| 1. |
- Begin by discussing water quality and drainage basins:
- BACKGROUND
- Water Quality is important to Kansans. It was reiterated
- on October 19, 1995, when Governor Bill Graves announced
a multi agency initiative designed to protect and restore the
quality of Kansas surface waters. The focus of the plan is the
Kansas Lower Republic river basin, an area that stretches across
10,500 square miles of north central and north eastern Kansas.
Three major pollutants are of concern in this plan; sediments,
the crop herbicide atrazine and fecal coliform bacteria found
in human and animal waste. Water quality data indicate that the
Delaware River, The Big Blue river and the Kansas river mainstream
corridor (Junction City to Kansas City ) contribute the highest
levels of contaminants, and, thus is the focus of attention in
the initial stages of the Water Quality plan. (The Governor’s
Water Quality Initiative, August 1996)
- Student’s need to understand that drainage basins do
not
- stop at state borders. Natural conditions of weather, geology
and land use practices that occur in one drainage basin effect
other drainage basins and populations downstream. Most of the
land in the Big Blue drainage basin is crop land, and agricultural
practices at the north end of this drainage basin, contribute
to the quality of water that flows in the Kansas Lower Republic
basin.
- Stream water quality in the Kansas and its tributaries is
effected by agricultural runoff, industrial and municipal effluents
and urban runoff. Suspended sediments concentrations were much
higher in the Kansas river than in the Big Blue river because
the reservoir at Tuttle Creek lake traps most of the sediment.
- By using flood of 1993 to illustrate the movement of water
- from one end of Big Blue Drainage basin to the other, students
can observe that conditions in Nebraska and northern Kansas effected
lake levels subsequent releases of water at Tuttle Creek dam
and reservoir.
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| 2. |
- Show overheads of the dominant weather pattern for the
- U.S. during June/July 1993 and discuss the system that caused
the rains. Illustrate using the Kansas and Nebraska rainfall
maps the massive amounts of moisture that fell on this drainage
basin. Ask the students to explain why the rainfall in accompanying
overheads had an effect on the Kansas Lower Republican and Big
Blue drainage basins? (Tuttle Creek Lake drains almost 10,000
square miles 1/16th the total
- area of the states of Kansas and Nebraska.) Show overhead
of the
- area drained by Tuttle Creek. At maximum flood control pool,
the lake
- covers 53,000 acres. Hold up the unlaminated map of Tuttle
Creek so
- students can see the shape of the lake and the area covered
at
- conservation pool level. Point out that the Reservoir drains
into the Big
- Blue River. This river meets with the Kansas River about
5 miles
- downstream in Manhattan, Kansas.
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| 3. |
- Have students volunteer reasons why this dam was built in
- the first place. Their answers should include the following.
If they do not list all of the following, then include the information
in your discussion of the purposes for the reservoir.
a.
b.
c.
d. |
- An important purpose of TCL (Tuttle Creek Lake) is flood
control. Four 10’ by 20’ gates weighing 25 tons each
control how much water is released from the lake into the Big
Blue River. Potentially damaging flood waters are held in the
lake until danger has passed. The gates are then opened and stored
water can be released downstream. The normal release through
the spillway is referred to as water through “the tubes”.
- TCL is also responsible for maintaining water quality downstream.
When the water is low in the Kansas River, TCL may increase it’s
outflow to supplement water supplied for downstream communities.
Increased flow in the river also helps to dilute impurities that
might diminish the quality of the water to various towns.
- One of the main purposes of TCL is to assist navigation.
During dry periods water can be released to raise the level of
the Kansas River and increase channel depth necessary to float
barges on the Missouri river.
- Approximately 1,000,000 people visit TCL each year. Camping,
swimming, skiing, hunting, hiking, picnicking, boating and just
plain relaxing are all recreational activities that attract visitors
to TCL each year.
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| 4. |
- Assign students to groups depending on the class size if
you want
- the students working independently or in groups. The Climatological
data and have them graph precipitation for selected sites that
drain the basin. Each site should be graphed in BLUE PENCIL on
a separate paper for a total of 13 (15) sites.
