A weir represents the simpler and immediate way in order to measure flow in channels. A typical system is made up of a calm tub with a septum, of a weir (with rectangular or triangular section, etc.) and of a piezometer.

The water level variations are measured by a piezometer probe, placed inside a pipe at the bottom of the tub, at a distance from the weir front such as to avoid measures errors caused by the flow perturbation induced by weir threshold.

The calm tub, that can be built in various materials (metals, plastic, fiberglass, composed materials, etc.), allows to control and reduce water fluctuations caused by turbulent stream. Using formulas depending from weir type and system geometry it's possible to obtain the water flow in relation to the water level in the tub.

The tub is equipped of a septum with the aim to intercept transported solid material, that periodically could be collected and carried in laboratory for chemical, physical and biological analyses.

Centro ISIDE's team is able to realize with maximum care complete systems for measures of water and sediment flow by weirs, in channels and rivers, integrating all the aspects regarding the planning, the building and the managing of the systems:

• good choice of installation points, in relation to:
  • reach and have access to the places;
  • rivers confluence;
  • presence of hydraulics structures;
  • particular flow conditions;
  • particular erosion conditions;
• hydrological analysis of drainage basin above the measure point;
• plan of the weir, of the calm tub and of sedimentation tub, according to the directives and the prescriptions of USDA (United States Department of Agriculture);
• choice of instrumentation with features according to the specific case (piezometers, capacitive piezometers, etc.);
• manual or automatic data download, using various data transmission systems (GSM, GPRS, radio, etc.);
• complete results with:
  • database managing;
  • reports either in graphical and in tabular layout;
  • data elaboration and statistical analyses;
  • data comparison with others measured hydrological parameters;
• ordinary and extra-ordinary maintenance , in order to guarantee good working of installed instrumentations.