这类井含有小口径的短筒筛(割缝管或穿孔管),筒筛通常会通过水压或人力,垂直或倾斜地插入疏松的沉积物中。在这种情况下,并不需要挖掘。
===适宜条件====Due to pumping requirements, it is best to site these wells:根据水泵的需求,最佳的水井选址为:* Within 30 metres of the pump location. 距水泵处30米以内。 * In areas where there are no high banks and where maximum floodwater height is lower than these banks – this is so that suction pumps can still operate (effectively will abstract water between 6 – 7 metres height). 为了使抽吸泵仍能运作(有效抽水6-7米高),则要在河堤不高、且洪水最高水位低于河堤的区域。 * There should be water remaining in the riverbed throughout the dry season.河床在整个旱季都要有水。
{| border="1" cellpadding="5" cellspacing="0" align="center"
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! width="50%" style="background:#efefef;" | Advantages优势! style="background:#f0f8ff;" | Disadvantages不足
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| valign="top" | - Speed and low cost of construction 修建速度快,成本低 <br>- High yields possible with small intakes. 入水口小,但可能产量高 <br>| valign="top" | - More difficult to do in sandy sediments that are mixed with clay. 较难在混有黏土的砂质沉积物中修建 <br>- No storage capacity as with large diameter wells. 没有像大口径水井那样的储水量 <br>- Cannot easily access intake for maintenance or in case of problems.当需要维护水井或水井出现问题时,无法轻易接触到入水口<br>
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===Construction, operations and maintenance建造、运作与维护===The screens and pipework should be ideally 1筛子(或称滤网)及管道系统离河床表面理想的最小深度应为1.5 metres minimum from the riverbed surface. This is so that:5米,为的是:* There is at least a minimum of infiltration that occurs from surface water during the wet season when the river is flooded.在雨季,河水泛滥时,地表水至少会有最小程度的渗透。* That there is less chance that the well shaft and pipework will be washed away in a flood event. Sand becomes mobile to a certain depth which differs for different rivers but has been recorded to be normally between 0.66 and 2 metres in seasonal riverbeds井道与管道系统较不可能在洪水中被冲走。沙子在某一特定深度可以流动,而这一深度视河流不同而变化,但在季节性河床中,通常记录为0.66至2米之间。
Screens used can be anywhere from 32 to 200 mm in diameter, and only 0.5 – 1 metre in length. For jetted wellpoints, they are commonly made from plastic. For driven wellpoints, they are made from steel and require wingtips on the pointed end使用的滤网直径可在32至200毫米中任选,长度则仅需0.5到1米。喷射井点通常用塑料制成;管井井点则通常由钢制成,在尖头处需要翼尖。
Jetting (also known as washboring) is one method of installing a screen into the saturated sand layer. There are various forms of jetting, with various pipe sizes. Key techniques are outlined below:喷射法(也称为冲洗钻井)是在饱和砂层中安装滤网的一种方法。喷射的方法和使用的管子规格均多种多样。关键技术提纲如下:* About 1,000 litres of water is required, possibly more depending on ease of procedure and size of sediment particles. This water can be brought with a bowser, or can be created using a hole dug into the ground and lined with a plastic sheet.需要约1000升水,根据工艺难易度和沉积物颗粒大小不同,可能需要更多。水可以用水车载来,或向地下挖洞并用塑料片材作内衬来产水。* A 2” Honda suction pump (600 litres通常使用2” Honda(本田)抽吸泵(600升/min) is normally used for both jetting and well testing, although larger capacity pumps will enable deeper jetting but will use more water per minute.分钟)来做喷射和试井,虽然更大容量的泵能喷射更深,但每分钟也会使用更多水。* During the jetting process, water emerges from the end of the jetting pipe and flows upwards to ground level. If the flow of water stops (e.g. water runs out, or to change a pipe), in most circumstances the sand around the jetting pipe在喷射过程中,水从喷射管末端出来,向上流到地面。如果水流停止(比如,水流尽,或需要更换管子),喷射管/screen will collapse, after which it is impossible to re-start the flow of water to the surface. However, in some cases the hole will remain open – only in these cases can you add another pipe and continue jetting, but otherwise the depth you can install the screen is dependent on the length of jetting that can be done in one go without stopping the pump.