Discharge and Sediment Transport Modeling Buck Creek Proposal
1. Modeling Pre-Dam Modification Discharge and
Sediment Transport: Snyder Park,
Springfield, Ohio, USA
James A Blumenschein
Department of Geology
Wittenberg University
Springfield, OH 45501-0720
USA
Proposal
Submitted in partial fulfillment towards the requirement of
the Floyd R Nave Endowment Award.
2. Introduction
The purpose of this study is to model discharge and
sediment transport through a recreational structure in Buck
Creek in order to create a stage-discharge rating curve
upstream of the structure. A stage-discharge rating curve
is a plot of flow stage against discharge (DeGagne et al,
1996). A stage-discharge rating curve is created so that
when coupled with a continuous gauging of a river’s stage,
a corresponding discharge can be approximated. Discharge
data can usually only be retrieved with a wading rod at
moderate flows, due to obvious dangers. A stage-discharge
rating curve can be used to estimate discharges at higher
flows by extrapolation, however, with increasing
uncertainty as discharge increases. Alternatively,
streamflow, in particular higher magnitude floods, can be
modeled through a channel reach model to compare to and/or
validate extrapolations made from lower magnitude events.
Hydrologic Engineering Center River Analysis System
(HEC-RAS) is a computer modeling program that provides one-
dimensional steady flow, unsteady flow, sediment transport,
mobile bed computations and water temperature modeling.
The program utilizes absolute elevation data,
parameterizing a channel’s geometry, and absolute water-
surface elevation data as baseline data to extrapolate its
3. variety of computations and modeling capabilities by
transitioning baseline data to a stage-discharge rating
curve.
Stage-discharge rating curves give detailed insight in
to the relation between stage or discharge with variables
such as bed geometry, bed stability and flood response
(Bullard et al, 2006). A continuous record of discharge
can aid in estimating the total discharge of a stream
hydrograph to determine sediment or solute load as well as
accumulated annual volumes of water that may pass through a
given stream cross-section of a reach (Clemmens & Wahlin,
2006). Resultant conclusions of stage-discharge studies
can help to determine effects on rivers produced from
measured or modeled climate and land-use change (McMillan
et al, 2010). Change in landuse and/or climate create
changes in both frequency and magnitude of discharge and
impact stream ecology (Doyle et al, 2005). Different
ranges of discharge drive different ecologic processes such
as algal growth, organic matter transport, nutrient
retention and replenishment, macroinvertebrate disturbance,
and habitat availability (Doyle et al, 2005).
Changes in frequency and magnitude of observed
discharges can change the slope of a stage-discharge curve,
4. evident in comparative analyses of two curves; denoting a
change in flow-stage for a given discharge.
Background Information
In 2010, a low-head dam situated in Buck Creek at
Snyder Park was modified and four recreational drop
structures, engineered to create hydraulics for kayaking,
were constructed in its place (figure 1). The change in
the cross-section at the upper most structure (Figure 2)
caused a change in the stage-discharge rating curve (Figure
3). Ten field discharge measurements were taken from April
through October of 2010, after completion of the waterway
structures, and characterize discharges from 38 to 335 cfs.
These measurements were taken as a part of a study
conducted by Wittenberg University to quantify the changes
in Buck Creek’s stage-discharge relationship resulting from
the low-head dam removal/modification. The goal of this
study is to use a computer model to extend the post-dam
modification, stage-discharge rating curve for Buck Creek
to include higher discharges.
Study Reach
The Buck Creek study reach starts at Plum Street and
is approximately 0.5 miles in length. The study reach ends
just after four recreational, waterway structures that were
5. constructed after the removal of a low-head dam in 2010
(figure 1). This straightened and channelized reach
contains a gauging station immediately downstream of Plum
Street, along the north bank (Figure 1). The gauge records
stage at fifteen-minute intervals. The width of the
channel varies from approximately 80 feet to 110 feet with
an average stage of 3.7 feet.
Methods
Baseline data will be collected through the use of a
TopCon GRS-1 GPS unit. The GRS-1 is a survey grade unit
that uses an integrated cellular modem and GNSS satellite
receiver, utilizing both GPS and Glonass satellite systems
to record elevation and position data with, when used with
an L1 antenna, sub-meter accuracy. Using the GRS-1 unit,
cross-sectional surveys will be performed throughout the
length of the study reach, with frequencies of every 50 to
80 feet. More drastic changes in the channel geometry may
call for increased frequencies of surveyed cross-sections.
