{"id":41,"count":4,"description":"Weirs are used for the measurement of flow rates in open channels and drainage channels.\r\n\r\n[expander_maker id=\"1\" more=\"More\" less=\"Close\"]\r\n\r\nThe measurement system consists of a weir with notch (with section chosen from traditional triangular, rectangular and trapezoidal shapes, depending on specific requirements) and a level meter of mechanical manual type (graduated staff gauges, in enamel sheet or profiled etched in enamel sheet or profiled etched in stainless steel) , or electrical with various sensors (LVDT with float, radar, ultrasound, piezometric or other), for automatic measurement in remote locations.\r\n\r\nDue to regulation of the flow ensured by the weir, which has an overflow section note, instantaneous flow rates can be calculated using the water surface level values measured upstream of the weir.\r\n\r\nFlow rate measurement in open channels is very used and applied in environmental \u00a0and geotechnical fields. This method is, particularly used in the measurement of leakages in earthfill or concrete dams, is one of the most important indicators of health status and work performance of the structure.. The amount of leakage is a function of the hydraulic level in the reservoir and depends on the characteristics and behaviour of the dam and is an indication of its structural condition and performance.\r\n\r\nTypical applications for this instrument are level measurements in:\r\n