Sam's Nenana River Project - 2010

Sam has been studying the water quality of the Nenana River for three years. He has measured the water temperature and conductivity and determined the suspended sediment load of the Neanana River on a weekly basis for the years 2008, 2009 and 2010.

He added four new sampling sites in 2010, one just upstream from the confluence of the Nenana River and Riley Creek, one just downstream from the confluence, one up Riley Creek itself and one on the Yanert Fork. You can see his data from:

• the Denali Education Center (or McKinley Village) (2008, 2009 and 2010),
• Riley Creek (2009 and 2010),
• the "Glitter Gulch" bridge (2009),
• Nenana River upstream of Riley Creek (2010),
• Nenana River downstream of Riley Creek (2010),
• upstream on Riley Creek (2010), and
• Yanert Fork (2010).

Sam presented his 2010 research at the Denali Borough School District Science Fair at the Tri-Valley School in Healy on 8 March 2011. He received a Grand Prize (there were 12) and the Best Earth Project Award from the Usibelli Coal Mine. This qualified him for the science fair in Fairbanks in March.

At the Interior Alaska Science Fair, held March 23-26, 2011 at the Pioneer Park Civic Center in Fairbanks, Sam received a first place ribbon. His brothers Hable (grade 7) and Ben (grade 2) also won prizes at the science fair.

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INTRODUCTION - 2010

This study is a follow-on from Sam's 2008 and 2009 research.

Questions

Part One:
Is there a significant difference in the amounts of dissolved ions and suspended sediment in a glacier-fed river and a non-glacier-fed creek?

Part Two:
Do the amounts of dissolved ions and suspended sediments in the Nenana River vary from year-to-year when sampled at the same location?

Hypotheses

Part One:
I think that there will be a significant difference in the amounts of dissolved ions and suspended sediment between a glacier-fed river and non-glacier-fed creek.

Part Two:
The amounts of dissolved ions and suspended sediment in the Nenana River will vary from year-to-year when sampled at the same location.

List of some important locations:

Sam's Sampling Sites
Denali Education Center (DEC)*    63° 44.23’N, 148° 53.22’W
Nenana River (upstream RC)    63° 43.56’N, 148° 52.92’W
Nenana R./Riley Creek Confluence    63° 43.62’N, 148° 53.01’W
Nenana River (downstream RC)    63° 43.62’N, 148° 52.20’W
Upstream on Riley Creek    63° 43.62’N, 148° 53.10’W
Yanert Fork    63° 37.44’N, 148° 13.56’W

* Also called McKinley Village

Weather Stations (airstrips)
Cantwell (PATW)    63° 23.47’N, 148° 57.34’W
Denali (PAIN)    63° 43.96’N, 148° 54.64’W
Healy (PAHV)    63° 52.06’N, 148° 58.14’W

Important Local Geography
Nenana Glacier    63° 29.72’N, 147° 48.02’W
Yanert Glacier    63° 35.61’N, 147° 52.48’W
Yanert Fork/Nenana R. Confluence    63° 40.92’N, 148° 46.78’W

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Data from the Yanert Fork and the Sites in the Vicinity of Riley Creek

In 2010, Sam made measurements at six different sites: at Yanert Fork; at Denali Education Center (DEC); at the confluence of the Nenana River and Riley Creek; upstream from this confluence; downstream from this confluence; and upstream on Riley Creek (map of sites). Riley Creek is fed by snow melt and precipitation. Yanert Fork is fed by Yanert Glacier. The Nenana River near Riley Creek is fed by the Nenana and Yanert glaciers as well as snow melt and precipitation. An explanation of the variables can be found here.

• — What do you see in the first graph? How do the data from Riley Creek (upstream) and Yanert Fork compare? How do you explain what you see?
• — What do you see in the second graph? How do the data from Riley Creek (upstream) and the confluence of the Nenana River and Riley Creek compare? How do you explain what you see?
• — What do you see in the third graph? How do the data from and the vicinity of the the confluence of the Nenana River and Riley Creek compare? How do you explain what you see?
• — What can you say about the observations at these sampling sites?

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Comparison of water data from 2008, 2009 and 2010 at the Denali Education Center

Sam now has three years of data from the Denali Education Center (McKinley Village). The graphs at right are a time series of these data. They are called "time series" because time is the variable on the X axis. An explanation of the variables can be found here.

• — What do you see in these graphs?
• — Are there any trends in these data?
• — Are there any similarities between graphs?
• — What might explain your observations?

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Comparison of water data from 2009 and 2010 at Riley Creek

Sam now has two years of data from the Nenana River where Riley Creek enters it. The graphs at right are a time series of these data. They are called "time series" because time is the variable on the X axis. An explanation of the variables can be found here.

• — What do you see in these graphs?
• — Are there any trends in these data?
• — Are there any similarities between graphs?
• — What might explain your observations?

