Water Level Measurement

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Water Level Measurement
2013-02-19 05:13:42

Water Level Measurement
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  1. Uses of a Tide Staff & Gauge
    • The reductions of soundings. Tidal observations are to be carried out for the full period when a ship is deployed to the survey area.
    • For predicting tidal characteristics & updating ANTT Observations. Obs should be carried out over at least 32days using a precise gauge.
  2. 6 uses of Tide Staff & Gauge info & data
    • Shipping Movements
    • Tide Tables
    • Definition of Coastlines
    • Flood & Storm Warnings
    • Mean Sea Level
    • Hydrography
  3. Criteria when considering a suitable site for a Tide Staff
    • Stability of site
    • Stability of structure
    • Stability of water column
    • Proximity to benchmarks
    • Proximity to power/phones
    • Ease of access
    • Minimum exposure to Tidal Ranges
    • Minimum exposure to tidal stream/current
    • Minimun exposer to waves
    • Minimum siltation
    • Minimum marine growth
    • Protection from vandalism
    • Avoid restricted entrances
  4. 4 Types of Tide Gauges
    • 1. Floatation Types
    • 2. Acoustic Types
    • 3. Pressure Types - Electronic Types
    • 4. Radar
  5. Flotation Types
    Floats upon the surface & heights are determined by RTK & wave action is removed through low pass filters.
  6. Acoustic Types
    The water level is measured by sending an acoustic pulse down a small pipe within the environmental tube.
  7. Pressure Gauges
    Gas (Bubbler gauge) Open/Closed: gas, usually nitrogen, is emitted from a submerged tube at a constant rate. Fluctuations in the hydrostatic pressure due to changes in the tidal height modify the emission rate of reading.
  8. Electronic Gauge
    • The changes in pressure are detected by a sensor immersed in the water and converted by an electrical signal.
    • In these systems the sensor may be a crystal transducer, stain gauge or other transducer.
  9. Radar
    Measure the change in sea level by monitoring the time-of-flight if a radar pulse from the sensor to the sea surface and back to the unit.
  10. 4 Main Tidal Records
    • Summary of Checks on Automatic Tide Gauge - F_03_05_AA217185
    • H148 - Record of Tidal Readings
    • Record of Tidal Observations - F_05_ALL_AA217190
    • Tide Gauge Deployment Log - F_03_05_AA217170