* Ideal where groundwater flow converges from a large catchment into a narrow passage.<br>
{{procontable | proborder="1" cellpadding="5" cellspacing="0" align="center"|-! width="50%" style="background:#efefef;" | Advantages! style="background:#ffdead;" | Disadvantages|-| valign="top" | - Subsurface dams are not likely to deteriorate, with little danger of breaching <br>
- Losses from evaporation are very much less than the 2.0 metres lost annually from a free water surface in a dry tropical area<br>
- Construction has long lifespan and require minimal maintenance <br>
- The breeding of insects and parasites such as mosquitoes and bilharzia parasites is prevented<br>
- Contamination of stored water, by people and animals, is greatly reduced, particularly if well and handpump are provided to abstract water in a hygienic and controlled manner<br>
| convalign= "top" | - Leakage is often difficult to detect <br>
- Water losses may occur through cracks in the impermeable layer (it may be possible to drill a well in the fracture zone and utilize the dam as an artificial recharge structure)<br>
- Downwater flow will be impacted to communities downstream<br>
- the river may change course<br>
- the possible dam construction sites may be too far from the water users<br>
}|}
==Resilience to changes in the environment==
