DECADE
Code 4000000 = data was obtained from1940s aerial photos
Code 9000000 = data was obtained from1990s aerial photos (actually
1988 in the case of the Mendocino Reach study area)
STUDY_AREA
Code 100000 = Mendocino Reach
Code 200000 = Alexander Valley Reach
Code 300000 = Middle Reach
ZONE
Code 50000 = Zone "C": The river channel and all areas
covered by riparian vegetation along the Russian River's "main
stem", including the wetted channel, active channel, vegetated
channel, channel banks, and that portion of the floodplain between
the top of the channel bank and the outer limit of "typical"
riparian vegetation. This zone supports various seral stages of
riparian vegetation, and it is assumed to be subject to relatively
frequent flooding wherever there are no artificial flood control
structures.
Code 60000 = Zone "U": Upper or "historical" floodplain terraces along the main stem; i.e., all lowland areas between the outer limit of the main stem riparian vegetation and the study area boundaries, including the channels, riparian areas, and floodplains of tributary creeks. The relatively level terrace areas are nevertheless high enough that they are assumed to be only rarely subject to flooding by the river (as mapped in the present study this zone may include some small areas that are actually within the river's active floodplains and some other small areas that are actually above the historical flood elevations).
Code 70000 = Zone "K": Uplands within the study area boundaries that are higher than the general level of the upper floodplain terraces along the main stem or its major tributaries, and which are separated from the floodplains by a distinct break in slope. It is assumed for the purposes of the present study that these upland areas are never subject to flooding by streamwaters.
BANK
Code 7000 = Mid-Channel
Code 8000 = Right Bank (facing downstream).
Code 9000 = Left Bank (facing downstream).
DECADE
Code 4000000 = data was obtained from1940s aerial photos
Code 9000000 = data was obtained from1990s aerial photos (actually
1988 in the case of the Mendocino Reach study area)
STUDY_AREA
Code 100000 = Mendocino Reach
Code 200000 = Alexander Valley Reach
Code 300000 = Middle Reach
ZONE
Code 50000 = Zone "C": The river channel and all areas
covered by riparian vegetation along the Russian River's "main
stem", including the wetted channel, active channel, vegetated
channel, channel banks, and that portion of the floodplain between
the top of the channel bank and the outer limit of "typical"
riparian vegetation. This zone supports various seral stages of
riparian vegetation, and it is assumed to be subject to relatively
frequent flooding wherever there are no artificial flood control
structures.
Code 60000 = Zone "U": Upper or "historical" floodplain terraces along the main stem; i.e., all lowland areas between the outer limit of the main stem riparian vegetation and the study area boundaries, including the channels, riparian areas, and floodplains of tributary creeks. The relatively level terrace areas are nevertheless high enough that they are assumed to be only rarely subject to flooding by the river (as mapped in the present study this zone may include some small areas that are actually within the river's active floodplains and some other small areas that are actually above the historical flood elevations).
Code 70000 = Zone "K": Uplands within the study area boundaries that are higher than the general level of the upper floodplain terraces along the main stem or its major tributaries, and which are separated from the floodplains by a distinct break in slope. It is assumed for the purposes of the present study that these upland areas are never subject to flooding by streamwaters.
BANK
Code 7000 = Mid-Channel
Code 8000 = Right Bank (facing downstream).
Code 9000 = Left Bank (facing downstream).
POLYGON
The identification code for an individual polygon is a whole number
having from one to three digits within the range 1 to 999, inclusive.
These numbers are unique within the same bank and zone, but are
not necessarily unique among different zones.
SUB_POLYGON
Some polygons have been divided by a river mile marker into
two or more parts. The sub-units of such a polygon are designated
by decimal numbers.
Note: On the field sheets the sub-polygons were originally
designated by lower-case letters. In the present decimal-number
system, sub-polygon 0.1 corresponds to the former sub-polygon a,
sub-polygon 0.2 to the former sub-polygon b, etc.
A "missing data" code of either "xxxx" (for
text fields) or "9999" (for numerical fields) was assigned
when data for a given map polygon was unavailable, in order to differentiate
such cases from legitimate "blank" fields in the database.
The accuracy of registration between each mylar overlay and the base
map was measured by the RMSE calculated in map units (meters). Since
the output maps for the project were to be plotted at a scale of 1:24,000,
the tolerance value specified by the National Map Accuracy Standards
for maps of this scale was used as a guide during the registration operation.
The appropriate RMSE value when registering the overlays to the digital
base maps was 7.31520 m (or 0.010 inch in digitizer units). 86% of the
individual mylar sheets for the 1990 coverage were able to meet this
standard, and 80% of those for the 1942 coverage.