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沙坝
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* Key into banks or construct wing walls to avoid erosion around edges of the sand dam. Where wing walls are built, a good technique is to start with the wing walls and work inwards to the centre, since community enthusiasm lags by the time wing walls are constructed (if not built first), yet they are essential to proper functioning. Length of the wing wall varies according to bank characteristic: loose riverbanks, 7 metres; hard soils, 5 metres; hard & impermeable soils or rocks, wing wall is not needed. Planting napier grass along upstream riverbanks controls erosion and fixes the course of the river in a flood.坝体需嵌入河堤，或建造翼墙来防止沙坝边缘侵蚀。建造翼墙的情况下，较好的方法是先从翼墙开始建造，然后向中心动工。如果不先建造翼墙，社群的建造热情会在翼墙竣工前就下降，而翼墙对沙坝的正常运作来说至关重要。翼墙的长度随河堤的特性而定：松散的河堤，7米；硬质的土壤，5米；不透水且硬质的土壤或岩石则不需要翼墙。在上游河堤种植象草可以控制侵蚀，并在洪水中修正河道。
* The height of wall built before each flood event should not exceed accumulation rate of coarse to medium sand during that flood event, otherwise ponding & silt deposition will occur, which can lower specific yield and higher capillarity, then lead to limited extraction rates in wells upstream and more water lost to evaporation. Dams at 1.3m depth showed that where finer material content (0.063 mm or less) is increased, specific yield is known to decrease remarkably. Accumulation rate and therefore height varies according to location and should be adjusted at each site after the first flood event demonstrates the rate of accumulation. Height per stage will probably be between 0.3 metre and 1 metre per stage according to experience from past projects. Some silt deposition will always occur as velocities decrease toward the end of the flood event; the idea is to limit its quantity in final sand volume.在每次洪水来临前建造的坝墙高度不能超过当季洪水里粗砂至中粒砂堆积速率，否则会出现积水成池和泥沙沉积，这将降低单位出水量且增加毛细管作用，而导致位于上游的井取水率有限且更多水分蒸发流失。观察1.3米深的水坝显示，当更精细的物质成分（小于等于0.063毫米）增高，单位出水量会显著降低。堆积速率及相应的坝墙高度根据具体位置而定，且需要在第一次洪水来临后得出堆积速率，从而对每一位置的坝墙高度进行调整。根据以往工程的经验来看，每一阶段的坝墙高度差不多在0.3米至1米之间。随着洪水结束，由于速率下降，总是会出现一些泥沙沉积；这一点用来限制最终沙量中的泥沙沉积。
* Avoid downstream erosion problems by making a protective slab (stilling basin) at the base of large stones set in concrete. Dimensions to be designed, but is not necessary where there is exposed rock bar downstream.通过在混凝土中的大石块底部建造防护板（消力池），防止下游的侵蚀问题。防护板尺寸需要设计，但不一定是下游有裸露石块的区域的大小。* In upstream parts of a catchment it is recommended that sand dams are always built in stages, since the availability of coarse material is generally limited and base flow is small or absent (base flow = sub-surface flow which aids surface flow so that silt/clay can still be flushed away once rainfall stops, rather than sinking directly into the sand bed). It has also been suggested that to build in stages over several years is also more beneficial for functioning of dam committees. Build them within a spillway, which was part of the first stage & wing wall construction.在流域的上游，由于粗粒物质通常有限，且建议沙坝始终分阶段建造，基流很小或没有基流（基流=有助于地表径流的地下水流，只要降雨停止，淤泥/黏土仍可被冲走，而不会直接沉入沙床。）
====Water extraction====