Visualization
of Flow Alternatives, Lower Missouri River
U.S. Geological Survey
Open-file Report OF02-122
Robert
B. Jacobson and Jeanne Heuser, U.S. Geological Survey, Columbia, Missouri
October 2001
Direct
Links to:
Background
The U.S.
Army Corps of Engineers (COE) "Missouri River Master Water
Control Manual" (Master Manual) review has resulted in consideration of many flow
alternatives for managing the water in the river (COE, 2001; 1998a). The
purpose of this report is to present flow-management alternative model results in a way that can be
easily visualized and understood. This
report was updated in October 2001 to focus on the specific flow-management alternatives
presented by the COE in the "Master Manual Revised Draft
Environmental Impact Statement" (RDEIS; COE,
2001). The original version (February 2000) is available by clicking
here.
The
COE, U.S. Fish and Wildlife Service (FWS), Missouri River
states, and Missouri River basin tribes have been participating in discussions
concerning water management of the Missouri River mainstem reservoir system
(MRMRS), the Missouri River Bank Stabilization and Navigation Project,
and the Kansas River reservoir system since 1986. These discussions
include general input to the revision of the Master Manual as well as formal
consultation under Section 7 of the Endangered Species Act. In 2000, the FWS issued a Biological Opinion that prescribed changes to reservoir management on
the Missouri River that were believed to be necessary to preclude jeopardy to
three endangered species, the pallid sturgeon, piping plover, and interior
least tern (USFWS, 2000).
The combined Missouri River system is large
and complex, including many reservoirs, control structures, and free-flowing
reaches extending over a broad region. The ability to assess future impacts of
altered management scenarios necessarily involves complex, computational models
that attempt to integrate physical, chemical, biological, and economic effects.
Graphical visualization of the model output is intended to improve
understanding of the differences among flow-management alternatives.
This report presents a visual, statistical presentation of five modeled
flow-management alternatives and two reference alternatives for four selected sites on
the Lower Missouri River at Sioux City, Iowa, Nebraska City, Nebraska, Kansas City, Missouri, and
Boonville, Missouri (fig. 1). The flow-management alternative data have been
generated by the COE using the Missouri River system Daily Routing Model (COE,
1998b). The Daily Routing Model calculates a water balance and routes water
through six dams in the system, providing modeled outflows at 14 sites.
Flow-management alternatives presented in this report are limited to those under consideration in the August 2001 Master Manual RDEIS (COE, 2001) and two reference alternatives, the Current Water Control Plan (CWCP) and a run of river scenario (ROR), explained in "Modeled Alternatives."
Figure 1. Missouri River basin and the Lower Missouri River. The Lower Missouri River is the part of the river downstream of Gavins Point Dam near Yankton, South Dakota, and extending to the junction with the Mississippi river near St. Louis. Flow-management alternative data are presented here for streamgages at Sioux City, Nebraska City, Kansas City, and Boonville. |
Selection of MRMRS water-control rules is a
complex and ongoing socio-economic and political process that attempts to
balance desires of multiple stakeholders in the Missouri River basin. Flows modeled in each of the alternatives can be evaluated in terms of
economic benefits and relative environmental effects; results of these effects
models are presented elsewhere (COE, 1994-1999; COE, 1998a, RDEIS; COE,
2001.)
This report presents modeled streamflows to enhance
visualization and understanding of proposed flow-management alternatives for the
Master Manual; it does not
attempt to evaluate relative performance, benefits, or environmental effects of
alternatives.
Daily Routing
Model
Results of flow-management
alternatives have been
modeled by the COE using the Daily Routing Model (COE,
1998b). The modeled flows are
synthesized from historical data on tributary inflows, calculations of streamflow depletions due to
evapotranspiration and consumptive use of water,
and modifications of outflows according to water-control rules that comprise a
flow-management alternative. The model reproduces how reservoirs would be
managed under a set of water control rules, given the actual range of
variability of historical inflow data. Historical data are available, or have been estimated, for the period
1898-1998. The Daily Routing Model uses these data and water-control rules to
generate 100 years of daily flows for each of 14 sites for each flow-management
alternative. The 14 sites consist of nine streamflow gaging stations on the Lower Missouri River and
five streamflow
gaging sites in inter-reservoir river segments. Model runs show the result of highly variable streamflow routed
through the reservoir system according to water-control rules of varying
complexity. Because storage in the Missouri River reservoir system is finite
and because many tributary inflows are not regulated by reservoirs, the natural
variability of the historical inputs is reflected in variability in the output
discharge (fig. 2). Additional information on the Daily Routing Model can be
found in COE (1998b).
