide a reliable source of water for 10 communities in the area. The project will in the future expand to other parts of the country also.
====Akvo RSR Projects====The following project utilize sand dams.<br>{|style="border: 2px solid #e0e0e0; width: 7060%; text-align: justify; background-color: #f5f5f5e9f5fd;" cellpadding="2"<!--rsr logo here-->|- style="vertical-align: top" |[[Image:akvorsr logo_lite.png|center|60px|link=http://akvo.org/products/rsr /]]<!--project blocks here-->|- style="vertical-align: bottom"|[[Image:project 393.jpg|thumb|nonecenter|200px140px|<font size="2"><center>[http://rsr.akvo.org/project/393/ RSR Project 393]<br>Dawa Eresa Subsurface and Sand Dam project</center></font>|link=http://wwwrsr.akvo.org/rsr/project/393/]]|'''Akvo RSR Project[[Image:''' project 404.jpg|thumb|center|140px|<font size="2"><center>[http://wwwrsr.akvo.org/project/404/ RSR Project 404]<br>Feasibility Study for Rainwater Harvesting</center></font>|link=http://rsr.akvo.org/project/393404/ Dawa Eresa Subsurface and Sand Dam project]]This |[[Image:project aims to provide the people in Konda and Kora with access to water674.png|thumb|center|140px|<font size="2"><center>[http://rsr. Currently the water source they use is of poor quality without year-round accessakvo.By constructing a sand dam and subsurface dam that harvest rainwater, the people will gain year-round access to water of better qualityorg/project/674/ RSR Project 674]<br>Wateroogst: <br> Konso Woreda/Eshimale</center></font>|link=http://rsr. This will reduce the time spent on collecting water and thus free time for school enrollment for children and other activities for womenakvo.org/project/674/ ]]
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<br>
{|style="width: 70%; text-align: justify; background-color: #f5f5f5;" |[[Image:rsr 404.jpg|thumb|none|200px|<font size="2"><center>Project 404</center></font>|link=http://www.akvo.org/rsr/project/404/]]|'''Akvo RSR Project:''' [http://www.akvo.org/rsr/project/404/ Feasibility Study for Rainwater Harvesting]The feasibility study area will be in Mashuru and Namanga districts, Kajiado County in Rift valley region. The main focus will be carrying out technical and socio-economic evaluation and feasibility for sand /sub-surface in Kajiado County to create access to safe, sustainable and affordable drinking water. The study will provide a basis for decision making such as piloting, up-scaling and collaborative support for the project.|} ==Manuals, videos and links===* MANUAL: [http://www.rainfoundationsamsamwater.orgcom/fileadmin/PublicSite/Manualslibrary/Sand_dam_manual_FINAL.pdf A practical guide to sand dam implementation]. Rainwater Harvesting Implementation Network (RAIN).
* MANUAL: [http://www.samsamwater.com/library/Manual_on_SAND_DAMS_in_Ethiopia.pdf Manual on sand dams in Ethiopia]: A practical approach on sand dam site selection, design and construction. A tool for combining sand dams with other rainwater harvesting structures. ERHA (Ethiopian Rainwater Harvesting Association) and RAIN Foundation.
* MANUAL: [http://www.internationalrivers.org/resources/before-the-deluge-coping-with-floods-in-a-changing-climate-3987 Before the Deluge: Coping with Floods in a Changing Climate]. How to adapt to floods caused by climate change. International Rivers Network.
* MANUAL: [http://practicalaction.org/docs/technical_information_service/sand_dams.pdf Sand Dams: Feasible Rainwater Harvesting Technology for Arid and Semi-arid Lands]. Practical action.
* DOC: [httpshttp://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDIQFjAA&url=http%3A%2F%2Fwescoordwescoord.or.ke%2Fdocuments%2FSandDams%2FFAQsonSandDams/documents/SandDams/FAQsonSandDams.doc&ei=VEWNUcXjMJCK9gSY_oCQCQ&usg=AFQjCNFxQR3BMwTlMMAkH77Q9-Vgyyj55A&sig2=ipWV5PXKshcFesepNeOdcw&bvm=bv.46340616,d.eWU FAQs on Sand Dams]. Provided by Excellent/ASDF with input from Dabane Trust.
====Videos====
====Links====
* [http://www.excellentdevelopment.com/home Excellent: Pioneers of San Sand Dams].* [http://wwwacaciawateruk.sanddamstandaardsite.org www.sanddam.org nl/pg-29143-7- All information on sand dams]* [http://acaciawater.com/site/pages89562/engpagina/homewelcome.php html ACACIA Water]. The strength of Acacia Water is the specialization in the field of groundwater, while at the same time being able to place issues in a broader perspective and to link up with other fields of action. As a result we often work in a multidisciplinary environment with a broad variety of expertise.
* [http://www.iah.org/recharge IAH]. IAH-MAR is a forum for information on the work within the international groundwater community on the management and enhancement of aquifer recharge, a vital tool in the sustainable management of the world's underground water resources.
===Acknowledgements===
* CARE Nederland, Desk Study: [[Resilient WASH systems in drought-prone areas]]. October 2010.
* Brikke, François, and Bredero, Maarten. [http://www.washdoc.info/docsearch/title/117705 Linking technology choice with operation and maintenance in the context of community water supply and sanitation: A reference document for planners and project staff] or ([http://www.who.int/water_sanitation_health/hygiene/om/wsh9241562153/en/ alternative link]). World Health Organization and IRC Water and Sanitation Centre. Geneva, Switzerland 2003.
* Maddrell S and Neal I, [http://www.samsamwater.com/library/Maddrell_and_Neal_2012_Sand_Dams_a_Practical_Guide_LR.pdf Sand dams: a Practical Guide], Excellent Development, London. 2012.
* Jacob H. Stern, Ph.D and Alvera Stern, Ed.D, et al. [httpshttp://wwwc.googleymcdn.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC8QFjAA&url=http%3A%2F%2Fechonetsites/www.echocommunity.org%2Frepositories%2Fdownload%2F964%2Fwesterhof%40irc.nl&ei=EwGQUdb8OYHO0wHvyYHwCA&usg=AFQjCNHsU/resource/collection/E66CDFDB-0A0D-4DDE-8AB1-5eYAA2HePCB2H4actFaJPEVw&sig2=JM2F0HxeWdudXmgeeOHkEw&bvm=bv.46340616,d74D9D8C3EDD4/Sand_Dams.dmQ pdf Water Harvesting Through Sand Dams]. ECHO Technical Note. 2011