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沙坝
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===建造、运作与维护===
[[Image:Sand dam diagram.JPG|thumb|right|200px|一座沙坝的横截面<br> 图片来源：荷兰水利工程。<br>点击图片查看详情。]]
[[Image:Sand dam trench.JPG|thumb|right|200px|People excavating a trench.人们正在挖取沟渠。 来源：[http://www.sswm.info/category/implementation-tools/water-sources/hardware/precipitation-harvesting/sand-dams RAIN (n.y.)]]]
First a trench needs to be dug. Its position is marked out using pegs. Then it is excavated and the soil placed downstream. It can also be dug out into bedrock. It should then be checked for weathering zones and cracks. Round bars are placed vertically along the trench to reinforce it. Then a foundation is laid consisting of 2 layers of cement with barbed wire in between. Once this has set, the trench is filled with masonry or mortar and hardcore. The wing walls and final dam wall can then be constructed. Finally any exposed parts of the construction are plastered. 首先，需要挖取一个沟渠，用桩子标记地点。随后，挖取沟渠，将土壤置于下游。也可以挖到基岩处。然后，需要检查风化带和裂缝。圆形杆子沿沟渠垂直放置，用以加固。之后，铺设地基。地基由两层含带刺铁丝网的水泥构成。一旦地基铺设完成，沟渠由砖石或灰浆和岩石碎块填满。随后，可建造翼墙和最终的坝墙。最后，粉刷建筑物上任何裸露的部分。
====取水====
After the dam is built, an outlet for water extraction must be constructed for drinking, agriculture, etc. Hand dug scoop holes are the simplest possibility, however the water can easily be contaminated. Covered shallow wells, either with or without [[Handpumps]] or a [[Rope pump]] protect the water much better. It is also possible to construct an outlet pipe with a tap. In certain designs for sand dams, a pipe is shown that takes water by gravity ''through'' the dam wall. These are said to not work well due to either a blocked intake, a broken tap on outlet side and the possibility of weakening the dam wall. Where water is abstracted directly, risk of contamination increases. In such a case, household water treatment should be advocated (e.g. [[Sodis]]). <br> 沙坝竣工后，必须建一个取水出口，用于饮水、农业等用途。用手挖勺洞是最简单的方法，但水容易受污染。有盖浅井，无论带不带有[[手压泵]]或[[拉绳泵]]，都可以更好地保护水资源。也可以建造带有龙头出水管来取水。关于沙坝的设计中，水管能运用重力输送水资源''经过''坝墙。据称，由于入水口堵塞或出水口龙头损坏，以及坝墙可能松动，取水管运作不良。而直接抽水的地方，污染的风险会增加。在这种情况下，应该提倡家庭用水的处理（如，[[Sodis太阳能消毒]]）。<br>
[[Image:Sand dam scoop hole.JPG|thumb|right|200px|Groundwater abstraction from the riverbed by means of a scoop hole. Kitui District, Kenya. Source: [http://www.sswm.info/category/implementation-tools/water-sources/hardware/precipitation-harvesting/sand-dams HOOGMOED (2007).]]]
