Application Study On Water Gaging Techniques For Lower Canals In The Inner Mongolia Hetao Irrigation District

Application and promote of technology in agriculture about water saving, water measurement was basic and pivotal technic in the irrigation district, and it was principle methods of water service. The work of water measurement in the channel of irrigation, water volume can be controlled in time , sequentially, avoid water volume of irrigation was wasted. And then, constitute a plan of using water by the rational irrigation requirement for reduce the costs of irrigation.The background of experiment about this paper locate in Inner Mongolia Hetao Irrigation District, unfold contrast of precision about use the Venturi flume and aerofoil flume and portable cut-throat flume in the last canal, also evaluate correlative index, by analysis had the conclusion as following:1) It has high correlation Both the discharge coefficient of Venturi flume and head ratio, discharge coefficient has different effect about different ratio to breadth of flume and breadth of channel. so that ,discharge coefficient of Venturi flume is not constant.2) By compare the result that Venturi flume apply the discharge coefficient of constant and non-constant , obtained error of applying constant discharge coefficient bigger than another, it is recommended to apply the discharge coefficient of non-constant.3) The result of measurement by Venturi flume close to the ways of velocity meter in the last channel, the relative error less than 5%,agree the criterion ofirrigation canal water. 4) Compare and analyse to aerofoil flume in the last canal, the results of relative error less than 5% with velocity meter.5) Variation in discharge was stable on the mouth of farmland, range of 0.01~0.02 m3s-1 at irrigation period, the results of portable cut-throat flume approximate with velocity meter. The results was perfect.6) Investment of Venturi system was large at first time, whereas, the charge of maintenance and observation more than 1200 Yuan to the ways of velocity meter in the every year, form the installation to fourth year, the charge was equation both the ways.In the Hetao irrigation, the case of slow slope, flow velocity was slow, easily sediment, by add sill to Venturi flume throat and reduce the error of reading water head, it realized application of Venturi flume in the last canal.