滤网周围的沙在多数情况下会塌陷,之后就不可能让水重新流向地面。然而,有些情况下,洞口仍然会保持敞开——只有在这些情况下,才能加入另一根管子,继续喷射;否则,能够安装滤网的深度将由单次不停泵的情况下喷射的长度来决定。* Digging a large pit to the water table is advantageous since:挖大坑至地下水位是有益的,因为:# In collapsing sands, you can jet to the base of the pit, after which you can glue extra pipes onto the screen to reach ground levelso that a deeper well is achieved. 在易陷沙中,您可以喷射水流至坑的底部,随后,可以将额外的管子粘合到滤网上,以达到地面高度。以此方法,井能修得更深。 # The chance of losing the water column is minimized due to less pressure head that the water must overcome in order to flow to the surface. With higher pressure heads (i.e. more distance from water level in ground to ground level), the water is more likely to choose the path of least resistance, which at some point will be to go into the aquifer rather than come to the surface. In such a case where you lose the water column in collapsing sands, the well will be finished at that depth.由于水流为达到地表而必须克服的压位差减小,因而水柱消失的可能性已降至最低。压位差越高(即,从地下水位到地表的距离越大),水就越可能流向阻力最小的通道,在某种情况下会流入含水层,而并不会流到地面上来。水柱若在易陷沙中消失,则代表挖井终止,且井深就固定在这一深度。* A screen can have a ball valve at the end – in this case, the jetting pipe and screen are made from the same piece. Alternatively the screen can be separate from the jetting pipe, where the jetting pipe creates the hole and then is removed once the screen is installed to required depth. If a screen with valve is chosen, care should be taken if installing handpumps as the ball valve has a tendency to open over time letting in sand.滤网末端可以装有球阀——在这种情况下,喷射管和滤网是由同一块材料制成的。或者,滤网也可与喷射管分离——在这种情况下,喷射管将洞打出,在滤网安装到需要的深度后,便将喷射管移除。如果选择了有阀门的滤网,且安装手动泵,则需要当心球阀可能会因打开过久,而导致沙子进入。* Flow velocity around the screen should be maximized. This can be done by adding a layer of perforated drainage pipe around the screen, followed by geotextile. Additionally, a gravel pack should be created around the screen. This can be done by:滤网周围的流速应当加至最快。要实现这一点,可以在滤网周围增加一层穿孔排水管,随后使用土工布。并且,在滤网周围应当以砾石充填。可如下施工:# Throttling the pump speed down once the screen is at the required depth – this will remove fines while allowing coarse sediments to settle around the screen depth.一旦滤网达到所要求的深度,则立即降低水泵速度——这样会让粗粒泥沙沉到滤网所在的深度周围,同时去除细粒土。# For sand rivers that have a significant clay content, permeability in the riverbed will be low, and yields will also be low. Increased flow velocity into the well can be created by making a large gravel pack around the well shaft – this gravel pack consists of aggregate and stones (rather than the traditional type of small diameter gravel pack used in boreholes).对于有大量黏土含量的沙河,河床渗透性及产水量都会较低。为了增加入井流速,可以在井道周围做大型的砾石充填——包括骨料和石头(而并非传统类型中用于井眼的小粒砾石充填)。
Extracting water can be done with handpump or mechanical pump. Handpump cylinder will need to physically be able to fit inside the screen that has been installed.抽水可用手动泵或机械泵完成。手动泵汽缸需要装得进已安装的滤网内部。
===Manuals, videos and links指南、视频与链接===* [http://www.indiawaterportal.org/articles/well-revival-effort-sees-many-other-benefits Well revival effort sees many other benefits努力复兴水井有许多其它益处] A community drive to revive wells in Mokhla talab near Udaipur results in water security for longer periods of time as well as making leaders out of women.有一个社区致力于复兴乌代浦附近Mokhlatalab的水井,从而能让用水安全更持久,也从女性中造就了领袖。* [http://www.indiawaterportal.org/articles/experiments-community-wells Experiments with 'community wells'“社区水井”实验] Mobilized farmers in Dhule, Maharashtra, show how communities can use groundwater as a common resource in an organised and collective manner.在马哈拉施特拉邦的图莱,受到动员的农民展示了社区如何能共同有序地利用地下水作为公共资源。
===Acknowledgements===
* CARE Nederland, Desk Study: 荷兰,初步研究:[[Resilient WASH systems in drought-prone areas易旱地区中,具有适应力的WASH(水、环境卫生与个人卫生)系统]] October 20102010年10月.