[[Image:aquifer rch icon.png|right|80px]]
[[Image:InfiltrationBasin.jpg|thumb|right|200px| An infiltration basin in Omdel, Namibia. The aquifer provides water to the coastal towns of Walvis Bay, Swakopmund and Henties Bay, and a large open pit mine at Rössing.]]
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Infiltration ponds (also called infiltration basins or percolation ponds) are large open water ponds that are either excavated or in an area of land surrounded by a bank, and normally will not exceed 15,000 m3. They store rainwater but with the main aim of infiltrating the water to aquifers where it can be extracted using boreholes, hand-dug wells, or nearby springs. They are constructed in areas where the base of the pond is permeable and where the aquifer to be recharged is at or near the surface.
===Suitable conditions===
The aquifer to be recharged needs to be at or near the surface. The base of the pond needs to be permeable. The typical amount of water going into the ground is 30 m/year for fine texture soils (e.g. sandy loams), 100 m/year for loamy soils and 300 m/year for coarse clean sands. A field method to determine seepage rates in the bottom of reservoirs has been developed which can be used to assist in design. Ideally infiltration rates should exceed evaporation rates.
===Resilience to changes in the environment===
====Drought====
'''Effects of drought''': Water quality deteriorates; Water levels in wells & boreholes reduce. <br>
De-silting will most probably need to be carried out at some stage. There may be more sustainable ways of doing this compared to the usual approach used in the recovery stage of DCM, where this process is often paid for by NGOs and where there is a lack of community will to contribute. Experience from infiltration ponds in India shows that securing participation is very difficult to achieve when users/farmers do not see any direct benefit from the ponds. An institutionally-resilient way to de-silt (or even construct) ponds may be to promote ponds on private land, where one landowner has a vested interest to maintain and de-silt the pond, thus reducing the need for NGO intervention in the longer run. Experience in India seems to support this where the farmer providing the land for the johad (pond) would be the prime beneficiary, of the recharged water on adjacent land, but where the community also benefited.
===Costs===
Percolation pond, capacity 10,000 - 15,000 m3 (India) US$ 5,000 - 15,000
Examples include dune infiltration ponds in South Africa, Tajamar ponds in Paraguay, and infiltration basins in Niger. Large dams can also be used to artificially recharge aquifers – in Jordan, one dam was constructed to recharge a well field 8km from the dam site, and experience from the past 6 years shows that groundwater levels have increased by 25-40 metres. In Nepal, small ponds traditionally helped to recharge spring water.
===Manuals, videos, and links===
* [http://www.liv.ac.uk/surcase/themes_actions/sustainable_drainage.html Sustainable Drainage Systems (SUDS)]. University of Liverpool.
* [http://www.artificialrecharge.co.za/strategydocument/ARStrategySectB.pdf The Artificial Recharge Concept, its Application and Potential] Some examples from Africa, Europe, the Middle East, Australia and USA.
* [http://www.samsamwater.com/library/Artificial_groundwater_recharge_for_water_supply_of_medium-size_communities_in_developing_countries.pdf ARTIFICIAL GROUNDWATER RECHARGE FOR WATER SUPPLY OF MEDIUM-SIZE COMMUNITIES IN DEVELOPING COUNTRIES.] or ([http://www.washdoc.info/docsearch/title/108685 alternative link]). E.H. Hofkes and J.T. Visscher. December, 1986.
===Acknowledgements===
* CARE Nederland, Desk Study: [[Resilient WASH systems in drought-prone areas]]. October 2010.
* [http://www.washdoc.info/docsearch/title/169828 Smart Water Harvesting Solutions: Examples of innovative, low cost technologies for rain, fog, and runoff water and groundwater.] (or [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CGsQFjAI&url=http%3A%2F%2Fwww.arcworld.org%2Fdownloads%2Fsmart%2520water%2520harvesting.pdf&ei=NXNzT7CYEIiTiQKdxviYCw&usg=AFQjCNECS9O4gaRRQadp5dd4B5RDPxTwQA&sig2=QwWuUbra7my8Dpq5c_0baw alternative link]) Netherlands Water Partnership, Aqua for All, Agromisa, et al. 2007.