Modeled flow data for the alternatives were obtained from the COE. These files consist of dates and modeled flows at nine streamflow gaging stations on the Lower Missouri River. Of these nine sites, four were chosen to represent the range of effects on the Lower Missouri River (fig. 1).
The data were reformatted and converted to watershed data management (WDM) format using the IOWDM program (Flynn and others, 1994; available at: http://water.usgs.gov/software/iowdm.html). The data were then analyzed for flow frequency using the program SWSTAT (Flynn and others, 1994; http://water.usgs.gov/software/swstat.html). The frequency hydrograph routine of SWSTAT calculates the relative frequency of flows for every day of the year for the period of record. Output from this program consists of flow exceedance percentiles (for example, 90th percentile, 50th percentile) and the corresponding flow for each day of the year. The program was run to extract flows that were equaled or exceeded 90, 75, 25, and 10 percent of the time.
The exceedance data were then plotted as shaded bands by day of the year to illustrate variations in flow during the year and over the 100 years of modeled record (fig. 3). Vertical variation in the graphs is a measure of variation among years and horizontal variation is a measure of seasonal variation. Overlays of reference alternatives present opportunities for visual comparisons. Each of the new flow-management alternatives is compared to the run of river scenario (ROR - shown in light gray in graphs) and the 90th and 10th percentile flows of the Current Water Control Plan (CWCP - shown as black lines).
For comparison, full-service and minimum-service navigation flow targets (table 1) are shown for Sioux City, Nebraska City, and Kansas City graphs (COE, 1998b). Releases from Gavins Point dam to maintain navigation targets typically are higher than the target (for example, a 28.5 kcfs release compared to a 25 kcfs target for minimum navigation; 34.5 kcfs release compared to 31 kcfs target for full-service navigation). Releases are higher than the targets to compensate for diminishing tributary inflows and to avoid having to increase flows during the tern and plover nesting season.
The approximate discharge corresponding to the flood stage
defined by the National Weather Service (NWS) flood stage also is indicated on each
graph. The NWS flood stage is specific to the gage sites, and is highly dependent on the
channel geometry as determined by levees and floodwalls. The NWS flood stage was converted to discharge
by reference to U.S. Geological Survey stage-discharge rating curves for each
gage.
A second set of four graphs was developed to
show the effects of flow alternatives on the highest flows. These graphs present the maximum flows
occurring for each day of the year over the 100 years of modeled flows. The ROR scenario and discharge at NWS flood
stage are shown for comparison.
Table
1. Full- and minimum-service
navigation flow targets at three locations on the Lower Missouri River (COE,
1998b). Flows from Gavins Point dam are managed to maintain navigation
targets at sites downstream, and so generally are somewhat higher than the
targets; see text for additional information. Navigation targets
are not defined by the Corps of Engineers for Boonville, Missouri. [kcfs, thousands of cubic feet per second] |
||
Location |
Full-Service Target [1] kcfs |
Minimum-Service Target [2] kcfs |
Sioux City, Iowa |
31 |
25 |
Nebraska City, Nebraska |
37 |
31 |
Kansas City, Missouri |
41 |
35 |
Boonville, Missouri |
Not defined |
Not defined |
[1]
Full-service navigation – Targeted flows to maintain approximately a minimum
of 8.5 feet of draft below Missouri River barges (COE, 1998a). |
[2] Minimum-service navigation – Targeted flows to maintain approximately a minimum of 7.5 of draft below Missouri River barges (COE, 1998a). |
Modeled
Flow-Management Alternatives
The following
flow-management alternatives are analyzed and
presented here. Except for ROR, all the alternatives include drought
conservation measures, reservoir unbalancing, and tern and plover mitigation
rules (see COE, 1998a). The alternatives are identified by the codes shown in
bold. The Master Manual RDEIS
(COE, 2001) emphasizes that the modeled Gavins Point (GP) management alternatives are meant to
indicate a range of spring rise and summer low-flow conditions. The starting point for
GP releases
would be the GP1528, but the actual Gavins Point dam releases would be
determined through an ongoing adaptive management process based on monitoring
of biological responses.
Reference
Alternatives:
·
ROR
The
run of river alternative where streamflow is modeled for the conditions of
constantly full reservoirs. Except for some evaporation from the reservoirs and
the effects of small, triburary reservoirs,, it
provides a realistic depiction of flows in the absence of regulation, that is, an
estimate of natural-river alternative.
