Effects of channel modifications on the hydrology of Chicod Creek Basin, North Carolina, 1975-87
Water-Resources
Investigations Report 90-4031
By R.R. Mason, Jr., C.E. Simmons, and S.A. Watkins
Abstract
Drainage modifications in this Coastal Plain basin from 1978 to
1981 consisted of channel excavation and clearing of blockages.
A study was begun in 1975 to define hydrologic conditions of the
basin before, during, and after modifications and to determine
what changes were attributed to modifications. Surface-water
conditions were altered during and following modifications.
Minimum flow at Juniper Branch was increased from less than 0.1
cu ft/sec to 0.4 cu ft/second;streamflow variability was
reduced from an index of 0.87 to 0.49. In-channel velocity at
Chicod Creek was increased from a mean of 0.4 ft/sec to 1.5
ft/sec. Substantial groundwater level declines were observed in
wells 180 and 250 ft from Juniper Branch during the
modifications phase;these were 0.4 and 0.2 ft, respectively.
However, most surface-water and groundwater conditions returned
nearly to premodification levels by 1987. Water-quality
characteristics monitored during the investigation included
physical, chemical, and bacteriological characteristics.
Physical characteristics monitored were suspended sediment,
temperature, dissolved oxygen, and pH. Of these physical
characteristics, only sediment concentrations increased
substantially during channel modifications. Chemical
characteristics studied were major dissolved constituents,
nutrients, trace metals, and pesticides. Substantial changes
ranged from a decline in total iron concentrations of 77% to an
increase in total nitrite concentrations of 130%. Changes in
many chemical characteristics persisted following channel
modifications. Bacterial counts did not change substantially.
Citation:
Mason, R.R., Jr., Simmons, C.E., and Watkins, S.A., 1990, Effects of channel modifications on the hydrology of Chicod Creek Basin, North Carolina, 1975-87: U.S. Geological Survey Water-Resources Investigations Report 90-4031, 83 p.
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