 Oahu
NAWQA Home
What
is NAWQA?
Study
Unit Description
 Surface
Water
Bed
Sediment and Tissue
Aquatic
Ecology
Ground
Water
Liaison
Committee
Publications
|
| The NAWQA study design for
surface water focuses on water-quality conditions in streams using three
interrelated components: water-column studies, bed-sediment and tissue
studies, and ecological studies. |
Water-column studies monitor
physical and chemical characteristics and their relation to hydrologic
conditions, sources, and transport. Water column studies are conducted
at sites termed either "basic-fixed sites" (BFS) or "intensive-fixed sites"
(IFS), according to the frequency of sampling and/or constituents analyzed.
The sampling sites are selected to determine the quality of water in relation
to important environmental settings
in the study unit. Basic and intensive fixed sites can be either indicator
or integrator sites. Indicator sites represent relatively homogeneous,
small basins associated with specific environmental settings, such as a
particular land use that substantially affects water quality in the study
unit. Integrator sites are established at downstream points in larger relatively
heterogeneous drainage basins with complex combinations of land-use settings.
Water samples also are collected at other locations as part of (short-term)
synoptic studies of specific water-quality conditions or issues during
a specific hydrologic period (for example during low streamflow) to provide
greater spatial coverage and to allow investigators to assess whether the
basic-fixed site or intensive-fixed sites are representative of streams
throughout the study unit. |
Fixed-Site Network
In March 1999 the Oahu NAWQA
study team began a 2-year water-column study at three locations, of which
one is a basic-fixed site on Waihee Stream and the other
two are intensive-fixed
sites on Manoa and Waikele Streams. All sites
were sampled for BFS constituents
(major ions, nutrients, dissolved organic carbon, suspended organic carbon,
and suspended sediment). At the intensive fixed sites, the samples also were analyzed for trace elements and pesticides. In addition, VOC samples
were collected at the Manoa intensive fixed site. A continuous record
of discharge, specific conductance, and water temperature was measured
at all sites. Field measurements done at the time of water-quality
sampling included water temperature, specific conductance, pH, dissolved
oxygen, and alkalinity. The sampling frequency was monthly plus six event-based
samples per year at all sites. Event-based samples were collected
using an automatic (point) sampler.
Synoptic-Site Network
Water-column samples were collected
during low streamflow conditions at six additional sites to provide greater
spatial coverage and to assess whether the basic fixed-site or intensive
fixed-sites are representative of streams throughout the study unit.
A description of each site
and available data can
be found by selecting the site number on the map or stream name listed in the table below.
|
|
Island of Oahu showing location of fixed and synoptic sites, drainage
areas, and land use (Hawaii State Office of Planning Land Use Districts, 2000).
|
|
List
of sites and sampling strategy
(MI:
major ions, NUT: nutrients, TE:
trace elements, PEST: pesticides, VOCs: volitale organic compounds, x:
sample analyzed for indicated parameter group, -
: parameter group not analyzed)
|
| Map |
Stream |
|
Land use |
MI |
NUT
|
TE
|
PEST
|
VOCs
|
| 9 |
Kaneohe |
Urban |
x
|
x |
x |
x |
|
| 5 |
Kaluanui |
Forest |
x
|
x |
|
|
|
| 1 |
Manoa |
Urban |
x |
x |
x |
x |
x |
| 6 |
Punaluu |
Forest |
x |
x |
|
|
|
| 7 |
Waiahole |
Forest |
x
|
x |
|
|
|
| 4 |
Waikakalaua |
Mixed |
x
|
x |
x |
x |
|
| 8 |
Waihee |
Forest |
x |
x |
x |
x |
|
| 2 |
Waiakeakua |
Mixed |
x
|
x |
x |
x |
|
| 3 |
Waikele |
Mixed |
x |
x |
x |
x |
x |
|
|