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Comparison of all the water data from the Denali Education Center and Riley Creek

The graphs below show the Denali Education Center and Riley Creek data together.

From left to right they are the 2008, 2009 and 2010 data. The first two columns of data can be seen here and a discussion of the 2008 and 2009 data can be found here. You can use that information to help you interpret these graphs and answer the questions. You can also refer back to your answers from the 2010 DEC and Riley Creek data.

• — What do you see in these graphs?
• — Are there any similarities between graphs?
• — What might explain your observations?

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The central tendencies and variation of the Nenana River, Riley Creek and Yanert Fork water data

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A comparison of the 2008, 2009 and 2010 summer air temperatures in the study area

The graphs below compare the average daily temperatures for 2008, 2009 and 2010 for the Cantwell, Denali and Healy airstrips. These sites are selected because they cover the whole area of sampling. The Cantwell airstrip is south of the sampling sites, the Denali airstrip is in the middle of the sampling area and the Healy airstrip is north of the sampling area (see the table in Introduction).

The graphs for the mean daily temperatures for 2008-2009, as well as the comparisons, can be found here.

The y-axis on each graph tells you what is being compared and how. For example, "Air Temp. 2010-2009 (°C), means that the 2009 average daily temperatures were subtracted from the values for the same day in 2010. The values are in degrees Celsius. If the 2010 value is larger than the 2009 value, subtracting them results in a positive number which means 2010 was warmer on that day. If the 2010 value is smaller than the 2009 value, the result is negative meaning the 2010 day was cooler.

Notice that several periods of negative or positive values are outlined with boxes on the graphs.

• — What can you say about these data?
• — What is the significance of the prolonged periods of positive or negative temperature differences?
• — What might this mean for the Nenana River water?

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An interpretation of Sam's data

If you want to remind yourself of the interpretation of Sam's 2009 project go here.

Looking At The Data And Putting It All Together

Yanert Fork, Riley Creek and the Nenana River in the vicinity of Riley Creek
The graphs comparing Yanert Fork and upstream on Riley Creek show that these two water bodies are very different. Yanert Fork has much more suspended sediment than Riely Creek. This is mainly due to the fact than Yanert Fork is glacier fed and Riely Creek is mainly fed by snowmelt and precipitation. The water conductivity is higher in Riley Creek than Yanert Fork. This is probably because the sources of water for Riley Creek go through vegetation and thin soil and spend some time on rocks - all opportunities for chemical weathering. By contrast, Yanert Fork water comes mostly from melting glacier ice.

The comparsion of upstream Riley Creek and the Nenana River at Riley Creek differ for similar reasons as Riley Creek and Yanert Fork. They are very similar in temperature, probably because they are within a short distance of each other (a few 100 meters).

The sites on the Nenana River in the vicinity of Riley Creek are very similar, although there is some variation. The inflow from Riley Creek does not appear to have a significant impact of the water characteristics of the Nenana River.

Denali Education Center - 2008, 2009 and 2010
The three years of data from the DEC site show some variability but the same general trends. The water temperature varies from week to week but generally warms up reaching its warmest towards th end of July and them cools down again (refreezing some time in November).

Water conductivity generally increases though the sampling season, although there are several deviaitons from this trend.

The Nenana River at Riley Creek - 2009 and 2010
Like the DEC data, these measurements show some annual variation but the general trends are much the same. The most obvious difference is in the total suspended sediment. While this value is fairly low in 2010, there are several peaks in the data in 2009, especially at the end of July - beginning of August.

Comparison of DEC and the Nenana River at Riley Creek Data
In both 2009 and 2010, the water temperatures are similar at both sites. The water conductivity (and dissolved ions) are generally higher at the Riley Creek location than at DEC. This may be from either the Yanert Fork, which enters the Nenana River after water flows past DEC or some influence from Riley Creek itself. The suspended sediment load is slightly higher at Riley Creek than DEC - again this reflects the influence of the contribution to the river by Yanert Fork (and Yanert Glacier). The most notable difference in suspended sediment load occurs at Riley Creek 2009. The series of sediment spikes may indicate some kind of rapid melting at Yanert Glacier.

Data Variations and Averages
The boxplots show the total variation in the data and indicate where most of the data lies. While all the sites over all the sampling years show variability in water conductivity and dissolved ions, the upstream Riley Creek site is most obviously different from all of the sites on the Nenana River and Yanert Fork. This is because it is the only site of non-glacial water. The Yanert Fork site shows the most variability of the other sites - this may be because it is close to its source (Yanert Glacier) and varies more on a daily basis depending on the melting rates at the glacier that day.

The suspended sediment data from 2009 shows the broadest range of values even at DEC. There may have been some intense melting events at both the Nenana and Yanert glaciers that summer, which released more sediment into the river system.

