4.2 Physical Unit Data and Database Structure

The definitions and descriptions for the codes of the physical unit database have been derived for the most part from the BC Physical Shore-zone Mapping Manual (Howes et al, 1994). A few terms have been added to the organic form and material secondary descriptors from the Terrain Classification System (Howes & Kenk, 1997). Field names, item types and widths as well as item descriptions are outlined in Table 3, and explanations of the codes are listed in Section 4.2.2.

Table 3 - Description of the Physical Unit Database.

Field Name	Type	Width of Field	Description
EstuaryID	Alphanumeric	14	Unique identifier for Estuary (eg. SEYMWSD0001890x)
Phy_ident	Alpha	13	Physical unit from BC Shorezone System if available
PhyunitID	Numeric	2	Unique identifier of estuary physical polygon
Order	Alpha	2	Degree of importance of subunit (D - dominant, S - subordinate)
AreaP	Numeric	10	Area of estuary physical polygon in square meters
Slope	Numeric	2	Slope of estuary physical polygon in degrees
Level	Numeric	1	Used only when a veneer of sediment overlies a subsurface
Primform_1st	Alpha	2	Primary Form Descriptor 1
Primform_2nd	Alpha	2	Primary Form Descriptor 2
Secform_1st	Alpha	2	Secondary Form Descriptor 1
Secform_2nd	Alpha	2	Secondary Form Descriptor 2
Secform_3rd	Alpha	2	Secondary Form Descriptor 3
Strata_1st	Numeric	1	Strata layer 1 (where 1 is the topmost)
Strata_2nd	Numeric	1	Strata layer 2
Depth	Numeric	6	Depth of each strata in meters (eg. .5 = 50cm)
Primmat_1st	Alpha	2	Primary material descriptor
Secmat_1st	Alpha	2	Secondary material descriptor
Percent_1st	Numeric	2	Percent cover of 1st material descriptor
Primmat_2nd	Alpha	2	Primary material descriptor
Secmat_2nd	Alpha	2	Secondary material descriptor
Percent_2nd	Numeric	2	Percent cover of 2nd material descriptor
Primmat_3rd	Alpha	2	Primary material descriptor
Secmat_3rd	Alpha	2	Secondary material descriptor
Percent_3rd	Numeric	2	Percent cover of 3rd material descriptor
Mapper	Alpha	25	Mapper name(s) (Last name, first name)
Date	Alpha	8	Date dd/mm/year

Explanation of the physical unit database

EstuaryID:	Refers to the estuary identification number from the estuary project and overview database
Phy_ident:	Physical unit from BC Physical Shore-zone Mapping System (if available)
PhyunitID:	Refers to the unique identification number assigned to the estuary physical unit from airphoto pretyping.

Order: each unit may consist of up to two components or subunits. Order is used when it not possible to map these subunits into discrete units. It indicates the degree of importance of the subunits when two have been identified and occur within a unit.

Code	Term	Definition
D	Dominant	Occupies >50% of the unit area
S	Subordinate	OCCUPIES <50% OF THE UNIT AREA

AreaP:	Area of the unit in square metres; generated by GIS.
Slope:	Slope of the unit is measured in degrees; slope can be recorded as an unique value (e.g. 8 degrees) or as a range (e.g. 3 -6 degrees).
Level:	Only used when a veneer of sediment (<1 metre in thickness) or blanket (> 1 metre in thickness) overlies sediment or bedrock whose surface determines the form or shape of the overlying surface. An example where the level would be coded or used is when a beach veneer of sediment overlies a bedrock platform. The upper level is coded as 1 (in this example: the beach veneer) and the underlying layer is coded as 2 (in this example: the rock platform).

Primary and Secondary Form Descriptors

Descriptors of the morphological character (form) or surface expression of a unit are described by the combination of primary and secondary form descriptors. Secondary descriptors provide additional information on the primary form types. Definitions of Primary and Secondary form descriptors are listed below.

Application of Form Terms

The primary form of each unit (or subunit as indicate by the order code) is described by a primary form descriptor (eg. A,B,S). Usually, only one primary form descriptor term is used to describe the primary form of a unit (or subunit). The only exception is when a veneer or blanket of sediment overlies sediment or bedrock whose surface determines the form or shape of the overlying surface. In this instance, two primary form descriptors are used to describe the unit (or subunit) however only one primary form descriptor can be applied to each the upper and underlying layer.

Additional information related to form can be indicated through the use of secondary form modifiers (eg. Ap, Bfxbu, S). Up to 3 secondary form modifiers may be used with each primary form descriptor. Their order has no significance.

PRIMARY FORM DESCRIPTORS

Code Term	Code Term
A     ANTHROPOGENIC	L     Lagoon
B     Beach	M     Organic
C     Cliff	O     Offshore Island
E     Dune	P     Platform
F     Reef	R     River (Fluvial)
	T     Tidal Flat