·
CWCP
The
Current Water Control Plan for the Missouri River Mainstem Reservoir System (MRMRS).
Management
Alternatives:
·
MCP
Modified Conservation Plan where, during drought
conditions, more water is conserved in upstream reservoirs by reducing
navigation earlier in the season than in the CWCP.
The following four flow-alternatives evaluate the
relative effects of high and low flow from Gavins Point (GP) dam. High flow is
added to releases that are sufficient to meet full-service navigation
targets, nominally 34.5 kcfs (see Table 1). The spring rise is
proposed to occur on an average of once very 3 years, as conditions allow.
·
GP1521
High: A 15 kcfs spring rise above full-service
navigation releases.
Low: A split navigation season with two low-flow periods during the summer of 21
and 25 kcfs.
·
GP1528
High: A 15
kcfs spring rise above full-service navigation releases.
Low: A release of 28.5 kcfs (full-service navigation)
throughout the navigation season.
·
GP2021
High: A 20
kcfs spring rise above full-service navigation releases.
Low: A split navigation season with two low-flow
periods during the summer of 21 and 25 kcfs as proposed in GP1521.
·
GP2028
High: A 20 kcfs spring rise above full-service
navigation releases.
Low: A release of 28.5 kcfs (full service navigation)
throughout the navigation season.
Results
The following
hydrographs for the modeled reference and
flow- management alternatives graphically show the differences among modeled
flow-management alternatives for
each site as well as showing the variable effects from upstream to downstream:
The
frequency
hydrographs show the seasonal and interannual variability of modeled flows that
would be equaled or exceeded 10, 25, 75, and 90 percent of the time. The degree of change associated with the
flow-management alternatives varies geographically, and is most pronounced at Sioux
City, the station closest to Gavins Point dam. Downstream on the Lower Missouri River, additions of discharge from
non-regulated or little-regulated tributary drainage basins modifies the
effects of reservoir regulation. As a
result, the modeled flow-management alternatives converge toward the Current Water
Control Plan (CWCP) and exhibit greater seasonal variation for downstream
stations.
The
maximum-flow
hydrographs show the seasonal variability of modeled maximum flows for each day
of the year. These flows are those that
are equaled or exceeded only one percent of the time on average. The discharges
associated with NWS flood stage are specific to the gage
sites, and are highly dependent on the channel geometry as determined by levees
and floodwalls. The flow-management
alternatives generally plot at lower discharges than the ROR alternative during
the spring and at greater or equivalent discharges during August-November. The CWCP, MCP, and GP alternatives all plot
nearly on top of one another; a few exceptions show 10-20 kcfs differences
among the alternatives. In Sioux City
the flow-management alternatives all plot substantially lower than the local flood
stage discharge, with the exception of flows in June 1984. Moving
downstream where flow is less regulated, maximum flows plot more frequently above flood-stage discharges.
References Cited
COE, 2001, Summary – Missouri River Revised
Draft Environmental Impact Statement, Master Water Control Manual Review and
Update: U.S. Army Corps of Engineers, Northwest Division, online publication
August 2001, http://www.nwd-mr.usace.army.mil/mmanual/mast-man.htm.
COE, 1998a, Revised Draft Environmental
Impact Statement: U.S. Army Corps of Engineers, Northwest Division Missouri
River Region, Master Water Control Manual Missouri River Review and Update
Study, v. 2A, 614 p.
COE, 1998b, Reservoir regulation studies –
daily routing model studies: U.S. Army Corps of Engineers, Northwest Division
Missouri River Region, Master Water Control Manual Missouri River Review and
Update Study, v. 2A, 137 p.
COE, 1994-1999, Master Water Control Manual Missouri River Review and Update Study: U.S. Army Corps of Engineers, Northwest Division Missouri River Region, v. 1-13.
Flynn, Kathleen M., Hummel, Paul R., Lumb,
Alan M., Kittle, John L., Jr., 1995, User's manual for ANNIE, version 2, a
computer program for interactive hydrologic data management, WRI 95-4085, p.
211.
USFWS, 2000, Biological Opinion on the
Operation of the Missouri River Main Stem Reservoir System, Operation and
Maintenance of the Missouri River Bank Stabilization and Navigation Project,
and Operation of the Kansas River Reservoir System: U.S. Fish and Wildlife
Service, 286 p.
|
||
Contact:
Dr. Robert B. Jacobson
USGS-CERC 4200 New Haven Road Columbia, Missouri 65201 573-875-5399 |
||
Last modified: 03/15/2002 |