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==Suitable Conditions==
Site reservoirs where the base will be impermeable (e.g. unfissured rock or clay) in order to save costs and prevent having to find a form of lining. Alternatively cracks and fissures could be sealed up with mortar or concrete. Rock catchment dams work well mostly in hilly or mountainous regions where other water sources are scarce. These types of dams should be bare and free of vegetation/soil. When siting for rock catchment dams make sure to maximize the natural topography – to get the best volume, make dams on the lower side of existing rock pools.
- The geology and surrounding populations must be suitable for a reservoir <br>
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==Resilience to changes in the environment==
====Drought====
'''Effects of drought''': Tend to dry up quickly, especially if unlined; Conflict over water for animals.
'''Underlying causes of effects''': Lack of rainfall; High evaporation rates; High seepage rates through base of pond and through dam; Storage not sufficient for demand – silting up of ponds due to high silt load, high level of work in constructing ponds.
'''To increase resiliency of WASH system''': Reduce evaporation & seepage; Follow proper construction methods; Reduce siltation to get more volume; Promote private ownership of ponds, so de-silting process more likely; Improve access to low-cost loans with long-time repayment conditions so that farmers can replicate technology; Use phased construction until capacity is sufficient for water demand.
====Floods====
With climate change, some regions experience more intense rainfall events. (Several) smaller dams will receive less damage than one larger dam and be less expensive to fix. Diversify water sources so that if floods knock out one system, community has alternatives while repairs proceed. Flow paths of rivers are more likely to change, so choose dam site in most stable place along river and make dam height in consideration of past flood lines on the bank.
==Construction, operations & maintenance==
'''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.
'''Specific advice'''
[[Image:WomenBuilding Dam.jpg|thumb|right|350px| [http://www.wfp.org/countries/uganda/media/karamoja-livelihoods Women construct surface dams in Ka’abong district.] Using food or cash incentives, WFP (World Food Programme) encourages communities to build productive physical assets and gain skills for protecting and regenerating the environment, enhancing nutrition and harvesting water.]]