The GPS unit will also be implemented in attaining
absolute water-surface elevation data. The HEC-RAS
requires the water-surface elevations be given for the
beginning and end of the study reach along with the
elevation’s corresponding discharge. Discharge
measurements will be taken using a Sontek Flowtracker. The
6. Flowtracker is a handheld Acoustic Doppler Velocimeter
(ADV) that attaches to a wading rod. It measures discharge
using an automatic discharge computation feature that
adheres to United States Geologic Survey and International
Standards Organization standards. It features an internal
quality control that checks for irregularities in both the
data collected and internal workings of the instrument.
The wading rod used in conjunction with the Flowtracker is
a 4-foot, top setting rod.
This baseline data will be tied to real-time stage
data that is collected by the gauging station, located
within the study reach, linking a gauge reading with an
absolute water-surface elevation and discharge value. The
step-back water method will then be used to extend the
post-dam modification stage-discharge rating curve for Buck
Creek. This method uses water surface profiles with
corresponding discharges and channel geometry to create a
stage-discharge rating curve (Kennedy, 1984). HEC-RAS will
be used to complete the step-backwater method, using the
baseline data by extrapolating multiple water surface
profiles with their corresponding discharge values. A
steady-state, stage-discharge rating curve is then
compiled.
7. Uncertainty with the model is largely dependent on the
number and range of known water surface elevations and
their corresponding discharge values. With numerous,
widely ranging known values, HEC-RAS’s extrapolations are
more constrained and less uncertain. The model generated
by HEC-RAS can be evaluated through the input of known
stage-discharge values. This method is optimally used when
controls other than channel geometry are present, including
in-line wiers, waterway structures, and dams (Kennedy,
1984).
Objectives
Establish absolute elevations for the gauging station
on Buck Creek.
Collect and integrate cross-sectional survey data
throughout the Buck Creek study reach
Collect water surface elevation and discharge data for
a variety of stages on Buck Creek
Create a functional, stage-discharge rating curve for
Buck Creek
Equipment
TopCon GRS-1 GPS Unit with L1 antenna
Sontech Flowtracker and top-setting wading rod
PC desktop or Laptop
8. Other miscellaneous items
Timeframe
Baseline data will be collected from week 1 to week 4 of
this project’s initialization. Water surface elevations
and discharge values can be collected independently of
cross-sectional elevations. After week 3 or when
sufficient baseline data exists, values can be inputted
into the HEC-RAS program and a stage-discharge rating curve
can be created. Additional water-surface elevations and
discharge values can be added after the generation of the
stage-discharge rating curve. Total estimated time to
completion, 8 to 10 weeks.
Proposed Budget
Much of the equipment to be used in this study is
provided for by the Geology Department of Wittenberg
University. This equipment includes the GRS-1 GPS unit,
the Sontech ADV Flowtracker, and much of the miscellaneous
items. The study reach is within 1 mile of Wittenberg
University, making travel expense, such as gasoline,
negligible.
12. References
Bullard, J., McTanish, G., & Martin, P, 2007, Establishing
Stage-Discharge Relationships in Multiple Channelled,
Ephemeral Rivers: a Case Study of the Diamantina
River, Australia: Geographical Research, v. 45, no.
3, doi: 10.1111/j.1745-5871.2007.00457.x
Clemmens, A., & Wahlin, B., 2006, Accuracy of Annual Volume
from Current-Meter-Based Stage Discharges: Journal of
Hydraulic Engineering, doi: 10.1061/(ASCE)1084-
0699(2006)11:5(489)
DeGagne, M., Douglas, G., Hudson, H., & Simonovic, S.,
1996, A decision support system for the analysis and
use of stage-discharge rating curve: Journal of
Hydrology 184, p. 225-241, doi: 0022-1694(95)02973-7
Doyle, M., Stanley, E., Strayer, D., Jacobson, R., &
Schmidt, J., 2005, Effective Discharge Analysis of
Ecological Processes in Streams: Water Resources
Research, v. 41, p. 1-16, doi: 10.1029/2005WR004222
McMillan, H., Freer, J., Pappenberger, F., Krueger, T., &
Clark, M., 2010, Impacts of Uncertain River Flow data
on Rainfall-Runoff model calibration and discharge
predictions: Hydrological Process, v. 24, p. 1270-
1284, doi: 10.1002/hyp.7587
