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Water Portal / Rainwater Harvesting / Surface water / Tyrolean weir

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{{stub}}[[Image:Tyrolean_weir_icon.pngLanguage-box|right]]Dams and water inlet structures in embankments are vulnerable and expensive elements in river-fed water systems. They are easily damaged by floods, underflow, seepage and suffer from build-up of sediment or rubbish in the water. The Tyrolean weir forms a more reliable and cheaper alternative. english_link=Water is abstracted through a screen (or inlet) over a gutter, usually made of concrete and built into the riverbed. The screen on the crest should slope downstream (15-30 degrees), to increase flow velocities and prevent sediment carried by the stream from blocking it. From the gutter, Portal / Rainwater Harvesting / Surface water enters a pipeline, which drains into a sedimentation tank and then flows by gravity into the rest of the system. [[Image:/ Tyrolean weir.JPG|thumbfrench_link= Coming soon |rightspanish_link= Toma Tirolesa |150pxhindi_link= वाटर पोर्टल / वर्षाजल संचयन / सतही जल / टाइरोलीन मेड़ |malayalam_link= Coming soon | tamil_link= Coming soon | korean_link= Coming soon | chinese_link=提洛尔堰 | indonesian_link= Bendungan Tyrolean weir]]| japanese_link= 水のポータルサイト／雨水貯留／表面水／チロリアン式堰 }}
{{procontable [[Image:Tyrolean_weir_icon.png| pro=- More reliable and cheaper compared to dams and water inlet structures in river embankments <br>right|80px]][[Image:Tyrolean weir.JPG|thumb|right|200px|Tyrolean weir| con= Man checking the grid at a Tyrolean Weir. Tanzania. Photo: D. Bourman, Aqua for All.]]
}}A '''Tyrolean weir''' is a water inlet structure in which water is abstracted from the main flow through a screen over a gutter. The gutter is usually made of concrete and built into the river bed. The screen on the crest should slope downstream (15-30 degrees), to increase flow velocities and prevent sediment carried by the stream from blocking it. From the gutter, water enters a pipeline, which drains into a sedimentation tank and then flows by gravity into the rest of the system.
== Costs ==Dams and water inlet structures in embankments are vulnerable and expensive elements in river-fed water systems. They are easily damaged by floods, underflow, seepage and suffer from build-up of sediment or rubbish in the water. The Tyrolean weir forms a more reliable and cheaper alternative.
* Material (excluding ===Suitable conditions ===Tyrolean intakes are used in small permanent rivers and streams where the pipe sediment content and sedimentation tank): US$ 300 - 600bed load transport are low, or on the crest of a dam spill. The weir or intake should be carefully sited.  The weir itself does not clean or purify the water. * Labour (if site is easily accessible): 30  {| border="1" cellpadding="5" cellspacing="0" align="center"|- ! width="50 man days.%" style="background:#efefef;" | Advantages* Operation and maintenance! style="background: several visits per year for inspection, cleaning #f0f8ff;" | Disadvantages|-| valign="top" | - More reliable and minor repairs. Overall easy cheaper compared to carry out due dams and water inlet structures in river embankments <br>- They do not affect water flow to lowcommunities downstream| valign="top" | -tech structure and None known|}  ===Resilience to changes in the use environment=== ====Drought effects on cement===='''Effects of local labour drought:''' Badly made concrete or cracked linings (e.g. in tanks, dams, waterways, wells, and materialsother structures). <br>'''Underlying causes of effects:''' Less water used for curing; Impure water used for mixing. <br>'''To increase resiliency of WASH system:''' Ensure adequate mixing, ratios, purity of ingredients; Minimize water content in mixture; Ensure adequate curing.
== Applying conditions ==More information on managing drought: [[Resilient WASH systems in drought-prone areas]].
* Tyrolean intakes are used in small permanent rivers ===Construction, operations and streams where the sediment content and bed load transport are low, or on the crest of a dam spill. maintenance===* The threshold can be a concrete elevation above the rocky bed of a mountain stream, or a vertical low [[Image:Tyro weir structure, anchored in the embankment. * The capacity of the inlet pipe / drain (diameter and gradient) should be 30% more than the design flow and have an uniform gradient jpg|thumb|right|200px|Tyrolian weirs are meant to prevent accumulation of sandintake water from mountain rivers that are very turbulent.* The sedimentation tank can accumulate 1Photo: [http://www.5-2 m3 of deposits and allows water to filter for 10 to 30 minutes at very low speedtuwien. It is cleaned by washing it outac.at/en/tuwien_home/ Vienna University of Technology]]]
A Tyrolean weir can either consist of parallel rods or a perforated plate, installed in the flow direction over the width of the stream with a 15-30 degree downward slope. Large stones, branches and large leaves cannot pass between the rods, and are prevented from entering the gutter. Because the rods / plate slopes downward, the material in the stream is pushed downstream, until it drops over the end of the weir.
== Maintenaince ==The threshold can be a concrete elevation above the rocky bed of a mountain stream, or a vertical low weir structure, anchored in the embankment. The capacity of the inlet pipe / drain (diameter and gradient) should be 30% more than the design flow and have an uniform gradient to prevent accumulation of sand. The sedimentation tank can accumulate 1.5-2 m<sup>3</sup> of deposits and allows water to filter for 10 to 30 minutes at very low speed. It is cleaned by washing it out.
* Regular ====Maintenance====Several visits per year to the site are necessary for inspection , cleaning and cleaning of the grit / rack minor repairs. Overall, maintenance is easy to carry out due to low-tech structure and possibly the gutter and sedimentation tank is required during use of local labour and after storm periodsmaterials.
Regular inspection and cleaning of the grit / rack and possibly the gutter and sedimentation tank is required during and after storm periods.
== Considerations =Costs===* Material (excluding the pipe and sedimentation tank): US$ 300 - 600. * Labour (if site is easily accessible): 30 - 50 man days.
===Manuals, videos and links===* The weir or [http://www.samsamwater.com/library/TP40_11_Surface_water.pdf Surface water intake should be carefully sitedand small dams]. * The weir itself does not clean or purify the waterChapter 11. Revised by Nhamo Masanganise. {{Joinus}}
== External links =Acknowledgements===* General Background CARE Nederland, Desk Study: [http://www[Resilient WASH systems in drought-prone areas]].aquaforallOctober 2010.nl www.aquaforall.nl]
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