Agricultural inputs of phosphorus are
major
contributors of nonpoint source pollution to surface water bodies.
Increased
attention has recently been focused on the differentiation between
total
phosphorus and the portion that is actually “bioavailable”.
Streambed/Pool
sediments have been shown to be the main storage of phosphorus released
from watersheds. It is believed that hydrodynamic processes play an
important
role in causing sediment resuspension, deposition, mixing, and
advective
and diffusive transport in the pools. Other factors such as the
grasses,
and plant material in the instream deposits and bank materials
can
also contribute to the erosion resistance of the channel material and
are
source of phosphorus. We are investigating the effects of hydrodynamic
processes and physicochemical factors on the mobility of sediments in
the
Yahara River and its tributaries. Both field
experiments
and modeling in different type of pools (dry ditch, wet natural pool,
and wet
dredged
pool) are conducted by our interdisplinary research team.
Our final goal is to elucidate and quantify the in-stream
processes
governing the fate and transport of bioavailable phosphorus in channels
and streams sediments.
Wetlands are unique features of the
landscape that can significantly affect the movement and quality of
surface and ground waters. By temporarily storing water, wetlands
can reduce flood peaks, sustain streamflow during dry periods, retain
sediment and phosphorus, and promote denitrification. But throughout
most of human history, wetlands have been considered "wastelands" and
many have been drained for agriculture and other uses. For example,
over 60 percent of the wetlands that once existed in the Midwestern
U.S. have been lost, mostly to agricultural uses. Many of the remaining
wetlands have been degraded, largely through ditching and channel
incision. These degraded wetlands are predominantly located in
agricultural areas where surface water quality is severely impaired by
excessive sediment and nutrient loads. Despite their prevalence, little
is known about the degree to which these degraded wetlands mitigate
this impairment. This project is aimed to better understand the role of
wetlands in controlling water quantity and quality through a nested
modeling approach and field validation.
Sponsor : US-EPA/USDA
Status : Active
Student Investigators: Khurran Khan (Ph.D.)
Graduated:
Evan Murdock (M.S..), Justin Roger
(M.S.),
Doo-Yong Choi (Ph.D.)
Publications:
- Choi, D.Y and Wu, C.H., Study of non-hydrostatic effects on
curvied channels using a curvilinear non-hydrostatic flow model. To be
submitted, 2009.
- Rogers, J. S. Potter, K.W., Hoffman, A.R., Hoopes, J.A, Wu, C.H., and Armstrong, D.E. Hydrologic and water quality functions of a small wetland, Journal of the American Water Resources Association, 45 (3), 628-640, 2009.
- Rogers, Justin M., Hydrologic and Water Quality Characteristics of a Small Wetland- Upper Dorn Creek Wetland, Wisconsin. Master Thesis, Dept. of Civil and Environmental Engineering, UW-Madison, 2006.
- Choi, D.Y., An non-hydrostatic model in open channel flows, Ph.D. Dissertation, Dept. of Civil and Environmental Engineering, UW-Madison, 2006.
- Evan Murdock, Transport and storage of sediments and solutes in a small agricultural stream, Dane County, Wisconsin, Master Thesis, Dept. of Civil and Environmental Engineering, UW-Madison, 2005.
Patttern of two sediment peaks occurring in
major storms