Kansas: Axtell, Blaine, Blue Rapids, Centralia, Marysville,
Tuttle Creek Lake
Nebraska: Barneston, Beatrice, Crete, Fairbury, Harbine, Western
Wymore. (For additional sites you may add Hastings and Minden
from the southwest station.)
- Have a second group of students (7) graph in ORANGE
- PENCILS the lake levels of TCL from March 1993 through Sept
22, 1993. The third set of students (7)
should graph in RED PENCIL the daily outflows from Tuttle through
the reservoir (or tubes) and the overflow emergency spillway.
Have them put a small “s” on the chart for the days
when the releases were through the spillway. The waters are released
from the spillway when the lake level reaches flood stage, in
this case, 1136 feet above sea level. Tainter gates are raised
and the water in the spillway goes under the gates and is released
into the Big Blue River.
- Have one or two of the remaining students color in the
- laminatedmap of the reservoir using blue overhead transparency
markers. Using the thin broken blue line that represents the
level of the Lake at flood control pool, color inside the perimeter
of the lake the area that would be filled with water when the
lake is at flood stage. This is to illustrate how far out of
the normal conservation pool boundaries the lake can extend during
a flood event.
- Allow students time to work on their charts, graphs, and
maps. I
- would allow about 10 minutes.
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| 5. |
- When students are finished have them stand side by side in
- a large circle and hold their papers in front of themselves,
so all students can see the charts. Have the rainfall graphs
displayed beside the lake levels and outflow graphs. Depending
upon your situation, you may want to have the students tape their
papers to walls and continue the discussion with the students
seated.
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| 6. |
- Ask a few students to briefly point out what interested them
- in the graph they made. Encourage them to notice patterns
in the graphs they created ( amount of rainfall, lake levels
and outflows.) Ask
- geographic questions about why the outflow decreased to 100
cubic feet per second before the flood stage was reached? (Water
was being held due to extreme flooding in the Kansas, Missouri
and Mississippi Rivers) What months were the most significant
in terms of rainfall? (June and July) Why is TCL located where
it is and not farther upstream? (due to elevation of the land
TCL was located near Manhattan) How were people downstream effected
(bridges and roads washed out, farms and homes near banks of
Big Blue and Kansas river abandoned, railroad bridges effected,
sand pits and landfill along the river
- threatened) Why did rainfall in Nebraska contribute to the
flooding of Kansas communities. (All part of the same drainage
basin, water does not stop at state borders.) At its peak the
outflow was 60,000 cfs. Have students compute how many gallons
of water were coming over the spillway each second. What effect
would this have on the land immediately below the dam, (erosion)
and analyze their findings. Encourage the students to continue
asking and asking their own
- geographic questions and analyze the charts for their answers.
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| 7. |
- The sediment at TCL was also effected. By using reconnaissance
- surveys that were done on TCL in June and September 1993,
estimates can be made of the impact of the flood on sediment
inflow and incremental storage loss due to this event. The closure
date for the TCL project was 1959, the Multi purpose pool level
is 425,000 acre feet, sediment allocation is 233,000 acre feet,
the storage loss since closure is 164, 100 acre feet, and the
loss during the 1993 was 2,600 acre feet. This means that 2,600
acre feet of sediment were brought in by the flood and remained
in trapped in the reservoir.
- When the movement of water is halted, the sediment load that
had
- been suspended in that water will drop out. Normally water
moves into the reservoir and the sediment is trapped in the reservoir
as the water is trapped behind the dam. During periods of high
water large amounts of sediment are washed. Significant amounts
of sediment may have passed through the emergency spillway gates,
however 2,600 acre feet of additional sediment remained after
the flood. This is why it is estimated that TCL lost about one
percent of it’s storage capacity.
- From these figures, one can calculate the following. 164,100
acre
- feet of storage lost divided by 233,000 acre feet of sediment
allocation indicates that since 1959, TCL has reached 70 percent
of its storage capacity for what was estimated to take 100 years.
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e-mail: pphillip@fhsu.edu