7.3: Problem set
- Page ID
- 38794
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- Use the curve number (CN) method to estimate the total runoff (mm) and the percent of annual precipitation partitioned to runoff (%) during the year 2013 for a field near Stillwater, OK, under two different scenarios:a.
a. Fallow – bare soil with poor hydrologic condition, hydrologic group C, and CN = 91.
b. Small grain – contour farmed with adequate crop residue, soil with poor hydrologic condition, hydrologic group C, and CN = 81.
An Excel spreadsheet with 2013 daily rainfall data from the Oklahoma Mesonet is available online [website] Work using rainfall in inches and convert the final result to mm.Perform daily runoff calculations, then compute the annual sum. The “IF” function in Excel may be helpful.This video tutorial explains the process step by step [website]
2. Use the WEPP cloud model (link) to estimate runoff and erosion for a watershed of your own choosing following the steps below. If you want further information on running WEPP cloud, consult this helpful playlist of tutorial videos [Website]
a. Use the map to zoom in to an area in the contiguous United States covering ~1 square mile
b. Click “Channel Delineation” in the list on the left side of the page.
c. Click the “Build Channels” button. Wait until the Status message reads “Displaying Channel Map...Success”.
d. Click “Outlet” on the left side of the page and click the button labeled “Use Cursor (Don’t Select a Confluence)”.
e. Click “Map” on the left side of the page and then click one of the blue stream channel pixels to define your desired watershed outlet. Do not pick a confluence, which is the place where two stream channels come together.
f. Click “Outlet” on the left side of the page again and from the Summary box record the actual outlet location longitude and latitude to three decimal places.
g. Click “Subcatchments Delineation” on the left side of the page.
h. Click the button labeled “Build Subcatchments”. Wait until the Status message reads “Fetching Summary...Success”. From the Summary box, record the total area of the selected watershed in acres.
i. Click “Landuse Options” on the left side of the page.j.Select the most recent land cover database from the dropdown menu, e.g. “nlcd/2021”. Runoff and water erosion| 141
k. Click the “Build Landuse” button and wait until the Status message reads “Building landuse...Success”. From the Summary box, record the two largest land cover types and their percent coverage.
l. Click “Soil Options” on the left side of the page, then click the “Build Soils” button, and wait until the Status message reads “Building soil...Success”. From the Summary box, record the Description of the two largest soil map units and their percent coverage.
m. Click “Climate Options” on the left side of the page, then under “Select Station”, click “Closest”. From the station summary, record the average annual precipitation in inches.
n. Scroll down to the “Climate Method” section and select “Vanilla” CLIGEN.
o. Scroll down to “Stochastic Climate Generation” and set the “Number of years to simulate” to 30.
p. Click “Build Climate” and wait until the Status message reads “Climate Build Successful”.
q. Click “WEPP” on the left side of the page, then click the “Run WEPP” button and wait until the Status message reads “Fetching Summary...Success”.
r. Under “Run Reports”, click on the “Watershed Loss Summary” and record the stream discharge(in/yr), the total hillslope soil loss (lb/ac/yr), and the sediment discharge (lb/ac/yr).
s. Report all the information you recorded above, along with one sentence explaining the similarity or difference between the estimated hillslope soil loss and the sediment discharge at the watershed outlet.