Lowest Astronomical Tide (LAT)

Definition

Lowest Astronomical Tide (LAT) refers to the lowest level of tide that can be predicted to occur under average meteorological conditions and fully applied tidal conditions. This measurement is crucial for navigation and bathymetric surveys, as it establishes a consistent reference point for determining water depths and ensuring safe passage for vessels.

5 Must Know Facts For Your Next Test

1. LAT is an essential reference for creating nautical charts, ensuring that depths are accurately represented for safe navigation.
2. The lowest astronomical tide typically occurs during specific astronomical conditions, such as during a new moon or when the gravitational pull from the sun and moon aligns optimally.
3. Variations in local weather conditions, such as storm surges or high winds, can cause actual tide levels to differ from LAT predictions.
4. Understanding LAT helps surveyors avoid hazards by knowing the minimum water depth in an area, which is vital for both commercial and recreational boating.
5. LAT is used alongside other tidal levels, such as Mean Sea Level (MSL), to provide a comprehensive understanding of tidal changes in coastal areas.

Review Questions

• How does the Lowest Astronomical Tide (LAT) impact the creation of nautical charts?
  • Lowest Astronomical Tide (LAT) serves as a critical reference point for establishing the minimum depth readings on nautical charts. By providing a consistent and predictable baseline, LAT helps ensure that navigators can safely identify areas with sufficient water depth. Accurate charting based on LAT is vital for preventing groundings and ensuring safe navigation through coastal waters.
• Discuss the relationship between LAT and local tidal variations caused by meteorological conditions.
  • While Lowest Astronomical Tide (LAT) offers a predictable minimum tidal level, local meteorological conditions can significantly affect actual tide heights. Factors such as storm surges, wind patterns, and atmospheric pressure can cause water levels to rise above LAT, leading to potential hazards for navigation. Understanding this relationship is important for mariners to adjust their plans and ensure safety in varying conditions.
• Evaluate the significance of LAT in conducting bathymetric surveys and its implications for coastal resilience engineering.
  • Lowest Astronomical Tide (LAT) is vital for conducting bathymetric surveys because it provides a consistent baseline against which underwater features can be measured. This precision is critical in coastal resilience engineering, where understanding water depths helps inform decisions on infrastructure development and environmental protection. The accurate mapping of underwater terrains aids in assessing risks associated with rising sea levels and flooding, ultimately contributing to more effective coastal management strategies.

Related terms

Tide Tables: Tide tables are published schedules that provide predictions of tide levels at various locations over a specific period, helping mariners anticipate changes in water levels.

Chart Datum: Chart datum is a reference level from which depths are measured on nautical charts, often based on LAT or another established tide level.

Bathymetry: Bathymetry is the study of underwater depth of ocean floors or river beds, often conducted using methods that rely on accurate tidal measurements like LAT.