[[Image:Tyrweir.jpg{{Language-box|thumbenglish_link=Water Portal / Rainwater Harvesting / Surface water / Tyrolean weir |rightfrench_link= Coming soon |150pxspanish_link= Toma Tirolesa | hindi_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, Tanzania]]| 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 }}
Dams and water inlet structures in embankments are vulnerable and expensive elements in river-fed water systems[[Image:Tyrolean_weir_icon.png|right|80px]][[Image:Tyrolean weir.JPG|thumb|right|200px|Tyrolean weir|Man checking the grid at a Tyrolean Weir. Tanzania. Photo: D. They are easily damaged by floods, underflowBourman, seepage and suffer from build-up of sediment or rubbish in the waterAqua for All. The ]] A '''Tyrolean weir forms ''' is a more reliable and cheaper alternative. Water water inlet structure in which water is abstracted from the main flow through a screen (or inlet) over a gutter, . The gutter is usually made of concrete and built into the riverbedriver 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. 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. ===Suitable conditions ===Tyrolean intakes are used in small permanent rivers and streams where the sediment content and bed 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.
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! width="50%" style="background:#efefef;" | Advantages
! style="background:#ffdeadf0f8ff;" | Disadvantages
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| valign="top" | - More reliable and cheaper compared to dams and water inlet structures in river embankments<br>- They do not affect water flow to communities downstream| valign="top" | <br>- None known
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== Costs =Resilience to changes in the environment===
* Material ====Drought effects on cement===='''Effects of drought:''' Badly made concrete or cracked linings (excluding the pipe e.g. in tanks, dams, waterways, wells, and sedimentation tankother structures): US$ 300 - 600. <br>* Labour (if site is easily accessible)'''Underlying causes of effects: 30 - 50 man days''' Less water used for curing; Impure water used for mixing.<br>* Operation and maintenance'''To increase resiliency of WASH system: several visits per year for inspection''' Ensure adequate mixing, ratios, cleaning and minor repairs. Overall easy to carry out due to low-tech structure and the use purity of local labour and materialsingredients; 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]. Chapter 11. * The weir itself does not clean or purify the waterRevised by Nhamo Masanganise.
== External links =Acknowledgements===* General Background CARE Nederland, Desk Study: [http://www[Resilient WASH systems in drought-prone areas]].aquaforallOctober 2010.nl www.aquaforall.nl]