Gulf Coast Low Water Datum (GCL WD): A tidal datum. Used as chart datum from November 14, 1977, to November 27, 1980, for the coastal waters of the Gulf coast of the United States. GCLWD is defined as mean lower low water when the type of tide is mixed and mean low water (now mean lower low water) when the type of tide is diurnal. See National Tidal Datum Convention of 1980.

 

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Gulf Coast Low Water Datum (GCL WD): A tidal datum. Used as chart datum from November 14, 1977, to November 27, 1980, for the coastal waters of the Gulf coast of the United States. GCLWD is defined as mean lower low water when . . . View Full Definition

Personal Allowance: Tax allowances are concessions by the Inland Revenue which can be used to reduce a person's Taxable Income. The main allowance for taxpayers is the 'personal allowance'; which is an amount o . . . View Full Definition

Perched Water Table: A water table that is isolated from and higher than the regional water table. This can occur when a hilltop is underlain by an impermeable rock unit. Infiltrating waters stack up on the impe . . . View Full Definition

Perched Groundwater: An isolated body of ground-water that is perched above and separated from the main water table by an aquiclude.