Site Description

Sycamore Creek is a meandering creek, so we had some minor difficulty locating a spot where the stream is straight enough to collect our data. Meanders in the stream have the potential to give misleading data. The reason for this is that the velocity has a high degree of variability near a meander. To compensate for the meandering stream difficulties, we chose to sample only in areas where the stream was relatively straight. In addition, it is very difficult to maneuver in point bars because the sediment is not compacted and is very silty.

The land cover of most of the sites was forested, with dense vegetation. Because of this, most of the sites were designated county parks. The surrounding land use was residential, with exceptions of one or two points being surrounded by commercial land use. Various species of birds, small animals, and fish were also observed.

Once a good site was found, we performed a brief survey of the conditions in the stream for safety reasons. In our case, we purchased a broom handle and paced the stream looking for areas in the river where we could get stuck or where the depth was over our heads.

Once that has been completed, we proceeded with the width measurement. We took a field tape measure, about 30 meters in total length, and measured the stream. We took the measurement from bank to bank. If we encountered a point bar, we moved slightly downstream to get a better measurement.

The second test we took was the depth measurement. We took multiple measurements because the depth varies depending on which part of the stream you are measuring. In addition, multiple depth measurements were needed to calculate an accurate average depth, which is a component of the discharge formula. We took about six or seven measurements on each of the test sites and then averaged them. We used the same measuring device as we used for the width measurements. All measurements were taken in centimeters, and later converted to meters.

There are three major factors that had an influence on our data, which in turn impacted our data analysis. The first is channelization. Humans have altered many parts of the stream bank. Although we avoided points where there was significant channelization, the effects of it are still evident.

Another factor that potentially influenced our data was the presence of knickpoints. The most evident knickpoint that was noticed was at Point J, where there were some mild rapids. This has the potential to increase the velocity above the expected results. To compensate, we decided to move further downstream.

The final factor affecting our data was the input of tributary streams. The increase in discharge, which conversely increases width, depth, and velocity, has the potential to give misleading data. Although tributaries are a natural component of a stream system, we decided to move either up or downstream to avoid collecting misleading data.

Discharge is defined as the product of width, depth, and velocity. As discharge increases, the stream enlarges to accommodate the increased amount of water. The stream adjusts itself, by adjusting width, depth, and velocity. As you progress downstream in a humid climate, discharge will usually increase due to the additional input from tributaries and other inlets of water.

According to the data collected at Sycamore Creek, all three discharge exponents are positive, which means that the velocity, width, and depth all increase progressively downstream. The depth had the highest rate of increase. There are several explanations why depth had a larger rate of increase. A large value for depth and a low value for width are common for banks formed from resistant and cohesive materials, such as silts and clays. This idea is consistent with the data from the Ingham County Soil Survey along Sycamore Creek. According to the survey, the area upstream is composed of Colwood-Brookston loam. Further downstream, the soil makeup changes to Cohoctah Silt Loam. Near the mouth of Sycamore Creek, where it discharges into the Red Cedar River, the soil makeup changes to Houghton Muck. In addition, the stream bank is not easily erodable due to dense vegetation. The dense root system provided by the diverse vegetation allows the soils to be more cohesive and less susceptible to erosion. That is the reason the exponential value for the depth is larger than that of the value for width. Since Sycamore Creek can not easily erode its banks, it will most likely responds to an increase in discharge by scouring the stream bed to pick up sediment.

Data Analysis

With the raw data we collected, we calculated Q, which is the mean discharge, from the formula below. Then we attempted to graph the data. In order to obtain a linear relationship with the data gathered and the mean discharge computed, we converted the numerical values to logarithmic values. We did this by taking the natural log of each value. Please see the following charts. Discharge was computed using this formula.

· Q=(w)(d)(v) where,

Q= discharge

w= width

v= average velocity

Once converted, the data was plotted on a linear scale. Once this is done, a correlation line was drawn that best fits the points. The graphs for the three variables we measured plotted against the mean discharge are shown below.

These graphs allow us to correlate each component of the discharge formula to discharge. Once the data has been plotted, we were able to extrapolate a line that best fits all of the data points. Once the line had been fit into the graph, we can determine its slope. The slope allows us to determine the discharge exponents with respect to each of the variables in the mean discharge equation. The formulas for each variable are listed as follows:

· Velocity

· Width

· Depth

The variables k, a, and c are constants and have no major influence on the slope. However, the variables m, b, and f are the numerical representations of the slope for its respected constituent. The slope can be obtained from the linear relationship formula:

y=mx+b

where the variable m is the slope. Using this formula we obtained the slope of the regression lines for all three variables. They are listed as follows:

· Width b= .34

· Velocity m= .14

· Depth f= .5

In theory, the discharge exponents (b, m, and f) must all add up to equal 1. The numerical coefficients to the discharge formulas (k, a, and c), must also equal one when added. This holds true because:

Q=(w)(v)(d), therefore…

In this case, our exponential data (b+m+f) for Sycamore Creek has the cumulative value of .98. The discrepancies have been previously explained. The following is a chart comparing our data to the research done at Brandywine Creek, Pennsylvania. Note the similarities of both streams in a similar climate.