The second graph that only shows the means (averages) and standard deviations tells a similar story. The broad variability of the 2009 suspended sediment values at Riley Creek and Glitter Gulch are obvious. If you compare the 3 data points for DEC, the 2009 average is slightly higher and the standard deviation much greater than in 2008 or 2010. The conductivity value for the upstream Riley Creek site is well out of step with the rest of the conductivity values in this graph.

Air Temperature Comparisons, 2008-2009 and 2009-2010
As discussed in Sam's 2009 research, on average, the summer of 2009 was warmer than 2008 all along the river. This is indicated by the large number of positive values from late June to mid-August. These higher temperatures cause melt events on the Nenana and Yanert glaciers that accounted for the spikes in the suspended sediment loads, especially at be beginning of August.

On average, the summer of 2010 was about as warm as the summer as 2009. However, that does not mean that they were similar all through the summer. Notice that the beginning of summer 2010 was cooler than 2009 (negative values). By the end of July, the 2010 air temperatures exceed those of 2009 (positive values). Taken togehter these two periods cancel each other out mathematically. However, in terms of the environment, they are important. Because it was cooler during the first part of summer 2010, the glaciers did not warm up enough to release large amounts of suspended sediment like they did in 2009. By the time the 2010 temperatures became higher than the 2009 values, it was too late in the season to create the conditions needed for rapid melting.

Results

These are the results that Sam presented based on his questions and hypotheses.

Part One:

There was a significant difference from the non-glacier creek (Riley Creek - upstream) data and the glacier-fed river (Yanert River) in both dissolved ions and suspended sediment.

The amount of dissolved ions and suspended sediment in the Nenana River did vary when sampled at different locations along the Nenana River. The sites on the Nenana River (Upstream from Riley Creek on the Nenana, Riley Creek on the Nenana, and Downstream from Riley Creek on the Nenana) were more similar in their trends for both dissolved ions and suspended sediment as compared to the site at Denali Education Center.

Part Two:

The amount of dissolved and suspended sediment in the Nenana River did vary from year to year when sampled at the same site. When comparing data at the Denali Education Center (2008, 2009, 2010), the dissolved ion values were very similar in all years, but the suspended sediment varied more in 2009 than it did in 2010.

When comparing data at the Riley Creek Site (2009, 2010), the dissolved ion values were very similar in both years, but the suspended sediment differed between 2009 and 2010. Sam presented some final conclusions and next steps for his research.

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Conclusions

Part One:

My hypothesis that the amount of dissolved ions and suspended sediment will vary between a glacier fed river and a creek that is not glacier fed is correct. In previous years, my data showed lower suspended sediment at Denali Education Center and higher suspended sediment in the Nenana River near Riley Creek. I think that this is due to high levels of suspended sediment in the Yanert River which is fed mostly from glacial runoff and has an outflow between these sites. To confirm this I took samples directly from the Yanert River to test for dissolved and suspended levels. As expected I found high levels of suspended sediment which explains why samples in the Nenana downstream of the Yanert outflow also have increased suspended sediment load. I also sampled Riley Creek which is not glacial fed. It is mostly fed from snowmelt and seasonal rain. These samples were high in conductivity and low in suspended sediments. The outflow of Riley Creek did effect the amount of dissolved sediment in samples downstream of Riley Creek while suspended sediment in the downstream site from Riley Creek remained nearly the same.

My data supports the hypothesis that there is a significant difference in the amount of dissolved ions and suspended sediment in glacial-fed streams as compared to non-glacial fed streams.

Part Two:

My hypothesis that the amount of dissolved ions and suspended sediment in the Nenana River will vary year to year when sampled at the same location was correct. I found that the amount of dissolved and suspended sediment in the Nenana River did vary from year to year when sampled at the same sites. When comparing the data at the Denali Education Center (DEC) over a three year period, the dissolved sediment was very similar in all years with a little variation but the suspended sediment varied much more in 2009 then it did in 2008 or 2010. When comparing data from my Riley Creek (RC) site over the last two year period, 2009 and 2010, I found similar results. Dissolved sediment varied slightly, but there was a significant difference in suspended sediment between 2009 and 2010.

I think this is because of the higher temperatures in 2009 which caused an increased glacial melt and therefore increased suspended sediment.

Thinking Ahead

I did some of my thinking further ideas that I had last year:

I was able to continue my study of the Nenana River at the Denali Education Center (DEC) site for a third year, and the Riley Creek (RC) site for a second year, and compare my data.

I took water samples upstream on Riley Creek and Yanert Fork which flows from the Yanert Glacier. I determined the amount of sediment and the conductivity for these tributaries to the Nenana River. I also did additional sampling along the Nenana River near Riley Creek (upstream and downstream).

My ideas for future work for this project include:

I would like to continue my study at the Denali Education Center, Riley Creek, Yanert Fork, and compare my data.

After a heavy rain, I could take samples every hour of the day to see how sediment load changes throughout the day.

I could take samples every hour for 24 hours and look at variations throughout the day.

If I could I would like to sample where the Yanert Glacier comes into the Yanert Fork.