Tiev, Visoth (2011) Vegetation and discharge effects on the hydraulic residence time distribution within a natural pond. PhD thesis, University of Warwick.

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Abstract

Results are presented from sets of field and laboratory experiments conducted to
measure and quantify the Hydraulic Residence Time Distribution in treatment
ponds containing vegetation. The field measurements were taken in the Lyby field
pond (Sweden) with complementary experiments on a distorted, laboratory scale
model pond designed and built in the University of Warwick’s engineering
laboratory. Rhodamine WT Dye tracer experiments were used in both the Lyby
field pond and the distorted physical scale model to investigate vegetation and
discharge affects on HRTD characteristics and the technique of PIV (Particle
Image Velocimetry) was used in the distorted physical scale model to investigate
how surface flow profiles were affected by different vegetation and discharge
configurations.
The results show that the distorted physical scale pond did not reflect the HRTD
characteristics of the field site, with the actual residence time, (tm), for the distorted
physical scale pond ranging from 85 % to 125% of its nominal residence time. For
the distorted scale model, pond vegetation and discharge did not affect the relative
HRTD centroid, em, or the actual residence time, tm. This finding is attributed to
the unique pond geography and associated aspect ratios However, flow rates did
have a significant effect on the HRTD e0 (time of first dye arrival at the outlet) and
ep (time of peak dye concentration). Changes in vegetation were found to have
little effect on e0 and ep. For the laboratory pond, vegetation had a significant
control on the surface flow field whereas, flow rates did not – the latter suggests
that surface flow fields are not representative of the internal flow field in different
layers of the pond.
The experiments demonstrate that the specific shape of the distorted physical
scale pond in this study enables optimal actual resident times to be achieved over
a wide range of vegetation and flow rate configurations. If full scale field ponds
based upon this design give the same stable centroid results, then this would be a
substantial breakthrough in pond design, which would aid the design and
management of pond treatment and allow more robust optimisation of treatment
efficiency.

Item Type:	Thesis (PhD)
Subjects:	T Technology > TD Environmental technology. Sanitary engineering
Library of Congress Subject Headings (LCSH):	Ponds -- Design, Pond plants, Water -- Purification, Fluid dynamics
Official Date:	February 2011
Dates:	Date Event February 2011 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Guymer, Ian
Sponsors:	University of Warwick. School of Engineering ; European Commission (EC) (KH/Asia-Link/04 142966)
Extent:	xxv, 292 leaves : ill., charts
Language:	eng

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