Evaluating the Effects of Piped Lengths of Buried Channels on Temporal
and Small-Scale Spatial Variations of Streams Dissolved Oxygen Dynamics
Abstract
Sunlight plays an important role in regulating the nutrient cycle in
streams. Throughout the years, more streams are buried to accommodate
for residential or commercial facilities. This results in severe impacts
on the health of streams due to altered exposure to sunlight, air, and
soil; it subsequently affects the growth of aquatic and riparian
vegetation, thus impairing the water quality of streams. Although
urbanization effects on urban surface streams are well understood, the
adverse effects of burying streams on dissolved oxygen (DO), reaeration,
photosynthesis and respiration processes have been mainly remained
theoretical. This study evaluated the effect of stream piping on DO for
two sections of Stroubles Creek in Blacksburg, VA through comparing the
water quality prior to entering, and post exiting the buried sections of
the Creek. Monitoring DO was conducted through manual readings and
continuous measurement for a number of days in Fall 2015 and 2016. The
results indicated that the water DO level decreased by approximately
11% as water flowed through the buried sections. The covered section of
the stream also caused variability of the water temperature, resulting a
possible disturbance to the downstream ecosystem. The buried
channels-induced DO variations effects on the Brook Trout (Salvelinus
sp.), a sensitive species present at the Stroubles Creek headwaters was
also assessed. Further, the photosynthesis rate, reaeration coefficient,
and daily respiration rate were computed prior and after one of buried
channels through a series of mathematical and empirical approaches to
assess the buried channels effect on the aforementioned parameters. The
photosynthesis and respiration rates were reduced at the inlet compared
to outlet, primarily due to less solar radiation and aquatic vegetation
oxygen uptake, however, reaeration rate was increased at the outlet
compared to inlet. This study can assist the decision makers and
resource planners in taking the appropriate decisions regarding
daylighting stream channels to improve water quality or/and accommodate
increasing demand for urbanization.